AN OVERVIEW OF THE
PATHOLOGY OF LABOR
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7
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AN OVERVIEW OF THE PATHOLOGY OF LABOR
By Dr. Ratnakar P. Kini
Objectives:
The learner will be able to explain
-
What are the signs and symptoms of pregnancy?
-
How to diagnose pregnancy?
-
The normal fetal presentation
-
The mechanism of normal labor
-
Abnormal fetal presentations
-
Other factors affecting normal labor
-
How to conduct labor in these circumstances?
This article is an overview of the pathology of labor. A labor is said to be pathological when
normal delivery is not possible due to either maternal or fetal causes. This article includes (in the
following order)
Diagnosis of pregnancy
Normal labor
Fetal malpresentations
Multiple pregnancies
Maternal causes of pathology of labor
Cephalopelvic disproportion
Multiple choice questions
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1. Diagnosis of pregnancy
Diagnosis of pregnancy is not very difficult in most of the cases. But sometimes
especially during the early months it may be difficult. In these circumstances the signs and
symptoms that develop during the course of pregnancy may be helpful. Pregnancy is divided in
to three trimesters. Each trimester has its own signs and symptoms.
Signs and symptoms of first trimester:
Amenorrhea – Cessation of menstrual periods
Morning sickness – This develops around 4-6 weeks of pregnancy in which the expectant
mother develops nausea and vomiting
Increase in the size of the breast and formation of secondary areola
Bluish discoloration of the vagina- This is called Chadwick’s or Jacquemier’s sign and it
develops around 4-8 weeks of pregnancy
Hegar’s sign- Softening and compressibility of the isthmus of uterus is called Hegar’s
sign. It is elicited by introducing two fingers in to the vagina behind the cervix with the
fingers of the other hand pressing down in to the abdomen from above the pubic
symphysis. In pregnancy the fingers of the two hands will almost meet as if there is no
tissue in between and the cervix and the uterus will be felt as two separate masses. This
sign is usually positive by 6-8 weeks of pregnancy and eliciting it should be avoided after
12 weeks of pregnancy.
Signs and symptoms of second trimester:
Quickening – Around 16 weeks of pregnancy, the fetal movements can be perceived by
the mother. This is called quickening
Skin Changes – Stretch marks and linea nigra which is a linear pigmented area between
the umbilicus and the pubis are seen
Increase in the size of the uterus- After 12 weeks the uterus comes out of the pelvis and it
can felt growing progressively
Braxton Hicks contraction – These are painless intermittent contractions of the uterus (
See in the later sections)
Palpation of the fetal parts
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Auscultation – Fetal heart sounds can be heard from the 17-20th week of pregnancy
Perception of fetal movements- Internal ballottement in which two fingers are introduced
in to the vagina and gentle tap is given upwards. This is transmitted to the fetus which
goes upwards and falls back on the fingers again after sometime. In external ballottement,
the uterus is steadied with one hand applied to a side and with the other hand a gentle tap
is given. The fetal parts may be felt by the opposite hand.
Signs and symptoms of third trimester:
The fetal movements are easily felt
The fetal parts are easily palpable
The uterus fills the entire abdomen
Pregnancy tests:
The following investigations are done to diagnose pregnancy:
Laboratory tests:
Bio assay
Immuno assay
ƒ Heagglutination inhibition test
ƒ Flocculation inhibition test
ƒ Radio immuno assay
ƒ Sub unit radio immuno assay
Radio receptor assay
ELISA test
Ultarsonography:
This confirms pregnancy as fetus can be visualized depending on the duration of pregnancy.
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2. Fetus in normal pregnancy
Attitude:
The attitude of the fetus is the relation of the fetal parts to one another. Usually the fetus
assumes the attitude of universal flexion in which the spinal column is bent forward, the head is
flexed, the chin rests on the sternum, the arms are flexed and folded across the chest, the lower
extremity are flexed so that the thighs rest on the abdomen, the legs bent at the knees and resting
on the thighs with the feet crossed in an attitude of dorsiflexion.
Presentation:
Presentation means the portion of the fetus which is in relation to the lower pole of the
uterus and which is the first to engage when labor starts. Thus there are
Cephalic – In this the head is at the lower pole
Podalic or breech – In this the legs are at the lower pole
Transverse and oblique – Here neither the head nor the legs lie in the lower pole
Different presentations:
In cephalic presentation there can be different presenting parts
Vertex
Brow
Face
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Lie:
It is the relation of the longitudinal axis of the fetus with that of the uterus. It could be
Longitudinal – when both are parallel to each other
Oblique or transverse when they are at an angle to each other
Position:
It is the relation of the presenting part of the fetus with the maternal pelvis. A particular
bony land mark in the fetus is taken and its relation to the four different quadrants of the pelvis is
noted. The bony land mark is called the denominator. The four quadrants are
Right anterior
Right posterior
Left anterior
Left posterior
The different denominators are
In vertex – Occiput
In face – Chin or the mentum
In brow – Frontal prominence
In breech – Sacrum
In shoulder – Acromion
There are four different positions possible with each presenting part. Thus for example in vertex
presentation
the
possible
positions
are
(as
illustrated
on
the
following
page):
Right occipito anterior - ROA
Right occipito posterior - ROP
Left occipito anterior - LOA
Left occipito posterior - LOP
6
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Fetal head and diameters:
The passage of fetal head through the maternal pelvis is the most important factor in the
delivery of the fetus. Two factors are responsible for it
Fetal head diameter
Moulding of head
Fetal head diameters:
The different head diameters are
Sub- occipito bregmatic – This is 9.5 cm and it is the engaging diameter in vertex
presentation
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Mento- vertical – This is 13.5 cm and it is the engaging diameter in brow
presentation and it is the largest diameter
Occipito frontal _ This is 11.5 cm and it is the engaging diameter if the head is
deflexed
Sub mento bregmatic – This is 9.5 cm and it is the engaging diameter in face
presentation
Biparietal diameter – This is 9.5 cm. It is used during ultra sonography to assess
the maturity of the fetus
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Different engaging diameters:
A.Suboccipito bregmatic
B. Occipito frontal
C.Mento vertical
D. Sub occipito frontal
Moulding:
Because the fetal skull bones are separated by membranes they can mould to become compact
during difficult labors.
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Different fontanelles and bones:
3. Normal labor
Labor is a process by which the products of conception, when they have reached full term
or nearing it, are expelled by the mother. When a full term fetus presenting by the vertex is
expelled by natural efforts, unaided, within a period of twenty four hours, it is called normal
labor. If it sets in before 37 weeks of gestation, it is called pre term or premature labor. If the
product of conception is expelled before 28 weeks of gestation, it is called abortion or
miscarriage.
Changes in the uterine architecture during labor:
Around the time of labor, the cervix undergoes a process called ripening because of
which its flexibility increases. Then the cervix thins out and is taken in to the body of the uterus
after which the differentiation of the body and cervix becomes difficult. This is called effacement
of the cervix. Once the labor starts the uterus gets differentiated in to two parts- the upper and the
lower uterine segment.
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Effacement and dilatation of cervix:
Upper uterine segment:
It is upper half of the uterus during labor
It is the active part during labor
It is thicker than the lower segment and its thickness increases as labor
advances
During labor, it contracts and retracts.
Lower uterine segment:
It is the lower half of the uterus during labor
It is the passive part during labor
It is thinner and gets thinner as labor advances
During labor, it gets stretched out to receive the descending fetus
The junction of the upper and the lower uterine segment is characterized by a ring of
circular muscle fibers which form the “physiologic retraction ring”.
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Formation of lower uterine segment:
Uterine contractions
There are two types of uterine contractions.
Braxton Hick’s contractions
Labor contractions
Braxton Hick’s contractions:
This occurs during ante natal period. The characteristic features are
Painless
Intermittent contractions
Irregular in time and force
Not coordinated
No diminishing gradient
Does not result in expulsion of the fetus
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Labor contractions:
This occurs at the time of labor. The characteristic features are
Painful
Contraction is accompanied by retraction. Retraction is a process in which the
uterine muscle after contraction does not relax to get back to original length, but
remain at a shorter length, but the tension the same as before contraction. This
helps to prevent the fetus from slipping back
The contractions are more dominant in the fundus of the uterus
There is a diminishing gradient of activity from the fundus through the body to
the lower uterine segment.
Stages of Labor:
Labor is divided in to three classic stages
First stage or the stage of dilatation
Second stage or the stage of expulsion
Third stage or the stage of placental delivery
Stage of dilatation / First stage:
First stage extends from the onset of true labor pains to the complete dilatation of the
cervix. In primigravida, it lasts for about 12 hours and in multigravida, it lasts for about 5-6
hours. The following 5 phenomena occur during the first stage.
Uterine contractions
This true labor pains occurs in episodes lasting for 45 seconds to 1 minute.
In the beginning each episode occurs at intervals of 30 minutes and in the
end they occur every few minutes. The labor pains are felt in the sacral
region and over the lower abdomen and sometimes down the legs.
Muco sanguineous discharge or “show’’
A small amount of cervical mucus mixed with blood is passed. It is an
evidence for cervical dilatation and effacement.
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Dilatation of the cervix
This is due to the contracting and retracting upper segment pulling the
cervix up.
Fixation of the head
The head becomes fixed at this stage if not fixed already in the last two or
three weeks of pregnancy. If the head is not fixed by now, it indicated there
are abnormalities.
Rupture of membranes
This occurs after the complete dilatation of the cervix.
Stage of expulsion / Second stage:
Second stage extends from the rupture of membranes to the expulsion of the fetus. In
primigravida, it lasts for 1-2 hours and in multigravida, it lasts for half to one hour.
The uterine contractions become stronger with a ‘bearing down’ character. The accessory
muscles of labor like diaphragm and the abdominal muscles begin to act and the fetus is pushed
down the dilated cervical canal. The vulva widens when the presenting part is fixed under the
symphysis pubis and this is called ‘crowning of head’. After the head is delivered, the patient
puts in one last effort and the rest of the fetus is born.
Stage of placental delivery / Third stage:
Third stage extends from the complete expulsion of the fetus to the extension of the
placenta and membranes and firm contraction and retraction of the uterus subsequently. This
stage extends for a period of about 15 minutes. The following 5 phenomena occur during the first
stage.
Uterine contraction
After the delivery of the fetus, the uterus becomes firm, round and hard
and lies at the level of the umbilicus. Rhythmic contractions may be felt.
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Separation of Placenta
After the fetus is delivered the placenta shrinks and is forced down by the
uterine contractions. There are two methods of placental separation.
Duncan’s method
In this method the placenta detaches by folding on to itself with its
longitudinal axis lying along the longitudinal axis of the uterus. The
margin of the placenta comes out through the cervix.
Schultze’s method
In this method a blood clot is formed behind the placenta and the
placenta is thus separated from the uterus. The central part of the placenta
thus comes out first with the attached cord like an inverted umbrella.
Methods of placental separation:
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Expulsion of the placenta
After the placenta is detached from the uterus by any one of the two methods
mentioned, it is expelled out.
Control of hemorrhage
The bleeding following hemorrhage is controlled by the following factors.
-
The contraction and retraction of the uterus constricts the blood vessels
-
The self occlusion of the blood vessels by vasospasm
-
Formation of blood clots which occlude the lumen
Permanent contraction and retraction of the uterus
The uterus thus comes to lie at the level of the umbilicus
Some obstetricians call the stage of control of bleeding as the fourth stage of labor.
Stages of labor:
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Friedman’s partography:
Friedman’s partography is the recording of the cervical dilatation and the fetal descent in
a graph. This graph provides a reliable guide to the course of labor and with its help
dysfunctional labor can be made out. The structures of the graph are (as illustrated on the
following page)
Duration of the labor in hours in the horizontal scale
Cervical dilatation in centimeter in the left vertical scale marked in crosses
Descent of fetal head or the stations in the right vertical scale marked in circles
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19
Measurement of fetal stations:
20
Components of the graph:
The onset of labor is defined as the onset of regular uterine contractions as perceived by
the patient. Points are entered as they are obtained during each examination. There are two
components during the first stage – latent and active to be followed by second stage.
Active phase of the first stage of labor:
This is divided in to three phases
Acceleration phase with cervical dilatation of 2.5 -4 cm
Phase of maximum slope with cervical dilatation of 4-9 cm
Deceleration phase with cervical dilatation of 9-10 cm
The normal curve is ‘S’ or sigmoid shaped.
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Interpretation of the graph:
Latent phase lasts for a maximum of 20 hours in primi and 14 hours in
multigravidae. If it exceeds it is prolongation of labor
The slope of the curve is 1.2 cm in primi and 1.5 in multigravidae. If it exceeds it
si called prolonged dilatation pattern
The deceleration phase in primi should not exceed 3 hours in primi and 1 hour in
multi gravidae If it exceeds it is called prolonged deceleration phase.
Thus by plotting on the graph abnormalities or the pathological labor can be made out and proper
intervention at the right time can be done.
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Mechanism of Normal Labor:
The mechanism of labor means the steps by which the fetus adjusts and passes through
the birth canal with least difficulty.
Three factors interact with each other for effective conduction of labor. They are
Pelvis and soft parts
Fetus
Uterine forces
Steps of normal labor:
There are seven basic steps of delivery of head in normal labor which can be easily
remembered with the help of the mnemonic “EDFIERE”
E - Engagement
D - Descent
F - Flexion
I - Internal rotation
E - Extension and birth of fetal head
R - Restitution
E - External rotation
Engagement:
This is the first step in the process of labor. It denotes that the greatest diameter of the
head has passed through the greatest diameter of brim of the pelvis. The antero posterior
diameter of the inlet of the pelvis is the narrowest one and hence the head never enters in that
plane. The head gets engaged in the larger oblique or the transverse plane – usually the
transverse plane.
The antero posterior suture or the sagital suture thus lie transverse in the pelvic cavity. But it is
never in the midline- it is either found near the pubic bone when it is called posterior asynclitism
or Litzman’s obliquity or near the sacral prominence when it is called anterior asynclitism or
Naegle’s obliquity. Naegle’s obliquity is seen in most of the cases.
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In primi gravida or the first time mothers the process of engagement occurs usually
during the last few weeks of pregnancy. In multi gravida or mothers who have had delivered
before, the process of engagement occurs only after the labor pain starts.
Descent:
This is the second step in the process of labor. Descent occurs only if the head size of the fetus is
proportionate to the inner diameter of the pelvis. The process of descent is brought about by
Amniotic fluid pressure
Uterine contractions
In primi gravida, descent may occur even before labor pains have started. But in multi
gravida, descent usually begins with engagement.
The descent continues throughout the process of labor. As mentioned already, Naegle’s
obliquity is common. So the anterior parietal bone keeps descending and the posterior parietal
bone remains more or less stationary.
Flexion:
This is the third step in the process of labor. As the head keeps descending, it meets
resistance from either of the following two parts.
Pelvic side wall
Pelvic floor
Because of the resistance, the head of the fetus flexes and the chin gets closer to the rib cage.
Because of this, the head gets engaged with the narrowest diameter – the sub occipito bregmatic
diameter which is 9.5 cm instead of the previously engaged occipito frontal diameter which is
11.25 cm.
Internal rotation:
This is the fourth and the most important step in the process of labor. During descent when
the presenting part reaches the ischial spines, internal rotation occurs. The ultimate aim of the
step is to bring the occiput of the fetus towards the pubic symphysis.
For the internal rotation to be effective
Flexion should be complete
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Uterine contractions should not be weak
Pelvic floor should not be weak or lacerated
If at the time of engagement, the occiput is at the transverse plane, then the head has to rotate
90 degrees to bring the occiput towards the pubic bone. If it is at the anterior oblique plane, it has
to rotate 45 degrees.
If the occiput is on the left, it has to rotate to the right to get near the pubic bone. If it is on
the right, it has to rotate to the left for the same purpose. Some times rotation happens in the
opposite direction and the labor gets delayed requiring further assistance.
At the end of internal rotation, the presenting part enters the longest diameter of the outlet of
the pelvis – which is the antero posterior diameter.
Extension & birth of fetal head:
This is the fifth step in the process of labor and is very important for the delivery of head.
At the end of the internal rotation, the occiput of the fetus lies near the pubic bone and the
chin remains flexed near the pelvic bone of the mother.
The uterine contractions from above and the pelvic floor resistance from below cause
extension of the head. As a result of it, the occiput gets hitched at the pubic bone. The face does
not have any such resistance and it starts sweeping over the perineum. Thus frontal parts, orbital
ridges, nose, mouth and chin are delivered with the occiput acting as a fulcrum.
During this process, the pelvic floor gets stretched and it has to be supported well. If it is not
done properly, laceration of the pelvic floor may occur.
Restitution:
This is the sixth step of the process of labor. During internal rotation, occiput rotaes towards
pubic bone and there is twisting of the neck. Once the head is delivered, the chin moves in the
same direction and untwists the twisted neck.
External rotation:
This is the last step of the process of labor. In this step, there is internal rotation of the
shoulder with simultaneous external rotation of the head. Because of this step, the anterior
shoulder gets hitched at the pubic bone like how it occurred for the occiput. Once this happens,
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the posterior shoulder sweeps over the perineum and is delivered by the process of lateral flexion
of the spine. The anterior shoulder slips forward and gets delivered. The rest of the body of the
fetus slips down and gets delivered.
10 -15 minutes later, the placenta and the membranes get separated and delivered. Once they
are delivered, the uterus contracts and retracts and bleeding stops.
Mechanism of labor
26
4. Fetal malpresentations
Abnormal presentations of the fetus which interferes with the normal labor are called
malpresentations. Caesarian sections are done nowadays in most of the cases which has brought
down both the maternal and infant mortality rates. The following discussion is about all the
possible treatment modalities during pathology of labor.
A.Occipitoposterior
Occipito posterior is a fetal malpresentation. It is the most common fetal malpresentation
comprising nearly 25-30% of all vertex presentation. In this malpresentation, the occiput of the
fetus lies in the posterior plane of the pelvis either on the right or the on the left side.
Causes:
The presentation of the fetus is decided by the diameter of the pelvic inlet. Usually the head
engages in the longest inlet diameter and in most of the cases it is the transverse diameter. This
is in the case of gynecoid pelvis.
But in android and anthropoid pelvis the oblique diameter is more than the transverse
diameter and so the head engages in the oblique plane either in the anterior quadrant or the
posterior quadrant. If it engages in the posterior plane, it results in the occipito posterior position.
Clinical findings:
The fetal parts are more easily felt than usual
The fetal parts are felt nearer the midline
The head is slightly deflexed
The maximum intensity of the heart beat is in the flanks
The posterior fontanelle is nearer the sacral hollow
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Course of labor:
The steps of labor are the same. Prolongation of labor is the biggest problem of occipito posterior
positions. The few differences are
Since the head is a little deflexed, the engaging diameter is the 11.5 cm occipito
frontal instead of the 9.5 cm sub occipito bregmatic diameter. This leads to
difficult and prolonged second stage of labor.
In 10% of the cases the head may not rotate at all or rotate only partially (resulting
in deep transverse arrest) or rotate in the opposite direction in to the sacral hollow
(malrotation). In the first two instances the delivery has to be assisted. In the last
case delivery occurs with the face of the fetus facing the pubis of the mother
(normally only the occiput faces the maternal pubis). This face to pubis delivery is
always associated with laceration of the perineum.
Nature of assistance:
It depends on
The level of arrest
The nature of pelvis
Arrest at the level of the pelvic brim:
Caesarian section is indicated
Forceps application is not recommended
Arrest in the mid cavity:
This is the commonest type. This usually occurs at the level of the ischial spines. All the
factors should be examined and assessed under anesthesia. There are three options available to
deliver in this type of arrest.
Manual rotation and forceps application and delivering
Rotation with forceps and delivering
Caesarian section
Manual rotation and forceps application:
This method is preferred
When the pelvis is adequate in diameter
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When the arrest is due to deflexed head
Under anesthesia, with one hand in the vagina, the fetal head is grasped and the head is
pushed upwards and brought in to the position of flexion. This makes rotation easier. Now with
the other hand the shoulder is located on the abdominal wall and with both hands the fetus is
manually rotated and the occiput is brought to the front. Now the forceps is applied and the
delivery is completed.
Manual rotation is difficult
If the head is impacted
Liquor is in adequate
The pelvis is android in type
Rotation with forceps:
This is preferred when manual rotation is not possible. This is done under anesthesia.
Kielland forceps are advantageous than the axis traction forceps. If not properly done it can
cause intra cranial hemorrhages in fetus.
Caesarian section:
Caesarian section is indicated
When the pelvic shape does not allow rotation at all as in android and platypelloid
pelvis
Elderly primigravida
B. Brow Presentation
When the portion of the fetal head between the anterior fontanelle and the glabella forms
the presenting part, it is called the brow presentation. In this presentation the head lies midway
between complete flexion and complete extension. This presentation is an unstable presentation
meaning it either gets converted in to a vertex presentation or the face presentation. Hence it is a
rare presentation.
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Causes:
The causes of brow presentation are
Contraction of pelvis
Big baby
Obliquity of uterus
Tumors in the neck of the child
Cord around the neck
Spasm of the sternomastoid muscle
When the fetal head is conical
Multiparity
Clinical finding:
The clinical findings are
The cephalic prominence is felt at a higher level and on the same side of the back
The chin lies at a lower level
On vaginal examination, the root of the nose and the orbital ridges can be made
out
Course of labor:
As said earlier, the brow presentation is rare and unstable as it gets converted in to a face
or vertex presentation. If the brow presentation persists, labor does not progress. This is because
the presenting diameter in brow presentation is the longest. The presenting diameter is mento
vertical which is 13.5 cm and the pelvis is not adequate to allow progress of labor. If the pelvis is
larger and the head of the baby is very small due to prematurity, labor can progress. The head is
delivered face to pubis and the rest of the body is delivered as in vertex presentation.
Delivery in brow presentation always results in injuries to both mother and child.
In mother
Laceration of the perineum
Shock
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In the child
Intra cranial injuries
Asphyxia
Management:
In brow presentation, time should be allowed for the fetus to get in to either face or vertex
presentation which normally occurs and spontaneous delivery is possible in both these cases. If
the fetus is large or the pelvis is inadequate and if brow presentation persists, then caesarian
section is done to deliver the baby.
C. Face Presentation
When part of the fetal cephalic pole between the chin and the frontal eminence forms the
presenting part, it is called face presentation. It is due to complete extension of the fetal head.
The engaging diameter is sub mento bregmatic which is 9.5 cm.
Causes:
The causes of face presentation are the same as that of brow presentation.
Contraction of pelvis
Big baby
Obliquity of uterus
Tumors in the neck of the child
Cord around the neck
Spasm of the sternomastoid muscle
When the fetal head is conical
Multiparity
Positions possible:
The chin is the denominator and the positions possible are
Left mento anterior – this is the commonest
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Right mento anterior
Left mento posterior
Right mento posterior
Clinical findings:
The clinical findings are
The cephalic prominence is felt on the same side as the back
By vaginal examination, the face, chin, mouth and nose are easily palpated.
Sometimes face presentation may be wrongly diagnosed as breech as the mouth
felt is mistaken for anus. The points to differentiate are,
™
The palpating finger may be meconium stained and the grip of the
sphincter can be felt in breech but not in face presentation
™
In face presentation the mouth does not lie at the level of the
ischial spines whereas in breech presentation, the anus lies at the
level of the ischial spines.
Course of Labor:
The mechanism is the same as that normal labor in vertex presentation expect that the
role of occiput in normal labor is taken by chin in face presentation. The steps of labor are
Descent with increased extension
Internal rotation of chin
Flexion
Restitution
External rotation
If the chin is anterior, there is 45 degrees internal rotation to bring the chin to the pubis. If
it is posterior, there is 135 degrees internal rotation to bring the chin to the pubis.
Management:
The engaging diameter is 9.5 cm which is the same as the normal vertex presentation. So a
normal labor is always possible. Difficulty of labor occurs when the chin rotates in the opposite
32
direction and results in mento posterior position in which case normal labor is virtually
impossible. In these cases caesarian section is usually done.
D. Breech Presentation
When the cephalic part of the fetus occupies the upper pole or the fundus of the uterus
and the podalic pole becomes the presenting part, it is called the breech presentation. The bisiliac
diameter is the engaging diameter. There are two main types of breech presentation
Complete
Incomplete
A. Complete
B& C. Incomplete
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Complete breech presentation:
In this presentation, the fetus maintains the attitude of universal flexion with the thighs
flexed at the hips and legs at the knees.
Incomplete breech presentation:
In this presentation, there are varying degrees of extension of the podalic pole. There are
three types of incomplete breech presentation.
Frank breech
Knee presentation
Footling
Frank breech:
This is also called extended breech. In this presentation, the thighs are flexed, but the legs
are extended so that the lower limbs lie along the ventral surface of the fetus.
34
Knee presentation:
In this presentation, the thigh is extended and the leg is flexed at the knee.
Footling presentation:
In this presentation, both the thigh and the legs are extended.
Causes:
Anything that interferes with the normal shape of the fetal ovoid or change the shape of the
uterine ovoid may result in breech presentation. Some of the causes are
Obliquity of the uterus
Multi parity
Fibroids
Placenta previa
Ovarian tumors
Contracted pelvis
Septate uterus – It is an important cause in recurrent breech presentation.
Hydramnios
Multiple pregnancy
Fetal anomalies like hydrocephalus
35
Positions possible:
The sacrum is the denominator and the positions possible are
Left sacro anterior – the commonest
Right sacro anterior
Right sacro posterior
Left sacro posterior
Clinical findings:
The clinical findings in breech presentation are
The cephalic pole lies at the fundus and the podalic pole at the lower level.
The fetal heart sounds are heard above the level of the umbilicus.
Vaginal examination reveals ischial tuberosties on both side and anus in the
middle.
In complete breech, the feet are felt along the sides. In extended breech, the feet
are not felt. In footling presentation only the feet are felt.
Course of labor:
The delivery in breech presentation occurs in three stages. They are
Delivery of the breech
Delivery of the shoulders
Delivery of the head
Delivery of breech:
There are three stages of delivery of breech. They are
Descent with compaction
Internal rotation
Lateroflexion
The breech enters the pelvis with the bisiliac diameter. All the body parts get a little more
flexed which is called compaction and then the descent occurs which brings the anterior buttock
to the floor of the pelvis.
36
Then internal rotation occurs which brings the anterior buttock to the pubis where it gets hitched
up. This is followed by lateroflexion which makes the posterior buttock to sweep through the
perineum and get delivered. This is followed by the delivery of the anterior buttock. Once both
the buttocks are delivered, the body up to the shoulders slips down.
Delivery of the shoulders:
The shoulders are delivered in a similar way with internal rotation making the anterior
shoulder hitching against the pubis. The posterior shoulder sweeps through the perineum and is
delivered followed by delivery of the anterior shoulder.
Delivery of the head:
The delivery of the head is similar to that of the shoulders. Here the occiput gets hitched
against the pubis and face is delivered to be followed by the delivery of the occiput.
Complicated breech:
A few conditions are associated with increased risk to the fetus and if they are present,
the presentation is called complicated breech presentation. The factors are
Prematurity
Maternal toxemia
Ante partum hemorrhage
Fetal abnormalities
Contracted pelvis
Maternal hypertension
Extended legs, arms
Cord prolapse
Difficulty in delivering the head
Primi gravida
Low Birth Weight baby
Big baby
Complete breech
37
In these cases the fetus is affected by any of the following complications.
Intra cranial injuries
Fracture of long bones like humerus and femur
Birth asphyxia
Brachial plexus injury
Management:
During ante natal Period:
Breech presentation is common up to 34 weeks of pregnancy. If it persists beyond that,
then a complete evaluation to find out the cause is done. Then efforts are taken to covert the
breech in to vertex presentation by external cephalic version. Breech delivery is associated with a
greater fetal mortality than vertex delivery after external cephalic version.
In external version, with gentle movements are done with the fetus held from outside the
abdomen of the mother and is converted in to vertex presentation. In the following conditions the
external version is contra indicated.
Multiple pregnancy
Ante partum hemorrhage
Ruptured membranes
38
Decreased liquor
Contracted pelvis
Congenital anomalies of the uterus
Delivery:
If external cephalic version is successful, then the fetus is delivered vaginally. If external
version is not possible the either vaginal delivery or caesarian section is done depending on the
situation.
Caesarian section:
If external version is not successful, caesarian section is done, if there is
Feto pelvic disproportion
Fetus weighs more than 3.5 kg
Primi gravida, elderly primi
If uterine inertia persists for more than 12 hours after rupture of membranes
Pre eclampsia
Cord prolapse
Bad obstetric history
Hyperextension of the head
Intra uterine growth retardation
Diabetes mellitus
Previous difficult labor
Uterine anomalies
Footling presentation
Contracted pelvis
There has been a considerable increase in the incidence of caesarian sections in breech
presentations and it has improved the fetal prognosis.
Vaginal delivery in breech presentation:
There are three options available to deliver the baby with breech presentation.
Spontaneous breech delivery
39
Assisted breech delivery
Routine breech extraction
There is not much difference between spontaneous breech delivery and assisted breech
delivery, as all deliveries need some assistance in delivering the head and the shoulder. Routine
breech extraction is usually not recommended.
Assisted Breech Delivery:
The initial preparation includes
Clearing the bowels at the onset of pains
Bed rest to prevent premature rupture of membranes and cord prolapse which is
more common in the flexed breech and footling presentation than the extended
one
Monitoring fetal heart rate
Sedation with pethidine after the onset of labor pains
In the absence of prolapse of cord the labor is allowed to continue. When the baby’s anus
is visible at the outlet, pudendal block anesthesia is given and medio lateral episiotomy is done.
This episiotomy helps in delivering the after coming head.
With increasing uterine contractions, the breech emerges out of the vulval outlet. In
flexed breech, a foot may be caught in the vagina. These can be released by hooking it out with
the finger. With further contractions, the baby is born as far as umbilicus. Now the body of the
baby is steadied and it is covered with a sterile towel to prevent premature respiratory efforts due
to the cutaneous stimulus. Gentle fundal pressure is given to facilitate delivery of arms. Normally
the arms are flexed and are easy to deliver. If it is not flexed, the delivery is prolonged and
Lovset’s maneuver is done to deliver the arms.
Lovset’s maneuver:
Gentle traction of the feet is done and the baby’s back is brought to the right or
left. This brings the axillary fold in to view below the symphysis pubis. A finger is
passed along the arm down to the elbow and is flexed. The arm drops down. Now the
other shoulder is brought under the pubic symphysis and the same procedure is repeated
and the other arm is delivered.
40
Once the two arms are delivered, only the head remains to be delivered. In most of the
cases it is delivered spontaneously aided by gravity. Sometimes assistance may be needed in the
form of Marshall Burns technique to deliver the head.
Marshall Burns technique:
Supra pubic pressure is given to promote flexion and descent of the head
Traction done holding the feet
The fetus is swung in an arc over the mother’s abdomen
This delivers the head.
Mauriceau Smellie Viet Technique:
This technique is used if there is difficulty in delivering the head after it has entered the
pelvic cavity.
The fetus is supported with the left forearm with the index or the middle finger in
the mouth of the baby
The index and the middle finger of the right hand are slipped over the clavicles
from behind
Traction is now given till the nape of the neck is seen
The head is now delivered with the Marshall Burns technique
Complications of the breech presentations:
Breech deliveries are associated with a lot of complications which are responsible for the
increased morbidity and mortality. Some of the complications are
Premature dilatation of membranes and incomplete dilatation of the cervix
Prolapse of the cord
Extended arms
Nuchal position of the arms
Difficulty in delivering the after coming head
Fetal impaction
Uterine inertia
41
Complication of breech deliveries in the fetus:
The following complications can occur in the fetus with breech presentation due to the
process of labor.
Fracture of long bones
Fracture dislocation of cervical vertebra
Intracranial hemorrhage
Injury to soft parts
Injury to nerve roots
E. Transverse or Oblique Lie
Transverse lie is a position in which the long axis of the fetus is approximately
perpendicular to that of the mother. A true transverse lie rarely occurs as in almost all instances it
either gets converted in to an oblique lie because the heavier cephalic pole slips down to one of
the iliac fossa.
An oblique lie is a position in which the long axis of the fetus lies at an acute angle to that
of the mother. It is an unstable lie as during labor it gets converted in to either vertex or breech
presentation.
Causes:
The causes of transverse lie anything which causes any other malpresentation. They
include
Contracted pelvis
Placenta previa
Tumors complicating pregnancy
Multiparty
Hydramnios
Uterine anomalies
42
Positions possible:
Two anatomical parts are used as denominators in oblique lie presentations- the dorsum
and the acromion.
The positions described with dorsum as denominator are
Left dorso anterior
Left dorso posterior
Right dorso anterior
Right dorso posterior
The positions described with acromion as the denominator are
Left acromio anterior
Left acromio posterior
Right acromio anterior
Right acromio posterior
Clinical findings:
Transverse and oblique lie presentations don’t pose any difficulty in diagnosing. The
diagnostic features are
Transversely stretched uterus
Fundus at a lower level than it normally should be for that gestational period
Head in one of the iliac fossae
Fetal heart sound heard at the level of the umbilicus
During labor a vaginal examination will show the hand, elbow or the shoulder
Course of the labor:
In oblique and transverse lie spontaneous delivery is virtually impossible. Sometimes
spontaneous version occurs due to which the presentation is converted into either vertex or
breech presentation. There are some extremely rare forms of deliveries which occur in these
presentations like
Spontaneous evolution
Birth corpore conduplicate
43
In these the fetus is folded up and delivered. These are possible only in premature babies
and macerated babies.
As the labor advances there is formation of upper and lower uterine segments as usual.
But as delivery is impossible, a pathological retraction ring called the Bandl’s ring is formed at
the junction of the upper and lower uterine segments which may rise even up to the level of the
umbilicus depending on the severity. A stage is reached when no further stretching of the uterus
is possible and this results in rupture of the uterus. Immediately after the rupture, the woman
feels a little relieved. But soon she goes in to shock as the placenta and the fetus slip in to her
abdomen.
Management:
Antenatal period:
If oblique lie is diagnosed during the later weeks of pregnancy, external version is done
to convert it in to a vertex presentation unless there are any contra indications.
During labor:
During early labor, if membranes are intact, external version is done. If it is not
successful, caesarian section is done
In primi gravida it is better to go for caesarian section
In multi gravida, if cervix is adequately dilated, internal podalic version and
breech extraction is done
If there is cord prolapse or hand prolapse, caesarian section is done if cervix is not
fully dilated. Classical caesarian section is a better option than the lower
segmental caesarian section in these circumstances as it is associated with a better
prognosis. If cervix is fully dilated, delivery is conducted in two stages – internal
version and later extraction. It is associated with high fetal mortality and so it is
usually done when the fetus is dead
Delayed Cases:
In delayed cases the fetus is usually dead. So in these cases the patient is
anaesthetized and the dead fetus is delivered after decapitation
44
If the uterus is on the verge of rupturing caesarian section is done
If rupture of uterus has occurred, laparotomy and hysterectomy is done
F. Cord Prolapse and Cord Presentation
Prolapse of the cord is a condition in which the umbilical cord lies in front of the
presenting part after the rupture of the membrane.
Cord presentation is a condition in which the umbilical cord lies in front of the presenting part
before the rupture of the membrane.
Cord Prolapse
Cord presentation
Causes:
The causes of cord prolapse include
Conditions which prevent the proper fitting of the presenting part to the pelvic
brim
•
Contracted pelvis
•
Malpresentations
45
•
Placenta previa
•
Tumors in the lower segment
Polyhydramnios
Artificial rupture of membranes
Accidental rupture of membranes during vaginal examination
Unduly long umbilical cord
Battledore placenta
Clinical findings:
In cord presentation the pulsations of the cord may be felt through the intact membranes.
Sometimes it may not be felt. This happens during uterine contractions. The pulsations can be
again felt after the contractions ceases. The other instance when the cord pulsation may not be
felt in cord presentation is when the fetal circulation is interfered as in case of cord compression.
In this case auscultation of the fetal heart sounds will indicate fetal distress where the heart rate
is either above 160 per minute or below 120 per minute.
In cord prolapse, a loop of the cord may be found lying outside the vagina.
Course of the labor:
The course of the labor is not influenced by the cord but by the presentation, uterine
contraction and the adequacy of the pelvis. The only problem due to the cord prolapse is that it
may get compressed by the presenting part leading to fetal distress.
Management:
The management depends on two factors.
The factors responsible for the cord prolapse and presentation
Whether the fetus is alive or dead
Cord Presentation:
If the cord presentation is due to contracted pelvis, then the management is as per the
guidelines for managing labor in contracted pelvis. In all the other cases, the only aim is to
46
prevent rupture of membranes and subsequent cord prolapse. When this is being done efforts are
done to correct the presentation. One such effort is the postural method.
Postural method:
The patient is made to adopt knee- chest, knee – elbow or the Trendlenburg’s position. In
these positions, the fundus lies at a lower level and the umbilical cord slips back in to the uterus
due to gravity.
After the umbilical cord has slipped down in to the uterus, the woman is made to lie on her back
and the presenting part is pressed down in to the brim of the pelvis and a tight abdominal binder
is applied. During the process the fetal heart is monitored. If any irregularity is found, there are
chances that the umbilical cord has slipped down again.
Cord Prolapse:
Cord prolapse is always a problem for the fetus. More the interval between the prolapse and the
delivery more is the danger for the fetus. So if an early diagnosis and a prompt management is of
utmost importance in case of cord prolapse.
Once cord prolapse is diagnosed the management is done as per the following guidelines
If cord pulsation is felt and the cervix is less than three fifth dilated immediate
caesarian section is done. Till the caesarian section is done efforts like postural
methods and manually pushing the cord back through vagina
In oblique lies internal podalic version and immediate extraction is done
If the vertex is in the mid cavity, delivery is completed with the help of forceps
In multi gravida, using a Willet’s traction forceps the fetal head is pulled down to
allow engagement. This should be done only after pushing the cord above the
presenting part
If no cord pulsation is felt and the fetus is dead, no active measure is needed
47
G. Compound presentation
In compound presentation, more than one fetal part presents at the pelvic brim at the
onset of labor.
Causes:
Any factor that prevents complete filling and occlusion of the pelvic inlet by the presenting part,
results in compound presentation.
Multiparity with lax abdominal wall
Contracted pelvis
Small fetus
Types:
There are many possible combinations of compound presentation. Some of the possible types are
Head and hand - common
Head and foot
Hand and foot
Head, hand and foot
Clinical features:
Vaginal examination is the only way by which it can be diagnosed. Diagnosis by
abdominal palpation as in other presentations is virtually impossible. Vaginal examination shows
more than one fetal part. Sometimes cord prolapse may be seen.
Course of labor:
The prolapsed part hardly interferes with labor and labor proceeds normally.
Management:
If the arm is prolapsed completely, it has to be moved back above the vertex
under anesthesia after which the vertex is pushed down by fundal pressure or
pulled down by Willet’s forceps and made to engage in the pelvic brim
48
In primi gravida caesarian section is done
If fetal heart sounds are inaudible, the fetus is dead and so it is delivered after
perforating its head
In head and foot presentation, if the head is not engaged, the foot is pulled down
and the fetus is extracted by breech. If the head is engaged, the labor is allowed to
progress keeping an eye on the status of the fetus and the mother. If fetal distress
occurs, the delivery is expedited with the help of forceps. If the fetus is dead,
craniotomy and subsequent delivery is done
If there is an associated cord prolapse, the treatment should be in lines of
treatment of cord prolapse irrespective of the type of compound presentation
5. Multiple Pregnancy
Multiple pregnancy means development of more than one fetus in the uterus
simultaneously. It could be
Triplets or three fetuses
Quadruplets or four fetuses
Quintuplets or five fetuses
Sextuplets or six fetuses
Causes:
Hereditary predisposition as autosomal dominant trait but mainly transmitted
through females
Intake of ovulation inducing drugs like clomiphene
Types:
Twin pregnancies are the most common and well studied types of multiple
pregnancies.There are two types, Monozygous and dizygous twins.
49
Monozygous Twins:
Monozygous twins develop from one fertilized egg that splits within the first 15-16 days of
development. The genetic make of these twins are identical but they look different in some cases.
They are also called identical twins. One interesting features of monozygous twins is that the rate
of monozygous twins is relatively constant an all races.
Monozygous twins may be having varying combinations of placenta and amnion depending on
the timing of the splitting of ovum. Thus they could be
Monochorionic monoamniotic - 4% of twins
Monochorionic diamniotic- 65% of twins
Dichorionic diamniotic – 30% of twins
Dizygous twins:
Dizygous twins develop from two fertilized eggs. The rate of dizygous twin varies in
different races. In United States two thirds of the twins are dizygous and the incidence is 8 per
1000 pregnancies. Dizygous twins always have dichorionic diamniotic placentation.
Clinical features:
Uterus larger for the gestational age
Palpation of multiple and excess fetal parts
Auscultation of multiple heart beats
Increased maternal serum alpha fetoprotein levels
Ultrasonography confirms the diagnosis
Risks of multiple pregnancies:
This can be divided in to maternal and fetal risks.
Maternal risks:
Hyperemeis gravidorum
Anemia
Preeclampsia
Gestational diabetes
Polyhydramnios
50
Fetal risks:
Increased incidence of congenital anomalies
Fetal growth disturbances
Vascular communications
Death of the fetus
Premature delivery
Conjoint twins where the twins are joined either in the head, thorax or abdomen
Presentations possible:
The combinations of presentations in decreasing frequency are
Both vertex
Vertex and breech
Both breech
Vertex and shoulder
Breech and shoulder
Both shoulders
Course of labor:
In uncomplicated twins labor usually occurs at term. But in other cases it occurs prematurely. As
the fetus are small spontaneous delivery is the rule unless there are any complications. The first
of the twins is delivered followed by an interval of up to thirty minutes which may sometimes be
longer to be followed by the birth of the second of the twin. The various steps of labor depend on
the presentation of the fetuses.
Management:
During antenatal period:
As premature labor with associated prolapse of cord is common in multiple pregnancies,
the patient should be hospitalized during the last few weeks of pregnancy and the complications
if any should be treated.
51
During labor:
In longitudinal lie the first fetus is delivered spontaneously and the cord is ligated
at two places and cut inbetween
The second twin is delivered as early as possible as more the interval between the
two deliveries more is the risk to the fetus
If the second fetus is of vertex or breech an oxytocin infusion is started to
expedite the delivery if it is prolonged. If it is breech and if delivery is getting
delayed, internal podalic version and extraction is done
In twins with malpresentations or contracted pelvis caesarian section is done
Complications:
Prolongation of labor
Prolapse of cord
Premature separation of cord
Interlocking of twins and prolongation of labor
ƒ
When both are vertex –
This is treated by putting the patient in
Trendlenberg position and pushing the head of the second fetus out of
pelvis
ƒ
When one is vertex and the other is breech – This is treated by pushing the
head of the second fetus out of pelvis. If it is not possible, the only other
option is decapitation of the first fetus to be followed by delivery of the
torso , second fetus and the head of the first fetus in that order
ƒ
First fetus breech and the second transverse – This is treated by pushing
the second fetus out of the way. If it is not possible, caesarian section is
done to deliver the twins
52
6. Dystocia due to anomalies of the expulsive forces
Dystocia due to expulsive forces are divided in to two categories.
Dystocia due to over efficient uterus
o Precipitate labor
o Tonic contraction of the uterus
Dystocia due to in efficient uterus
o Hypotonic inertia
o Incoordinate uterine action
A. Precipitate Labor
When labor is terminated in a disproportionately shorter time than anticipated, it is called
precipitate labor. It is due to strong uterine forces.
Causes:
Precipitate labor is more common in the multiparae than the primi gravidae.In multiparae, the
soft parts are lax and the passages are ready for an easy delivery. Precipitate labor is also
common among women with cardiac diseases and anemia.
Complications:
The complications can be divided into maternal and fetal complications.
Maternal complications:
Laceration of the cervix, vaginal walls and perineum
Post partum hemorrhage
Inversion of the uterus
Puerperal sepsis
Fetal complications:
Asphyxia
Intra cranial hemorrhage
Snapping of cord
Physical injuries
53
Management:
It is very difficult to anticipate precipitate labor in any patient. Only during delivery, a
diagnosis can be made. If there is a history of precipitate labor, precautions can be undertaken as
soon as the labor pains starts. The patient is hospitalized immediately and anesthetized to prevent
strong uterine contractions.
If precipitate labor occurs with tears it should be promptly sutured.
B.Tonic Contraction of the uterus
In this condition, the uterus is in a state of continuous contraction and retraction so that
there is no relaxation or rhythmic action of the uterine musculature.
Causes:
Tonic contraction occurs in conditions in which the labor is obstructed. In these cases the
uterus, tries to contract vigorously to overcome the obstruction. The other causes being
inadvertent use of ergot alkaloids or pituitary extracts .
Clinical features:
The features include
Dehydration
Abdominal pain
Nausea and vomiting
Hard tender uterus with prominent round ligaments
Pathological retraction ring
Absent fetal heart sounds
Large obscure presenting part
As the labor progresses the upper and lower uterine segments get prominently
demarcated by the in between, pathological retraction ring called the Bandl’s ring. If no
intervention is done, the tense uterus ruptures and the patient collapses.
54
Complications of tonic contraction of uterus:
The complications are divided in to maternal and fetal complications.
Maternal complications:
Rupture of uterus
Post partum hemorrhage
Puerperal sepsis
Fistula formation
Fetal complication:
Asphyxia
Intra uterine death
Management:
Management is divided in to prophylactic and therapeutic managements.
Prophylactic treatment:
Diagnosing causes of obstruction in the ante natal period itself and treating
accordingly
Avoiding inadvertent use of ergot alkaloids
Curative treatment:
Sedation with opiods like morphine
Delivering the fetus which is usually dead by craniotomy or decapitation
Hysterectomy in case of rupture of uterus
C.Hypotonic Inertia
In this condition the contractions of the uterus is very weak and the fetus does not
descend down.
Causes:
The possible causes include
Developmental defects of the uterus
Hormonal imbalances
55
Clinical features:
Contractions are weak, decreased in amplitude in and frequency
Uterus flabby on palpation and never hardens even at the height of
contractions
This condition is harmful to neither the fetus nor the mother. The only cause of concern is
that if the membranes ruptures prematurely, intrauterine infections can occur which have
deleterious effects on both the mother and the fetus.
Management:
Hypotonic inertia is managed with infusion of oxytocin. After cephalopelvic
disproportion and malpresentations are ruled out, 2.5 units of oxytocin in 500 ml of 5% dextrose
is given as infusion. Some up to 10 units may be needed in 24 hours. During this infusion, fetal
monitoring is done. If there are any signs of fetal distress, then the infusion is stopped. If
oxytocin infusion is not proved to be effective, then the only option available is delivering by
caesarian section.
D. Incoordinate Uterine action
In this condition, the uterine contractions are irregular and hence ineffective. The resting
tone of the uterus is increased. The normal resting tone is 5 mm of Hg. In incoordinate uterine
action the tone may rise even up to 30 mm of Hg causing severe pain.
Clinical features:
The features include
Severe abdominal pain due to increased resting tone of uterus which
occurs well before the uterine contractions and lasts even after the
contractions
Increased frequency of micturition
Dilatation of the stomach
Anxious patient
Prolongation of labor
56
Management:
The patient is sedated and well hydrated
Oxytocin is avoided
The normal uterine action is established after sometime
If its does not occur and if the patient is an elderly primi or if there is
malpresentation or cephalopelvic disproportion, then caesarian section is
done
If the cervix is fully dilated and head engaged, the fetus is delivered with
the help of a forceps.
6. Dystocia due to abnormalities of maternal soft parts
Vulva, cervix and uterus form the maternal soft parts. Abnormalities of these parts can
lead to difficulties in labor.
Abnormalities of the vulval outlet:
Atresia of the vulva – incomplete closure of the vulva. This is treated by
episiotomy
Rigid perineum – Episiotomy is done to aid delivery
Edema of vulva – If edema is marked hot compresses are given
Elephantoid growth of vulva – Bilateral episiotomy is done to aid delivery
Healed scars – Caesarian section is done
Hematoma of vulva –Before delivering the hematoma is incised and the
clots are cleared
Abnormalities of the vagina:
Incomplete atresia – Caesarian section is done
Double or septate vagina- If it is longitudinal normal delivery is possible.
If it is transverse, it has to be incised and normal delivery is possible
57
Abnormalities of cervix:
Organic rigidity of the cervix- If head is engaged forceps delivery is done.
If the head is unengaged or if there is malpresenation caesarian section is
done
Functional rigidity- It is due to incoordinate uterine actions and is
managed as discussed in the section above
Labor following operation for prolapse- If the cervix does not dilate
caesarian section is done. If it dilates and if the labor is prolonged, there
are chances of recurrence of prolapse and hence delivery should be
expedited by doing episiotomy
Malposition of cervix- In milder cases normal delivery is possible. In
sever cases caesarian section is done
Abnormalities of the uterus:
Malformations of the uterus:
The different malformations are
Arcuate uterus – There is a depression in the fundus
Uterus diadelphys – Two separate uterus with their own vagina and cervix
Uterus bicornis bicollis – The upper parts of uterus are divided and lower
parts are fused with a septum in between
Uterus bicornis unicollis - the upper parts are divided and the lower parts
are normal
Uterus septus – A septum is present in the cavity along the whole length
Uterus sub septus – A septum is present in the cavity but not along the
whole length
Uterus unicornis – In this there is a non communicating rudimentary horn
attached to the normal uterus
The complications include abortion, weak uterine action, post partum hemorrhage and
adhesion of placenta. In most of the cases vaginal delivery occurs. Occasionally caesarian
section might be necessary if there is prolongation of labor
58
Displacement of the uterus:
Retroversion or backward displacement:
The patient usually complains of retention of urine. The bladder is drained and infection
is treated. The retroversion is treated by making the patient adopt knee chest position for half an
hour everyday. The uterus corrects itself as it grows.
Ante version and ante flexion:
These are anterior displacements and are normal. Only when they are exaggerated they
become pathological. The labor is usually prolonged as dilatation is delayed. There may be
associated malpresentation and the membranes may rupture prematurely. Proper antenatal care
along with applying abdominal corset, avoiding heavy exercises can revert the uterus to normal
position. The labor is managed according to the presentation of the fetus and if the pelvis is
contracted caesarian section is done.
Prolapse of uterus:
In first and second degree prolapses, spontaneous rectification is possible as the uterus
grows and rises in to the pelvis. In third degree prolapse, abortion, urinary infection and damage
to cervix can occur. In this condition the patient is put to bed with the foot end raised. The cervix
is treated for its injuries and infection. Later the cervix is pushed inside. As the uterus grows and
rises in to the pelvis the prolapse is totally rectified. If these steps are not possible and if the
mother has completed her family, termination of pregnancy followed by Fothergill’s operation
for prolapse of uterus is done. The other option available is applying ring pessary till 20 weeks of
pregnancy by which time the uterus rises in to the pelvis.
Fibroids complicating pregnancy:
Fibroids are benign tumors of the uterus. They may be present during pregnancy
complicating labor. During the earlier weeks of pregnancy they may be asymptomatic. During
later weeks they may produce the following symptoms.
Pain due to degeneration and also sometimes due to torsion of the uterus
Pressure symptoms like to pressure on adjacent structures
59
The treatment options available are
Enucleation of the fibroid alone and allowing the pregnancy to continue
especially when the pregnancy is between 20-28 weeks
Caesarian section – In younger women
Caesarian hysterectomy – in elderly women and with multiple fibroids
7. Contracted Pelvis
If one or more of the diameters in one or more of the planes is shorter than normal, then
the pelvis is called a contracted pelvis. There are no universal standards to define a normal
pelvis. It varies in different countries. Various factors like socio economic factors and genetic
factors influence the shape and size of the pelvis.
Munro Kerr’s Classification of contracted pelvis:
1. Pelvic deformity due to faulty development
Justo major pelvis
Justo minor or generally contracted pelvis
Simple flat non rachitic pelvis
Naegle’s pelvis – imperfect development of one sacral ala
Robert’s pelvis – imperfect development of both sacral alae
Split pelvis- imperfect development of pubis
Assimilation pelvis
2. Pelvic deformity due to diseases of the pelvic bones and joints
Rickets
Osteomalacia
Fractures
Diseases of the sacro iliac and sacro coccygeal joints
Sub luxation of sacro iliac joint
3. Pelvic deformity due to diseases of the spine
Kyphosis
60
Scoliosis
Spondylolisthesis
4. Pelvic deformity due to diseases of the pelvic bones and joints
Coxitis
Dislocation of one or both hip joints
Atrophy or loss of one limb
Diagnosis of Contracted pelvis:
A pelvis has an inlet, cavity and outlet. The contraction may affect all the three levels or
just any one level. A pelvis contracted in all the diameters in the inlet is also contracted in the
cavity and the outlet. A contraction in one diameter is sometimes compensated by an increase in
other diameters. The diagnosis of contracted pelvis is done with the following methods.
Physical examination
Obstetric examination
External pelvimetry
Internal pelvimetry
Physical Examination:
The following physical features in a woman are associated with contracted pelvis
Short stature
Pendulous abdomen
Deformities of spine especially the lumbar region
Shortening of the lower limb
Tilting of the pelvis
Waddling gait
Rickets
61
Obstetric examinations:
Obstetric examination around term may give a clue to contracted pelvis. If in a primi
gravida, at term, the head is floating and not engaged, then contracted pelvis should be
suspected. But one should remember that a deflexed head closely mimic it.
External pelvimetry:
Only external pelvimetry of the outlet is used nowadays. The external pelvimetry of the
inlet is not used nowadays as it is less accurate. The pelvic outlet diameters commonly measured
are (as illustrated on the following page):
The transverse diameter – This is the distance between the inner surfaces of the two
ischial tuberosities.It is measured with Jarchos or Thomas calipers or by putting the
patient in the lithotomy position and measuring it with a ruler. The average diameter
is 10.5 – 11 cm.
The antero posterior diameter – This is the distance between the tip of the
sacrocooccyx and the under margin of the pubic symphysis.It can be measured with
an ordinary pelvimeter. The average diameter is 12.5 cm.
The posterior sagital diameter – This is the distance between the mid part of the
transverse diameter and the sacrococcygeal tip. The average diameter is about 7 cm.
The sub pubic arch – This is measured by direct palpation during the course of a
vaginal examination by sweeping the fingers side to side.The normal arch is about 85
degrees.
62
Posterior sagital – 7 cm
Internal Pelvimetry:
There are two methods of doing internal pelvimetry.
By vaginal examination
By instruments
Using instruments for internal pelvimetry is cumbersome and the results are also not
accurate. Hence internal pelvimetry with instruments is not done nowadays.
Vaginal examination:
This is one of the most important as well as valuable methods of assessing the pelvic
capacity. It is usually done after the 36th week of pregnancy. The following are assessed during
the vaginal examination.
The sub pubic arch
The ischial spines
The sacral concavity
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The length of the sacrotuberous ligament
The pelvic sidewalls
The diagonal conjugate
The sub pubic arch – This is measured by direct palpation during the course of a vaginal
examination by sweeping the fingers side to side.The normal arch is about 85 degrees.
The ischial spines - There should not be marked projection of these spines
The sacral concavity – The concavity from the promontory to the tip should be well developed.
In a well developed sacrum, it is difficult to palpate at the middle and higher levels. A straight
sacrum which is usually seen in the android pelvis may result in transverse arrest.
The length of the sacrotuberous ligament- In a well developed pelvis two fingers can be placed
on it which indicates pelvic adequacy at the lower level.
The pelvic sidewalls- They should be either parallel or divergent and never convergent. The
convergent sidewalls, as in the android pelvis, may result in difficulty during labor.
The diagonal conjugate - The middle and forefinger are passed in to the vagina till the
promontory is reached. With the forefinger of the other hand, the level of the sub pubic ligament
is measured. The diagonal conjugate is the distance between the tip of the middle finger and the
point marked by the fore finger of the other hand. It is normally about 12.5 cm. A true conjugate
is 2 cm less than this. Some features of the pelvis may influence this measurement
•
Depth of the pubic symphysis
•
Inclination of pubic symphysis
•
Height of the promontory
•
False promontory
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Cephalo-pelvic disproportion (CPD):
Sometimes the pelvis may have normal diameters. But the fetal head may be very big
causing difficulty in labor. This mimics contracted pelvis and it is called cephalo pelvic
disproportion. Cephalo pelvic disproportion can be assessed by Munro Kerr Muller method.
Munro Kerr Muller method of assessing cephalo pelvic disproportion:
The patient is made to lie on the dorsum
Standing by the side of the patient the obstetrician grasps the fetal head with the
left hand and pushes against the pelvic brim
The other hand is passed into the vagina and with the thumb the fetal head is
palpated above the pubic symphysis
The degree of overriding of the head gives an estimate of the cephalo pelvic
disproportion and it is categorized into no, mild and major cephalo pelvic
disproportion
This has to be done during active labor because the deflexed head prior to labor
gives a false impression of cephalo pelvic disproportion. This deflexed head
becomes flexed during active labor
The other methods used are
Radiological examination – This is rarely used because of the hazards of radiation. In the
United States, Precision stereoscope is being popularized by Caldwell and Moloy. The four
views taken are
Lateral
Antero posterior
Supero inferior picture of the brim
Outlet
Cephalometry:
The diameter of the fetal skull is measured by ultarsonogram and cephalo pelvic disproportion
can be assessed.
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Implications of pelvimetry:
The inlet:
In pelvis with obstetric conjugate above 9.5 cm vaginal delivery is possible
In pelvis with obstetric conjugate below 8.5 cm vaginal delivery is not possible
and caesarian section is done
Between 8.5 and 9.5 cm, it is difficult to establish the prognosis
The cavity:
If the distance between the spines is less than 9.5 cm vaginal delivery is difficult
and caesarian section is done
In straight sacrum vaginal delivery is difficult as forward rotation of the fetus is
not possible
If the pelvic side walls are convergent it results in deep transverse arrest
The outlet:
Most of cases of the outlet contraction are associated with contraction of the
cavity
A sub pubic arch below 75 degrees results in difficult labor
When the sum of the transverse and the posterior sagital diameters of the outlet is
15cm or more, vaginal delivery is possible
Management in contracted pelvis and cephalo pelvic disproportion:
Two methods are commonly employed for delivering in these cases.
Elective Caesarian section
Trial labor
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Elective Caesarian section:
Caesarian section is called elective if it is done before the onset of labor. In contracted pelvis and
cephalo pelvic disproportion, elective caesarian section is done if there are
Gross contracted pelvis and cephalo pelvic disproportion
Elderly primi
Bad obstetric history
Toxemia of pregnancy
Post maturity
Persistent malpresentation
A few advise caesarian section after the onset of labor pains indicating the following advantages.
The lower segment is well formed and this helps during the operation
The bleeding is less as the uterus has started contracting
The fetus would have the maximum intra uterine existence and its benefits
A well dilated cervix aids in proper drainage of the lochia
But there are a few disadvantages like
It is an emergency procedure
The labor pains may start sometimes well after term and this may affect the fetus
because of placental insufficiency
Trial Labor:
A few points need mention for explaining trial labor.
Gross contracted pelvis and cephalo pelvic disproportion are rare nowadays
The deflexed fetal head flexes during labor
The fetal head undergoes moulding and the pelvic ligaments relax. These
eliminate the borderline disproportion
Uterine contractions become stronger only after the rupture of membranes
Taking these factors into consideration, borderline cases can be subjected to trial vaginal delivery
or trial labor.
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Selection of patients for trial labor:
The patients with the following criteria are selected
Contraction only at the inlet
Platypelloid pelvis
Young woman
Vertex presentation
The fetus must not be post mature
Contraindications for trial labor are
Eclampsia
Fetal malpresentations
Elderly primigravida
Outlet contraction
Cardiac disease
Post maturity
Post caesarian
Conduct of trial labor:
The patient should be mentally well prepared
The general condition of both mother and fetus are periodically assessed
The patient is sedated
After rupture of the membranes, the following is assessed by vaginal examination
o
Nature of cervix
o
Position and situation of the head
o
Any possible cord prolapse
o
Reassessment of the degree of disproportion
o
Degree of moulding of the fetal head and the caput
formation
The signs of good prognosis are
Good uterine contraction
Early engagement of head
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Rupture of membranes after full cervical dilatation
Well thinned out and effaced cervix closely applied to the vertex
Flat pelvis with no contraction
Vertex anterior position
The signs of bad prognosis are
Weak uterine contraction
Slow descent of head
Premature rupture of membranes
Uneffaced partially dilated cervix
Android or generally contracted pelvis
Occipito posterior pelvis
When the head presents at the outlet instead of waiting for the spontaneous delivery to occur, it is
better to deliver the head with the help of a forceps.
Indications for termination of trial labor:
Trial labor is terminated and caesarian section is done to deliver the fetus in the following
conditions
Fetal distress
Maternal distress
Delivery not accomplished within 12 hours of onset of good uterine contractions
References:
-
Mudaliar and Menon’s Clinical Obstetrics
-
Images from Google images, Sweet Haven Publishing services, www.who.int,
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