External cephalic version for breech presentation
at term: a prospective interventional study
Dr. Saja Abdul Bari Abdul Jawad Al-Jwadi1, 2
Email: [email protected]
Dr. Bara'a Lukman Mohammed Humo Al-Ibrahim1,2,
Corresponding author
Email: [email protected]
1
Department of Obstetrics & Gynecology, Mosul Medical College, Mosul University, Mosul,
Al-Shifaa Q., Iraq.
2
Al-Batool Maternity Teaching Hospital, Mosul, Iraq.
1
Abstract:
Background: External cephalic version (ECV) is an important intervention to reduce the
incidence of breech presentation at term. The objective of this study was to evaluate the
ECV procedure for the management of at term breech presenting fetuses.
Methods: In a prospective interventional study, between January 2011 and March 2012, 90
patients who had uncomplicated breech presentations at or after 37 weeks' gestation were
considered for ECV. The main outcome measure assessed was the success rate of ECV
attempt and the rate of cesarean section following a successful procedure. Parity, type of
breech, placental location and birth weight of the baby were evaluated as predictors of
success. Also any fetal or maternal complications happened during the procedure were
evaluated. Data were analyzed by X2 test. Statistical significance was determined at a level
of P <0.05.
Results: The success rate in our study was 80%. The rate of cesarean section following
successful procedure was only 12.5%. Prognostic parameters associated with successful
ECV in our study were multiparity and flexed type of breech. There were no serious fetal or
maternal complications associated with our attempt.
Conclusions: With appropriate selection of the patients, external cephalic version is highly
successful and is a safer alternative to vaginal breech delivery or cesarean delivery.
Key words: Breech presentation, external cephalic version, cesarean section.
2
Background:
External cephalic version (ECV) refers to a procedure in which the fetus is rotated from
the breech presentation to the cephalic presentation by manipulation through the mother's
abdomen [1].
Breech presentation is the most commonly encountered malpresentation, accounting for
3 to 4% of births at term [2, 3]. Vaginal breech deliveries are associated with increased
maternal and newborn morbidity and mortality [4, 5]. Although an elective cesarean section
is safer for the baby than vaginal breech delivery, it increases maternal morbidity and carries
a risk for future pregnancies [4, 6]. The incidence of cesarean section for breech presentation
has increased markedly in the last 20 years and further with the publication of the term
breech trial. This means that measures to reduce the incidence of breech presentation have
become more important and that the effect of any such measure on the incidence of cesarean
section will be more marked [7]. ECV reduces the incidence of breech presentation at term
and of breech delivery, whether vaginal or by cesarean section and thereby reduces the
morbidity and mortality associated with the breech delivery for both the mother and the fetus
[2, 8, 9]. This makes ECV an important obstetric intervention and it is therefore
recommended by the Royal College of Obstetricians and Gynecologists and has been given a
level (Ia) of recommendation [4, 7]. Likewise the American College of Obstetricians and
Gynecologists (2001) recommended that efforts should be made to reduce breech
presentation by external cephalic version whenever possible [1, 2].
3
External cephalic version should be offered to all women with uncomplicated breech
presentation at term [6, 7, 8]. There are no specific contraindications to attempting ECV after
the estimated date of delivery, although data are sparse [1, 7].
ECV should only be performed in a setting where urgent cesarean section is possible
should there be evidence of fetal compromise during or soon after the procedure [3, 7].
Certain contraindications should be considered before attempting the procedure which
can be absolute or relative. Absolute contraindications include multiple pregnancy,
antepartum haemorrhage, need for cesarean section regardless of presentation, ruptured
membranes,
major
uterine
anomaly
and
suspected
fetal
compromise.
Relative
contraindications include previous cesarean section, maternal disease like hypertension or
diabetes, fetal growth restriction, oligohydramnios and major fetal anomalies[7, 10, 11, 12].
ECV has a very low complication rate [7, 13]. A common risk of ECV is transient fetal
heart bradycardia, occurs in 8 – 10% of cases. It usually resolves within five minutes of ECV
attempts and is not usually associated with adverse sequelae for the fetus. Uncommon risks
include premature rupture of membrane (<2%), abruptio placentae (<1%), fetomaternal
haemorrhage (however, this is often minor and of little clinical significance as long as anti-D
is administered appropriately), and cord entanglement (<1.5%) [7, 13, 14].
For the mother, attempting ECV causes negligible morbidity. Morbidity consists of the
discomfort at the time of procedure, the possibility of adverse effects from any of the drugs
4
used to facilitate version, and the hazards of placental abruption (a rare but recognized
complication of ECV) [7, 15, 16].
ECV is still not a common practice to manage breech presentation in our locality. On
the other hand, there is increasing trend to deliver breech presenting baby by cesarean
section. We aim to assess this procedure for the management of at term breech presenting
fetus and evaluate its value in clinical practice.
Methods:
This was a prospective interventional study performed in the period between January
2011 and March 2012. The study protocol was approved by the local research Ethics
Committees of Mosul Medical College. Patients with breech presentation at or after
37completed weeks of gestation were recruited from the antenatal clinic at Al Batool
Teaching Hospital, which is a tertiary obstetric and gynecological hospital in Mosul / Iraq,
or referred, by the obstetricians from private clinic. The antenatal course, the past obstetric
history, and the medical history were evaluated for possible contraindications to the
procedure. Patients with contraindications to ECV were excluded.
Exclusion criteria:
The exclusion criteria considered in our study were the followings:
1. Multiple pregnancy.
5
2. Evidence of utero-placental insufficiency.
3. A non-reassuring fetal monitoring pattern.
4. Significant third-trimester bleeding.
5. Ruptured membrane.
6. Amniotic fluid abnormalities especially oligohydromnia.
7. Uterine malformations.
8. Placenta praevia.
9. Uncontrolled hypertension.
10. Major fetal anomaly.
11. Need for cesarean section regardless of presentation.
12. Declined consent.
Protocol for ECV:
The protocol for ECV was applied as follows:
1. Verbal consent for ECV was obtained following a description of the procedure to the
patient, its benefit, its possible risks, and the possibility of being unsuccessful.
2. Recent ultrasound to confirm the placental position, an adequate liquor volume, a normal
fetus and to assess the fetal attitude and position of the fetal legs.
3. Documentation of fetal well-being (e.g., reactive fetal heart rate pattern or satisfactory
biophysical profile score).
4. Obtaining blood sample for blood group and Rh.
6
5. Salbutamol in the form of oral tablet was used in some patients for tocolysis if this was
decided to be necessary by the doctor.
6. In some patients, the procedure was done under real time ultrasound guidance as needed.
Technique of ECV:
The procedure was done as a single operator technique by both authors themselves. We
performed ECV in the casualty unit, outpatient clinic, or ultrasound clinic. In all cases,
adjacent operating theatre was available for an emergency cesarean section if required.
We followed the technique described by Richard H.[8] and Andrew S.C. et al [13].
When the prerequisites for ECV were met, the woman was positioned supine with slight
lateral tilt. The breech was first disengaged from the pelvis and each fetal pole was grasped
with one hand. The buttock was then gently guided toward the fundus, while the head was
directed toward the pelvis. Pressure was maximally aimed at moving the breech upward. The
fetus was gently rotated with steady and controlled movements rather than rushed or jerky. A
forward roll was attempted first. This involves flexing the fetal spine and turning the fetus
through 180
in the direction that maintains fetal flexion throughout. If this sequence
should prove unsuccessful, rotation in the opposite direction may be tried (backward roll).
Fetal heart rate (FHR) was auscultated every two minutes either with Pinard's
stethoscope or sonic aid or observed through ultrasound if the procedure was done under
ultrasound guidance. Monitoring was continuous during the procedure. If FHR fell below
7
100 beats per minute, the procedure was stopped and the fetus might rotated back to its
original position. A second attempt was made only after FHR returned to normal (if at all).
The uterine manipulation was limited to a total of 10 minutes' duration (the vast
majority turned within five minutes). Procedures were also discontinued for any
unreasonable maternal discomfort to ensure that the mother is not subjected to excessive
discomfort.
Successful procedure was defined as conversion from breech to cephalic presentation at
the time of the procedure.
Following an ECV attempt, whether successful or not, repeated CTG was performed. If
this is normal and reassuring, the patient can be allowed home with an appointment after few
days to confirm the persistence of the cephalic presentation.
Also following ECV attempt, whether successful or not, non-sensitized Rhesus-negative
women received anti-D immunoglobulin because of the risk of alloimmunization.
The woman was asked to return if she had reported a reduction of fetal movement,
vaginal bleeding or leaking liquor.
Follow up of the patients was done about the presentation of the fetus at time of
delivery, mode of delivery, neonate condition and birth weight at delivery, and any perinatal
or maternal complications, either by the authors themselves if they continue the follow up of
the patients or through telephoning the patient to ask her about these results.
8
Parity(nullipara or multipara), type of breech (flexed, extended or footling), placental
location (fundal, anterior or posterior) and birth weight of the baby were chosen as factors
that might predict the success of the procedure. We used birth weight instead of estimated
fetal weight in view of the inaccuracy of the estimate, knowing that the majority of patients
delivered within a short period of ECV procedures. Data were analyzed by z-test for one
proportion to determine the significance of the outcome of the procedure and x2 test for
univariate analyses to assess the effect of each chosen predictive variable on the likelihood of
successful version. Statistical significance was determined at a level of P<0.05.
Results:
ECV was performed on a total of 90 women. It was successful with 72 (80%) women.
Of this group of 72 women with successful ECV, 63 (87.5%) delivered vaginally, while nine
(12.5%) women delivered by cesarean section for various indications: four (5.5%) of them
because their fetuses underwent spontaneous version to breech presentation & transverse lie
at the onset of labour, three (4.2%) for poor progress in labour and two (2.8%) for fetal
distress. So the cesarean section rate for successful ECV group was 12.5% (9 out of 72),
while 87.5% of the patients with successful ECV were delivered vaginally.
A large proportion (78%) of the patients in the failed ECV group declined further
assessment for vaginal breech delivery & underwent an elective cesarean section. Only four
9
women were agreeable for trial of vaginal breech delivery and underwent clinical assessment
for that, they were judged to be suitable, and all of them were delivered vaginally with no
complications. The overall cesarean section rate for failed version group was 78%.
The outcome of the study and mode of delivery in both groups is shown in table (1).
Table (1): Outcome of ECV and mode of delivery in the study sample (n =90).
Successful ECV No. (%)
Total women *
Failed ECV No. (%)
Total No. (%)
72(80%)
18(20%)
90(100.0%)
Vaginal delivery
63(87.5%)
4(22%)
67(74.4%)
LSCS
9(12.5%)
14(78%)
23 (25.6%)
* P = 0.001 using Z-test for one proportion.
The effect of the parity on the success of ECV procedure is shown in table (2). Success
rate for primipara was 36% while that for multipara was 94% and this difference was
statistically significant (p=0.001).
Table (2): Relationship between the outcome of ECV and the parity in the study
sample.
Parity
Successful ECV
Failed ECV
No. (%)
No. (%)
Total No. (%)
P-value*
0.001
Primipara
4(36%)
7(64%)
11(12.2%)
Multipara
68(94%)
11(6%)
79(87.8%)
* Chi-square test was used.
10
The type of breech and its relation to the outcome of ECV procedure is shown in table
(3): For each type of breech, ECV was most successful with the flexed type (94.7%) which
represented a statistically significant difference (p=0.002).
Table (3): Relationship between the outcome of ECV and the type of breech.
Type of breech
Flexed
Successful ECV
No. (%)
36 (94.7%)
Failed ECV
No. (%)
2 (5.2%)
Total
No. (%)
38 (42.2%)
Extended
33 (73.3%)
12 (26.7%)
45 (50%)
Footling
3 (42.9%)
4 (57.1%)
7 (7.8%)
P-value*
0.002
* Chi-square test was used.
The relation of placental site to the results of ECV is shown in table (4): For each site of
the placenta, ECV was most successful with the posteriorly located placenta (86%), but the
difference was not significant (p=0.439).
Table (4): Relationship between the outcome of ECV and the placental location.
Placental site
Fundal
Successful ECV
No. (%)
10(77%)
Failed ECV
No. (%)
3(23%)
Total No. (%)
P-value*
13 (14.4%)
0.439
Anterior
26(74%)
9(26%)
35 (38.9%)
Posterior
36(86%)
6(14%)
42 (46.7%)
* Chi-square test was used.
11
The effect of the birth weight of fetuses on the success of the procedure in this study is
shown in table (5). There was no significant difference in the birth weight of failed group to
successful group.
Table (5): Relationship between the outcome of ECV and fetal weight.
Birth weight at Successful ECV
time of delivery No. (%)
≥ 3000g
34 (77.3%)
Failed ECV
No. (%)
10 (22.7%)
Total
No. (%)
44 (%)
< 3000g
8 (17.4%)
46 (%)
38 (82.6%)
P-value*
0.527
* Chi-square test was used.
One version attempt was abandoned because of a prolonged fetal bradycardia at the start
of the procedure. The bradycardia resolved promptly once maternal manipulation ceased and
the patient was admitted for more observation. The patient developed recurrent attack of fetal
bradycardia in the same day and underwent emergency cesarean section and the baby was in
good condition at time of birth. There was transient fetal bradycardia during version attempts
in five patients (5.6%) that resolved spontaneously by giving short pause and did not require
us to stop the version attempt. No other fetal complications had happened and all babies were
delivered in good health. There were no maternal complications apart from mild discomfort
which got less by giving short pause throughout the procedure.
12
Discussion:
External cephalic version effectively reduces the rates of breech presentation and
cesarean section in women with fetus presenting as breech at term.
In our study, ECV was successful in 80% of cases. The reported success rate of ECV
ranges from 35 to 86%, with a commonly quoted figure of 50 % [ 6, 7, 10].
Our result is higher than the result achieved in many similar studies. Nassar N. et al
[17], Teoh T [18], and Cho LY. et al [19], in their study reported a success rate of 39%, 56%
and 63% respectively. The high success rate in our study may be attributed to good selection
of patients, lower proportion of primigravida in the study groups and experience of the
obstetricians who performed the procedure as all the attempts were performed by the authors
themselves.
The vast majority (87.5%) of those with successful ECV delivered by normal vaginal
delivery of a cephalic presenting fetus, and this is very important as the main purpose of
ECV procedure is to avoid the possible complications that are associated with the two other
options that may be chosen for the management of breech presentation at term which are
elective cesarean section or vaginal breech delivery i.e.: to reduce the number of elective
cesarean section with its associated morbidity particularly on the mother and to avoid the
possible morbidity associated with vaginal breech delivery particularly on the fetus.
13
This result is higher than the result achieved in many similar studies. The rate of
vaginal delivery in the successful ECV group in Mezei G. et al [20], study, Gerhard B. et al
[21], study and El-Toukhy T. et al[22], study was 84%, 81.1% and 69% respectively. Norchi
S. et al, in their study achieved a vaginal delivery with a vertex presentation of the fetus after
successful ECV in 90% of their patients [23]. However this study was done in the period
between 1990- 1994, where the threshold for cesarean delivery was higher than that
observed in the recent years in all obstetrics centers.
Numerous studies have investigated the factors that could affect the success rate of
ECV; however, the majorities of studies differ considerably in methodological quality and
sample size. The variables most commonly used in previous studies were maternal weight,
parity, amount of amniotic fluid, placental location, uterine tone, type of breech (footling,
frank, complete), nonengagement of the breech and fetal weight estimated by ultrasound. A
literature review was performed and no single factor that was common to all studies was
found; some factors that were found to be associated with ECV success in some studies were
reported to have no effect on the success rate in other studies.
Our study showed that parity has a very strong influence on the success of ECV. The
success rate for multipara was 94% compared to 36% for primipara and this difference was
statistically significant (P= 0.001). Our result was consistent with many studies done in this
subject like Kok M. et al [24], [25], Ben-Meir A. et al [26], and Gottvall T [27] studies who
all found that multipara was a significant predictor for successful ECV outcome.
14
For the type of breech, our study showed that flexed breech had a significantly better
success rate when compared to extended and footling breech and this difference was
statistically significant (P=0.002). Our result was in agreement with the result observed by
Toeh T. [18] study and Ben-Meir A. et al [26], study.
Although the success rate in our study was higher with the posteriorly located placenta
(86%), the result was not statistically significant. This result was in agreement with the
observation of Toeh T. study, who also found that placental site did not have a statistically
significant effect on the outcome of ECV [18], while Ben-Meir A. et al, [26] and Gary A. et
al, [28] found that non- anterior placental location was significant predictor of success. The
same for the birth weight where no statistically significant difference were found between
the successful and failed ECV group and our result was consistent with the findings of Toeh
T. [18] and Aisenbrey GA et al [28]; however, Kok M. et al [24] found that increasing
estimated fetal weight was favorable predictor of successful ECV.
We already excluded cases with oligohydromnia from our study, so liquor volume is
not taken as a predictive factor in our study. We acknowledge that our sample size was small
and each predictive factor was analyzed individually rather than using logistic regression for
multivariate analysis, so our conclusions regarding predictive factor for successful ECV
might be regarded as inconclusive; however, we can conclude that attempting ECV in
multiparous with flexed type of breech is more likely to be successful.
15
The procedures were performed with few maternal and fetal complications. These
findings were in agreement with many similar studies that were performed in the recent
years where ECV procedures were performed for at term breech with adequate ultrasound
assessment , and frequent fetal heart monitoring during the procedure like Mezei G. et al
[20], Gerhard B. et al [21], El-Toukhy T. et al [22], and Norchi S. et al [23], who all reported
a favorable neonatal outcome and no significant maternal or perinatal complications. The
most commonly encountered complication in our study was transient fetal heart bradycardia
(5.6%) that resolved spontaneously. Toeh T.[18] reported transient bradycardia in four cases
(out of 80 cases) and Aisenbrey G.A. et al [28], reported transient bradycardia in 20 cases
(out of 128). There was no any perinatal mortality in the study groups. Also maternal
complications were negligible apart from mild discomfort. Our policy in adopting gentle
manipulation of the fetus rather than forceful movement is an important factor in reducing
maternal and fetal complications rate.
Conclusion:
With appropriate selection of the patients, external cephalic version is highly
successful and is a safer alternative to vaginal breech delivery or cesarean delivery.
Attempting ECV at term reduces the chance of breech presentation and therefore the
associated risks, particularly of avoidable cesarean section. Furthermore, ECV is an
16
inexpensive maneuver that can be performed at the outpatient clinic; it does not require very
special condition for its successful implementation; however, immediate availability of
operative facilities should be present before attempting ECV.
Finally, we would like to emphasize the need to spread and improve ECV skills. It is
essential that skills for performing ECV should be developed, promoted and improved with
continuous practice at teaching hospitals. It might be appropriate to appoint two or three
experienced obstetricians in each hospital to evaluate the patients and perform the procedure
so their skill can be more readily improved and their result can be more adequately
evaluated.
Abbreviations:
ECV: external cephalic version, FHR: fetal heart rate.
Competing interests:
The authors declare that they have no competing interests.
Authors' contributions:
SA carried out the procedure and participated in data acquisition, analysis and
interpretation. BM conceived of the study and designed it, drafted the manuscript and
17
participated in carrying out the procedure and data acquisition. Both authors have read and
approved the final manuscript.
Acknowledgement:
We would like to thank Dr. Ahmed Jassim for his thoughtful comment on reading the
article, Dr. Humam Ganim for his assistance in statistical analysis of the data and Mrs.
Wafaa Mudhaffar for her assistance in reviewing the English language of the manuscript .
Also we would like to thank the obstetricians in Al_ Batool hospital who were cooperative
in referring their patients with breech presentation to be included in this study.
Reference:
1. Hofmeyr GJ.: External cephalic version. Up to date.com. September 2009. Available
at http://www.uptodate.com/contents/external-cephalic-version.
2. Cunningham FG, Kenneth JL, Steven LB, John CH, Larry CG, Katharine DW: Breech
presentation and delivery. In Williams Obstetrics. 22nd edition. McGraw-Hill
Companies, Inc.; 2005, p. 316–328.
3. Arulkumaran S.: Malpresentation, malposition, cephalopelvic disproportion and
obstetric procedures. In Dewhurst's Textbook of Obstetrics and Gynecology, 7th
18
edition. Edited by Edmonds D. K. Oxford, Blackwell Publishing Ltd; 2007, p. 214 –
217.
4. Vlemmix F., Rosman AN, Fleuren MA, Rijnders ME, Beuckens A, Haak MC,
Akerboom BM, Bais JM, Kuppens SM, Papatsonis DN, Opmeer BC, van der Post JA,
Mol BW, Kok M. : Implementation of the external cephalic version in breech
delivery. Dutch national implementation study of external cephalic version. BMC
Pregnancy
and
Childbirth.
May
2010.
Available
at
http://www.biomedcentral.com/1471-2393/10/20.
5. Lede R: External cephalic version for the management of breech presentation. The
WHO Reproductive Health Library; Geneva: World Health Organization. March 2006.
Available at http://apps.who.int/rhl/pregnancy_childbirth/childbirth/breech/cd000083
_leder_com/en/index.html .
6. Baker PN, Kenny LC: Antenatal obstetric complications. In: Obstetrics by Ten
Teachers, 19th edition. Hodder & Stoughton Ltd; 2011, p. 95–101.
7. External cephalic version and reducing the incidence of breech presentation. Royal
College of Obstetricians and Gynecologists Guideline No. 20a. December 2006.
8. Richard H: Breech presentation. In Obstetrics and Gynecology. An evidence-based
text for MRCOG. 1st edition. Edited by David ML, Philip NB. Oxford, Rotis serif by
Charon Tec Pvt. Ltd; 2004, p. 413-26.
19
9. Zoe P: Breech presentation. In High Risk Pregnancy, 3rd edition. Edited by David KJ,
Carl PW, Philip JS, Bernard G. Elsevier Inc. Ltd; 2006, p. 1334–1358.
10. Richard F: Breech presentation. Medscape Reference. April 2011. Available at
http://emedicine.medscape.com/article/262159-overview.
11. Stacey EB: External cephalic version. Medscape Reference. November 2011.
Available at http://emedicine.medscape.com/article/1848353-overview.
12. Hofmeyr GJ, Kulier R: External cephalic version for breech presentation at term
(Review).
The
Cochrane
Collaboration.
2007.
Available
at
http://www.thecochranelibrary.com.
13. Andrew SC, Stephanie D, Silverman: External cephalic version. Am Fam Physician,
September 1998, 58:731-738.
14. External cephalic version. Women's Health Program Guideline and Protocols. March
2004.
Available
at
http://www.capitalhealth.ca/nr/rdonlyres/eym5ktsts32znnpaik
6ieedqziui7h7us7fwtittgcsvtogcktol3te4mu6aivoljc4fh4jn7v257ggsxm523astilf/ecv.pdf.
15. McParland P, Farine D: External cephalic version. Does it have a role in modern
obstetric practice?. Can Fam physician, April 1996, 42: 693-698.
16. Ann E, Lee D: Safety of term external cephalic version. Evidence-Based Practice,
January 2008, 11: 9-10.
17. Nassar N, Roberts CL, Cameron CA, Peat B: Outcome of external cephalic version
and breech presentation at term, an audit of deliveries at a Sydney tertiary
20
obstetric hospital, 1997 -2004. Acta Obstetrica et Gynecoligica Scandinavica, October
2006, 85: 1231-1238.
18. TeohT: Outcome of 80 cases of external cephalic version. Med J Malaysia,
December 1996, 51:469-474.
19. Cho LY, Lau WL, Lo TK, Tang HH, Leung WC: Predictors of successful outcomes
after external cephalic version in singleton term breech pregnancies: a nine-year
historical cohort study. Hong Kong Med J, February 2012, 18(1):11-19.
20. Mezei G, Jurus D, Ural S: P16.07: Prognostic parameters for ultrasound-guided
external cephalic version: a retrospective review of 92 cases. Ultrasound in
Obstetrics & Gynecology, October 2011, 38(S1): 226.
21. Bogner G, Xu F, Simbrunner C, Bacherer A, Reisenberger K: Single-institute
experience, management, success rate, and outcome after external cephalic version
at term. International Journal of Gynecology & Obstetrics, February 2012, 116(2):
134-137.
22. El-Toukhy T, Geyoushi B, Ramadan G, Hanna L: Mode of delivery and neonatal
outcome after successful external cephalic version at term: a five-year study. Kasr
Al-Aini Journal of Obstetrics & Gynecology, August 2010, 1(2): 57-64.
23. Norchi S, Tenore AC, Lovotti M, Merati R, Teatini A, Belloni C: Efficacy of external
cephalic version performed at term. European Journal of Obstetrics & Gynecology
and Reproductive Biology, February 1998, 76 (2): 161–163.
21
24. Kok M, van der Steeg JW, van der Post JA, Mol BW: Prediction of success of
external cephalic version after 36 weeks. Am J Perinatol., February 2011, 28 (2):
103-110.
25. Kok M, Cnossen J, Gravendeed L, van der Post JA, Opmeer B, Mol BW: Clinical
factors to predict the outcome of external cephalic version: a metaanalysis.
American Journal of Obstetrics & Gynecology, December 2008, 199 (6): 630.e1630.e7.
26. Ben-Meir A, Erez Y, Sela HY, Shveiky D, Tsafrir A, Ezra Y: Prognostic parameters
for successful external cephalic version. Journal of Maternal-Fetal and Neonatal
Medicine, September 2008, 21 (9): 660-662.
27. Gottvall T, Ginstman C.: External cephalic version of non-cephalic presentation; is
it worthwhile?. Acta Obstetricia et Gynecologica Scandinavica, December 2011, 90
(12): 1443–1445.
28. Aisenbrey GA, Catanzarite VA, Nelson C: External cephalic version: predictors of
success. Obstetrics & Gynecology, Novomber 1999, 94: 783–786.
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