Does low cord blood pH gasses determines fetal outcome?
Dr. Ahmad Tayyib Azizan, Dr. H. Krishna Kumar
Tuanku Jaa’far Seremban Hospital, Negeri Sembilan Darul Khusus, Malaysia
In 1958, James et al recognised that umbilical cord blood gas
analysis can give an indication of preceding fetal hypoxic
stress. It has since become widely accepted that umbilical
cord blood gas analysis can provide important information
about the past, present and possibly the future condition of
the infant. Umbilical cord blood gas analysis is now
recommended in all high‐risk deliveries by both the British
and American Colleges of Obstetrics and Gynaecology, and
in some centres particularly Tuanku Jaa’far Seremban
Hospital (HTJS), Negeri Sembilan Darul Khusus, Malaysia it
is practised routinely following all caesarian section
deliveries, instrumental and high – risk deliveries. It is
therefore of increasing clinical and medicolegal importance
that substantial studies to show the correlation between low
cord blood pH gasses and fetal outcome in the form of
Apgar’s score.
It has been shown, however, that there is a poor correlation
between Apgar scores and acid base status in the cord blood
(cord blood pH) of neonates. The purpose of this study was
to determine retrospectively the relation between Apgar
scores, and cord blood gases.
Methods
This is a cross – sectional study which was done in a single
tertiary obstetric center, Tuanku Jaa’far Seremban Hospital
(HTJS), Negeri Sembilan Darul Khusus, Malaysia. A total of
492 consecutive deliveries at >35 weeks of gestation were
selected for a period of time. Selected deliveries were only
via Lower Segment Caesarian Sections including both
elective and emergency caesarian sections regardless of the
obstetric indications. However, this study excludes caesarian
sections for premature deliveries <35 weeks. The gestational
age was determined by the date of the mother's last normal
menstrual period and early in utero ultrasound scan of the
fetus. This study also exclude all vaginal birth deliveries.
Results
Conclusions
The Apgar’s score was not affected by the fact that the cord
blood pH was <2.0. Babies were born with good fetal
outcome 49 babies (89.1%) as compared to 6 babies (10.9%)
with poor Apgar’s scores. Majorities of these babies delivered
via emergency lower segment caesarian section for Acute
fetal distress, 46 babies (83.6%) with pH<2.0 were born with
good Apgar’s score. The rest of 9 babies (16.4%), caesarian
sections were for other obstetric indications; such as, poor
progress, prolonged second stage of labour, pre – eclampsia
or bleeding placenta praevia.
We were unable to substantiate the hypothesis that low cord
blood pH gasses was related to poor fetal outcome in the
form of Apgar’s score. Thus, cord blood pH gasses may not
prognosticate and determines the baby’s outcome during
intrapartum.
50
45
35
30
25
20
15
Good
10
At delivery the umbilical cord was double clamped within 30
seconds; heparinised blood was obtained from both the
umbilical artery and vein, placed on ice, and taken for
immediate blood gas analysis. Arterial and venous
blood was collected separately into heparinised 1 ml
polyethylene syringes. Blood pH, Po2, and Pco2 were
measured immediately after a blood sample was collected.
Cord blood pH of less than 2.0 was taken as acidotic which
may suggest fetal asphyxia and on the other hand, pH of
more than 2.0 was taken as normal value.
It is possible that the results we report do not
reach significance because of the small numbers of
neonates in some of the gestational age groups
analysed. This lack of statistical significance persisted
however, when some of the groups were combined.
Poor
40
Apgar's score
Objectives
5
0
Acute Fetal Distress
0
Others
10
20
30
40
50
However, normal cord blood pH gasses may suggest good
fetal outcome as shown in this study but further studies may
need to be done to further evaluate these.
Indications
The results also show that the cord blood pH >2 does not
effect the babies outcome in terms of Apgar’s score. This
study has shown that 107 babies (98%) have good fetal
outcome. Only 2 babies (2%) delivered with poor Apgar’s
score. Most of the obstetric indications were Acute fetal
distress 43 babies (39.4%). Other obstetric indications; such
as, poor progress, prolonged second stage of labour, pre –
eclampsia , bleeding placenta praevia and elective lower
segment caesarian section cases were 66%.
Graph below shows the
percentage of cases done in this
study for either emergency or
elective caesarian sections.
We report elsewhere that 98% of the cord blood pH gasses
>2 gives good fetal outcome. We suggest that these babies
less likely to suffer from birth asphyxia. This may also show
that cord blood pH gasses have high specificity to determine
good fetal outcome. However, we cannot elaborate further
due to the limitations in this study.
96.4
100
90
The Apgar score was assigned by the senior medical officer
from the paediatric department and senior midwife present at
the delivery. The score was given at 1 and 5 minutes.
Apgar’s score in the 1st minute would be considered good
and normal if it is more than 5 and more than 7 at 5th minutes.
However, Apgar’s score in the 1st minute of less or equals to
5 and at 5th minutes of less or equals to 7 would be
considered poor.
80
70
60
50
40
30
20
120
100
0
Emergency
96.4
Elective
LSCS pH<2
73.4
80
60
40
26.6
20
3.6
0
Emergency
Elective
LSCS pH<2
Student's t test was used when comparing
mean values. The prevalence of pH<2.0 (acidotic) and fetal
outcome as measured by baby’s Apgar’s score was
calculated. The prevalence of pH>2.0 (normal) and fetal
outcome as measured by babys’s Apgar’s score was
calculated.
3.6
10
Emergency
Elective
Value in percentage.
LSCS pH>2
There was no statistical difference as shown by t-test
performed in the fetal outcome (Apgar’s score) in relation to
cord blood gasses either low (<2) or normal pH (>2).
The results of an unpaired t-test performed is as below;
T (test)= 1.48 Standard deviation= 31.6 with the degrees of
freedom = 10 The probability of this result, assuming the null
hypothesis, is p< 0.17.
The 95% confidence interval for cord blood gasses of pH>2
is 25.75 to 83.25.The 95% confidence interval for cord blood
gasses of pH<2 is -1.246 to 56.25. We were unable to show
any relation between Apgar score and cord blood gas
analysis.
References
1. White C, Doherty D, Kohan R, Newnham J, Pennell C. Evaluation of selection
criteria for validating paired umbilical cord blood gas samples: an observational
study. BJOG 2012; DOI: 10.1111/j.1471-0528.2012.03308.x.
2. Does intravenous fentanyl affect apgar scores and umbilical vessel blood gas
parameters in cesarean section under general anesthesia? Maghsoudloo M,
Eftekhar N, Ashraf MA, Khan ZH, Sereshkeh HP. Department of Anesthesiology,
Imam Khomeini General Hospital, Tehran University of Medical Sciences, Tehran,
Iran.
3. Neonatal outcomes and operative vaginal delivery versus cesarean
delivery.Contag SA, Clifton RG, Bloom SL, Spong CY, Varner MW, Rouse DJ,
Ramin SM, Caritis SN, Peaceman AM, Sorokin Y, Sciscione A, Carpenter MW,
Mercer BM, Thorp JM Jr, Malone FD, Iams JD. Department of Obstetrics and
Gynecology at Wake Forest University, Winston-Salem, North Carolina, USA.
[email protected]
4. Screening of foetal distress by assessment of umbilical cord lactate. Borruto F,
Comparetto C, Wegher E, Treisser A. Department of Obstetrics and Gynaecology
and Genetic Biology, University of Verona, Italy.
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