PREDICTING MODE OF DELIVERY USING MIDPREGNANCY ULTRASONOGRAPHIC MEASUREMENT OF CERVICAL LENGTH

Abstract

BACKGROUND Previous studies have documented the role of cervical length at
term in determining the course of labour and the mode of delivery. More recent
researchers suggest a direct relationship between labour process at term and earlier
development of the uterus before the onset of labour. It has been recognised that preterm
labour is related to short cervical length and that poor progress in labour is a major
indication for Caesarean section at term. We therefore hypothesize that long cervix is
associated with increased risk of Caesarean delivery during labour at term.
AIMS AND OBJECTIVES
The aim of the study is to predict the mode of delivery at term using the mid pregnancy
cervical length. The objective is to determine the relationship between cervical length at
mid-pregnancy and mode of delivery and preterm delivery.
METHOD Trans-vaginal ultrasonographic scan measurement of cervical length was
done for 281 pregnant women who met the criteria for recruitment at a mean gestational
age of 22 weeks. These women were followed up in two obstetrics units till delivery,
after which the mode of delivery and the cervical length were analysed for associations.
RESULTS One hundred and ninety seven women (70.1%) delivered vaginally at term,
fifty one pregnant women had Caesarean section (18.2%) and thirty three women
(11.7%) had preterm vaginal delivery. Caesarean section due to poor progress in labour at
term constituted 11.7%. The Caesarean section rate at the lowest quartile cervical length
(15-19mm) was 6%, second quartile cervical length (20-30mm) was 16.0%, third
quartile Cervical length (31-40mm) was 28% and the highest quartile cervical length (40
67mm) was 50% (P-value 0.0018 for trend). The odds ratio for Caesarean section among
women with the highest cervical length is 3.37 (95% CI 1.6-7.0, P-value 0.0016) and the
Odds ratio for preterm delivery among women with the lowest cervical length is 19.52
(95% CI 5.48-69.42, P-value <0.0001), Odds ratio for term vaginal delivery among
women with the cervical length quartile of 31-40mm was 2.90 (95% CI 1.59-5.31, P
value 0.00062). The likelihood ratio of Caesarean section due to poor progress of labour
at term among women at the upper quartile cervical length is 10.28 (P-value 0.0013)
CONCLUSION Long cervical length at mid- pregnancy predicts the possibility of
Caesarean delivery early in pregnancy and short cervical length at mid- pregnancy
predicts the possibility of a preterm birth. Hence, cervical length in mid-pregnancy can
be of value in predicting the mode of delivery in early pregnancy.

PREDICTING MODE OF DELIVERY USING MIDPREGNANCY ULTRASONOGRAPHIC MEASUREMENT OF CERVICAL LENGTH