Obstetric outcome in sonologically short cervix: a prospective observational study

Vinod Nair, Ajai Srivastava, Manoj Tangri


Background: Preterm delivery is associated with significant perinatal morbidity and mortality. The prediction or early detection of preterm labour is often difficult because signs and symptoms often vary only a little from the normal physiological symptoms and signs of pregnancy. Prediction of preterm birth should ideally be by a screening test with high sensitivity and high negative predictive value. The screening tools available today have not enabled obstetricians to decrease the incidence of preterm birth. However, they may allow time for in-utero transfer to a tertiary care centre as well as administration of glucocorticoids to enhance fetal lung maturity. Till 24 weeks period of gestation, a cervical length measurement of <25 mm increases the risk of preterm labour by 4.5 times. Only limited data are available about the significance of cervical length measurement beyond 24 weeks period of gestation.

Methods: Antenatal patients were screened with trans-vaginal sonography (TVS) between 24 and 28 weeks period of gestation and cervical length recorded. Those who had undergone cervical encirclage prior to 24 weeks, those who were having vaginal bleeding or leaking of amniotic fluid, multifetal gestation and those who were unwilling for trans-vaginal sonography were excluded. A total of 611 antenatal patients were enrolled in the study, out of which 86 were lost to follow up. Relationship of cervical length with spontaneous preterm delivery at <34 weeks (primary outcome) and <37 weeks (secondary outcome) was statistically analyzed.

Results: There was a significant association between cervical length <26 mm and risk of preterm delivery at <34 weeks. However, no such association could be found for PTD <37 weeks.

Conclusions: The study confirmed that there is an increased risk of preterm delivery in women with sonologically short cervix. The study has brought out the significance of cervical length measurement after 24 weeks and its association with preterm labour at <34 weeks. Cervical length measurement by trans-vaginal sonography is a cost effective and simple method for prediction of preterm delivery at <34 weeks period of gestation.


Cervical length, Preterm delivery, Trans-vaginal sonography

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