Cervical incompetence and the role of emergency cerclage

To evaluate the role of emergency cerclage for women who present with a dilated external cervical os and bulging or "hour-glassing" membranes. We examined overall experiences at Kingston General Hospital (KGH) from 2000 to 2004 and conducted a literature review for the period January 1, 1995, to December 31, 2004.

A search for cerclages placed by operators in Kingston revealed 12 pregnancies in the period between 2000 and 2004. We reviewed the charts for these women and for their infants. We conducted a literature review, using the terms "cerclage," "cervical," "emergent or emergency cerclage," "rescue cerclage," and "incompetent cervix," using an OVID interface to access MEDLINE records. We excluded articles in which the diagnosis of cervical incompetence was made using ultrasound, because its predictive value has not been shown in randomized trials. The most recent review of this type was carried out in 1995; since then, an additional 24 articles have been published that met our inclusion and exclusion criteria.

The average time between cerclage placement and delivery at KGH was 7 weeks, which allowed for 10 of 13 infants (one twin pregnancy) to be born at 28 weeks or later. Three infants were born weighing under 1 kg; the 10 remaining infants weighed over 1 kg. Histological data are available for 12 placentas of the 13 infants delivered; 7 infants had a histological diagnosis of chorioamnionitis; none of the blood cultures from any of the infants post-delivery revealed septicemia. The literature review identified 638 women. Where reported, the average prolongation of the pregnancy was 7 weeks plus 1 day. This allowed for 60% of infants (range 26% to 80%) to be born after 28 weeks, with an average neonatal survival of over 70% (range 47.2% to 96%). Preterm premature rupture of membranes complicated an average of 29% of pregnancies (range 1% to 58%), and chorioamnionitis was reported in 5% to 80% of pregnancies.

The KGH data collected and the data available in the literature suggest that emergency cerclage, under ideal circumstances, can significantly prolong pregnancy and increase the chance of viable pregnancy outcome. However, in counselling women about the potential therapeutic benefit of emergency cerclage, the increased risk of chorioamnionitis and its associated risk of fetal inflammatory brain injury, as well as the risk of extending a pregnancy from pre-viability to severe prematurity, should be discussed. A longer-term follow-up than has been carried out here is required for better elucidation of the effect of chorioamnionitis on those infants in childhood and beyond.