Latency duration beyond viability in women undergoing ultrasound-indicated cerclage

Abstract

In women with short cervical length (CL< 25 mm) and prior spontaneous preterm birth (SPTB), cerclage reduces preterm & previable birth. Of women who undergo an ultrasound-indicated (USI) cerclage, approximately 5-10% will deliver prior to viability, i.e. 23 wks gestation. However, it is unknown if CL and GA at cerclage placement affect pregnancy duration beyond viability. The aim of this study is to compare pregnancy latency beyond viability by CL and GA at the time of cerclage. Secondary analysis of a multicenter cerclage trial of women with prior SPTB & mid-trimester CL< 25mm. Women who were randomized to and underwent USI cerclage and attained 23 wks gestation comprised the study sample. The primary outcome is latency (wks) beyond 23 wks gestation in those with CL < 15mm vs CL 15-24 mm at cerclage placement, and similarly in those ≤ 18 wks vs > 18 wks at cerclage. Secondary outcomes are births < 32 wks, < 37 wks and perinatal death. Of 138 eligible women, 132(95.6%) reached viability: 34 with CL < 15mm & 98 with CL 15-24 mm at cerclage. Maternal age, BMI, race, marital status, cigarette use, drug use, number of prior preterm births, GA at first scan, GA at randomization were similar between the CL groups. Women with CL < 15mm at cerclage differed in GA of earliest prior delivery (p=0.03), and in years of education (p=0.04), Table 1. Latency beyond 23 wks gestation was similar in both CL groups (< 15 mm: 12.4±5.0 wks vs 15-25 mm: 12.9±4.2 wks), p=0.60, Table 2. 30 women underwent cerclage ≤ 18 wks and 102 > 18 wks gestation. Latency was similar in the GA groups (≤ 18 wks: 12.0±4.4 wks vs > 18 wks: 12.0±4.4 wks), p=0.30, Table 2. Results were consistent after controlling for education and GA of earliest prior birth. The CL & GA groups also had similar rates of birth < 32 wks gestation, < 37 wks gestation and perinatal death. In women with prior SPTB who undergo USI cerclage for short CL and reach viability, neither CL nor GA at cerclage affect pregnancy latency or rates of PTB and perinatal death.View Large Image Figure ViewerDownload Hi-res image Download (PPT)