P27.07: Intrauterine pregnancy of uncertain viability: what influences outcome of the first trimester?

Abstract

The aim was to determine variables that are associated with a higher risk of miscarriage in the 1st trimester in women with an intrauterine pregnancy of uncertain viability (IPUVI). Prospective observational study. Women in the 1st trimester of pregnancy presenting to the Early Pregnancy Unit (EPU), between Nov 2006 and Dec 2010, underwent a transvaginal scan (TVS). Data was collected from women with an IPUVI at the first ultrasound (US). More than 40 historical, clinical and US end points were recorded for analysis. US measurements included gestational sac (GS) and yolk sac (YS) in three planes, crown–rump length (CRL) and fetal heart rate (FHR). Women were followed up until the outcome was established: viable or non-viable IUP at the end of the 1st trimester. Univariate analysis to study the effect of the variables on the first trimester outcome was performed using ANOVA F-test and Fisher's exact test. 346 pregnancies were included. 45.7% (158/346) were viable at the end of the 1st trimester, 41.6% (144/346) were non-viable and 10.4% (36/346) did not have 1st trimester outcomes available. The continuous variables that were significantly associated with a higher rate of miscarriage were: higher maternal age (mean maternal age for viable pregnancies 26.9 yrs vs. mean maternal age for miscarriages 30.7 yrs, P value = 3.33E-05), higher gestational age (GA) in days by LMP (mean GA for viable pregnancies 41.9 days vs. mean GA for miscarriages 52.7 days, P value = 1.78E-12), and higher CRL (mean CRL for viable pregnancies 0.22 mm vs. mean CRL for miscarriages 0.95 mm, P = 1.91E-05). The categorical variables that were associated with a higher rate of miscarriage were: previous miscarriage, history of vaginal bleeding with clots and the presence of a CRL at first scan. The rate of miscarriage in our IPUVI population was high. We have identified 7 variables, which can be established at the first visit to the EPU that were associated with an increased risk of miscarriage in that group.