P27.03: Outcome of the 1st trimester of intrauterine pregnancies of uncertain viability (IPUVIs)

Abstract

To determine the first trimester outcome in women classified with an IPUVI at the primary scan. Prospective observational study. All pregnant women presenting to the Early Pregnancy Unit, between Nov 2006 and Dec 2010, underwent a transvaginal scan (TVS). Data was collected from all women classified with an IPUVI at 1st TVS. An IPUVI was defined if there was an empty gestational sac of < 20 mm diameter; a gestational sac with a yolk sac, but no CRL; or a gestational sac, a yolk sac, and a CRL of < 6 mm with no detectable fetal heart rate (FHR). The women were followed up until the outcome was established: viable or non-viable pregnancy at the end of the 1st trimester. 346 women were classified with an IPUVI. 276/346 (79.8%) women had no CRL seen at the first scan, 67/346 (17.9%) had a CRL of < 6 mm. For 297/346 (85.8%) IPUVIs the 1st trimester outcome was known. 154/297 (51.9%) were viable and 143/297 (48.1%) had a miscarriage. Of those IPUVIs which had no CRL on the first scan, 55.9% had a viable pregnancy and 44.1% had a miscarriage. The IPUVIs which had a CRL of < 6 mm with no FHR at the first TVS, 36.1% were viable and 63.9% were non viable at the end of the first trimester. In our study population the rate of miscarriage in the IPUVI group was high, especially in the subgroup that had a small CRL with no FHR demonstrated at the first scan. We are currently developing a model to predict the outcome of the first trimester for IPUVIs.