First-trimester, three-dimensional transvaginal ultrasound volumetry in normal pregnancies and spontaneous miscarriages

Abstract

The aim of this study was to perform three-dimensional ultrasound volumetry of intrauterine contents in cases of normal and failed pregnancies and correlate these with conventional two-dimensional measurements. This was a cross-sectional observational study. Three-dimensional volumetric data were collected from a total of 111 patients with first-trimester singleton pregnancies together with conventional two-dimensional measurements. A single investigator performed all ultrasound scans and volume measurements. Among 111 participants, 30 had an ongoing pregnancy and 81 had a miscarriage (anembryonic pregnancy 30, missed miscarriage 30, and incomplete miscarriage 21). There were no significant differences in age, parity, or gestational age between groups. A positive linear correlation was demonstrable between the crown-rump length and gestational sac volume in normal pregnancies (r = 0.962) and between gestational sac volume and gestational age, but the correlation was weaker in cases of missed miscarriage (r = 0.561). The volume of the retained products of conception as measured by three-dimensional ultrasound volumetry in cases of incomplete miscarriage also showed a strong linear correlation (r = 0.938) to their maximum anterior-posterior diameter. There was an exponential correlation between the mean gestational sac diameter and gestational sac volume and the crown-rump length and embryonic volume in cases of both normal and failed pregnancies. The mean gestational sac diameter:crown-rump length ratio (P = 0.008) and gestational sac volume:embryonic volume ratio (P = 0.023) in missed miscarriages were significantly higher than those in ongoing pregnancies. Three-dimensional ultrasound volumetry of intrauterine contents in normal and failed pregnancies correlates well with conventional two-dimensional measurements. Volumetric assessment does not seem to improve the diagnosis of miscarriage. However, its potential to predict pregnancies that will fail and determine the appropriate management regime for individual patients merits further research.