Fetal disruptions: assessment of frequency, heterogeneity, and embryologic mechanisms in a population referred to a community-based stillbirth assessment program.

The Wisconsin Stillbirth Service Project (WiSSP) is a community-based program for the investigation of the cause of fetal death. From its inception in 1983 through July 1988, 629 referrals were made to WiSSP. All referrals were assessed for the presence of disruptional characteristics, and 23 were found to have major or primary disruptive effects. Most of these were either early amnion disruption/limb-body wall disruption (treated as a single group, since analysis suggests a continuum of clinical characteristics) and twin-twin disruptions. Therefore, disruptions accounted for 3.6% of all referrals (including liveborn and miscarriage referrals) to WiSSP. When only stillborn fetuses are considered, approximately 2.4% appear to have died because of disruptions. This makes disruptions one of the most frequent, identifiable causes of late intrauterine death. We estimate that 0.6-1.4% of all stillborn fetuses die because of early amnion disruption/limb-body wall disruption which, when taken with previous estimates of the frequency of such problems in early miscarriages and liveborn infants, suggests that these disruptions result in a 95% prenatal mortality rate. We suggest a unified model of likely pathogenetic mechanisms which may help explain the continuum of multisystem involvement seen in those with early amnion disruption/limb body wall disruption. In addition, 3 patients with atypical disruptions are reviewed who exemplify the difficulty and importance of differentiating disruptional and malformational processes.