Fetal midgut herniation into the umbilical cord: improved definition of ventral abdominal anomaly with the use of transvaginal sonography.

The most common anomalies of the fetal ventral abdominal wall include omphalocele and gastroschisis. Umbilical cord hernia is another abdominal wall defect that is poorly defined and usually mistakenly considered as a small omphalocele. The present report describes the sonographic features and clinical significance of four cases of umbilical cord hernia identified transvaginally in the early second trimester of pregnancy. These cases seemed to present a different entity from that of simple omphalocele. The transvaginal sonographic approach provided a clear image of the midgut protruding into the umbilical cord, precise localization of cord insertion in the region of the umbilical ring. Doppler flow evaluation of the umbilical vessels and their relation to the protruding mass. Serial sonographic observations revealed a stable umbilical cord mass in three fetuses, and an enlarging mass in one. Normal karyotype was determined and no associated malformations were detected prenatally. However, in one case that underwent immediate correction of the hernia after delivery at term, the neonate was subsequently found to have pulmonic stenosis and severe neonatal seizures developed at 4 months of age. In two cases, pregnancy was terminated due to parental request. The fourth fetus was delivered vaginally at term and catastrophic division of the umbilical cord containing a loop of small intestine was avoided only by the diligent observation of the midwife. We suggest that umbilical cord hernia is a distinct anomaly originating at a different stage of embryogenesis, thereby having a unique clinical significance, unlike simple omphalocele. Umbilical cord hernia should therefore be defined and considered as a separate entity.