Thoraco-Omphalopagus Conjoined Twins Associated with Omphalocele and an Umbilical Cord Cyst

Abstract

A 27-year-old primigravid woman was referred for sonographic examination at 19 gestational weeks because of suspected fetal abnormalities. The parents involved in this pregnancy were unrelated, and there was no history of diabetes mellitus, twinning or congenital malformations. The mother denied any exposure to drugs for ovulation prior to conception, and to teratogenic medications, irradiation or infectious diseases during the pregnancy. Sonographic examination performed at 19 gestational weeks revealed conjoined twins. The amniotic fluid volume was normal. The fetal biometry of both twins was consistent with the menstrual age. The twins were united face-to-face from the upper thorax down to the umbilicus, with associated omphalocele at the umbilical cord insertion. There was a 3 × 4 cm umbilical cord cyst around the omphalocele (Figure 1). The twins shared a common heart, liver and the anterior chest wall. The parents opted to terminate the pregnancy. The thoraco-omphalopagus conjoined twins, weighing 460 g, were delivered. Chromosome analysis revealed a karyotype of 46,XX. Autopsy confirmed the diagnosis of thoraco-omphalopagus. The twin fetuses shared a common sternum, heart, spleen, liver, diaphragm, pericardium and upper abdominal wall, with associated omphalocele and an umbilical cord cyst (Figures 2 and 3). Conjoined twinning is a rare congenital malformation that occurs in 1 in every 100 sets of monozygotic