We retrospectively reviewed 27 cases of omphalocele and 15 cases of gastroschisis occurring among 62, 572 deliveries between 1987 and 1994. All cases had undergone prenatal sonographic examinations at a mean gestational age of 28 weeks. In cases of omphalocele, 59.3% (16/27) of fetuses were associated with multiple malformations and 16% (4/25) had chromosomal abnormalities. Among the 4 cases with an abnormal karyotype, three cases were associated with extracorporeal livers and two cases were associated with umbilical cord cysts. Prenatal ultrasound examinations during the second and third trimesters were able to detect 66.7% (18/27) of the cases of omphalocele and 66.7% (10/15) of the cases of gastroschisis. Failure in correctly diagnosing abdominal wall defects by prenatal ultrasound occurred mostly in cases associated with small defects, ruptured omphalocele, multiple fetal anomalies, intrauterine fetal death, twin pregnancies, or cases referred in late gestation. A comparison of perinatal data between omphalocele and gastroschisis reveals fetuses with omphalocele carry higher risks of associated malformations, chromosomal abnormalities, prematurity, and neonatal death. Although fetuses with gastroschisis have higher incidences of oligohydramnios and small for gestational age, the fetal prognosis after pediatric surgery is good.

Amniocentesis is a better method for cytogenetic evaluation of fetal cystic hygroma associated with intrauterine fetal death than postmortem chorionic villus sampling and cystic hygroma paracentesis. However, in the case with a living hydropic fetus and oligohydramnios, cystic hygroma paracentesis appears to be a practical alternative for cytogenetic assessment.

The umbilical cord cysts most commonly associated with omphaloceles are pseudocysts and allantoic cysts. Among our three cases and the six other cases published in the literature, four out of these nine cases were trisomy 18. Prenatal diagnosis of omphaloceles or umbilical cord cysts by ultrasound warrants cytogenetic analysis and detailed sonogram to rule out the possible combination of both abnormalities and trisomy 18. If an omphalocele is associated with a large umbilical cord cyst and a normal karyotype, cesarean section is recommended to prevent the dilemma of intrauterine vascular compromise of umbilical blood flow during labor.

We report the prenatal diagnosis, pathology, cytogenetics, and molecular studies of a retroperitoneal fetus in fetu. Prenatal ultrasonography of the host fetus in the third trimester showed an anencephalic, acardiac mass with identifiable extremities and spine within an intra-abdominal cystic mass. Pathological examination revealed a fetiform mass weighing 20 g with four extremities, digits, vertebral bodies, an oral cavity with developing teeth, primitive male external genitalia, a urinary bladder, a cloaca with an external opening, large intestines, a membranous capsule, and an umbilical cord with one artery, one vein, and Wharton's jelly. Histological examination demonstrated nerve bundles in the fibrocollagenous tissue below the cuboidal surface epithelium of the membranous capsule, and absence of lamina elastica interna and vasa vasorum in the single artery of the umbilical cord. Both the host infant and the fetus in fetu had a normal 46,XY karyotype. Molecular analysis using informative genetic markers showed no genetic difference between the host infant and the fetiform mass. We report this case as an unusual example of fetus in fetu in co-existence with an amnion-like membrane containing nerve bundles and with a well-formed umbilical cord. We demonstrate that fetus in fetu can be diagnosed prenatally if the fetiform mass has well-developed limbs and spine. We emphasize the necessity for suspicion of fetus in fetu when a well-defined encapsulated cystic mass with calcified solid components is detected prenatally in a fetus by ultrasonography.

Omphalocele-Exstrophy-Imperforate anus-Spinal defects (OEIS complex), a combination of omphalocele, exstrophy of the bladder, an imperforate anus and spinal defects, arises from a single localized defect in the early development of the mesoderm that will later contribute to infraumbilical mesenchyme, cloacal septum, and caudal vertebrae. In this report, we document the perinatal features of two cases of OEIS complex associated with meningomyeloceles and severe lower limb defects, and discuss the prenatal diagnosis, inheritance, and differential diagnosis of this association of malformations. Although long-term survival can be achieved by successful corrective surgery, the associated structural defects such as large meningomyelocele and severe limb aplasia or hypoplasia, as seen in our patient, can influence the patient's quality of life. We would like to emphasize that an accurate prenatal diagnosis of OEIS complex and associated malformations is important for the detailed counseling of the family as well as appropriate perinatal management by the obstetricians, pediatric surgeons, urologists, neurosurgeons, and neonatologists.