Meconium peritonitis occasionally occurs as a localized, encysted collection of meconium ranging from a few centimeters in size to huge cysts occupying most of the abdominal cavity. The cyst wall consists of fibrous granulation tissue and the cyst may contain only meconium or may also encase loops of bowel. Gas within the cyst indicates persistent communication between the perforated bowel and the cyst cavity; if the perforation seals over in utero the cyst remains gasless. Calcification is a variable finding. Sonography in two neonates with cystic meconium peritonitis showed well-defined, echogenic masses, one of which contained calcifications and was detected in utero.

Ultrasound has proven to be a useful tool in the diagnosis of fetal These abnormalities may exist with intrauterine fetal demise. The characteristic sonographic findings in one of these anomalies, cystic hygroma, have been previously d e~c r i b e d .~-~ This anomaly is often associated with Turner's syndrome. We report a case of cystic hygroma seen at sonography in a fetus with Noonan's syndrome.' CASE HISTORYA 24-year-old primagravida at 22 weeks gestational age by dates was referred to MageeWomens Hospital for delivery of an intrauterine fetal demise. The patient had felt no fetal movement for 3 weeks and the uterus was small for dates.Sonography on admission showed a single fetus with a BPD equivalent to 15 weeks gestation. Neither fetal motion nor cardiac activity was seen. A large septated cystic mass (Fig. 1) projected posteriorly from the head and neck. Fetal ascites and generalized subcutaneous edema were present (Fig. 2). The impression was intrauterine fetal demise with findings suggesting a cystic hygroma.Labor was induced by Pitocin and shortly thereafter the patient delivered a 210-g stillborn male. A t autopsy there were cystic hygromas in the neck and left axilla, a small chest, lymphangiectasia, hypertelorism, low-set ears, webbed neck, broad nasal base, coarctation of the aorta, and a hypoplastic left heart with a ventricular septa1 defect and a persistent left inferior vena cava. The testes were undescended but otherwise normal. No myelomeningocele was present. A From the

No abstract