Alimentary tract duplication cysts are rarely diagnosed in utero. We report
two fetal patients that presented with intrathoracic alimentary tract dupl
ication cysts, mediastinal shift and hydrops. In one fetus, the cyst contin
ued into the fetal abdomen and pelvis through a left diaphragmatic hernia.
Despite successful ultrasound-guided needle aspirations in both fetuses, th
ere was rapid reaccumulation of the fluid and recurrence of the mediastinal
shift, prompting the placement of a thoracoamniotic shunt. In one fetus, t
here was rapid resolution of the mediastinal shift with the disappearance o
f the hydrops within 2 weeks. The second fetus suffered an intrauterine dem
ise 2 days after the shunt placement. Postnatal resection in the surviving
infant revealed a large cyst consistent with an intrathoracic duplication o
f the stomach. The autopsy of the second fetus revealed an intrathoracic du
plication cyst of the stomach and proximal small intestine.