Cystic colon duplication as differential diagnosis to ovarian cyst.

<bold>Objective: </bold>We report the case of a female fetus with a single spherical anechoic cyst on the right side of the lower abdomen first diagnosed at 22 weeks of pregnancy. <bold>Methods: </bold>Serial ultrasound monitoring and needle aspiration of the cyst were performed. <bold>Results: </bold>The cyst grew during pregnancy up to 8 cm diameter. Needle aspiration was performed at 33 and 36 weeks. At 38 weeks labor was induced and a girl was delivered spontaneously. Postnatally the child showed abdominal distention, vomiting, and an obstruction of venous return of the right leg. To improve venous circulation, another needle aspiration of the cyst was performed. Laparoscopy revealed cystic colon duplication. <bold>Conclusions: </bold>Prenatal differentiation of a single round anechoic cyst in the pelvis of a female fetus can be difficult. As a rare abnormality cystic colon duplication has to be considered. [ABSTRACT FROM AUTHOR]