ABSTRACT
Isolated cystic lesions are quite common and are usually considered benign. Their relationship to the fetal bladder usually gives a clue to their origin. Cystic lesion supero-lateral to the fetal bladder is suggestive of an ovarian cyst in a female fetus. In either sex, it could represent a mesenteric cyst or an intestinal duplication cyst. The occurrence of a cyst posterior to the bladder should raise the possibility of an anterior meningocele or hydrometrocolpos. Rarely, the cyst may be seen totally unrelated to the bladder and in the upper abdomen. If these are in the right side, one should consider a benign liver cyst if the gallbladder is visualized and appears normal. The lack of an imageable gallbladder, especially on repeated scanning, suggests a choledochal cyst, which has more serious implications, such as associated biliary atresia. Additional features such as echogenic bowel or ascitic fluid collection indicates meconium peritonitis and the prospective parents should be offered screening for cystic fibrosis.
