Fetal ovarian cyst decompression to prevent torsion.

Background/purpose: Neonates who have ovarian torsion caused by an ovarian cyst often lose their ovary because the torsion and infarction occurred antenatally. Because ultrasound scan has been so effective in diagnosing ovarian cysts in utero, we have a better understanding of their natural history and can select appropriate cases for cyst decompression in utero to prevent torsion. The authors reviewed experience with seven fetuses who had fetal ovarian cyst.

Methods: During a 26-month period, seven patients were referred for the evaluation of fetal ovarian cyst. The mean gestational age at presentation was 31.9 +/- 3.6 weeks (+/-SD; range, 27 to 37 weeks). There was no history of maternal risk factors such as diabetes mellitus or fetal risk factors such as hyperthyroidism or placentomegally. All seven cases involved isolated unilateral cysts without associated anomalies or chromosomal abnormalities. Mean initial cyst diameter was 3.4 +/- 1.7 cm (+/-SD; range, 1 to 6.1). Indications used for ovarian cyst decompression included anechoic cysts with a diameter > or =4 cm, a cyst "wandering" about the abdomen on serial sonograms, or demonstrating rapid enlargement (>1 cm/wk).

Results: All but one cyst progressed in size during observation. One fetal ovarian cyst (diameter, 2 cm) subsequently regressed spontaneously and another (diameter, 2.1 cm) stabilized during prenatal ultrasound surveillance. One "cyst" observed with a diameter of 3.5 cm proved to be a persistent cloaca. Four fetal ovarian cysts met criteria for decompression. Because of fetal position, decompression could not be performed in one. One cyst (seen before defining criteria for decompression) with a diameter of 5 cm was observed only and underwent torsion. Two cysts (diameters, 6.1 cm and 4 cm) were decompressed in utero under local anesthesia with ultrasound guidance, of 95 mL and 35 mL, respectively. High cyst fluid progesterone (12,041 and 1,990 ng/dL, respectively) and testosterone (1,298 and 2,900 ng/dL, respectively) confirmed the etiology of the cyst as ovarian. Neither cyst recurred, and postnatal ultrasound scan confirmed resolution. There was no maternal or fetal morbidity or mortality and only the patient observed before development of criteria for decompression lost her ovary because of torsion.

Conclusions: Fetal ovarian cysts tend to present as isolated unilateral lesions in normal fetuses in the third trimester. Spontaneous regression of fetal ovarian cysts may occur. Fetal ovarian cyst decompression, in select cases, may preserve ovaries at risk for torsion.