The importance of fluid analysis in fetal intra‐abdominal cyst aspiration

The importance of fluid analysis in the evaluation of intraperitoneal cysts in female fetuses is demonstrated. Case 1: A 30‐year‐old woman had an unremarkable pregnancy until 29 gestational weeks, when a routine US examination revealed an anechoic cyst of 4.0 cm in diameter located in the lower abdomen of a female fetus. At 33 weeks of gestation the cyst enlarged to 6.5 cm. Intrauterine aspiration of the cyst was performed. A volume of 75 mL of yellow fluid was obtained and collapse of the cyst was noted. Fluid biochemistry revealed estradiol >200000 pg/mL, progesterone 1648 ng/mL, creatinine undetectable. A fetal ovarian cyst was diagnosed. At 34 weeks of gestation the cyst enlarged again to 6 cm and 78 mL of yellow fluid was obtained on intrauterine aspiration. Again, collapse of the cyst was noted on US. Repeated scans until birth showed an anechoic cyst of 4.0 cm. Postnatal abdominal US confirmed the diagnosis and a complete disappearance of the cyst after 2 weeks. Case 2: A 28‐year‐old woman had an unremarkable pregnancy until 34 gestational weeks, when a routine US examination revealed an anechoic cyst of 6.0 cm in diameter located in the lower abdomen of a female fetus. Intrauterine aspiration of the cyst was performed. A volume of 147 mL of yellow fluid were obtained and collapse of the cyst was noted. Fluid biochemistry revealed estradiol 781 pg/mL, progesterone 37 ng/mL, and creatinine 4 mg/dL. An unusual urinary tract malformation was diagnosed. Repeated scans until birth showed an anechoic cyst of 6 cm. After delivery a fistula between the urinary bladder and the upper vagina, and an imperforated hymen, were diagnosed. In cases of prenatal needle aspiration, fluid biochemistry may be helpful to establish the origin of intraperitoneal cysts in the female fetus, especially when recurrence occurs, and prevent unnecessary attempt of decompression of intraperitoneal cysts.