Objective: The authors describe prenatal ultrasound findings of rapidly increasing cystic masses in the abdominal and pelvic region and bilateral hydronephrosis in a female foetus at 31 week of gestation. The pregnancy was terminated at 34 week of gestation. Design: Case report. Setting: Department of Pathology, University Hospital in Pilsen. Subject and method: The hydrometrocolpos (HMC) with cystoureterohydronephrosis, compression of a bowel, productive peritonitis, hypoplasia of the lungs, and malformed external genital organs were found at autopsy. Additionally, a very thick placenta showing chorangiosis was detected by ultrasound, which was confirmed by histological examination. Conclusion: The case shows the importance of prenatal ultrasound diagnosis of HMC and suggests treatment possibilities to prevent complications.

        Key words: hydrometrocolpos, genital malformations, chorangiosis of placenta, ultrasound findings, autopsy findings