Outcome of first-trimester fetal abdominal cysts: cohort study and review of the literature.

OBJECTIVES: The aims of this study were to ascertain the outcome of fetuses with an abdominal cyst detected at 11-14 weeks' gestation in our unit and to undertake a review of cases reported in the literature.

METHODS: This was a retrospective study that included all fetuses found to have an abdominal cyst on ultrasound examination at 11-14 weeks, identified over a 14-year period. Pregnancy management and outcome were ascertained from maternal and neonatal records. We also performed a review of the literature using a systematic search strategy, to identify the outcome of similar cases and propose a management algorithm.

RESULTS: Fourteen cases were identified during the study period, of which four had associated abnormalities. Of the 10 isolated cases, the cyst had resolved at follow-up scan in eight (80.0%), one fetus died in utero at 15 weeks' gestation and the other case underwent surgery for a choledochal cyst 9 weeks after birth. An additional 19 cases were reported in the literature. In eight fetuses there were associated structural abnormalities, of which four had a diagnosis of anorectal malformation after birth. In two of these four, the cyst resolved in the second trimester. Of those cases with an isolated cyst (n = 11), the cyst resolved in seven (63.6%). The remainder were variably diagnosed as hepatic cyst, ileal duplication or choledochal cyst.

CONCLUSION: Fetal abdominal cysts at 11-14 weeks' gestation are rare. They constitute an isolated finding in the majority of cases and are usually associated with a good perinatal outcome. In view of the reported association with anorectal and other gastrointestinal malformations, perinatal assessment is recommended, even if the cyst resolves during pregnancy.