Prenatal and postnatal evolution of isolated fetal splenic cysts.

Objectives: The aim of this study was to evaluate the prevalence, the prenatal, and postnatal evolution of isolated fetal splenic cysts.

Methods: All cases of suspected fetal splenic cyst or abdominal unidentified cyst discovered during routine ultrasound scan, from 2007 to 2017, and referred to a French tertiary care center, were retrospectively collected. For each case, several prenatal parameters and postnatal evolution were reported.

Results: Among 5450 cases of fetal anomalies, 14 patients (0.3%) had a prenatal diagnosis of fetal splenic cysts. Median gestational age at diagnosis was 30.1 weeks. A unique cyst was present in 78.6%, whereas 2 cysts were observed in 14.3% and 3 cysts in 7.1%. During the pregnancy, cysts remained the same (78.6%) or disappeared (21.4%). Ultrasound scans at 6 months of age found total disappearance of the cysts (36.4%), spontaneous reduction from 2 to 1 cyst (18.2%) or persistence of the cysts (45.4%).

Conclusion: Fetal splenic cysts are rare images, always isolated, usually unique and mainly found during third trimester of pregnancy. Their evolution is to disappear spontaneously during pregnancy or at 6 months of age leaving only half of them to remain beyond that age but without any symptoms.