Antenatal course and clinical outcomes of fetal intra-abdominal cystic lesions: a single tertiary center experience.

Fetal intra-abdominal cystic lesions are relatively common. The morphological assessment of the cyst, determination of the fetal sex, and evaluation of its relationship with adjacent structures can guide the differential diagnosis. The aims of this study were to evaluate the diagnostic accuracy of ultrasound in detecting fetal intra-abdominal cysts and to develop a predictive model for spontaneous regression or persistence.We retrospectively reviewed 61 fetuses with intra-abdominal cystic lesions between October 2020 and November 2024. Maternal-fetal characteristics, ultrasonographic features of cystic lesions, and postnatal outcomes were collected. A total of 61 fetuses with intra-abdominal cysts were analyzed. Spontaneous regression occurred in 15 cases (24.6%) during the prenatal period, while 46 (75.4%) persisted postnatally. Mean cyst size was 24.1 mm (+/- 11.2) in the regression group and 40 mm (- 16.5) in the persistent group. Cysts that regressed were diagnosed at a median of 25 weeks, whereas persistent cases were diagnosed at 30 weeks. In univariate logistic regression analyses, gestational age at diagnosis and initial cyst diameter were identified as significant predictors of spontaneous prenatal regression (p=0.006, 0.003, respectively). Prenatal US is an effective tool to accurately diagnose fetal intra-abdominal cysts. The combination of a lower gestational age at diagnosis and a smaller initial cyst diameter is associated with a higher likelihood of spontaneous prenatal regression. An evaluation based on gestational age at diagnosis and ultrasound characteristics with a primary focus on the largest diameter of the cystic lesions may help to guide parental counseling.