Supplementary Material for: Differences in Origin and Outcome of Intra-Abdominal Cysts in Male and Female Fetuses

Objective: To investigate the origin and outcome in a cohort of male and female fetuses with intra-abdominal cysts, in order to provide recommendations on management and to improve prenatal counselling. Methods: From 2002 to 2016, intra-abdominal cysts were detected by ultrasound in 158 fetuses. Cases with an umbilical vein varix were excluded. Fetal, neonatal, and maternal characteristics were retrieved from electronic patient files. Results: In female fetuses (n = 114), intra-abdominal cysts were diagnosed at a later gestational age compared with male fetuses (n = 44) (median 32.0 vs. 21.5 weeks, p < 0.001). The maximum prenatal cyst diameter was larger in female fetuses (median 35 vs. 17 mm, p < 0.001). Associated anomalies were less frequent in females (n = 15, 13.2%) compared with males (n = 15, 34.1%). In females (n = 114), most cysts were of ovarian origin (n = 81, 71.1%). Surgery was performed in 30 (26.3%) female and 15 (34.1%) male neonates (p = 0.33). Anorectal malformations were present in 6 cases and often not recognized prenatally. Conclusions: The differences in the origin of intra-abdominal cysts between male and female fetuses, resulting in differences in prenatal presentation and postnatal outcome should be taken into account in prenatal counseling within a multidisciplinary team. Evaluation of the fetal perianal muscular complex is indicated.