The finding of isolated fetal ascites has been associated with intrauterine infections (cytomegalovirus, parvovirus, syphilis, toxoplasmosis, listeria, hepatitis), upper or lower gastrointestinal obstruction, perforated bowel (meconium peritonitis), genitourinary tract abnormalities,  trisomy 21 (Down syndrome) , Turner syndrome, and early hydrops. Often the cause of the ascites is unknown.