Abstract： Objective:To explore the correlation between prenatal clinical data with etiological diagnosis and neonatal outcome in isolated fetal ascites.Methods:Totally, 36 pregnancy cases diagnosed as isolated fetal ascites by ultrasound in Provincial Hospital Affiliated to Shandong University from June 22nd, 2016 to September 28th, 2018 were collected. Invasive prenatal diagnosis was performed by taking fetal cord blood, amniotic fluid, and fetal ascites respectively for cytogenetics, molecular genetics and biochemical examination and the impact of intrauterine therapeutic procedures on neonatal outcomes was evaluated as well. The correlation among prenatal examination, pathogeny and prognosis was analyzed by Fisher′s exact test.Results:(1) The prognosis of isolated fetal ascites initially presenting ≥28 weeks was better than that before 28 weeks, survival rate of 1-year-old were 13/15 and 9/17,respectively, the difference was statistically significant ( P<0.05). (2) The etiologic diagnosis rate of ascites before delivery was 31%(11/36), which increased to 53%(19/36) totally after birth. Characteristics of cases which were defined prenatally were as follows: 8 cases of digestive tract diseases showed ultrasonic abnormalities, including echogenic bowel, bowel dilatation and polyhydramnios; platelet level in umbilical cord blood of fetuses infected with cytomegalovirus were below 100 × 10 9/L in 2 cases; 1 case of urinary system malformation showed megalocystis and hydronephrosis. Cases which were defined causes after birth included: 3 fetuses with chyloperitonium presented persistent fetal ascites; 3 cases of digestive-related causes were rectal duplication with infection, mesentery stenosis, and intestinal atresia; other causes included Pierre-Robin syndrome and Budd-Chiari syndrome. (3) The live birth rate was 72% (26/36) and survival rate of 1-year-old was 61% (22/36). And 9/10 of infants who underwent surgeries got good outcomes. Fetal ascites due to abdominal or pelvic factors turned well in 13/16 of cases. Conclusions:The pregnancy outcome of fetal isolated ascites depends mainly on primary causes. Gastrointestinal abnormality is one of the most common causes. Excluded intrauterine infection, chromosomal abnormality and abnormal systemic ultrasonic findings, fetus with reduced ascites as the pregnancy progresses will get good outcome.