Fetal Ascites

Causes of fetal ascites (urine, meconium, bile, blood, or pus) include:

• Urinary obstruction: Leading to urinary tract perforation and leakage of urine.
• Hydrops: Presence of at least two abnormal fetal fluid collections (pleural effusion, pericardial effusion, ascites, or subcutaneous edema).
• Chromosomal abnormality: Most commonly trisomy 21.
• Infection: Presence of a thick placenta with fetal ascites and anasarca suggests infection from syphilis or cytomegalovirus.
• Gastrointestinal atresia/obstruction: Meconium peritonitis from bowel rupture. Look for intraabdominal masses, bowel dilatation and intraabdominal calcifications.
• Cardiac issues: For example, congestive heart failure.
• Fetal trauma: Look for presence of abruptio placentae to suggest abdominal trauma.
• Pseudoascites: Due to hypoechoic abdominal wall muscles. The "fluid" does not extend beyond the anterior margin of the ribs.

References

• Akduman EI, Luisiri A, Launius GD. Fetal abuse: a cause of fetal ascites. AJR Am J Roentgenol. 1997 Oct;169(4):1035-6.
• Fleischer AC, Killam AP, Boehm FH, Hutchison AA, Jones TB, Shaff MI, Barrett JM, Lindsey AM, James AE Jr. Hydrops fetalis: sonographic evaluation and clinical implications. Radiology. 1981 Oct;141(1):163-8.
• Hashimoto BE, Filly RA, Callen PW. Fetal pseudoascites: further anatomic observations. J Ultrasound Med. 1986 Mar;5(3):151-2.
• Rosenthal SJ, Filly RA, Callen PW, Sommer FG. Fetal pseudoascites. Radiology. 1979 Apr;131(1):195-7.
• Zelop C, Benacerraf BR. The causes and natural history of fetal ascites. Prenat Diagn. 1994 Oct;14(10):941-6.