A cytologic study of fetal ascites and usefulness of the differential diagnosis

Objective : Diagnostic accuracy in determining the cause of fetal ascites has improved with advances in ultrasonic techniques, on the other hand, a definitive diagnosis is not always achieved. More reliable diagnostic techniques need to be developed. We investigated the usefulness of cytological examination for fetal ascites in the early diagnosis. Study Design : Concordance among the clinical picture, cytological findings, and final diagnosis were investigated for 8 patients who were referred to our hospital with fetal ascites and underwent cytological examination, between April 2010 and September 2013. Results : Exudative ascites, meconium peritonitis, and chylous ascites were diagnosed in 1, 2, and 5 patients, respectively. The patient with exudative ascites had low levels of cell components. Patients with meconium peritonitis showed clusters of squamous epithelial cells with comparable levels of neutrophils, histiocytes, and lymphocytes. In patients with chylous ascites, squamous epithelial cells were observed in some cases ; however, they were sporadic, and lymphocytes accounted for ≥90% of the differential leukocyte count. Results of cytological examination matched the final diagnosis in all cases. Conclusion : These findings suggest that cytological examination for fetal ascites enables more reliable diagnosis than ultrasonography alone, and that it should be actively used in cases in which diagnosis proves difficult.