Hydrothorax in the presence of ascites is a serious condition, but it is not well studied, particularly in pediatrics. We aim to identify risk factors for having hydrothorax, compare morbidity and mortality, and report the prevalence of hepatic hydrothorax and non-hepatic hydrothorax in pediatric patients with diagnosis of ascites and hydrothorax.

This is a retrospective study of pediatric patients under 22 years of age with both ascites and hydrothorax. Hydrothorax was categorized into hepatic and non-hepatic hydrothorax. Demographic data and clinical data including ascites grade, ascites etiology, treatments, length of stay, and death were collected and analyzed using logistic regression.

We identified 120 patients with ascites and hydrothorax, 63 (53%) being female. The median age was 13 years (IQR: 4–18). Patients 6 years of age or older (OR=1.90; 95% CI=1.16–3.17; p = 0.012), patients with higher grades of ascites (OR=1.77; 95% CI=1.27–2.47; p < 0.001), those treated with furosemide (OR=2.27; 95% CI=1.37–3.76; p = 0.001), and those with hepatorenal syndrome (OR=4.22; 95% CI=1.19–15.63; p = 0.025) had increased risk of hydrothorax. The underlying etiology of ascites was not associated with mortality, but it was associated with length of stay (p = 0.013), with veno-occlusive disease being the largest contributor. Hepatic versus non-hepatic hydrothorax was also not found to be associated with mortality, but length of stay was significantly greater in former (23 days; IQR=13–38) compared to the latter group (14 days; IQR=8–26) (p = 0.009).

With pediatric ascites, there are  certain risk factors that are associated with having hydrothorax, and ascites etiology may be associated with morbidity.