Pleural fluid/serum immunoglobulin ratio is a diagnostic marker for congenital chylothorax in utero.

OBJECTIVE

To distinguish congenital chylothorax from other causes of hydrothorax in utero.

METHODS

Serum and pleural fluid samples from 8 fetuses with congenital chylothorax and 5 control fetuses with other causes of hydrothorax were tested for total protein, albumin, IgG, IgA, and IgM.

RESULTS

Fetuses with congenital chylothorax had higher levels of IgG in pleural fluid, but not the other four proteins, than control fetuses (P<0.05). There were no significant differences in serum proteins among fetuses. When we examined pleural fluid to serum ratios, the IgG ratio in fetuses with congenital chylothorax was significantly higher than that of control fetuses (P<0.05). The IgG ratio in chylothorax was greater than 0.6 regardless of lymphocyte count.

CONCLUSIONS

Pleural fluid/serum IgG ratio may be a diagnostic marker for congenital chylothorax in utero.