RT Journal Article SR Electronic T1 Pleural Effusion And Hydronephrosis In A Newborn JF The Journal of the American Board of Family Practice JO J Am Board Fam Med FD American Board of Family Medicine SP 55 OP 57 DO 10.3122/jabfm.2.1.55 VO 2 IS 1 A1 Sharon D. Lee YR 1989 UL http://www.jabfm.org/content/2/1/55.abstract AB While the association of obstructive uropathy with ascites has been known since 1863, and with pleural effusion since 1954, the latter combination remains rare. This case report describes a male newborn with a massive left pleural effusion that was caused by same-sided hydronephrosis from obstructing posterior urethral valves. The effusion disappeared within a few days after adequate urinary drainage was established, and the infant has remained well since the abnormal urethral valves were fulgurated cystoscopically. Review of the clinical and experimental literature reveals no consensus about how pleural fluid accumulates in the presence of obstructive uropathy, and this neonate showed a direct inverse relation between the amount of pleural fluid drainage and urinary output via catheter. Hydronephrosis should be considered diagnostically when a newborn has a pleural effusion that is otherwise unexplained. (J Am Bd Fam Pract 1989; 2:55-7.)