Catamenial Pneumothorax

Five cases of a bizarre syndrome of recurrent right-sided pneumothorax occurring in women only at the time of menstrual flow are compared with 15 previously reported cases. Intrathoracic endometrial implants have been demonstrated in some instances, and pelvic endometriosis probably occurs in most cases even if there is no clinical evidence of pelvic disease. Administration of ovulation-suppressing hormones usually prevents the development of catamenial pneumothoraces, but the attacks recur when the drugs are discontinued. The pathogenesis of the pneumothorax is not understood. Leakage of air from the lung due to subpleural endometrial implants seems to be the most plausible explanation. Another theory suggests that air enters the peritoneum through the genital tract during menstruation and then passes through congenital perforations in the right hemidiaphragm to result in a pneumothorax.