Relationship between Catamenial Pneumothorax or Non-catamenial Pneumothorax and Endometriosis

Study Objective: To evaluate the clinical characteristics of women presenting with catamenial pneumothorax and compare them with those with noncatamenial pneumothorax. Design: A case-control study (Canadian Task Force II-2). Setting: A multicenter study. Patients: Forty-two women with pneumothorax: 21 women had catamenial pneumothorax (study group), and 21 were age-matched women with noncatamenial pneumothorax (control group). Interventions: All patients underwent video-assisted thoracoscopy and pleural biopsy. We also evaluated the presence and stage of pelvic endometriosis in 16 women with catamenial pneumothorax who had undergone laparoscopic surgery. Measurements and Main Results: The number of known episodes of catamenial pneumothorax before treatment was between 2 and 8 episodes. Symptoms were mainly chest pain and shortness of breath; 1 patient had hemoptysis. The prevalence of right-sided pneumothorax was 95.2% in the study group and 57.1% in the control group (p =.004). Besides 2 cases with complete collapse of the right lung, most of the cases in the study group had apical pneumothorax. Pelvic endometriosis was found in 15 of 16 women (93.7%), mainly stage 3 or 4, and thoracic endometriosis in 12 of 20 women (60%). None of the patients in the control group had thoracic endometriosis. Conclusion: Thoracic endometriosis is found in over half of women with catamenial pneumothorax but absent in those with noncatamenial pneumothorax. Right apical pneumothorax is predominant in women with catamenial pneumothorax. Endometriosis plays an important role in the mechanism of catamenial pneumothorax.