FIGURE 4.

Comparison of hypothesized pathogenesis of catamenial pneumothorax or endometriosis‐related pneumothorax (CP/ERP) and catamenial hemoptysis (CH). A, The clockwise flow of peritoneal fluid containing endometrial cells reaches the right subdiaphragmatic area. Endometrial cells implant on the diaphragmatic surface or enter the thoracic cavity through the defects. B, Intrapulmonary endometriosis, which causes catamenial hemoptysis, is developed by lymphatic or hematogenous microembolization of endometrial cells