FIGURE 3.

Hypothesized pathogenesis of catamenial pneumothorax (CP) and endometriosis‐related pneumothorax (ERP). A, The clockwise flow of peritoneal fluid containing endometrial cells reaches the right subdiaphragmatic area, while the peritoneal fluid is deviated away from the left hemidiaphragm due to obstruction by the falciform ligament of liver and sigmoid colon. Endometrial cells, which have reached the right hemidiaphragm, adhere to the surface of right hemidiaphragm or migrate into the thoracic cavity through congenital or acquired fenestration in the diaphragm. B and C, Several hypotheses have been proposed regarding how air enters the thoracic cavity. B, Transdiaphragmatic passage of air theory. In this theory, air passes from vagina and uterus into peritoneal cavity through the fallopian tubes. Subsequently, this air enters into thoracic cavity through the diaphragmatic defects, which is congenital or secondary to diaphragmatic endometriosis. C, The visceral pleural and/or superficial parenchymal endometriotic lesion causes the alveoli to rupture and air to flow from the lungs into the thoracic cavity