The disease is believed to be largely undiagnosed or misdiagnosed, leaving the true frequency unknown in the general population.

[4] Thoracic endometriosis is the most common non-abdominal site of involvement and is also the primary risk factor for catamenial pneumothorax.

[5] Catamenial pneumothorax is the primary clinical presentation of thoracic endometriosis, and is defined as recurrent episodes of lung collapse within 72 hours before or after menstruation.

In the anatomical model, researchers believe that the absence of the cervical mucous plug, which is normally there during the menstrual cycle, allows air to pass from the genital tract to the pleural space through fenestrations in the diaphragm.

Generally the parietal pleura is involved, but the lung itself, the visceral layer, the diaphragm, and more rarely the tracheobronchial tree may also be afflicted.

Nearly 90% of cases occur on the right hemithorax, a phenomenon thought to potentially be due to the direction of flow of retroperitoneal fluid.

[9][10] Defects in the diaphragm, which are found often in affected individuals, could provide an entry path, as could microembolization through pelvic veins.

Endometrial cells undergo structural changes during the secretory phase of the menstrual cycle, in a process called decidualization.

[11] Diagnosis can be hinted by high recurrence rates of lung collapse in a woman of reproductive age with endometriosis.

Surgery may be used to excise endometrial tissue from the lungs and pleural space as well as repair damage and holes in the diaphragm.

[15] Pleurodesis may also be effective in removing the space between the lung and the chest wall; preventing air build up between these layers.

Oral contraceptives appear to be preferable for patients due to fewer negative side effects than treatment with GnRH agonist therapy, which can lead to hypoestrogenic effects including osteoporosis, resulting in discontinuation of therapy and thus a higher likelihood of recurrence of catamenial pneumothorax.