Catamenial pneumothorax (CP) is defined as recurrent pneumothorax (at least two episodes) occurring between the day before and within 72 hours after the onset of menstruation. It may represent up to one-third of women with spontaneous pneumothoraces1. It is encountered in 3-6% of spontaneous pneumothorax cases among menstruating women2. There is right side preponderance3, 4, 5. It usually involves the right-side (85-95%) and can be left-sided or bilateral2. It is associated with diaphragmatic perforations and/or thoracic endometriosis2.
Thoracic endometriosis syndrome (TES) is the presence of endometrial tissue in or around the lung. Although endometriosis in general can affect up to 15% of women in their reproductive years, TES remains an exceedingly rare condition6, 7.
TES occurs almost exclusively in the right hemithorax (approximately 95% of cases) 8, 9. Although congenital diaphragmatic hernias are far more common on the left side, congenital diaphragmatic defects, particularly fenestrations, are known to occur more commonly on the right, leading to the right-sided predominance of TES10.
CP is responsible for only 2.5% to 5% of cases of women with spontaneous pneumothorax 11, 12 even though it accounts for 73% of the cases of TES6. The first case of CP was described by Maurer et al13 in 1958, but the term catamenial pneumothorax was not introduced until 1972.14 CP is typically defined as spontaneous and recurrent pneumothorax occurring within 72 hours from the onset of menstruation.8, 11 According to Karpel et al, 15 the number of recurrent pneumothoraces can range from 2 to 42 per patient.
Three theories have developed to explain this entity. The first is trans diaphragmatic passage, or movement, of air from the vagina to the peritoneum via the fallopian tubes,
and subsequently to the thorax via diaphragmatic fenestrations. This is thought to occur during the menstrual cycle when the cervical mucus plug is absent.5, 7, 13. The
second is air leakage triggered by sloughing of the endometrial implants located on the pleura.5, 7 The third proposes a hormonally mediated mechanism in which high levels of prostaglandin from thoracic endometrial implants cause vascular and bronchiolar vasoconstriction, leading to ischemic injury and ultimately causing alveolar rupture and
subsequent air leakage.5 Another theory that has been proposed as a cause of catamenial pneumothorax is the spontaneous ruptures of blebs.
Whenever a female patient in reproductive age group present with chest pain or recurrent pneumothorax; it's worthwhile to take elaborated mensuration history and evaluate for catamenial pneumothorax.