What Is Catamenial Pneumothorax? Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is catamenial pneumothorax?
Catamenial pneumothorax is air that enters the space between the lungs and chest wall around the time of a menstrual period, sometimes collapsing part or all of a lung, most often the right. [8] Endometriosis and hormone changes are the leading suspected causes. [8] Chest pain and shortness of breath always need medical evaluation. [8] Surgery or hormone medications can help prevent recurrence. [8]
Key takeaways
Catamenial pneumothorax is air in the chest cavity around your period that can compress the lung and sometimes collapse part or all of it, most often on the right side. [8]
Chest pain and difficulty breathing are the main symptoms, and they typically begin within a few days before or after your period starts. [8]
Endometriosis is the main suspected cause: uterine-like tissue growing in the lungs, lung linings, or diaphragm can let air into the pleural space. [8] Hormone-like prostaglandins and small diaphragm openings are other possible factors. [8]
It usually is not life-threatening, but the symptoms overlap with other serious conditions, so chest pain and breathing trouble always deserve prompt medical evaluation. [8]
Without treatment, it often keeps coming back; surgery such as VATS and pleurodesis plus hormone-regulating medications can prevent recurrence. [8]
What the research says
The right lung and the diaphragm are the usual sites, and recurrence is common after surgery. In a retrospective review of 114 women who had video-assisted thoracic surgery for spontaneous pneumothorax, 28 (24.6%) had catamenial pneumothorax, right-sided in all but one. Diaphragmatic perforations or nodules were seen in 22 of those 28, and endometriosis was confirmed under the microscope in 18 of the 28. After surgery plus 6 months of antigonadotropic treatment, recurrence over a mean follow-up of 32.7 months was 32% for catamenial pneumothorax, 27% for non-catamenial endometriosis-related pneumothorax, and 5.3% for pneumothorax unrelated to either. This was a single-center study of women referred for surgery, so it may not represent everyone with the condition (Alifano et al., Am J Respir Crit Care Med, 2007) [1].
Hormone therapy after surgery was linked to fewer recurrences. A systematic review and meta-analysis of 11 studies (111 patients) found a pooled postoperative recurrence risk of 17.3% (95% CI, 8.9% to 25.8%) with hormonal treatment, compared with 54.2% (19 of 35 patients) among those who did not receive postoperative hormonal therapy. The studies were small and observational and publication bias was detected, so the figures are suggestive rather than definitive. The authors still recommend hormonal treatment after surgery unless there are clear contraindications (Elsayed et al., Eur J Obstet Gynecol Reprod Biol, 2022) [2].
It is one part of a wider condition called thoracic endometriosis syndrome. A systematic review of 202 studies covering 592 patients found that catamenial pneumothorax was the most common presentation (68.4%), lesions were mostly in the right lung only (79.9%), and symptoms recurred after treatment in 10.1% of cases. These are pooled published case reports, so the numbers describe reported cases, not the general population (Nikolettos et al., J Pers Med, 2024) [3].
What Is Catamenial Pneumothorax?
Catamenial pneumothorax (pronounced cat-uh-MEE-nee-uhl new-mo-THOR-axe) happens when air collects in the space between your lungs and the inside of your chest wall at around the time of your period. [8] The name breaks down simply: "catamenial" means related to menstruation, and "pneumothorax" means air in the chest cavity. [7] [8]
That trapped air can surround and squeeze the lung. In some cases it collapses part or all of the lung. [8] In most people, catamenial pneumothorax affects the right lung. [8] [2]
The link between your menstrual cycle and a collapsed lung might seem mysterious, and healthcare providers are not always certain about the cause either. Explanations range from endometriosis to period-related hormone changes. [8]
The important point is that chest pain and shortness of breath always deserve a medical evaluation. While most cases of catamenial pneumothorax are not life-threatening, pneumothorax can sometimes be dangerous, and its symptoms look similar to other serious health conditions. [8]
Symptoms and Causes
What Are the Symptoms of Catamenial Pneumothorax?
Symptoms of catamenial pneumothorax include:
Chest pain
Difficulty breathing
Cough
Coughing up blood (hemoptysis)
Fast breathing or heart rate
Bluish skin, lips, or nails (cyanosis)
Symptoms usually start within a few days before or after the start of your period. [8]
What Causes Catamenial Pneumothorax?
Healthcare providers believe endometriosis is the main cause of catamenial pneumothorax. [8] Endometriosis is when tissue similar to the lining of your uterus (the endometrium) grows somewhere else in your body. If that endometrial tissue grows in your lungs, in the pleurae (the linings of your lungs and chest wall), or on your diaphragm, it can allow air to enter the space between the linings of your lungs (the pleural space). That can lead to a pneumothorax. [8] When endometriosis is confirmed as the cause, the condition is also called endometrial pneumothorax. [8]
Not everyone with catamenial pneumothorax has endometriosis. [8] Hormones and inflammation can cause body changes that affect the lungs during your period. [8] Possible contributing factors include:
What Happens When Endometriosis Spreads to the Lungs?
Endometriosis in or around the lungs can cause thoracic endometriosis syndrome. Along with pneumothorax, this syndrome can lead to blood in the pleural space (hemothorax), pulmonary (lung) nodules, and coughing up blood around the time of your period (catamenial hemoptysis). [8] [4]
A pneumothorax that happens between periods can still result from endometrial tissue growing in or around the lungs or diaphragm, even if you have never received an endometriosis diagnosis. [8]
Who Is at Risk for Catamenial Pneumothorax?
Catamenial pneumothorax is most common in people who ovulate. [8] It rarely occurs in people on hormonal birth control or during pregnancy. [8] You may be at higher risk if you or someone in your family has endometriosis. [8]
What Are the Complications?
In some cases, pneumothorax can lead to serious complications such as respiratory failure or heart failure. This is uncommon. [8] However, you should always have a healthcare provider evaluate you if you have pneumothorax symptoms, especially because those symptoms can resemble other serious health conditions. [8]
Diagnosis and Tests
How Is Catamenial Pneumothorax Diagnosed?
Providers usually diagnose catamenial pneumothorax by listening to your lungs and examining them with imaging. Imaging might include chest X-rays, CT scans, or a lung ultrasound. [8]
To help your provider pinpoint a cause, it helps to mention if you are expecting your period soon, recently started your period, or have experienced these symptoms around the time of your period before. Your provider may not be able to diagnose the exact cause without surgery or a biopsy. [8]
Management and Treatment
How Is Catamenial Pneumothorax Treated?
Pneumothorax usually gets better on its own, but you might need thoracentesis or a chest tube to reduce the air in your chest. [8]
To prevent it from happening again, your provider might recommend:
Video-assisted thoracoscopy (VATS). During this surgery, the provider can remove endometrial tissue, repair issues with the diaphragm, or close air pockets (blebs). [8]
Medications. Your provider might prescribe medications that regulate hormones, such as oral contraceptives, gonadotropin-releasing hormone (GnRH) agonists, or danazol. [8]
Pleurodesis. During surgery, the provider can attach the lung to the chest wall using chemicals or by gently scraping the pleura. [7] [8]
Hysterectomy with bilateral oophorectomy. If other treatments do not work, surgery to remove the uterus and ovaries will stop ovulation. [8]
Questions to Ask Your Healthcare Provider
Do you know what caused this?
What are my treatment options?
If I need to have a chest tube, how long will I have it?
Will I need to stay in the hospital?
How do I take care of myself at home?
How do I take this medication?
When Should You Seek Care?
Talk to your healthcare provider if you have concerning symptoms that happen around your period. Always see a provider if you are having chest pain or trouble breathing. [8]
Go to the emergency room if you have symptoms of pneumothorax, such as chest pain or difficulty breathing. These can be signs of many serious health conditions, and you may need emergency treatment. [8]
Outlook / Prognosis
What Can You Expect if You Have Catamenial Pneumothorax?
Catamenial pneumothorax is usually not life-threatening. [8] However, if it has happened once, it will often keep coming back without treatment. [8] You may need more than one type of treatment, such as surgery combined with medications, to manage it. [8]
Prevention
Can Catamenial Pneumothorax Be Prevented?
Catamenial pneumothorax usually comes back many times. [8] Depending on the cause, surgery, hormone-regulating medications, or both can prevent it from happening again. [8]
Conclusion
Catamenial pneumothorax turns a familiar monthly rhythm into something unsettling: chest pain and breathlessness arriving right on the heels of your period. The good news is that it is usually not life-threatening, the collapsed lung often heals on its own or with a simple air-draining procedure, and surgery plus hormone-regulating medications can stop the repeat episodes that so often follow a first one. The key is not to dismiss chest pain and difficulty breathing as normal period symptoms. These signs overlap with many serious conditions, and prompt evaluation keeps you safe while a provider works out the cause and a lasting prevention plan.
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Frequently Asked Questions
What is catamenial pneumothorax?
Catamenial pneumothorax is air in the space between the lungs and the inside of the chest that occurs around the time of your period. The trapped air can compress the lung and sometimes collapse part or all of it, and it most often affects the right lung. [8]
How do you pronounce catamenial pneumothorax?
It is pronounced cat-uh-MEE-nee-uhl new-mo-THOR-axe. [8]
What does "catamenial" mean?
"Catamenial" means related to menstruation, or your period. [8]
What does "pneumothorax" mean?
Can a lung collapse during your period?
Yes. In catamenial pneumothorax, trapped air can collapse part or all of the lung, most often the right lung, around the time of your period. [8]
Is catamenial pneumothorax life-threatening?
It usually is not life-threatening. However, pneumothorax can sometimes be dangerous, and its symptoms resemble other serious conditions, so medical evaluation is always needed. [8]
Why does catamenial pneumothorax happen around my period?
The timing points to causes connected to the menstrual cycle, most notably endometriosis, plus hormone and inflammation changes that affect the lungs during your period. [8]
Is endometriosis the main cause of catamenial pneumothorax?
Healthcare providers believe endometriosis is the main cause. When endometrial tissue grows in the lungs, lung linings, or diaphragm, air can enter the pleural space and cause a pneumothorax. [8]
Do all people with catamenial pneumothorax have endometriosis?
No. Not everyone with catamenial pneumothorax has endometriosis. Hormones and inflammation can also contribute. [8]
What is endometrial pneumothorax?
Endometrial pneumothorax is another name for catamenial pneumothorax used when endometriosis is confirmed as the cause. [8]
What is thoracic endometriosis syndrome?
Thoracic endometriosis syndrome is when endometriosis grows in or around the lungs. It can cause pneumothorax, blood in the pleural space (hemothorax), pulmonary nodules, and coughing up blood around your period (catamenial hemoptysis). [8] [4]
Can catamenial pneumothorax happen between periods?
Yes. Pneumothorax between periods can still result from endometrial tissue growing in or around the lungs or diaphragm, even without a prior endometriosis diagnosis. [8]
How do prostaglandins cause catamenial pneumothorax?
Prostaglandins are hormone-like chemicals that can reduce blood flow and cause air pockets in the lungs to rupture, letting air escape into the pleural space. [8]
How can air travel from the reproductive tract to the lungs?
Air can pass through small holes in the diaphragm and enter the pleural space during your period. [8]
Who is most at risk for catamenial pneumothorax?
It is most common in people who ovulate. Risk is higher if you or a family member has endometriosis. [8]
Can you get catamenial pneumothorax on hormonal birth control?
It rarely occurs in people taking hormonal birth control. [8]
Can you get catamenial pneumothorax during pregnancy?
It rarely occurs in people who are pregnant. [8]
What are the symptoms of catamenial pneumothorax?
Symptoms include chest pain, difficulty breathing, cough, coughing up blood, fast breathing or heart rate, and bluish skin, lips, or nails. [8]
When do symptoms of catamenial pneumothorax start?
Symptoms usually start within a few days before or after the start of your period. [8]
What is catamenial hemoptysis?
Catamenial hemoptysis is coughing up blood around the time of your period, and it can occur with thoracic endometriosis syndrome. [8]
Can catamenial pneumothorax affect the left lung?
It most often affects the right lung, though the condition can occur in the chest cavity on either side.
What complications can catamenial pneumothorax cause?
In some cases it can lead to respiratory failure or heart failure, though this is uncommon. [8]
Why do symptoms of pneumothorax always need evaluation?
Because pneumothorax symptoms look similar to other serious health conditions, a provider evaluation determines how serious your situation is.
How is catamenial pneumothorax diagnosed?
Providers listen to your lungs and use imaging such as chest X-rays, CT scans, or lung ultrasound. [8] Cycle timing details help point toward the cause.
What information should I give my provider about my symptoms?
Mention if you expect your period soon, recently started your period, or have had these symptoms around your period before. [8]
Can imaging alone diagnose the exact cause of catamenial pneumothorax?
Not always. A provider may need surgery or a biopsy to identify the exact cause. [8]
Does catamenial pneumothorax heal on its own?
Pneumothorax usually gets better on its own, but you might need thoracentesis or a chest tube to reduce the air in your chest. [8]
What is a chest tube for catamenial pneumothorax?
A chest tube drains the trapped air from the chest cavity so the lung can reinflate.
What is VATS surgery for catamenial pneumothorax?
Video-assisted thoracoscopy (VATS) lets the provider remove endometrial tissue, repair diaphragm issues, or close air pockets called blebs. [8]
What medications treat catamenial pneumothorax?
Providers may prescribe hormone-regulating medications such as oral contraceptives, gonadotropin-releasing hormone (GnRH) agonists, or danazol. [8]
What is pleurodesis?
During pleurodesis, the surgeon attaches the lung to the chest wall using chemicals or by gently scraping the pleura [7] [8], sealing the space where air collects.
When is hysterectomy with oophorectomy recommended for catamenial pneumothorax?
If other treatments do not work, removing the uterus and both ovaries stops ovulation [8] and can prevent recurrence.
Will catamenial pneumothorax come back without treatment?
If it has happened once, it will often keep coming back without treatment. [8]
Can catamenial pneumothorax be prevented?
Depending on the cause, surgery, hormone-regulating medications, or both can prevent it from happening again, since it usually recurs many times without intervention. [8]
When should I go to the ER for catamenial pneumothorax?
Go to the emergency room for pneumothorax symptoms such as chest pain or difficulty breathing, because these can signal many serious conditions and may need emergency treatment. [8]
Related Reading
Learn more in our guide to Pleurodesis: Chemical vs. Mechanical, Procedure, Success Rates and Recovery.
References
Alifano M, Jablonski C, Kadiri H, et al. Catamenial and noncatamenial, endometriosis-related or nonendometriosis-related pneumothorax referred for surgery. Am J Respir Crit Care Med. 2007;176(10):1048-1053. PMID: 17626909. https://doi.org/10.1164/rccm.200704-587OC
Elsayed HH, Hassaballa AS, Mostafa MH, et al. Is hormonal manipulation after surgical treatment of catamenial pneumothorax effective in reducing the rate of recurrence? A systematic review and meta-analysis. Eur J Obstet Gynecol Reprod Biol. 2022;278:141-147. PMID: 36179536. https://doi.org/10.1016/j.ejogrb.2022.09.019
Nikolettos K, Patsouras A, Kotanidou S, et al. Pulmonary endometriosis: a systematic review. J Pers Med. 2024;14(11):1085. PMID: 39590577. https://doi.org/10.3390/jpm14111085
Visouli AN, Zarogoulidis K, Kougioumtzi I, et al. Catamenial pneumothorax. J Thorac Dis. 2014;6(Suppl 4):S448-S460. PMID: 25337402. https://doi.org/10.3978/j.issn.2072-1439.2014.08.49
Kardaman N, Nizami M, Marciniak S, et al. Catamenial pneumothorax. Ann R Coll Surg Engl. 2022;104(4):e109-e112. PMID: 34825583. https://doi.org/10.1308/rcsann.2021.0164
Nguyen K, Nudelman BG, Quiros J, et al. Catamenial pneumothorax: a rare diagnosis among menstruating women. Cureus. 2023;15(9):e45769. PMID: 37872905. https://doi.org/10.7759/cureus.45769
Rahman NM. Pneumothorax. Merck Manual Professional Edition. Merck & Co., Inc.; last updated September 2026. https://www.merckmanuals.com/professional/pulmonary-disorders/mediastinal-and-pleural-disorders/pneumothorax
Cleveland Clinic. Catamenial pneumothorax. Cleveland Clinic Health Library. Last updated April 24, 2025. https://my.clevelandclinic.org/health/diseases/catamenial-pneumothorax
Medical disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.
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