Endometriosis is a common condition where tissue similar to the lining of the uterus, called the endometrium, grows outside the uterus. While this tissue typically implants in the pelvic region, it can rarely appear in distant locations, known as extra-pelvic endometriosis. When found in the chest cavity, it is called thoracic endometriosis (TE). TE is the most common form of endometriosis found outside the pelvic and abdominal areas. The presence of this tissue in the chest causes specific chest pain often tied to the menstrual cycle.
The Specific Sensation: Describing Thoracic Endometriosis Pain
The chest pain associated with thoracic endometriosis is typically described as sharp, stabbing, or pleuritic, meaning it worsens when taking a deep breath, coughing, or moving. This pain follows a predictable, cyclical pattern, which medical professionals refer to as catamenial. The discomfort often begins shortly before or within the first 72 hours of the start of the menstrual period, reflecting the hormonal response of the ectopic tissue.
The pain can range from a mild ache to debilitating agony. Although often felt in the chest wall, it frequently presents as referred pain. This discomfort may radiate up to the shoulder, neck, or back, particularly around the shoulder blade. Right-sided shoulder tip pain is a common symptom because the diaphragm, a primary site for implants, shares nerve pathways with the shoulder area.
The intensity of the pain can be severe enough to cause respiratory symptoms, such as shortness of breath or difficulty breathing. Some individuals report a feeling of tightness or a heavy sensation during their menstrual cycle. The cyclical nature of the pain is the defining characteristic. Over time, this pain can occasionally become continuous instead of strictly cyclical.
Understanding Thoracic Endometriosis: Location and Mechanism
Thoracic endometriosis syndrome (TES) occurs when endometrial-like tissue implants on structures within the chest cavity, most commonly the diaphragm and the pleura, which is the lining surrounding the lungs. These implants swell and bleed in response to monthly hormonal fluctuations, causing irritation and inflammation in the chest. The chest pain is a direct result of this cyclical irritation of the nerve-rich tissues in the diaphragm and the chest wall.
The presence of these lesions can manifest in several ways that generate intense chest pain.
Catamenial Pneumothorax
One of the most common is catamenial pneumothorax, a collapsed lung that occurs around the time of menstruation. This happens when air leaks into the space between the lung and the chest wall, often through defects created by endometrial implants in the diaphragm or pleura. The sudden collapse causes sharp chest pain and acute shortness of breath.
Catamenial Hemothorax
A less frequent but serious manifestation is catamenial hemothorax, which involves the accumulation of blood in the pleural space. This bleeding, caused by the shedding of the endometrial implants, irritates the pleura and can cause pleuritic chest pain and shortness of breath. Collectively, these conditions, along with others like catamenial hemoptysis (coughing up blood) and isolated chest pain, fall under the umbrella of Thoracic Endometriosis Syndrome.
Differentiating Endometriosis Pain from Other Chest Conditions
Because chest pain can signal a medical emergency, distinguishing thoracic endometriosis pain from other conditions is important. The primary differentiator is the consistent, cyclical timing of the pain, which occurs just before or during the menstrual period. Pain caused by cardiac issues or common musculoskeletal problems does not follow this strict catamenial pattern.
Cardiac chest pain, such as that from a heart attack, is often described as a crushing, squeezing, or heavy pressure sensation, usually felt in the center of the chest. This pain may radiate to the left arm, jaw, or back, and it does not change with movement or deep breaths. In contrast, endometriosis-related pain is frequently sharp and stabbing, often changing in intensity with breathing or specific body movements.
However, certain “Red Flag” symptoms should prompt immediate emergency medical care, regardless of the menstrual cycle timing. These include sudden, severe, crushing chest pressure, pain that radiates down the arm or into the jaw, profuse sweating, or severe shortness of breath. While a collapsed lung from endometriosis requires urgent treatment, a medical professional can use the patient’s history of cyclical symptoms to guide the diagnostic process after ruling out life-threatening cardiac events. Any persistent or recurrent chest pain should be evaluated by a healthcare provider to ensure an accurate diagnosis and appropriate management.