Beyond the Abdomen: Endometriosis in the Diaphragm and Nerves

Endometriosis is usually discussed as a pelvic condition. But some people develop symptoms that don’t “fit” the typical story: shoulder or chest pain that flares with periods, sudden shortness of breath, sciatica that predictably worsens during menstruation, numbness, weakness, or even bladder/bowel changes that feel neurologic. When that happens, patients are often told it must be a lung problem, a spine problem, anxiety, or “just bad cramps.”

Recent research and clinical reports highlight an important reality for a small subset of patients: endometriosis can involve the diaphragm (the muscle separating chest and abdomen) and, more rarely, pelvic nerves. These are uncommon presentations—but they can be high-impact, easily overlooked, and sometimes time-sensitive if nerves are being damaged. This article pulls together findings from multiple recent papers to help you recognize red flags, understand how diagnosis usually works, and prepare for informed conversations with a multidisciplinary care team.

The big picture: “Rare” doesn’t mean “not real”

Two themes show up consistently across the evidence:

First, thoracic endometriosis syndrome (TES)—endometriosis affecting the diaphragm, pleura, lungs, or airways—often announces itself through catamenial symptoms, meaning symptoms that cluster around menstruation. Catamenial pneumothorax (a collapsed lung around the time of a period) is repeatedly described as the most common TES presentation, typically within about the first 72 hours of bleeding.

Second, endometriosis involving major pelvic nerves is described as rare but likely under-recognized, in part because nerve-related symptoms can mimic orthopedic or neurologic conditions—and because routine pelvic imaging may not fully assess the lateral pelvic spaces where key nerves run.

In other words: if your symptoms are cyclical and unusual for “typical” pelvic endometriosis, it may not be coincidence.

Diaphragm and thoracic endometriosis: symptoms patients often miss (or get dismissed)

Diaphragmatic and thoracic endometriosis can present in a range of ways, from vague discomfort to emergencies. Patterns across case reports and reviews highlight these patient-relevant clues:

1) Chest/shoulder/upper abdominal pain that tracks with your cycle

Many patients describe right-sided chest pain, pain under the ribs, shoulder-tip pain, or pain with deep breathing that flares around menstruation. This timing matters: several reports emphasize that clinicians may not think “endometriosis” unless you explicitly mention the menstrual association.

2) Shortness of breath, recurrent pneumothorax, or pleural effusion around periods

Some people experience sudden breathlessness and chest pain from a pneumothorax, while others develop fluid around the lung (pleural effusion or hemothorax). In one report from a low-resource setting, the pleural fluid was described as “chocolate-colored,” and drainage both relieved symptoms and helped support the diagnosis when advanced procedures weren’t accessible.

3) Coughing up blood (catamenial hemoptysis)

Less commonly, TES may present with hemoptysis that clusters around menstruation. In two patients with suspected TES (and histories of endometriosis/adenomyosis), symptoms improved with ovarian suppression followed by longer-term progestin therapy, and imaging remained stable or improved over time—suggesting that hormone-responsiveness can be a meaningful diagnostic clue when pathology isn’t available.

Why symptoms are often right-sided

A 2026 systematic review and meta-analysis found a striking pattern: thoracic lesions were overwhelmingly right-sided in unilateral cases, while many pelvic sites skewed left-sided. This doesn’t mean left-sided thoracic disease can’t happen—it can—but right-sided symptoms (right chest, right shoulder, right pneumothorax) are common enough that they should raise suspicion rather than reassurance.

How is diaphragmatic/thoracic endometriosis actually diagnosed?

Patients are often told “your CT is normal, so it can’t be endometriosis.” The problem is that TES doesn’t always announce itself clearly on noninvasive testing.

Imaging can show complications, not always the cause. CT may identify a pneumothorax or pleural effusion, yet fail to show obvious endometriosis deposits or a diaphragmatic mass. That mismatch is described in multiple reports: imaging can be essential for triage, but it may not map disease.

Surgery is sometimes the only way to confirm and fully assess extent.

Several case reports emphasize that looking at the diaphragm from the abdominal side during laparoscopy can underestimate what’s happening on the chest side. In a case of coexisting diaphragmatic and thoracic disease, definitive thoracic findings emerged during VATS (video-assisted thoracoscopic surgery), where pleural and diaphragmatic endometriosis were treated more comprehensively than abdominal inspection alone could have guided.

Pathology matters when it’s feasible.

In one catamenial pneumothorax case with diaphragmatic lesions, tissue confirmation showed endometrial-type glands/stroma with estrogen receptor positivity—strong evidence that symptoms truly were endometriosis-related. At the same time, real-world care doesn’t always allow for pathology (patients may decline surgery, or resources may be limited). In those situations, clinicians may rely on a combination of cyclical symptoms, imaging patterns, exclusion of other causes, and response to hormonal suppression.

What treatment looks like: surgery, hormones, or both

Because the available evidence includes mostly observational cohorts and case reports, there isn’t a one-size-fits-all “best” plan. But the combined literature points to three common strategies:

1) Combined thoracic + gynecologic surgery (when appropriate)

For severe or recurrent pneumothorax—especially when symptoms are classic for catamenial pneumothorax—teams may recommend coordinated care between thoracic surgery and gynecologic endometriosis specialists.

In reported cases, combined approaches can include resection of diaphragmatic lesions (sometimes full-thickness), pleurectomy, and pleurodesis (to reduce recurrence), alongside pelvic evaluation/treatment. Short-term outcomes in individual reports are encouraging, including symptom resolution and months to years without recurrence—but it’s important to remember that recurrence remains a known challenge in thoracic endometriosis-related pneumothorax overall.

A large surgical mapping study of thoracic endometriosis-related pneumothorax found diaphragmatic lesions clustered in a specific ventral-lateral region and commonly along the border between diaphragm muscle and membrane. That kind of anatomical work doesn’t prove a superior treatment, but it helps explain why targeted inspection and experienced surgical technique may matter.

2) Hormonal suppression (sometimes long-term)

Hormonal strategies aim to suppress cycling and bleeding in endometriosis implants.

Across multiple reports, regimens included:

• GnRH agonist “induction” for several months, sometimes with add-back therapy, followed by
• maintenance progestin therapy (such as dienogest), with long-term follow-up describing sustained symptom control in select patients.

In a resource-limited setting, continuous combined oral contraceptives after pleural drainage were associated with symptom improvement and resolution of effusion on follow-up imaging. This matters because it highlights a practical reality: while ideal care may include VATS and pathology, meaningful symptom control may still be possible when surgery isn’t accessible or desired.

3) Stepwise, shared decision-making

The “best” option depends on:

• your presentation (pneumothorax vs pain vs hemoptysis),
• severity and recurrence,
• fertility goals,
• medication tolerance,
• surgical risk and access to experienced teams.

What comes through clearly in the reports is that patient preferences (declining surgery, declining chest tubes, cost constraints) frequently shape the plan—and clinicians can sometimes adapt safely when the diagnosis is strongly suspected.

Pelvic nerve endometriosis: when endometriosis behaves like a nerve disorder

Endometriosis involving pelvic nerves (like the sciatic nerve or pelvic plexuses) is described as uncommon, but potentially life-altering. The key patient-facing message from recent imaging-focused work is simple: neurologic symptoms plus endometriosis symptoms deserve a nerve-aware evaluation.

Symptoms that should raise suspicion

Pelvic nerve involvement may cause:

• Sciatica that is cyclical (often called catamenial sciatica): pain shooting down the buttock/leg that flares with periods, sometimes becoming constant over time
• Numbness, tingling, weakness, or gait changes
• Foot drop (more urgent)
• Perineal burning or pain worse with sitting
• Bladder/rectal dysfunction that seems neurologic rather than purely pain-related

These symptoms can be misattributed to disc disease, piriformis syndrome, or “muscle tightness,” especially if pelvic endometriosis has not been surgically confirmed.

Why MRI protocol matters (a lot)

For suspected pelvic nerve endometriosis, MRI is emphasized as the imaging test most likely to detect and map disease—particularly because transvaginal ultrasound may struggle in the lateral pelvic compartments where many nerves run. The most practical takeaway is not “get an MRI,” but:

Get the right MRI, read by the right team.

Optimized protocols—such as high-spatial-resolution 3D T2-weighted sequences with multiplanar reconstructions—can improve visualization of nerves and their relationship to deep endometriosis.

Just as important: structured reporting that clearly describes proximity to ureters, vessels, sacral roots, and pelvic plexuses can directly affect surgical planning and counseling about risks (including potential postoperative bladder or rectal dysfunction when the inferior hypogastric plexus is involved).

Why early recognition can protect function

A particularly sobering point in the imaging literature is that advanced nerve involvement can be associated with muscle denervation and atrophy, which may be difficult to reverse. That doesn’t mean every nerve symptom is permanent—but it does argue for not “watching and waiting” indefinitely when progressive weakness or objective deficits are appearing.

Practical takeaways: what to do if you suspect diaphragm or nerve involvement

Use these questions to guide your next appointment (and to signal clearly that you’re concerned about extra-pelvic disease):

• “My symptoms flare with my period—could this be thoracic/diaphragmatic endometriosis or catamenial pneumothorax?”
• “If we do imaging, who will interpret it with endometriosis expertise, and will it answer a specific question?” (e.g., complication vs mapping disease)
• “Should I be referred to a multidisciplinary team (thoracic surgery + endometriosis specialist, or radiology + neurology/pain + endometriosis surgeon)?”
• “For nerve symptoms: can we order an MRI with an endometriosis/nerve protocol that evaluates the lateral compartments and pelvic nerves?”
• “What symptoms would make this urgent?” (new weakness, foot drop, severe shortness of breath, recurrent pneumothorax)

What we still don’t know (and why your case may look different)

Even with growing awareness, the evidence base for diaphragmatic/thoracic and nerve endometriosis is still limited.

• Much of what guides care comes from case reports, small series, and specialized surgical cohorts rather than large comparative trials. That means recurrence rates, best surgical techniques, and best medication strategies are not fully settled.
• Diagnosis is often inconsistent because many patients cannot or do not undergo the procedures that provide confirmation (VATS for thorax; targeted MRI protocols and expert reads for nerves; biopsy when safe and feasible).
• Side-to-side patterns (like right-sided thoracic predominance) are strong at the population level, but they cannot predict an individual’s disease or symptoms with certainty.

The most important “unknown” is also the most important practical point: which patients need which specialists, how early, and in what sequence. Until research catches up, the safest approach is to treat red-flag symptom patterns—especially cyclical chest symptoms or progressive neurologic symptoms—as worth specialized evaluation rather than dismissal.

In this “beyond the pelvis” phase of the endometriosis conversation, the goal isn’t to frighten you. It’s to give you language for what you’re experiencing and a clearer path to the right team—because in diaphragm and nerve endometriosis, being believed and being properly evaluated can change outcomes.