Umbilical endometriosis is a rare form of endometriosis in which tissue similar to the lining of the uterus grows inside or just beneath the belly button. It usually shows up as a small, firm lump at the navel that swells and becomes painful around the time of a menstrual period. It is uncommon — it accounts for a small fraction of all endometriosis cases — but it is well documented in the medical literature and can be treated with surgery.
What Is Umbilical Endometriosis?
Endometriosis is a condition where tissue resembling the endometrium — the lining of the uterus — grows outside the uterus. It most often involves the pelvis: the ovaries, the tissue behind the uterus, the ligaments that support the uterus, and the lining of the pelvic cavity. Umbilical endometriosis is a form of extrapelvic endometriosis, meaning the implants sit outside the pelvic region entirely, in this case at the umbilicus, or navel.
The tissue involved is not identical to normal uterine lining, which is why researchers and clinicians often describe it as “endometrial-like.” It still responds to hormonal signals, which is central to how the condition behaves.
Umbilical endometriosis is uncommon. Estimates vary, but it is generally described as accounting for a small percentage of all cases of extrapelvic endometriosis. It can occur on its own or alongside endometriosis elsewhere in the body. Some people have pelvic disease as well; others do not.
This is a condition that is often missed at first. A painful belly button lump is easy to dismiss or misattribute, and the cyclical pattern that points to the diagnosis is not always obvious unless someone asks specifically about timing.
What Causes Umbilical Endometriosis?
The exact cause is not fully understood, and that is true of endometriosis as a whole. Several mechanisms have been proposed, and more than one may be at work in the same person.
Direct spread from nearby endometriosis
The umbilicus sits close to the abdominal cavity. Endometrial-like tissue from the pelvic cavity can, in some cases, spread along the abdominal wall or through the tissue planes to reach the navel. This is one explanation for why umbilical endometriosis sometimes occurs alongside more extensive pelvic disease.
Lymphatic or blood vessel spread
Some researchers believe endometrial cells can travel through lymphatic channels or the bloodstream and settle in distant tissue, including the navel. This would help explain cases where the umbilical implant appears without any nearby pelvic disease.
Surgical implantation
Endometrial tissue can be carried to the umbilicus during abdominal or pelvic surgery. This is a recognized mechanism, and it is one reason umbilical endometriosis is sometimes reported after procedures such as laparoscopy or cesarean delivery. It is not the only route, though — many people with umbilical endometriosis have no relevant surgical history.
Embryologic remnants
During fetal development, the umbilicus connects to internal structures. Some researchers have proposed that remnants of tissue left behind during development could give rise to endometrial-like growths at the navel. This remains a hypothesis rather than a confirmed mechanism.
The honest position is that no single theory explains every case. Research into endometriosis overall continues to examine genetic, immune, and hormonal factors, and the picture is likely to be complex.
What Are the Symptoms of Umbilical Endometriosis?
The defining symptom is a lump at the navel that changes with the menstrual cycle. It swells, becomes tender, or hurts more just before or during a period, then settles afterward. That cyclical pattern is the strongest clue.
Common features include:
- A small, firm nodule or lump at or just under the belly button
- Pain at the navel, often cyclical
- Swelling that comes and goes with the cycle
- Bleeding or discharge from the navel, sometimes dark or brownish
- Tenderness to touch
Not everyone has bleeding. Some people have a lump with pain only. Others notice a bluish or dark spot under the skin. The size can range from small to a few centimeters, though the exact size varies widely.
Because the symptoms can mimic other problems — a hernia, a cyst, an infection, or a benign skin growth — a careful history matters. A clinician who hears that a painful belly button lump flares with periods should have endometriosis on the list of possibilities.
How Is Umbilical Endometriosis Diagnosed?
Diagnosis starts with history and physical exam. Your clinician will ask about the timing of symptoms relative to your menstrual cycle, any prior abdominal or pelvic surgery, and whether you have pelvic pain or other signs of endometriosis elsewhere.
Imaging can help but is not definitive. Ultrasound and MRI may show a mass at the umbilicus, but imaging alone cannot confirm the diagnosis. In many cases, the diagnosis is confirmed only after the tissue is removed and examined under a microscope.
That microscopic exam is the gold standard. A pathologist looks for endometrial-like glands and stroma — the supporting tissue — in the sample. This is what separates umbilical endometriosis from other causes of a navel lump.
It is worth being clear: a clinical suspicion is not the same as a confirmed diagnosis. If a lump is present, it should be evaluated by a clinician rather than assumed to be endometriosis.
What Are the Treatment Options?
Surgery is the main treatment for umbilical endometriosis. The typical approach is complete surgical removal of the lesion, which serves two purposes: it confirms the diagnosis and it treats the problem. Removal is generally considered curative for the umbilical implant itself.
Because the umbilicus is small and visible, the surgeon will try to remove the whole lesion while preserving the appearance of the navel where possible. Reconstruction of the umbilicus is sometimes part of the procedure. How this is done depends on the size and depth of the lesion.
Hormonal treatments — such as combined hormonal contraceptives or other medications that suppress ovarian hormone production — are used widely for endometriosis. For umbilical disease specifically, the evidence is more limited. Some clinicians use hormonal therapy to manage symptoms or to reduce the chance of recurrence after surgery, but this is not strongly established by large trials. It is fair to describe hormonal treatment for umbilical endometriosis as common clinical practice rather than a proven standalone cure.
Pain relief with over-the-counter medications may help with symptoms in the short term, but it does not treat the lesion.
Recurrence after complete removal appears to be uncommon, though it has been reported. Follow-up with your clinician is reasonable, especially if symptoms return.
How Does Umbilical Endometriosis Differ From Other Navel Lumps?
A lump at the belly button has several possible causes, and distinguishing them matters for treatment. Umbilical endometriosis is one of the less common ones.
| Possible cause | Typical clue |
|---|---|
| Umbilical hernia | Bulge that changes with coughing, straining, or standing; may be reducible |
| Umbilical endometriosis | Lump that swells and hurts with periods; may bleed |
| Sebaceous cyst or skin lesion | Slow-growing, often painless, not clearly cyclical |
| Infection or abscess | Redness, warmth, fever, tenderness; not cyclical |
| Metastatic tumor (rare) | Hard lump, sometimes called Sister Mary Joseph nodule; requires urgent evaluation |
The cyclical pattern is the feature that most points toward endometriosis. A lump that does not change with the cycle is more likely to have another cause. Any new, persistent, or changing navel lump deserves a clinician’s assessment — especially if it is hard, fixed, or associated with other symptoms.
What Should You Do If You Notice a Painful Navel Lump?
Get it looked at. Most navel lumps are not serious, but a few are, and the only way to know is an exam. Track your symptoms for a cycle or two if you can — note when the lump swells, when it hurts, and whether it bleeds. That pattern is useful information for your clinician.
Be specific about timing. Saying “it hurts around my period” is the detail that can move endometriosis onto the differential. If you have had abdominal or pelvic surgery in the past, mention that too.
Umbilical endometriosis is treatable, and surgical removal is generally effective for the umbilical lesion. The condition is uncommon, so it may not be the first thing a clinician considers — but it is well recognized, and the cyclical pattern is a strong clue.
Frequently Asked Questions
Is umbilical endometriosis dangerous?
It is not considered life-threatening, but it can cause ongoing pain and should be evaluated by a clinician. Rarely, a navel lump can be something more serious, so a proper exam matters.
Can umbilical endometriosis go away on its own?
It usually does not resolve without treatment, though symptoms may vary with hormonal changes. Surgical removal is the main treatment.
Does umbilical endometriosis always cause bleeding?
No. Some people have a painful lump without any bleeding or discharge. The cyclical pattern of pain and swelling is often the more reliable clue.
Can umbilical endometriosis come back after surgery?
Recurrence after complete removal appears to be uncommon, but it has been reported. Follow-up is reasonable if symptoms return.
