The Overlooked Link: Allen-Masters Syndrome and Endometriosis
How a Little-Known Condition Can Complicate Diagnosis and Treatment for Women in Pain
The Overlooked Link: Allen-Masters Syndrome and Endometriosis
How a Little-Known Condition Can Complicate Diagnosis and Treatment for Women in Pain
What Is Allen-Masters Syndrome?
Allen-Masters Syndrome (AMS) refers to a condition where the ligaments that support the uterus become torn or stretched, often due to trauma or childbirth. The damage causes the uterus to become hypermobile, or “floppy,” which can lead to chronic pelvic pain, abnormal uterine positioning, and a range of gynecological symptoms.
First described in the 1950s by gynecologists Allen and Masters, the syndrome was initially observed in women who experienced difficult or forceful deliveries. However, it's now known that other pelvic trauma—such as surgeries, repeated inflammation, or even invasive endometriosis—can also play a role.
How It Feels: The Symptoms
The symptoms of AMS often overlap with other pelvic disorders, including endometriosis, which makes it incredibly hard to diagnose:
• Chronic pelvic pain, especially on one side
• Pain during intercourse (dyspareunia)
• A feeling of “heaviness” or dragging in the pelvis
• Irregular bleeding or spotting
• Referred pain to the lower back or legs
• Pain made worse by certain movements or positions
These symptoms can persist even after surgery for endometriosis or fibroids, leaving women frustrated and wondering why their treatments didn’t work.
The Complication with Endometriosis
Endometriosis and Allen-Masters Syndrome can coexist—and when they do, they complicate each other.
Endometriosis and Allen-Masters Syndrome can coexist—and when they do, they complicate each other.
Here’s how:
1. Mimicking or Masking Each Other
AMS pain can feel nearly identical to endometriosis. In laparoscopic surgery, torn ligaments or peritoneal defects might be mistaken for endometriosis—or missed entirely.
2. Worsening Each Other
The uterine instability caused by AMS may increase friction and inflammation in the pelvis, potentially exacerbating endometriosis symptoms. Likewise, the invasive nature of endometriosis can weaken uterine ligaments, creating a cycle of worsening pain.
3. Delaying Diagnosis
Because AMS isn’t well known, many surgeons focus only on excising visible endometriosis lesions. If ligament tears or pelvic instability aren’t also addressed, pain may persist despite "successful" surgery.
4. Influencing Fertility
While endometriosis is a known contributor to infertility, AMS can add to the challenge by altering the position of the uterus, interfering with sperm transport, or making embryo implantation more difficult.
Diagnosis: Why It’s Often Missed
AMS is best diagnosed through clinical examination and often requires a high index of suspicion from an experienced gynecologic surgeon. Imaging like MRI or ultrasound may not show ligament damage clearly. In some cases, laparoscopic exploration is the only way to confirm it, by observing a hypermobile uterus or peritoneal defects (like dimples or windows in the pelvic lining).
Unfortunately, many OB/GYNs are not trained to look for Allen-Masters Syndrome, which means it’s often overlooked—especially in patients already diagnosed with endometriosis
What Can Be Done?
If AMS is suspected, the treatment may include:
• Pelvic physical therapy to support surrounding muscles and reduce pain
• Surgical repair or suspension of the damaged ligaments, often during laparoscopy
• Pain management strategies including nerve blocks or hormonal regulation if endometriosis is also present
• Lifestyle modifications to reduce strain on the pelvis (avoiding certain exercises, managing constipation, etc.)
The Takeaway
Allen-Masters Syndrome may not be as well-known as endometriosis, but its impact is very real—especially for women who feel like they've tried everything and still have no answers.
If you’ve had surgery for endometriosis and your pain persists, or if your symptoms don’t quite fit the typical endo profile, it might be worth asking your doctor about Allen-Masters Syndrome.
Women deserve full answers—not partial relief.
Sources & Further Reading
• Howard FM. (2003). Chronic Pelvic Pain. Obstetrics and Gynecology
• Vercellini P et al. (2006). Chronic pelvic pain: pathogenesis and therapy. Best Practice & Research Clinical Obstetrics and Gynaecology
• Tu FF et al. (2017). Beyond Endometriosis: Recognizing and Treating Comorbid Pelvic Pain Disorders. Clinical Obstetrics and Gynecology
What Is Allen-Masters Syndrome?
Allen-Masters Syndrome (AMS) refers to a condition where the ligaments that support the uterus become torn or stretched, often due to trauma or childbirth. The damage causes the uterus to become hypermobile, or “floppy,” which can lead to chronic pelvic pain, abnormal uterine positioning, and a range of gynecological symptoms.
First described in the 1950s by gynecologists Allen and Masters, the syndrome was initially observed in women who experienced difficult or forceful deliveries. However, it's now known that other pelvic trauma—such as surgeries, repeated inflammation, or even invasive endometriosis—can also play a role.
How It Feels: The Symptoms
The symptoms of AMS often overlap with other pelvic disorders, including endometriosis, which makes it incredibly hard to diagnose:
• Chronic pelvic pain, especially on one side
• Pain during intercourse (dyspareunia)
• A feeling of “heaviness” or dragging in the pelvis
• Irregular bleeding or spotting
• Referred pain to the lower back or legs
• Pain made worse by certain movements or positions
These symptoms can persist even after surgery for endometriosis or fibroids, leaving women frustrated and wondering why their treatments didn’t work.
The Complication with Endometriosis
Endometriosis and Allen-Masters Syndrome can coexist—and when they do, they complicate each other.
Endometriosis and Allen-Masters Syndrome can coexist—and when they do, they complicate each other.
Here’s how:
1. Mimicking or Masking Each Other
AMS pain can feel nearly identical to endometriosis. In laparoscopic surgery, torn ligaments or peritoneal defects might be mistaken for endometriosis—or missed entirely.
2. Worsening Each Other
The uterine instability caused by AMS may increase friction and inflammation in the pelvis, potentially exacerbating endometriosis symptoms. Likewise, the invasive nature of endometriosis can weaken uterine ligaments, creating a cycle of worsening pain.
3. Delaying Diagnosis
Because AMS isn’t well known, many surgeons focus only on excising visible endometriosis lesions. If ligament tears or pelvic instability aren’t also addressed, pain may persist despite "successful" surgery.
4. Influencing Fertility
While endometriosis is a known contributor to infertility, AMS can add to the challenge by altering the position of the uterus, interfering with sperm transport, or making embryo implantation more difficult.
Diagnosis: Why It’s Often Missed
AMS is best diagnosed through clinical examination and often requires a high index of suspicion from an experienced gynecologic surgeon. Imaging like MRI or ultrasound may not show ligament damage clearly. In some cases, laparoscopic exploration is the only way to confirm it, by observing a hypermobile uterus or peritoneal defects (like dimples or windows in the pelvic lining).
Unfortunately, many OB/GYNs are not trained to look for Allen-Masters Syndrome, which means it’s often overlooked—especially in patients already diagnosed with endometriosis
What Can Be Done?
If AMS is suspected, the treatment may include:
• Pelvic physical therapy to support surrounding muscles and reduce pain
• Surgical repair or suspension of the damaged ligaments, often during laparoscopy
• Pain management strategies including nerve blocks or hormonal regulation if endometriosis is also present
• Lifestyle modifications to reduce strain on the pelvis (avoiding certain exercises, managing constipation, etc.)
The Takeaway
Allen-Masters Syndrome may not be as well-known as endometriosis, but its impact is very real—especially for women who feel like they've tried everything and still have no answers.
If you’ve had surgery for endometriosis and your pain persists, or if your symptoms don’t quite fit the typical endo profile, it might be worth asking your doctor about Allen-Masters Syndrome.
Women deserve full answers—not partial relief.
Sources & Further Reading
• Howard FM. (2003). Chronic Pelvic Pain. Obstetrics and Gynecology
• Vercellini P et al. (2006). Chronic pelvic pain: pathogenesis and therapy. Best Practice & Research Clinical Obstetrics and Gynaecology
• Tu FF et al. (2017). Beyond Endometriosis: Recognizing and Treating Comorbid Pelvic Pain Disorders. Clinical Obstetrics and Gynecology
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Join Us: Make a Difference Today
Your support can transform lives. Every donation helps us fund research, advocate for better care, and provide essential grants to women facing debilitating conditions.
Endometriosis: A Cancer-Mimicking Disease
A recent article published in the Annals of Research in Oncology (Vol. 5 June 2025) looks at the similarities between the behavior of some cancers and endometriosis. The article states, "Endometriosis, defined by the presence of endometrial-like tissue beyond the uterine cavity, afflicts over 190 million young women worldwide and often significantly reduces quality of life. Despite being historically classified as a benign gynecologic disorder, endometriosis can mimic cancer in imaging findings, serum tumor markers, and molecular signature." The article urges a different approach to the disease due to the fact that the current approach takes so long to diagnose (8-10 years on average) and leads many women down the path of repeated surgeries and hormone therapy that does little to treat the disease. The impact statement of the article urges a different approach altogether, "This perspective advocates a structured translational approach, integrating meticulous preclinical validation, phase-appropriate clinical trials, and rigorous safeguards in artificial intelligence and biomarker development, to bridge critical gaps in understanding disease biology."
We have summarized the points of the article below and also put the link to the full article. We fully believe that it is time for a different approach and are looking for opportunities to support research that is happening in the study of Endometriosis. Please join us in raising awareness and making some noise on the topic.
Summary of Article (in an oversimplified manner):
Why Endometriosis Acts Like Cancer
It spreads like cancer.
It can grow into nearby organs and even travel around the body—just like cancer does. It invades nearby tissue and can spread to just about any place in the body including the brain, the tissue in your legs, lymph nodes...they have found it just about everywhere.
It tricks doctors.
On scans and in lab tests, it looks just like cancer, so people sometimes get misdiagnosed. Even trickier, more often than not, Endometriosis lesions are not detectable on imaging which means that a diagnostic laparoscopic surgery is needed for diagnosis. Imagine how long that prolongs diagnosis and how often the diagnostic surgery is not covered by insurance. Even worse, how often women are told that "all is normal" because nothing was detected on imaging.
It won’t stop growing.
The tissue doesn’t follow normal rules—it keeps growing even when it’s not supposed to. Healthy cells know when to stop growing. Endometriosis doesn't. It uses the same tricks that cancer cells do to stay alive and keep growing.
It builds its own blood supply.
Like cancer, it tells the body to grow new blood vessels to feed it. The article gets into more specifics by explaining that endometriosis uses high levels of VEGF, MIF, and prostaglandins to build blood vessels - a hallmark of tumor growth.
It hides from the immune system.
It finds ways to stay safe, so the body doesn’t attack it—just like some cancer cells.
It has messed-up signals.
Inside the cells, the “messages” that tell cells when to grow or die are broken. These are the same bad messages found in cancer cells.
What These Doctors Are Saying:
Endometriosis has many of the same cell problems that cancer does.
Some women with endometriosis have a higher risk of getting a certain kind of ovarian cancer.
Doctors think we should study and treat it more like cancer, using:
Special medicines that stop growth
Tests to find it earlier
Research on how to stop it from coming back
