Endometrial Fibrosis: Causes, Signs, and Treatment

Endometrial fibrosis is the replacement of the normal uterine lining with scar tissue, and it develops most often after surgical procedures inside the uterus or following infections that damage the endometrium. The scarring can block the uterine cavity partially or completely, a condition clinicians call Asherman syndrome or intrauterine adhesions (IUA). When severe, it ranks among the hardest gynecologic problems to fix, with limited options for restoring the lining to functional health.¹ The condition sits at the intersection of inflammation, tissue repair gone wrong, and fertility medicine, and understanding it means understanding why the uterus sometimes heals with scars instead of fresh lining.

What Causes Endometrial Fibrosis

The endometrium is one of the most regenerative tissues in the human body, rebuilding itself after every menstrual cycle. But certain injuries overwhelm that regenerative capacity. The most common trigger is surgical trauma inside the uterus, particularly dilation and curettage (D&C) performed after a miscarriage, abortion, or postpartum hemorrhage. Repeated procedures multiply the risk. When the deep basal layer of the endometrium is damaged, the tissue that grows back may be collagen-rich scar rather than the glandular, blood-vessel-rich lining needed for menstruation and pregnancy.²

Infection is the other major driver. Chronic endometritis, a persistent low-grade infection of the uterine lining, can set off a fibrotic response even without surgery. Tuberculosis deserves special mention: in parts of the world where TB is endemic, genital tuberculosis remains one of the most important causes of intrauterine scarring and is often discovered only during an infertility workup.³ Other pelvic infections, including those following IUD placement or cesarean delivery, can contribute as well.

At the molecular level, a signaling molecule called TGF-β plays a central role in pushing the tissue toward scarring. When TGF-β is activated in damaged endometrial cells, it drives a process in which the normal epithelial cells lining the uterus transform into myofibroblasts, the cell type responsible for laying down collagen. Research has shown that stress signals within the cells amplify TGF-β activity, creating a feedback loop that favors scar formation over normal tissue regrowth.⁴ The same pathway also suppresses normal cell growth and promotes cell death in endometrial cells, compounding the damage.⁵

Inflammation adds another layer. Women with intrauterine adhesions tend to have elevated levels of pro-inflammatory and pro-fibrotic cytokines in their blood, along with disrupted microbial communities in the reproductive tract. One study found that women with IUA had significantly higher levels of inflammatory markers like IL-6 and TNF-γ, and their cervical and vaginal bacterial diversity was sharply reduced compared to women without adhesions.⁶ Whether the microbial imbalance causes the adhesions or results from them is still being worked out, but the association is consistent enough that researchers are paying close attention to it.

Signs and Symptoms

Endometrial fibrosis does not always announce itself with dramatic symptoms, which is part of what makes it tricky to catch early. The hallmark sign is a change in menstrual bleeding. If scar tissue covers a large portion of the uterine cavity, periods may become lighter than usual (hypomenorrhea) or stop entirely (amenorrhea). Some women experience painful periods (dysmenorrhea) because menstrual blood gets trapped behind adhesions and has nowhere to go. The degree of menstrual disruption generally tracks with how much of the cavity is affected: mild scarring may cause no obvious menstrual changes, while extensive scarring can eliminate periods altogether.

For many women, the first indication of a problem is difficulty getting pregnant or repeated miscarriages. Scar tissue can physically prevent an embryo from implanting, and even in areas that are not visibly scarred, the endometrium may be too thin or lack adequate blood supply to support a pregnancy. Research on women with recurrent implantation failure has found that the lining in these patients has reduced blood-vessel density and lower expression of factors that promote new vessel growth, compared to women with normal fertility.⁷ In other words, the tissue is not just scarred in places but functionally impaired even where it looks intact.

How It Is Diagnosed

Hysteroscopy, in which a thin camera is inserted through the cervix into the uterine cavity, is the gold standard for diagnosing intrauterine adhesions. It lets the clinician directly see bands of scar tissue, assess how much of the cavity is involved, and evaluate the remaining endometrium. Because it provides both a visual and a tactile sense of the adhesions (some are thin and filmy, others are thick and muscular), hysteroscopy gives the most complete picture of severity.

A hysterosalpingogram (HSG), which uses dye and X-ray to outline the uterine cavity, is sometimes used as a first-line screening tool because it is less invasive. However, its accuracy is limited. One comparative study found that HSG had a sensitivity of about 81% and a specificity of about 80% when measured against hysteroscopy, with substantial false-negative and false-positive rates.⁸ Transvaginal ultrasound, particularly with saline infusion to expand the cavity, can also detect adhesions, though it is operator-dependent and can miss mild cases.

Grading the severity of adhesions matters for treatment planning, but the field has struggled to agree on a single system. Multiple classification schemes exist, some based on the extent and type of adhesions, others on menstrual pattern, and still others on fertility outcomes. A review found seven distinct classification systems, none of which had been universally adopted or validated.⁹ More recently, a scoring system called the Loddo score was proposed, which combines elements from earlier classifications and adds ultrasound-measured endometrial thickness as a factor.¹⁰ Whether it gains broader traction remains to be seen, but the push toward incorporating endometrial thickness reflects a growing recognition that thin lining, even without visible adhesions, is clinically important.

Surgical Treatment

The primary treatment for significant endometrial fibrosis is hysteroscopic adhesiolysis: cutting or separating the scar bands under direct camera visualization. The procedure is typically done with small scissors, a resectoscope, or laser, and in cases with dense, extensive adhesions, simultaneous abdominal ultrasound guidance helps the surgeon avoid perforating the thinned-out uterine wall.¹¹ For mild cases, the scar tissue may be easily separated, and menstrual function often improves. For severe cases, where the cavity is nearly or completely obliterated, surgery may need to be staged over multiple sessions, gradually reopening the space and giving the lining time to regrow between procedures.

An important nuance that patients with mild adhesions should know: surgery may not meaningfully improve outcomes if the scarring is minimal. A retrospective cohort study comparing women with mild intrauterine adhesions who underwent adhesiolysis before embryo transfer to those who did not found no significant difference in live birth rates.¹² The researchers recommended that women with mild adhesions consider watchful waiting rather than automatic surgery. This does not apply to moderate or severe cases, where the physical obstruction and lining damage are substantial enough that leaving them untreated would almost certainly compromise fertility.

Preventing Adhesions from Returning After Surgery

One of the most frustrating aspects of treating endometrial fibrosis is the high rate of adhesion recurrence after surgery. The raw surfaces left behind after scar tissue is cut can stick together again as they heal, sometimes recreating the problem the surgery was meant to fix. Several strategies have been developed to keep the walls of the uterus apart while the lining regenerates.

A cohort study comparing three common approaches found that placing an intrauterine balloon after surgery was the most effective at reducing adhesion scores on follow-up, outperforming both an intrauterine device (IUD) and hyaluronic acid gel applied to the cavity. The IUD also performed significantly better than the gel alone.¹³ In practice, many surgeons use a balloon catheter left in place for about a week, sometimes combined with a course of antibiotics and estrogen to encourage regrowth of the endometrial lining. The gel-based barriers, while less effective on their own, are sometimes used as an adjunct alongside a physical barrier.

The Uncertain Role of Estrogen Therapy

Post-surgical estrogen supplementation is widely prescribed on the logic that estrogen stimulates endometrial growth and could help a healthier lining regenerate over the healing scar.¹⁴ The practice has been standard for decades. However, the evidence supporting it is surprisingly thin. A randomized trial directly testing whether estrogen after adhesiolysis improved outcomes found that it did not influence the chance of adhesion recurrence, and reproductive outcomes were no better in the estrogen group than in the control group.¹⁵

This does not necessarily mean estrogen is useless in every case. The trial studied women with Asherman syndrome broadly, and it is possible that specific subgroups, such as those with very thin lining or those whose ovaries produce little estrogen on their own, might still benefit. But it does suggest that routine post-operative estrogen for all patients is not the evidence-based slam dunk it was once assumed to be, and some clinicians are reconsidering how aggressively they prescribe it.

Emerging and Experimental Therapies

For women with severe endometrial fibrosis who do not respond well to conventional surgery and hormonal support, a growing body of research is exploring regenerative approaches. These are still largely experimental, but several directions show genuine promise.

Stem Cell Therapy

Stem cells from various sources, including bone marrow, menstrual blood, umbilical cord, and fat tissue, have been tested for their ability to coax a scarred endometrium to regenerate. In animal models and small human studies, transplanting stem cells into the uterine cavity has been associated with reduced fibrotic area, increased gland formation, new blood vessel growth, and improved endometrial thickness.¹⁶ Stem cell therapy is considered especially relevant for patients with severe, refractory adhesions who have exhausted standard treatments.¹⁷ However, nearly all of the data comes from small pilot studies and animal experiments, so it is too early to consider this a standard option.

Platelet-Rich Plasma

Platelet-rich plasma (PRP), a concentrated preparation of a patient’s own blood platelets, is rich in growth factors that promote cell proliferation, new blood vessel formation, and tissue healing. When infused into the uterine cavity, PRP has shown the ability to increase endometrial thickness in women with persistently thin lining. A pilot study found that all treated patients had measurable increases in endometrial thickness, and a majority achieved pregnancy.¹⁸ A larger comparative study reported that women who received PRP had significantly thicker endometrium and a clinical pregnancy rate of about 44%, compared to roughly 20% in the control group.¹⁹ A comprehensive review concluded that PRP promotes cell growth, new vessel formation, and reduced inflammation in the endometrium.²⁰ PRP is appealing because it uses the patient’s own blood and avoids the ethical and logistical complexities of stem cell sourcing, though the optimal timing, concentration, and number of treatments are still being refined.

Bioengineered Scaffolds

Perhaps the most forward-looking approach involves creating physical scaffolds that mimic the natural structural environment of the endometrium, then seeding them with stem cells or growth factors and placing them in the uterine cavity. Researchers have tested hydrogels made from natural materials like collagen and hyaluronic acid, as well as synthetic polymers, designed to support cell growth and gradually dissolve as real tissue takes over.²¹ In a mouse model of endometrial damage, animals treated with a hydrogel derived from decellularized endometrial tissue and supplemented with growth factors showed more gland formation, more blood vessel development, less collagen scarring, and higher pregnancy rates compared to untreated animals.²² This technology is still in early preclinical stages, but it represents a fundamentally different strategy: rather than just removing scar tissue and hoping good tissue grows back, it provides the architectural and biochemical blueprint for the tissue to rebuild itself correctly.

Pregnancy Risks After Treatment for Endometrial Fibrosis

Successfully treating adhesions and achieving pregnancy is a real victory, but it does not mean the pregnancy is risk-free. Women who conceive after treatment for Asherman syndrome face elevated rates of several serious obstetric complications. A propensity-matched cohort study found that compared to controls, women previously treated for Asherman syndrome had dramatically higher rates of abnormally invasive placenta (about 42% vs. 0%), retained placenta requiring manual or surgical removal (about 47% vs. 7%), and peripartum hemorrhage (about 32% vs. 3%). Premature delivery was also more common, at about 28% vs. 5%.²³²⁴

The underlying reason for the placenta problems traces directly back to the scarring. When the deep basal layer of the endometrium has been damaged, the barrier that normally limits how deeply the placenta can anchor is weakened or absent. The placenta can then grow into or through the uterine muscle wall, a condition called placenta accreta. This can cause life-threatening bleeding at delivery and sometimes requires hysterectomy.²⁵ Any woman who becomes pregnant after treatment for significant intrauterine adhesions should be monitored with this risk in mind, ideally at a center equipped for high-risk deliveries. Prenatal ultrasound can often detect abnormal placentation early enough to plan a safer delivery.

The Psychological Weight of Asherman Syndrome

The emotional and psychological burden of endometrial fibrosis is real but frequently overlooked in clinical settings. A study assessing mental health in women with Asherman syndrome found that roughly 16% reported moderate to severe depression and nearly half screened positive for clinical anxiety. Reduced vitality affected about half the group, and nearly a third reported cognitive difficulties such as trouble concentrating.²⁶

These numbers are striking, and the sources of distress are not hard to understand. Many women develop Asherman syndrome after a pregnancy loss, meaning they are coping with grief on top of the new diagnosis. The condition often requires multiple surgeries with uncertain outcomes, and the threat of infertility hangs over every step. Unlike more visible gynecologic conditions, intrauterine adhesions produce no external signs, which can make it harder for friends, family, and even some clinicians to appreciate how much the diagnosis disrupts daily life. The researchers who reported these findings urged gynecologic surgeons to actively screen for psychological distress in this population, arguing that untreated anxiety and depression can undermine treatment adherence and recovery. If you are dealing with this diagnosis, seeking psychological support alongside your medical care is not an afterthought; it is part of good treatment.

Microbiome Connections and Endometriosis Overlap

The relationship between reproductive-tract bacteria and fibrotic tissue changes is an area gaining momentum across gynecology, not just in the context of intrauterine adhesions. The finding that women with IUA have altered cervical and vaginal bacteria, with reduced microbial diversity and elevated inflammatory cytokines, suggests that the microbiome may play a more active role in fibrosis than previously thought.⁶

A parallel story is emerging in endometriosis research. One study found that a specific bacterium, Fusobacterium, was present in the endometrium of about 64% of women with endometriosis but fewer than 10% of controls. The infection activated TGF-β signaling, the same pathway involved in endometrial fibrosis, and triggered the transformation of quiescent fibroblasts into active, proliferative myofibroblasts. In a mouse model, inoculation with Fusobacterium increased the size and number of endometriotic lesions, and antibiotic treatment largely prevented their formation.²⁷ Endometriosis and intrauterine adhesions are distinct conditions, but the shared molecular machinery (TGF-β, myofibroblast activation, collagen deposition) raises the possibility that bacterial communities in the reproductive tract influence fibrotic processes more broadly. If that connection holds up, it could eventually open the door to prevention strategies, including targeted antibiotics or probiotics, that address the biological environment before scarring takes hold.