What Are Uterine Abnormalities? Types and Treatments

Uterine abnormalities are structural differences in the uterus that can be present from birth or develop later in life, and they are more common than most people realize. Systematic reviews estimate that roughly 5 to 7 percent of the general population has some form of congenital uterine anomaly, with rates climbing sharply among those who experience recurrent miscarriage or infertility. Acquired conditions like fibroids, polyps, and scar tissue inside the uterus are even more widespread. Some of these abnormalities cause no symptoms at all, while others lead to painful periods, difficulty getting pregnant, or complications during pregnancy. Understanding the different types and what can be done about them matters whether you are trying to conceive, managing symptoms, or simply want to know what an imaging report means.

How Congenital Uterine Anomalies Form

The uterus, fallopian tubes, cervix, and upper vagina all develop from a pair of embryonic structures called the Müllerian ducts. During fetal development, these two ducts are supposed to fuse together and then the central wall between them is reabsorbed, leaving a single, hollow uterine cavity. When something interrupts that process, the result is a congenital uterine anomaly, sometimes called a Müllerian duct anomaly.¹ Depending on where the process stalls, you can end up with a uterus that has an internal wall down the middle, is partially split into two halves, is missing one side entirely, or in rare cases is absent altogether.

How common are these? A large systematic review found that about 5.5 percent of women in unselected populations have a uterine anomaly when diagnosed with reliable imaging. Among women with infertility alone, the rate was around 8 percent. It jumped to about 13 percent in women with recurrent miscarriage, and to roughly a quarter of women dealing with both miscarriage and infertility.² A separate review placed the general population figure slightly higher, at about 6.7 percent, and noted that the most common anomaly in the general population was the arcuate uterus (a mild indentation at the top of the cavity), while the septate uterus (an internal dividing wall) was the most common type among women who were infertile.³ That pattern hints that not all anomalies carry the same reproductive consequences.

Types of Congenital Anomalies

Classification systems have gone through several revisions over the years, and two major ones coexist today: the American Society for Reproductive Medicine (ASRM) 2021 system and the European ESHRE/ESGE system. They sometimes categorize the same anatomy differently, which can cause confusion if you are comparing reports from different clinics.⁴ One comparison study found that the ESHRE/ESGE criteria diagnosed septate uterus almost three times as often as the ASRM criteria did in the same group of patients, because the European system uses a wider definition of what counts as a septum.⁵ Despite this overlap, the main types are well recognized:

Septate uterus: The outer shape of the uterus looks normal, but a wall of tissue (a septum) divides the cavity partially or completely. This is the type most strongly linked to miscarriage and subfertility.
Bicornuate uterus: The uterus has two partially separated horns that share a single cervix, giving it a heart-like shape. It was the most common anomaly in one large study of pregnancy complications, accounting for over half the cases.
Unicornuate uterus: Only one side of the Müllerian duct develops fully, resulting in a smaller, banana-shaped uterus. A rudimentary horn on the other side may or may not be present.
Uterus didelphys: The two Müllerian ducts never fuse at all, producing two separate uterine bodies, each with its own cervix and sometimes a doubled vagina. Though it accounted for only about 13 percent of anomalies in one population, women with didelphys had the highest rates of preterm birth before 34 weeks.
Arcuate uterus: A mild concavity at the top of the uterine cavity. This is the most common anomaly under some classification schemes and is generally considered the least clinically significant.

A U.S. study of obstetric outcomes across these types found that about two-thirds of patients with congenital anomalies delivered by cesarean section. The risk of severe maternal complications varied by type: septate uterus carried the highest risk of hemorrhage, followed by didelphys and unicornuate forms, while bicornuate and arcuate shapes had lower but still elevated risk compared to a normal uterus.⁶

MRKH Syndrome and Uterine Absence

At the far end of the spectrum is Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, in which the uterus and the upper vagina fail to develop at all. Ovaries function normally, puberty proceeds as expected, and chromosomes are a typical 46,XX pattern. The first sign is usually the absence of a first period in an otherwise normally developing teenager.⁷ Estimates put its prevalence at roughly 1 in 4,500 to 5,000 female births.⁸

MRKH is classified as type I when only the reproductive tract is affected, or type II when renal, skeletal, cardiac, or hearing abnormalities are also present. The cause remains unclear, though familial clustering and emerging genetic findings suggest a hereditary component in at least some cases. Treatment traditionally focused on creating a neovagina through dilator therapy or surgery so that sexual intercourse is possible. Until recently, gestational surrogacy was the only path to biological motherhood, but uterus transplantation has changed that picture, as discussed later in this article.

Acquired Uterine Abnormalities

Not all uterine abnormalities are present from birth. Several conditions can alter the shape, lining, or function of the uterus over a lifetime.

Fibroids

Uterine fibroids (leiomyomas) are benign muscle-and-connective-tissue growths in the uterine wall. They are extremely common, and while only a minority cause symptoms, those that do can seriously affect quality of life through heavy menstrual bleeding, pelvic pressure, and problems with fertility.⁹ Where a fibroid sits matters: a growth that bulges into the uterine cavity (submucosal) tends to cause more bleeding and more fertility trouble than one embedded in the outer wall. The FIGO classification system maps fibroid location relative to the endometrium, the muscle layer, and the outer surface, which helps clinicians decide what treatment makes sense.

Endometrial Polyps

Polyps are finger-like overgrowths of the uterine lining that range from a few millimeters to several centimeters. Most are benign, but they are not entirely harmless. A meta-analysis found that the overall rate of premalignant or malignant change in resected polyps was about 3.4 percent. Abnormal uterine bleeding, being postmenopausal, age over 60, diabetes, obesity, high blood pressure, and tamoxifen use all raised the likelihood that a polyp harbored something more serious.¹⁰ Another systematic review confirmed that symptomatic polyps (those causing bleeding) carried a higher malignancy risk than asymptomatic ones, at roughly 5 percent versus 2 percent.¹¹

Adenomyosis

Adenomyosis occurs when tissue that normally lines the uterus (endometrium) grows into the muscular wall. This can cause the uterus to enlarge and become tender, producing painful and heavy periods and, increasingly recognized, reduced fertility. Because symptoms overlap heavily with fibroids and endometriosis, adenomyosis is one of the trickiest uterine conditions to pin down.¹² It often coexists with fibroids, which adds to the diagnostic challenge.

Asherman’s Syndrome

When the inner lining of the uterus is damaged, bands of scar tissue (intrauterine adhesions) can form, partially or completely closing off the cavity. This is Asherman’s syndrome, and the most common trigger is a uterine curettage (scraping) performed after a pregnancy loss or delivery.¹³ Symptoms range from lighter-than-normal periods to a complete absence of periods, pelvic pain, and infertility. It can also cause abnormal placentation in future pregnancies.¹⁴

How Uterine Abnormalities Are Diagnosed

Many congenital anomalies are found incidentally during imaging for something else, or only come to light after repeated pregnancy losses. The gold-standard imaging debate has historically been between 3D transvaginal ultrasound (3D-US) and MRI. A study comparing the two found that MRI had the edge in complex or subtle cases, with an overall diagnostic accuracy (area under the curve) of 0.92 versus 0.88 for 3D-US.¹⁵ That said, the practical concordance between the two methods is very good. One study reported a kappa index of 0.88, meaning they agreed on the diagnosis most of the time, and discrepancies occurred in only a handful of cases.¹⁶ Another study found that 3D-US matched MRI perfectly for some subtypes (hemi-uteri, dysmorphic uteri) and very closely for septate and bicorporeal forms.¹⁷

In practice, 3D-US is often the first step because it is cheaper, widely available, and does not require contrast agents or sedation. MRI is typically reserved for when ultrasound findings are unclear or when surgical planning requires more anatomical detail. For acquired problems like polyps or adhesions, hysteroscopy, in which a thin camera is passed through the cervix into the uterine cavity, doubles as both a diagnostic and treatment tool. Office hysteroscopy can be done without anesthesia and allows direct visualization and biopsy of suspicious lesions.¹⁸

Treatments for Congenital Anomalies

Not every congenital anomaly needs treatment. An arcuate uterus, for instance, is often left alone because it rarely causes problems. When treatment is warranted, it is usually driven by fertility concerns or pregnancy complications.

The septate uterus has historically been the most treated anomaly because hysteroscopic septum resection is relatively straightforward: a camera-guided instrument cuts through the septum from inside the uterus, with no abdominal incision. Retrospective studies have consistently shown dramatic improvements in pregnancy outcomes after surgery: one study reported that live birth rates rose from under 4 percent to about 85 percent, and early miscarriage rates dropped from over 80 percent to under 9 percent.¹⁹ Those before-and-after numbers are striking, but it is worth knowing that a Cochrane review flagged a major limitation: nearly all the evidence comes from studies comparing outcomes in the same women before and after surgery, a design that inherently favors the treatment because the women had time to try again regardless of the procedure.²⁰ High-quality randomized trials remain limited, so the true benefit is still debated, even as the procedure remains widely offered.

For a bicornuate uterus, surgical unification (Strassman metroplasty) is occasionally performed but is far more invasive, requiring an abdominal approach, and is reserved for cases with documented severe pregnancy losses. Unicornuate uterus and didelphys are generally managed through close obstetric monitoring rather than surgical correction, since the anatomy is not easily altered.

Treatments for Acquired Conditions

Acquired abnormalities span a wider range of therapeutic options, from medication to minimally invasive procedures to major surgery.

For fibroids, treatment depends on symptoms, size, location, and whether you want to preserve fertility. Hormonal medications can shrink fibroids and control bleeding. A newer combination therapy, relugolix with estradiol and norethindrone acetate, showed strong results even in women who had coexisting adenomyosis: about 84 percent were treatment responders, and roughly 65 percent achieved the absence of menstrual bleeding entirely during the study period.²¹ When medication is not enough, uterus-sparing procedures include myomectomy (surgically removing the fibroids while leaving the uterus intact), uterine artery embolization (blocking blood supply to the fibroids so they shrink), radiofrequency ablation, and high-intensity focused ultrasound.²² For women who have finished having children and have severe symptoms, hysterectomy remains definitive.

Asherman’s syndrome is treated by hysteroscopic adhesiolysis, using scissors or a specialized instrument to cut the scar bands under camera guidance. Results depend on the severity of the scarring. In one study, women who regained normal periods after surgery conceived about half the time, but those who remained without periods had much lower chances, around 18 percent. Women whose adhesions reformed after surgery fared even worse, with only about 12 percent conceiving, compared to roughly 59 percent of those with a normal cavity at follow-up.²³ Preventing adhesion recurrence is an active area of research, with barriers, balloons, and hormonal treatments used after surgery to keep the cavity open while the lining heals.

Impact on Fertility and Pregnancy Complications

Uterine abnormalities, both congenital and acquired, can affect fertility at multiple stages: implantation, placentation, and the ability of the uterus to expand and sustain a growing pregnancy. One population-based study found that uterine malformations were independently linked to a six-fold increase in the odds of cervical insufficiency, a condition in which the cervix opens too early during pregnancy and is a leading cause of second-trimester loss.²⁴ Preterm birth is a recurring theme: the highest preterm delivery rates (about 35 percent) were seen in women with uterus didelphys.⁶

That said, many women with congenital anomalies carry pregnancies successfully, sometimes without ever knowing about the anomaly. A bicornuate uterus, for example, does raise the risk of malpresentation and preterm birth, but the majority of pregnancies still reach a viable gestational age. The key is awareness: when an anomaly is known, clinicians can plan for closer monitoring, cervical-length screening, and timely intervention such as cerclage for cervical insufficiency.

When Uterine Anomalies Show Up in Adolescence

Many congenital anomalies remain silent until someone tries to get pregnant, but obstructive anomalies often announce themselves during adolescence. When part of the reproductive tract is blocked, menstrual blood has no way out, and it pools behind the obstruction. This typically presents as worsening pelvic pain that cycles monthly in a teenager who may or may not have visible periods. One study of 50 adolescents with obstructive anomalies found that nearly half had developed endometriosis by the time of surgery, with rates reaching 100 percent in girls with cervicovaginal aplasia and 73 percent in those with obstructive uterine anomalies.²⁵

MRI is particularly valuable in the pediatric and adolescent population because it can precisely identify the obstruction site, map associated findings like blood-filled collections in the vagina or fallopian tubes, and detect absent kidneys on the same side, a common association.²⁶ Surgical correction, typically resecting an obstructing vaginal septum or removing a non-communicating rudimentary uterine horn, is usually successful. A series of 42 adolescents treated surgically reported complete resolution of obstruction and clear improvement in pain.²⁷ However, about 28 percent of adolescents in another cohort continued to have pain resistant to standard painkillers after surgery and required ongoing hormonal treatment or a second procedure, underscoring that clearing the blockage does not always resolve associated endometriosis.

The Emotional Side of Uterine Abnormalities

A diagnosis of a uterine abnormality, particularly one that affects fertility or involves the absence of the uterus, carries a psychological weight that medical discussions sometimes underplay. This has been studied most closely in MRKH syndrome, where the discovery in adolescence that the uterus and part of the vagina are absent can be profoundly distressing. A systematic review found that MRKH is associated with higher rates of anxiety and depression compared to age-matched peers, as well as difficulties with sexual self-image, arousal, lubrication, and orgasm.²⁸ Mental-health-related quality of life was notably impaired, even though physical-health quality of life was not. A separate review highlighted that difficulties managing intimacy and disclosing the condition to partners were particularly challenging aspects of living with MRKH.²⁹ These findings reinforce that counseling and psychological support should be part of care for any significant uterine anomaly, not an afterthought.

Uterus Transplantation

For women with absolute uterine-factor infertility, whether from MRKH syndrome, prior hysterectomy, or a nonfunctional uterus, the emergence of uterus transplantation has been transformative. The first live birth following a uterus transplant occurred in Sweden in 2014, and the procedure has since expanded internationally. A report from the U.S. Uterus Transplant Consortium covering the first 33 recipients in the country found that graft survival at one year was 74 percent. Among those whose grafts survived to the one-year mark, more than 80 percent went on to have at least one live birth.³⁰

A more recent study of 20 participants reported that 14 (70 percent) had successful allografts, and all 14 gave birth to at least one healthy infant with no congenital malformations. Complications were not rare: about half of successful pregnancies involved issues like gestational hypertension, cervical insufficiency, or preterm labor, and some living donors experienced surgical complications as well.³¹ The transplanted uterus is not meant to be permanent; it is removed after the recipient has completed childbearing, allowing immunosuppressive medications to be discontinued. The procedure remains limited to specialized centers and is still considered experimental in many countries, but for women with MRKH or other causes of uterine absence, it represents the first realistic option to carry their own pregnancy.