A uterine septum is a wall of tissue that divides the inside of the uterus, either partially or completely. It forms before birth when tissue that should have dissolved during fetal development stays in place instead. A septate uterus is the most common congenital uterine anomaly, and many people don’t know they have one until they experience pregnancy complications or undergo imaging for another reason.
How a Uterine Septum Forms
During early fetal development, the uterus starts out as two separate tubes called paramesonephric ducts. These tubes fuse together to create a single uterine cavity, and the tissue where they joined is supposed to be reabsorbed by the body before the 20th week of embryonic development. When that resorption doesn’t happen completely, a band of tissue remains, hanging down from the top of the uterine cavity like a curtain. That leftover tissue is the septum.
Because this happens so early in development, there’s nothing a person does or doesn’t do that causes it. It’s simply a variation in how the uterus formed. The outside of the uterus looks completely normal, which is one reason a septum can be tricky to diagnose with certain imaging methods.
Partial vs. Complete Septum
Septate uteri exist on a spectrum. A partial (or incomplete) septum extends partway down from the top of the uterine cavity toward the cervix but doesn’t reach it. The uterus still has a single outer shape and a single cervix, but the interior space is divided to some degree. A complete septum, on the other hand, extends all the way from the top of the uterus down to the cervical opening, effectively creating two separate channels inside what appears from the outside to be one normal uterus.
The size and length of the septum matter because they influence how much the interior space is restricted. A small partial septum may cause no noticeable problems, while a complete septum can significantly affect how a pregnancy develops.
Symptoms and How It’s Discovered
Most people with a uterine septum have no symptoms at all outside of pregnancy. Periods may be normal, and there’s typically no pain directly caused by the septum itself. For this reason, many septate uteri are found incidentally during imaging for unrelated issues, or during a workup after recurrent miscarriages or difficulty conceiving.
During pregnancy, a septum can cause problems because it reduces the space available for a growing fetus and because the tissue of the septum itself tends to have a poor blood supply. An embryo that implants on or near the septum may not receive adequate nourishment. This can lead to early pregnancy loss, preterm birth, or the baby settling into a breech or other abnormal position because of the restricted space. Recurrent first-trimester miscarriage is one of the most recognized patterns that leads to a diagnosis.
How It’s Diagnosed
Getting the diagnosis right is critical because a septate uterus can look similar to a bicornuate uterus (a “heart-shaped” uterus with a dip on the outside) on basic imaging, and the two conditions are managed very differently. The key distinction is the outer shape of the uterus: a septate uterus has a normal, rounded top on the outside, while a bicornuate uterus has a visible indentation.
Three-dimensional transvaginal ultrasound is considered the best first-line tool for making this distinction. A meta-analysis comparing it to MRI found that 3D ultrasound had significantly higher sensitivity for detecting a septate uterus, at 99% compared to 81% for MRI. It’s also more accessible and less expensive. A standard two-dimensional ultrasound or an X-ray dye test of the uterus and tubes can show that something is dividing the cavity, but neither can reliably tell you whether the cause is a septum or a different uterine shape. When 3D ultrasound isn’t available, MRI is a reliable alternative.
Effects on Fertility and Pregnancy
A uterine septum doesn’t necessarily prevent conception. Many people with a septum get pregnant without difficulty. The bigger concern is what happens after conception. The septum’s tissue composition is different from the normal uterine lining. It tends to be more fibrous with fewer blood vessels, making it a poor site for an embryo to implant and grow. If the embryo attaches to the septum rather than the healthy uterine wall, the pregnancy is at higher risk of ending in miscarriage.
Even when implantation occurs on the normal uterine wall, a large septum can crowd the developing baby and contribute to preterm delivery or malpresentation (the baby being positioned feet-first or sideways). Among all congenital uterine anomalies, the septate uterus is associated with the highest rates of poor obstetric outcomes, which is notable because it’s also the one most amenable to surgical correction.
Surgical Correction
The procedure to remove a uterine septum is called a hysteroscopic metroplasty (or septoplasty). It’s done through the cervix using a thin camera and instruments, with no abdominal incisions. The surgeon cuts through the septum to open up the uterine cavity into a single, unified space. The procedure is typically outpatient, meaning you go home the same day.
Recovery is relatively quick compared to abdominal surgery. Most people can return to normal activities within a few days, though guidelines on how long to wait before trying to conceive vary. Whether to cut through the cervical portion of a complete septum or leave it intact has been a longstanding debate among surgeons, with practice varying by individual case and surgeon preference.
Who Should Consider Treatment
The decision to surgically remove a septum depends largely on your reproductive history and goals. For people who have experienced recurrent miscarriages or preterm births and are found to have a septum, surgical correction is commonly recommended because it addresses a clear structural contributor to those losses.
The picture is less straightforward for someone whose septum was discovered incidentally, with no history of pregnancy problems. If you haven’t tried to conceive or have had uncomplicated pregnancies, the benefit of proactive surgery is less certain. The American Society for Reproductive Medicine published updated guidelines in 2024 addressing these nuances, reflecting the fact that while the surgery is low-risk, the evidence for operating on asymptomatic septa is not as strong as it is for people with documented pregnancy complications.
For those undergoing fertility treatments like IVF, the presence of a septum is often evaluated and addressed beforehand, since optimizing the uterine cavity can improve the chances of a transferred embryo implanting successfully and progressing to a healthy pregnancy.
What Sets It Apart From Other Uterine Anomalies
The septate uterus is often confused with two other conditions. A bicornuate uterus has a deep notch on the outer surface, creating two partially separate “horns,” while a septate uterus looks normal on the outside. A uterine didelphys is even more distinct, with two completely separate uterine bodies, often with two cervices. The treatment for each is different: a septum can be removed with a simple hysteroscopic procedure, but a bicornuate or didelphys uterus involves actual structural separation of the uterine muscle, which cannot be corrected the same way.
This is why accurate imaging matters so much. Misidentifying a bicornuate uterus as a septate uterus could lead to surgery that isn’t appropriate, while missing a true septum means missing the one anomaly that’s most straightforward to fix.