An arcuate uterus is a minor variation in uterine shape where the top of the uterus has a small, shallow dip instead of the typical smooth curve. The indentation measures at least 1 centimeter but is shallow enough that it doesn’t significantly alter the overall pear shape of the uterus. It’s one of the most common uterine shape variations, and most people who have one never know it unless it shows up incidentally on imaging.
How It Differs From a Normal Uterus
A typical uterus is slightly rounded at the top, forming a smooth dome between the two fallopian tube openings. In an arcuate uterus, that dome has a shallow concave dip. Think of the difference between the top of a balloon and the bottom of a shallow bowl. The dip doesn’t create a wall or divide the uterine cavity in any meaningful way, which is why the American Society for Reproductive Medicine classifies it as “clinically insignificant.”
The shape results from how the uterus forms before birth. During fetal development, two tube-like structures called Müllerian ducts merge together to create a single uterus. If the fusion is very slightly incomplete at the top, it leaves behind that small indentation. This makes an arcuate uterus a type of Müllerian duct anomaly, though it sits at the mildest end of the spectrum.
Arcuate vs. Septate Uterus
The distinction that matters most is between an arcuate uterus and a septate uterus, because the two can look similar on basic imaging but carry very different clinical significance. A septate uterus has a wall of tissue (a septum) that extends down into the uterine cavity, partially or fully dividing it. That septum can interfere with implantation and pregnancy. An arcuate uterus, by contrast, only has a shallow surface indentation with no significant dividing wall.
The ASRM draws the line at indentation depth: an arcuate uterus has an indentation of 1 centimeter or more but remains shallow, while a septate uterus involves deeper tissue that meaningfully encroaches on the cavity. Getting this distinction right matters because a septate uterus sometimes benefits from surgical correction, while an arcuate uterus almost never does.
How It’s Diagnosed
Most arcuate uteruses are discovered during imaging done for another reason, such as a fertility evaluation, pelvic pain workup, or routine pregnancy ultrasound. A standard two-dimensional ultrasound can sometimes suggest an unusual shape, but it’s not reliable enough to distinguish between different types of uterine anomalies.
Three-dimensional transvaginal ultrasound is the go-to tool for a clear diagnosis. It reconstructs the uterine cavity and outer contour in a coronal view, letting a clinician see both the inner dip and the normal external shape at the same time. Research comparing 3D ultrasound to MRI found “almost perfect” agreement between the two methods when identifying an arcuate uterus, with a Cohen’s kappa of 0.82. In practical terms, 3D ultrasound is at least as accurate as MRI for this diagnosis and is far more accessible and less expensive. MRI is typically reserved for complex or unclear cases.
Pregnancy and Birth Outcomes
This is the question most people are really asking when they search for this condition: will it cause problems if I want to get pregnant? The short answer is that outcomes are reassuring. A large study published in Fertility and Sterility analyzed nearly 6,800 pregnancies in women with an arcuate uterus and found a full-term live birth rate of about 91%. The preterm birth rate was 7.8%, the lowest among all types of uterine anomalies studied. Pregnancy loss (miscarriage or stillbirth) occurred in 1.3% of cases.
Those numbers are broadly in line with what you’d expect in the general population. For context, the background miscarriage rate for clinically recognized pregnancies is roughly 10 to 15%, and the overall preterm birth rate in the United States hovers around 10%. An arcuate uterus doesn’t appear to push those numbers in a worrying direction.
The relationship between an arcuate uterus and recurrent pregnancy loss remains a point of debate in reproductive medicine. Some older studies suggested a modest association, but more recent evidence and the ASRM’s own classification treat the condition as clinically insignificant. If you’ve experienced recurrent miscarriages and have been told you have an arcuate uterus, the shape variation alone is unlikely to be the primary explanation.
Treatment and Surgical Correction
In the vast majority of cases, an arcuate uterus requires no treatment at all. It’s a normal variant, not a disease, and most people with one go through pregnancy and delivery without any complications related to the shape of their uterus.
For the small number of people with an arcuate uterus who also have unexplained infertility or recurrent miscarriage, a procedure called hysteroscopic metroplasty is sometimes considered. This involves inserting a thin scope through the cervix and shaving down the indentation to smooth out the uterine cavity. It’s a minimally invasive outpatient procedure with a short recovery. However, whether it actually improves outcomes is genuinely uncertain. Multiple studies have reached conflicting conclusions, and no strong consensus supports routine surgical correction. Most reproductive specialists will look for other explanations before attributing fertility problems to an arcuate uterus.
What It Means if You’ve Been Told You Have One
Finding out you have an arcuate uterus can feel alarming, especially if you hear the words “uterine anomaly” during a fertility workup or pregnancy. But this particular variation sits at the boundary between a true anomaly and a normal uterus. The indentation is minor, the cavity remains functional, and pregnancy outcomes are favorable. If you’re trying to conceive or are already pregnant, the presence of an arcuate uterus on its own is not a reason to expect complications or to change your care plan.