A uterine septum is a congenital anomaly where a wall of tissue divides the uterine cavity. This condition results from an issue during the development of the female reproductive system in the fetus. It is considered the most common type of congenital uterine abnormality, occurring in approximately 1 to 15 cases per 1,000 women. While the presence of a septum may not always cause symptoms, it is frequently discovered during an investigation into recurrent pregnancy loss or infertility. This structural variation can significantly affect the ability to sustain a pregnancy, but it is a highly treatable condition.
Anatomical Definition and Embryological Development
The uterus develops from two paired structures called the Müllerian ducts during fetal development. These ducts must first fuse together and then the central wall of tissue created by this fusion must be completely absorbed by the body. A uterine septum occurs when the second part of this process—the resorption of the midline tissue—is incomplete. This failure of resorption leaves a partition of tissue that divides the single uterine cavity into two smaller spaces.
The septum itself is typically composed of fibrous and connective tissue, which is notably poor in blood vessels, or avascular. The extent of the septum determines its classification. A partial septum extends only partway down the uterine cavity, while a complete septum extends to the cervix and may even reach the vagina.
It is important to differentiate a uterine septum from other similar anomalies, such as a bicornuate uterus. A bicornuate uterus results from a failure of the Müllerian ducts to fully fuse, giving the uterus a distinct heart-shape with a deep indentation on its outer surface. In contrast, a uterus with a septum retains a normal, smooth, or convex external contour. The distinction matters because the septum can often be surgically corrected with favorable results, whereas the bicornuate uterus is rarely treated surgically.
Clinical Presentation and Detection Methods
The presence of a uterine septum is frequently asymptomatic and is often an incidental finding during a routine pelvic exam or imaging. For many women, the condition is only identified when they seek medical help due to adverse reproductive history, such as recurrent miscarriage or unexplained infertility.
Diagnosis requires specialized imaging to accurately assess the internal structure of the uterus and distinguish the septum from other anomalies. Two-dimensional transvaginal ultrasound is typically the initial tool, but it often lacks the detail needed for a definitive diagnosis. Three-dimensional (3D) transvaginal ultrasound is a preferred method because it can produce a coronal view of the uterus, providing a clear image of both the internal cavity and the external contour.
Magnetic Resonance Imaging (MRI) is also a valuable tool, offering superior soft-tissue contrast to help identify the composition of the dividing tissue. MRI is particularly useful for measuring the depth of the septum and confirming the normal external contour of the uterus. Saline Infusion Sonohysterography (SIS) can also be used, where saline is instilled into the uterus to distend the cavity, allowing for a clearer view of the septal partition.
Effects on Pregnancy and Fertility Outcomes
The primary problem caused by a uterine septum is not that it prevents conception, but that it compromises the ability to sustain a pregnancy. Embryos often implant onto the septal tissue, which is composed of avascular, fibrous tissue with a poor blood supply. This inadequate vasculature prevents the successful formation of a robust placenta necessary to support the developing fetus.
This lack of proper blood flow and structural support leads to a significantly increased risk of adverse outcomes. Untreated uterine septa are associated with high rates of first and second-trimester recurrent miscarriage, with some studies reporting a risk of pregnancy loss in the range of 26% to 94%.
Beyond early pregnancy loss, a septum can also increase the risk of complications later in gestation. These include preterm labor and delivery, as the reduced space in the uterine cavity may trigger premature contractions. Fetal malpresentation, such as a breech position, is also more common because the septum can restrict the baby’s ability to turn.
Surgical Correction: Hysteroscopic Metroplasty
The standard and highly effective treatment for a symptomatic uterine septum is a minimally invasive surgical procedure called hysteroscopic metroplasty, also known as septoplasty. This procedure is performed using a hysteroscope, a thin, lighted telescope inserted through the vagina and cervix, eliminating the need for any abdominal incisions. The surgeon uses specialized instruments passed through the hysteroscope to carefully cut and resect the fibrous septal tissue.
The goal of the surgery is to restore the uterine cavity to a single, normal shape, thereby maximizing the surface area of well-vascularized endometrial tissue available for implantation. The procedure is typically performed on an outpatient basis. The overall complication rate is low, though risks include uterine perforation or the formation of intrauterine adhesions.
The success rates following hysteroscopic metroplasty are very encouraging for women with a history of recurrent pregnancy loss. Studies show that after the surgery, the live birth rates increase substantially, with some data indicating a rise from rates as low as 2.4% to over 80%. This improvement in reproductive prognosis, often resulting in live birth rates comparable to the general population, makes the procedure the recommended course of action for women who have experienced pregnancy complications.