Septate Uterus

Septate uterus is the commonest congenital uterine anomaly, accounting for about 35 percent of all anomalies. Prevalence is about 1 to 2 percent of women, and 5 to 15 percent of women with recurrent pregnancy loss. It results from failure of resorption of the midline septum after fusion of the Müllerian ducts.

The external fundal contour is normal or has a cleft of less than 1 cm. The cavity is divided by a septum of fibromuscular (mostly fibrous) tissue. The septum may be:

• Partial, not reaching the internal os.
• Complete, reaching the cervix and sometimes extending down the vagina.

The septum has poor vascularity and a thin endometrial lining, which impairs implantation and placental development.

It is distinguished from bicornuate uterus by the flat or minimally indented external fundus and an acute angle between the uterine cavities (less than 90 degrees).

• Usually asymptomatic; found at investigation of recurrent loss or infertility.
• First trimester miscarriage (about 25 to 40 percent, higher than other anomalies), second trimester loss, preterm delivery (about 10 to 20 percent), malpresentation (breech in 20 to 25 percent), fetal growth restriction, placental abruption, retained placenta, and caesarean section.
• Menstruation is usually normal; dysmenorrhoea is occasionally present. Rarely there is a longitudinal vaginal septum with dyspareunia.
• Associated renal anomalies are uncommon.

• Three dimensional ultrasound in the luteal phase is the first line test: shows a flat or convex fundal contour with an internal septum, with a normal outer contour; sensitivity above 90 percent.
• MRI pelvis in doubtful cases, to differentiate septate from bicornuate uterus and measure septal length, thickness and composition.
• Hysterosalpingography shows two cavities with a narrow intercornual angle (less than 60 to 75 degrees); saline infusion sonography also helps.
• Hysteroscopy with laparoscopy offers the definitive diagnosis and allows simultaneous treatment.
• Septum length above 1 cm, or a ratio of septal to cavity length above 50 percent, is regarded as significant.

• Hysteroscopic septum resection (metroplasty) is the standard treatment.
• Indications: recurrent miscarriage (two or more), or a history of second trimester loss or preterm birth with no other explanation; infertility with other causes excluded; and before assisted reproduction where there is a history of failure. The evidence supports resection in women with prior losses.
• In women with no history, resection is not routinely recommended but may be offered after counselling.
• Technique: day case surgery under general or regional anaesthesia, using saline distension. Instruments include a small hysteroscope with microscissors, a bipolar electrode, or a hysteroscopic morcellator or laser.
• Incise the septum in the midline, starting at the lower free edge and moving towards the fundus. Stop when the tubal ostia are visualised at the same level and the incision reaches the myometrium. Avoid the fundal thickness, characterised by increased bleeding and a change in tissue colour.
• Laparoscopy or ultrasound guidance reduces the risk of uterine perforation.
• Divide a complete septum by cutting up from the cervical canal, avoiding the cervix to prevent cervical insufficiency.
• Pre-operative endometrial preparation is optional (gonadotrophin releasing hormone analogue or a progestogen for 4 weeks to thin the endometrium).
• Post-operative: many use oestrogen therapy (estradiol valerate 2 mg twice daily for 30 days, with progestogen for the last 10 days) to promote re-epithelialisation. An intrauterine balloon or gel may be used in selected cases to prevent adhesions. Second look hysteroscopy is at 1 to 3 months.
• Complications: uterine perforation, fluid overload, bleeding, intrauterine adhesions (about 5 to 10 percent), and residual septum.
• Outcomes: miscarriage rates fall from about 80 percent to about 10 to 20 percent after resection, with live birth rates of 70 to 85 percent. Conception is allowed after one or two menstrual cycles (about 2 months).
• Pregnancy after resection: standard antenatal care with early ultrasound, cervical length assessment, and delivery according to obstetric indications. Caesarean section is not necessary after a simple resection unless a deep myometrial incision was made.
• Untreated pregnancy: cervical length surveillance; progesterone if short cervix.