Intrauterine adhesions, also known as synechiae or scar tissue, are bands of fibrous scar tissue that can form within the uterus. A normal uterine cavity and endometrial lining is necessary in order to conceive and maintain a pregnancy. Scar tissue within the uterine cavity can partially or completely obliterate the normal cavity and can interfere with conception, or increase the risk for miscarriage or other complications later in the pregnancy. Intrauterine adhesions can be minor, or they can affect the entire uterine cavity, possibly even leading to complete cessation of menstrual flow. These severe adhesions are referred to as Asherman’s syndrome.
Adhesions are most commonly caused by trauma to the uterine lining from a D&C (dilation and curettage), especially if there is infection or inflammation around the time of the surgery. Less commonly, they can form after uterine surgeries such as Cesarean section or myomectomy. Having multiple D&Cs increases the risk for developing scar tissue in the uterus. A D&C done for retained placental tissue postpartum is much more likely to cause Asherman's. Some studies estimate the risk after postpartum curettage to be as high as 25%.
Hysteroscopy (outpatient surgery) is generally used to remove intrauterine adhesions. Transabdominal ultrasonography can be helpful in combination with hysteroscopy and can assist the physician in avoiding perforation of the uterus. In severe cases, it may take more than one procedure to successfully treat uterine adhesions. The patient is placed on relatively high doses of estrogen post-operatively to encourage the uterine lining (endometrium) to regenerate and cover over the raw surfaces where the scar tissue used to be. In cases of severe adhesions, it is preferable to place an intrauterine balloon into the uterine cavity (few days to 2 weeks) after the procedure in order to keep the uterine walls apart as they heal. The physician will recommend that you have some type of follow up study (sonohysterogram, HSG) 4-6 weeks after surgery to confirm complete resection of the adhesions.
After hysteroscopic removal of severe uterine adhesions, any pregnancies that follow have an increased likelihood of complications, such as preterm labor, third trimester bleeding, and abnormal placenta attachment to the uterine lining. For women who have extensive endometrial damage that does not respond to hysteroscopy treatment, using a gestational carrier may be the best or only option to achieve pregnancy.