Uterine scarring, often described as intrauterine adhesions, can complicate conception, but it does not make pregnancy impossible. The ability to conceive and carry a pregnancy to term depends on the extent and location of the scar tissue within the uterine cavity. The scarring interferes with the uterine lining, which must be receptive for an embryo to successfully attach and develop.
Causes and Types of Uterine Scar Tissue
Uterine scarring forms when the basal layer of the endometrium is damaged. This trauma triggers an inflammatory response, causing fibrous bands of scar tissue to form, often connecting opposing walls of the uterus. The most severe form is known as Asherman’s Syndrome, characterized by variable scarring inside the uterine cavity.
The most common cause is dilation and curettage (D&C), especially when performed after a miscarriage or to remove retained placental tissue. The recently pregnant uterus is vulnerable to damage during a D&C, increasing the likelihood of scar tissue formation. Other procedures, such as a myomectomy or a cesarean section, can also lead to the development of these adhesions.
Asherman’s Syndrome is classified based on the amount of scar tissue present and the extent to which it obliterates the uterine cavity. Adhesions are categorized as mild, moderate, or severe, affecting the prognosis for fertility. Mild scarring involves thin adhesions, while severe cases involve thick, dense scar tissue that can completely fuse the uterine walls.
How Scar Tissue Affects Implantation
The presence of scar tissue directly impairs fertility by interfering with implantation, the process where the embryo attaches to the uterine wall. Successful implantation requires a healthy, adequately thick endometrial lining, which scar tissue compromises. The adhesions reduce the functional surface area of the endometrium, diminishing the number of viable sites where an embryo can settle.
Scar tissue often lacks the necessary blood flow and hormonal responsiveness of normal endometrial tissue. This reduced vascularity means an embryo attempting to attach near a scarred area may be cut off from required nutrients. Furthermore, the scarred tissue may exhibit a compromised response to the steroids necessary for a receptive environment.
Severe scarring can also physically distort the shape of the uterine cavity, potentially blocking the path for sperm or an embryo. This distortion can make it difficult to properly place an embryo during an in vitro fertilization (IVF) transfer procedure. If conception occurs, the compromised uterine environment significantly increases the risk of early miscarriage and recurrent pregnancy loss.
Medical Interventions to Restore Fertility
The primary treatment for uterine scarring is hysteroscopic adhesiolysis, the standard procedure for Asherman’s Syndrome. This minimally invasive technique involves inserting a hysteroscope through the cervix into the uterus. Specialized instruments are used to carefully cut and remove the fibrous bands of scar tissue, restoring the normal shape of the uterine cavity.
In cases of severe scarring, the procedure is sometimes performed with concurrent abdominal ultrasound guidance or laparoscopy. This monitoring helps ensure the dissection is performed in the correct tissue plane and reduces the risk of accidental perforation. The success of the procedure is linked to the initial severity of the adhesions; for example, one study showed a higher conception rate for women with mild scar tissue compared to those with severe scarring.
Postoperative care is important because there is a risk that the adhesions will reform. To prevent the newly separated walls from sticking back together, a physical barrier is often temporarily placed inside the uterine cavity. This barrier, such as an intrauterine balloon catheter or an intrauterine device (IUD), keeps the damaged endometrial surfaces apart while they heal.
Patients are typically given high-dose estrogen therapy, sometimes combined with progesterone, to promote the regrowth of a healthy endometrial lining. The estrogen encourages the remaining basal layer cells to proliferate and cover the raw surfaces left by the removed scar tissue. Follow-up procedures, known as second-look hysteroscopies, are often scheduled to check for adhesion recurrence and remove them if necessary.
Potential Complications During Pregnancy
Even after successful treatment, a pregnancy following uterine scarring is considered higher risk and requires careful monitoring. Damage to the endometrium can affect how the placenta develops and attaches to the uterine wall. This increases the likelihood of abnormal placentation, which refers to problems with the placenta’s position or depth of attachment.
There is an elevated risk of Placenta Previa, where the placenta partially or completely covers the cervix, potentially causing severe bleeding. Another serious complication is Placenta Accreta, where the placenta implants too deeply into the uterine wall, sometimes growing into the muscle layer. This deep attachment can prevent the placenta from detaching naturally after birth, often leading to massive hemorrhage.
Women treated for uterine scarring also have an increased chance of experiencing preterm labor (delivery before 37 weeks). The risk of miscarriage remains higher even after treatment, and there is a possibility of fetal growth restriction or low birth weight. Due to these potential complications, pregnancies are generally managed by an obstetrician specializing in high-risk care.