What is Uterine Synechiae? Meaning, Causes and Symptoms

What are Uterine Synechiae? Understanding the Basics

Uterine synechiae, or intrauterine adhesions (IUAs), are scar tissues that form inside the uterus. Signs may include irregular menstrual cycles, light periods (hypomenorrhea), absent periods or sometimes even normal menstrual flow.

A more severe form of this condition is Asherman’s syndrome (AS), which involves extensive adhesions that can lead to infertility, menstrual irregularities or recurrent pregnancy loss. The key difference between IUAs and AS is the severity of scarring and its impact on fertility, often requiring more intensive medical treatment in AS.

Both IUAs and AS are associated with adverse reproductive outcomes, including implantation failure, reduced uterine and fetal blood flow, infertility and recurrent miscarriage. These complications can significantly affect a woman’s fertility and ability to conceive.

What Causes Uterine Synechiae in Women?

Uterine synechiae form due to infection, injury or inflammation of the uterine lining. Understanding these causes is important for early prevention, timely diagnosis and improved reproductive outcomes.

1. Previous Uterine Procedures

Uterine synechiae often occur after procedures that damage the uterine lining. Currently, in more than 90% of women, pregnancy-related procedures are the main cause, particularly repeated dilation and curettage (D&C) after miscarriage. Studies show that multiple D&C procedures increase the risk of intrauterine adhesions to 19.1% and are associated with lower live birth rates and delayed conception.

2. Infections of the Uterus

Pelvic inflammatory disease (PID) significantly raises the risk of intrauterine adhesions. Severe or chronic infections are linked to more extensive scarring.

3. Complications After Childbirth or Miscarriage

Adhesions may occur post-partum, especially after curettage for retained placental tissue. The risk increases further when uterine evacuation is performed weeks after delivery or following recurrent miscarriages, often requiring repeated procedures.

4. Repeated Uterine Instrumentation

Frequent uterine procedures, particularly those involving suction, can damage the uterine lining and lead to adhesions. Repeated or prolonged instrumentation further increases this risk. For this reason, non-surgical alternatives are preferred whenever possible.

What Are the Common Symptoms of Uterine Synechiae?

Uterine synechiae can cause menstrual and reproductive issues, though some women may have no obvious symptoms.

Reproductive Disorders

• Infertility: Studies show that synechiae develop in nearly 43% of women experiencing infertility. They may interfere with conception. In some cases, fertility appears normal, but implantation is affected, causing very early pregnancy loss, sometimes called “false sterility.”
• Abnormal placental implantation: Conditions such as placenta praevia and placenta accreta may be linked to intrauterine synechiae and can sometimes lead to diagnosis during pregnancy.
• Repeated abortions and premature delivery: Synechiae can cause repeated abortions or premature delivery by altering the shape of the uterine cavity or weakening the cervix, leading to cervical incompetence.

Disorders of the cycle

• Amenorrhea: Amenorrhea is a common and often revealing symptom of synechiae, reported in about 37% of cases. Hormone levels are usually normal, and menstrual bleeding does not respond to hormonal treatment.
• Dysmenorrhea: Painful periods are rarely the only symptom, but when combined with hypomenorrhea, they may indicate adenomyosis developing in the endometrium surrounding the synechiae.
• Hypomenorrhea: Lighter menstrual flow occurs in around 31% of cases, linked to a reduced area of functioning endometrium or changes in the uterine lining around scar tissue.
• Asymptomatic synechiae: Many women have no noticeable symptoms, and intrauterine synechiae are often discovered incidentally during investigations for other reasons.

How Does Uterine Synechiae Affect Menstrual Health?

Uterine synechiae can affect normal menstrual periods by altering the shape and lining of the uterus. The type and severity of changes depend on the location and extent of adhesions:

• Amenorrhea (absent periods): Extensive scar tissue or cervical blockage can stop the menstrual cycle completely. This occurs when little healthy lining remains or it fails to respond to hormones. Absent periods are commonly seen in severe cases, such as Asherman’s syndrome.
• Hypomenorrhea (light periods): When adhesions involve only part of the uterus, menstrual flow may be very light due to reduced healthy uterine lining.
• Dysmenorrhea (painful periods): Scar tissue can alter the uterine shape or block normal menstrual flow, causing pain, especially when adhesions are near the cervix or lower uterus.
• Irregular menstrual patterns: Some women may experience abnormal or unpredictable cycles, while in a few cases, periods may appear normal despite the presence of adhesions. Symptoms vary depending on how much the uterine lining is affected.

Can Uterine Synechiae Impact Fertility and Pregnancy?

Uterine synechiae can affect a woman’s ability to conceive and maintain a healthy pregnancy. These bands of scar tissue alter the normal shape of the uterus, making it difficult for an embryo to implant properly. They often develop after uterine injury, such as following an early pregnancy abortion or when placental tissue remains after childbirth. Uterine synechiae are linked to menstrual problems and are strongly associated with recurrent miscarriages.

What Are the Treatment Options for Uterine Synechiae?

Uterine Synechiae are primarily treated with hysteroscopic surgery, supported by preventive and hormonal therapies.

1. Accurate Diagnosis

Hysteroscopy is the gold standard for diagnosing uterine synechiae. It allows healthcare providers to directly view the uterus, assess scar tissue, its severity and the health of the uterine lining. Other tests, such as hysterosalpingography (HSG), pelvic ultrasound or saline ultrasound, can be useful but are less precise. Pelvic ultrasound helps evaluate the thickness of the uterine lining, which can affect treatment outcomes.

2. Hysteroscopic Surgery (Adhesiolysis)

The main treatment is hysteroscopic surgery, where scar tissue is carefully cut and removed using small instruments while preserving healthy uterine tissue. In complex cases, ultrasound guidance may be used to reduce the risk of injury.

3. Preventing Adhesion Recurrence

Preventing recurrence is important, especially in severe cases. Doctors may use:

• Special gels (e.g., hyaluronic acid) to reduce new scar formation.
• Temporary balloons or catheters placed inside the uterus to keep the walls apart.
• Intrauterine devices (IUDs).

Using a combination of methods (balloon/IUD plus gel) may improve outcomes.

4. Hormonal and Supportive Therapy

After surgery, estrogen therapy is often prescribed to help the uterine lining heal and regenerate. In some cases, estrogen may be used before surgery to improve the lining. Other medications or supplements to enhance lining recovery are being studied, but more research is needed.

Conclusion

Uterine Synechiae are an often overlooked cause of abnormal menstrual cycles, infertility and pregnancy complications. Symptoms can range from light or absent periods to recurrent miscarriages, depending on scar tissue extent. These adhesions frequently occur after pregnancy-related procedures or uterine surgery. Early recognition and timely medical evaluation, combined with appropriate treatments like hysteroscopic surgery and supportive therapy, can restore uterine function, improve fertility and help women achieve healthier reproductive outcomes.