Asherman Syndrome, alternatively known as intrauterine adhesions or synechiae, refers to the presence of adhesions within the uterine cavity. Adhesions are threads or thicker bands of scar tissue that form within the cavity and they connect and ultimately fuse together two or more surfaces of the interior lining of the uterus, thus reducing the cavity’s volume or even obliterate it completely in more severe cases.
Asherman Syndrome is most frequently caused by endometrial injury during dilation and curettage procedures for termination of pregnancy or removal of retained products of conception, following incomplete miscarriage or delivery. On occasion it may occur after similar procedure for gynaecological indications, such as treatment of excessive uterine bleeding, endometrial sample retrieval for histology assessment and removal of endometrial polyps.
Since Asherman Syndrome may remain undiagnosed for long, due to the absence of notable clinical symptoms, it is challenging to reliably say how common it is. Studies have estimated that it may occur in up to 1 in 8 women undergoing termination of pregnancy during the first trimester and in up to 1 in 3 women undergoing curettage for late miscarriage. The risk is increased for repeated procedures.
The injury caused to the endometrium by the various curettage procedures triggers an inflammatory response in the exposed areas, which ultimately results in the formation of scar tissue connecting to the endometrial surface opposite to the site of injury. This is exacerbated when both opposing surfaces have been scratched and undergo inflammation, resulting in thicker and stronger adhesions, covering larger areas and resulting in significant reduction of the available space in the uterine cavity.
Clinical symptoms that usually accompany Asherman Syndrome are the following:
- Amenorrhea (complete absence of menstrual periods): this is usually present in severe cases, where most of the endometrial surfaces are covered with adhesions and/or fused together, therefore there is no space for endometrial growth and thus no endometrium is shed at the end of the cycle, resulting in absence of bleeding.
- Hypomenorrhea (lighter periods): for milder cases, where there is still enough available surfaces in the uterus for endometrial growth.
- Dysmenorrhea (severe pain during menstrual period): even in the absence of bleeding, some patient may experience severe pain due to the obstruction of normal blood flow by adhesions in the cervical area.
- Infertility and/or repeated miscarriages: the symptom that usually constitutes the reason most women seek medical attention. The reduction of available healthy endometrium areas, combined with impaired vascularization of the endometrium due to scarring, create a hostile intra-uterine environment. This may be present without any menstrual disturbances.
Since clinical symptoms, if present, may be misleading or inconclusive, thorough investigation is usually required. Initial assessment may include ultrasound, saline sonography or hysterosalpingogram, however these investigations still lack the diagnostic sensitivity to detect all cases. Hysteroscopy remains the method of choice, as the direct visualization of the uterine cavity via camera offers the definitive evidence needed to confirm the diagnosis and at the same time evaluate the extent of the disease. Hysteroscopy also offers the option for direct therapeutic intervention, as it allows for the excision of the formed adhesions. Additional estrogen treatment, or intrauterine device placement may assist in preventing the formation of new adhesions postoperatively.
Several additional interventions, such as endometrial infusions of hyaluronidase and stem cells have had promising results in experimental protocols, but are not widely applied in the clinical context. One intervention that is currently applied and has shown considerable efficacy is the endometrial infusion of platelet-rich plasma (PRP). PRP is a blood product derived from the patient’s own blood that contains high concentrations of platelets and growth factors. When infused in the endometrium, it proliferates growth and rejuvenated the top layer, the most important for embryo implantation. At the same time, it is safe intervention, as no medications are used and its autologous origin ensures that no allergic reactions occur.
Overall, Asherman Syndrome is a relatively common occurrence after surgical interventions in the endometrium and may result in infertility or recurrent miscarriages. Assessment and treatment with hysteroscopy, in addition to endometrial support via PRP infusion constitute an effective way of restoring the uterine cavity to its normal anatomy and function and improving reproductive outcomes.
