Uterine synechiae, or intrauterine adhesions (IUA), are often underdiagnosed but can lead to infertility and abnormal menstruation. They most commonly occur after uterine instrumentation. Often, the underlying pathophysiology is damage to the basilar endometrium [1]. This results in fibrous connective tissue bands that may have glandular tissue [2]. Synechiae range from minimal adhesions to total obliteration of the uterine cavity. Adhesions can be filmy or dense. Most often, they are located in the cavity but can also occur in the cervicoisthmic area. On histology, adhesions can be fibromuscular, endometrial, myometrial, or connective tissue. The worst prognosis is seen with dense fibrous adhesions without endometrial glands [2].

17.1 Risk Factors

Endometrial curettage in pregnancy is the most frequent cause of uterine adhesions, with 30% of synechiae forming after a curettage for a missed abortion [3]. Postpartum curettage is another major risk factor, particularly in the first 2–4 weeks postpartum [4]. Additionally, 2% of patients who undergo manual placenta removal develop synechiae [4]. Several other pregnancy-related risks include previous cesarean sections, placenta accreta, and postpartum endometritis [5].

Hysteroscopic surgery, both endometrial ablation and resectoscopic surgery, can lead to synechiae. Studies have shown that using bipolar energy results in less adhesion formation than monopolar energy when resecting fibroids [6]. Other causes of synechiae include dilation and curettage in nonpregnant women, severe endometritis or fibrosis, pelvic irradiation, and endometrial tuberculosis [2]. Adhesions can form from myomectomy and intrauterine surgeries [2].

17.2 Symptoms

Patients with IUAs can present with a spectrum of symptoms. Some may have no disturbances in their menstrual cycle but present with infertility secondary to obstruction of the tubal ostia (Figs. 17.1 and 17.2) or partial obstruction of the endocervix (Figs. 17.3 and 17.4). Women may also present with recurrent abortions [7]. Commonly, patients present with menstrual irregularities or amenorrhea [2]. About two-thirds of women will present with amenorrhea [8]. However, the severity of menstrual disturbances does not necessarily correlate with the extent of adhesions [7]. Two to three percent of patients with severe disease will have no menstrual irregularities or pain [8]. In some women, scarring of the cervix or lower uterine segment can cause cyclic pain due to functional endometrium and blood trapped above the scarred tissue. If these patients do not undergo treatment promptly, retrograde menstruation can occur through a patent fallopian tube and possibly lead to endometriosis [7].

Fig. 17.1
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Endocervical stenosis from adhesions

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Fig. 17.2
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Correction of endocervical canal after lysis of adhesions

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Fig. 17.3
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Cornual scarring after endometrial ablation

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Fig. 17.4
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Right tubal ostia visualized after adhesiolysis of cornual scarring

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17.3 Diagnosis

The true incidence of uterine synechiae is unknown. One study, however, did find an incidence of 1.5% in women who underwent hysterosalpingography (HSG) [9]. Another study found a rate of 13% in those undergoing a routine infertility workup [10].

Diagnosis of synechiae begins with a thorough history evaluating for predisposing risk factors and causes of endometrial trauma. Other reasons for amenorrhea and menstrual irregularity, such as pregnancy, should be ruled out. Hysteroscopy is the diagnostic gold standard. Direct visualization allows for evaluation of endometrial quality and the extent and type of adhesions. Physical examination often fails to diagnose synechiae. However, a transcervical sounding can reveal obstruction near the cervical os [11].

Radiologic investigation is somewhat inferior to hysteroscopy in diagnosing IUA. 2D transvaginal ultrasound can evaluate endometrial thickness and the presence of hematometra (Figs. 17.5 and 17.6) [8]. Saline infusion sonohysterography (SIS) is highly accurate at diagnosing synechiae as well as other intrauterine abnormalities. The respective sensitivity and specificity of diagnosing IUAs have been reported up to 82 and 99% [8]. Both methods can show “skip lesions” created by focal or partial obliteration of the endometrium [8]. HSG is fairly sensitive (75–81%), and specific (80%) for diagnosis [8]. However, it has a very high false-positive rate of 39% and positive predictive value of 50% [8]. Some experts recommend performing an HSG before hysteroscopy. It offers the opportunity to determine tubal patency, is more cost-effective, and allows for surgical planning. When an HSG is correctly performed, a normal exam rules out IUA [7]. 3D ultrasound can be more effective in diagnosing synechiae with an 87% sensitivity and 45% specificity [8]. At this time, magnetic resonance imaging is not recommended for diagnosis [8].

Fig. 17.5
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Transvaginal sagittal image of central hematometra

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Fig. 17.6
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Transvaginal sagittal image of central hematometra outlined within red circle

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There are several classification systems for synechiae, but none have been agreed upon as the universal standard. The first system was created by March et al. based on hysteroscopic findings. Table 17.1 shows a summary of several of the classification systems.

Table 17.1 Classification of Uterine Synechiae
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17.4 Treatment

Surgical management is the ideal treatment for synechiae. Hysteroscopic lysis of adhesions can be performed to restore the uterine cavity to its normal shape and free the tubal ostia. Surgery is very effective with 80% of patients having a normal cavity after one hysteroscopic adhesiolysis by high-volume surgeons [8]. About 70% of patients have a return to regular menstrual cycles [18]. For filmy adhesions, blunt dissection can be performed. For more substantial adhesions, adhesiolysis can be done with hysteroscopic scissors, electrosurgery, or laser. Adhesions should be separated until the normal anatomy is restored and both ostia are visualized.

Dense adhesions that feel hard may need electrosurgery to take them down [10]. This can be performed with monopolar or bipolar energy. The latter is advantageous because it allows for the use of normal saline, decreasing the risks of fluid absorption. Bipolar energy also has a decreased thermal effect [7].

In general, it is better to perform adhesiolysis without electrosurgery to minimize damage to healthy endometrium and prevent recurrence. Additionally, using electrosurgery has been shown to have decreased pregnancy rates [8]. There is some evidence of decreased bleeding with the use of electrosurgery [7]. However, increased bleeding occurs when myometrium is unintentionally lysed because of difficulty distinguishing the tissue from synechiae [1].

Another technique is the use of the yttrium-aluminum-gamet (YAG) laser. The laser allows for quick dissection of lateral wall adhesions. However, it is expensive and not readily available. Additionally, the laser can cause thermal damage, up to 1 cm, from heat diffusion and create bubbles that obstruct the operative field [10].

Most patients can undergo hysteroscopic adhesiolysis in the office. Optimal candidates for in-office procedures will have minimal to moderate adhesions, an anticipated procedure time of 15 min or less, and no cervical stenosis [8]. In-office hysteroscopy does not require IV sedation, and the majority of cases are done with NSAIDs, avoiding the risks associated with anesthesia.

The severity of adhesions is correlated with increased risk of perforation. The risk increases with each subsequent adhesiolysis. Severe adhesions have a 7% risk of perforation during dilation and a 1–3% risk during dissection [10]. If perforation occurs, electrosurgery poses a risk of thermal injury to surrounding organs and structures [8]. Intraoperative transabdominal ultrasound guidance can help identify anatomy that has been distorted by the adhesions and reduce the risk of perforation.

Fluoroscopic guidance may also be used in cases of severe disease. A spinal needle is used in parallel to the hysteroscope to inject radiographic contrast medium. This allows for radiographic orientation and assessment of tubal patency [10].

Laparoscopy concomitantly with hysteroscopy can be performed to decrease the risk of perforation. However, given the increased risks and complications, it is not currently standard practice.

There are several non-hysteroscopic techniques that may be used. The first is a pressure lavage in which saline is injected into the uterus under ultrasound guidance to expand the cavity and break up mild to moderate filmy adhesions [19]. Another form of blunt disruption uses an insemination catheter filled with iodine contrast medium. This creates a continuous, ongoing HSG leading to complete adhesiolysis [19].

Lastly, hysterotomy can be performed if the adhesions prevent a hysteroscope from entering the endocervical canal and lower uterine segment. This should only be done if imaging previously showed some areas of normal endometrium and the cavity is not completely obliterated [7].

17.5 Postoperative Care

Multiple methods have been proposed for the prevention of recurrent synechiae. The more severe the initial adhesions, the more likely they are to reform. The majority of patients receive high-dose estrogen, with or without progesterone, immediately postoperatively to stimulate growth of the atrophic and damaged endometrium. Most commonly, estrogen is given for 1–3 months, and a progesterone test can be done to induce menstruation if needed [10]. Of those patients who receive hormone therapy, 64–100% will have improvement in menstruation patterns [20]. In our practice, we use estradiol 2 mg twice daily for 30 days with micronized progesterone added on days 26–30.

A less agreed upon method is the insertion of an intrauterine device (IUD) to maintain the separation between the uterine walls. The copper and levonorgestrel T-shaped IUDs may disrupt the development of normal endometrial tissue because of their local inflammatory reactions. Therefore, the preferred IUD is an inert loop, but it is not available in many areas [21]. This technique has shown some promise in mild to moderate adhesions. It is important that the removal of the IUD is done carefully to avoid damage to the endometrium [10]. Newer studies have been performed by wrapping an IUD in anti-adhesive barriers like Interceed, an oxidized, regenerating cellulose. However, patients had over a 75% recurrence rate with both just the IUD and the IUD with Interceed. The IUD alone group required a median of four repeat surgeries versus three in the Interceed group [22].

Another mechanical method is the use of an intrauterine balloon or Foley catheter [1]. It is placed immediately post hysteroscopy and kept intrauterine. Most clinicians place the catheter for 7–14 days. If long term, the patient will need prophylactic broad-spectrum antibiotics like doxycycline [2]. Some surgeons place the patient concomitantly on estrogen [2].

Several barrier methods have been developed but are considered more experimental. Seprafilm is a bioabsorbable membrane from chemically modified hyaluronic acid and carboxymethylcellulose. In randomized, controlled, blind studies, Seprafilm has been shown to be very effective. Of those patients with no previous history of curettage treated with Seprafilm, 100% achieved pregnancy within 8 months versus 54% of control patients. For those who had one or more previous D&Cs, 90% of those treated with Seprafilm had no adhesions on repeat hysteroscopy versus 50% of the controls [23]. Another technique is the use of auto-cross-linked hyaluronic acid gel (ACP). In a study looking at adhesion formation after resectoscope hysteroscopy, ACP was shown to significantly decrease the development of synechiae and the severity of adhesions [24].

A retrospective study comparing the intrauterine balloon, IUD, and hyaluronic acid gel found that the intrauterine balloon and IUD were significantly more effective at preventing recurrent adhesions. The rate in the hyaluronic acid gel group was similar to the control group [25].

Amnion grafts with stem cells to regenerate the uterine endometrium have been studied as well. However, current randomized controlled studies have shown no significant improvement with their use [8]. Researchers are also investigating if autologous cell therapy with CD 133+ bone marrow-derived stem cells may help treat refractory cases. The results are promising and show return to menstruation and successful pregnancy, but the cohort was small [26].

A second-look outpatient hysteroscopy can be performed after withdrawal bleeding to assess for recurrence. Alternatively, this can be performed by HSG. Some experts recommend a second-look hysteroscopy within 2 weeks of initial surgery to bluntly break newly reforming adhesions before they are dense [8]. Another hysteroscopy is performed at 4 weeks to evaluate resolution of synechiae [8]. When performing a repeat hysteroscopy or adhesiolysis, it is important that the surgeon does not damage normal endometrium.

17.6 Impact on Fertility

The resolution of infertility and conception rate is related to adhesion severity. It may also depend on return to regular menstruation and the reformation of synechiae. One retrospective study found that after adhesiolysis, the conception rates in women with mild, moderate, and severe disease were 64.7%, 53.6%, and 32.5%, respectively [27]. When compared to the general population, these patients had a slightly lower live birth rate of 64.1% and a higher miscarriage rate of 20.5% [27]. Another retrospective study found that the mean time to conception after adhesiolysis was 12.8 months. The conception rate for mild, moderate, and severe disease was 58%, 30%, and 33.3%, respectively. The likelihood to conception increased with improved menstruation, 44.3%, versus those who had amenorrhea, 10%. Overall, 97.2% of patients conceived within 24 months. The live birth rate in this study was higher at 86.1% with a lower miscarriage rate of 11.1% [28]. Previous research has shown these pregnancies have an increased risk for placenta accreta and second trimester loss secondary to cervical incompetence [1].

Key Learning Points

  • Uterine synechiae can cause infertility, disruptions in menstrual cycles, and pregnancy complications.

  • The gold standard for diagnosis is hysteroscopy, but hysterosalpingography and saline infusion sonohysterography can also be used.

  • The best treatment is hysteroscopic adhesiolysis which can be done in an office setting. A second-look hysteroscopy can be performed to evaluate for recurrence.

  • Most practitioners use hormone therapy postoperatively. Inert IUDs and intrauterine balloons have been shown to be effective in preventing recurrence.

  • Overall patients without severe disease do well, with a high rate of return to menstrual cycles and increased live birth rates.