Blog

In assisted human reproduction, we refer to secondary infertility when a couple already have a child together and they want a second baby but they do not manage to obtain a pregnancy after a full year of unprotected sexual intercourse. There are multiple reasons why a couple may suffer from secondary infertility. One of them is related to the scar defects that may occur after a caesarean section. This condition is known as an an isthmocele or isthmoceles.

Given that more and more women give birth by means of caesarean section, the incidence of isthmoceles is relatively high. Next, we discuss the causes, clinical signs and symptoms of this condition.

What is an isthmocele?

An isthmocele is a spontaneous partial tear of a scar in the wall of the uterus. Most commonly, scars are a result of hysterotomy procedures such as the surgical incision of the uterus during a caesarean section. This condition is often described as a diverticulum or a niche in the uterine scar where the hysterorrhaphy was performed (the suture of the uterine wall). The exact causes of the uterine isthmocele are not yet fully understood, but research suggests they may be related to the abnormal or incomplete healing of the uterine incision after a caesarean section.

How does it occur and what causes an isthmocele?

In order for an isthmocele to occur, the woman must first have undergone a caesarean section (surgical procedure). Recent studies reported isthmoceles in 60% of women who, prior to diagnosis, had given birth to their first child. After three caesarean sections, the incidence of isthmoceles can reach 90-100%.

Some theories attribute this complication to the surgical technique, the material, and the type of suture used in the caesarean section. Also, the difference is size between the anterior and posterior sides of the sutured incision, as well as how the uterus is position (most commonly retroflexed) could also play an important part.

What are the symptoms of an isthmocele?

An isthmocele does not always cause clinical symptoms. Often, the isthmocele is an incidental finding of routine ultrasound investigations. When it does trigger noticeable symptoms, most commonly they include post-menstrual bleeding, especially in the form of a brownish discharge which persists after the menstruation period, dyspareunia (pain during sexual intercourse), and sometimes abdominal pains.

Also, the isthmocele has been proven as one cause of secondary infertility, as it can make it more difficult for spermatozoa to reach inside the uterus. The isthmocele is suspected to have a negative impact on embryo implantation; if the scar defect in the uterine wall contains leftover menstrual material which may subsequently travel inside the uterus, this can reduce the probability of successful embryo implantation.

How is an isthmocele diagnosed?

The diagnosis of an isthmocele requires a detailed clinical examination with the help of imagistic techniques such as the endovaginal ultrasound and diagnostic hysteroscopy.

During the endovaginal ultrasound, the the defect is measured and assessed: the isthmocele appears as a feature with low echogenic properties, ellipsoidal or triangular in shape. Both diameters can be measured and the surface of the defect can be calculated as well.

The diagnostic hysteroscopy provides clear evidence of the defect and reveals its severity, thus enabling the clinician to decide on the appropriate solution (interventional hysteroscopy or even laparoscopy).

Occasionally, magnetic resonance imagining (MRI) technology, due to its accuracy, can be used to decide which surgical solution is most suited to correct the defect depeding on the thickness, in millimetres, of the anterior surgical margin.

When and how is an isthmocele treated?

The treatment of an asymptomatic isthmocele is generally conservative. An isthmocele requires surgical intervention only when it triggers clinical symptoms or if the patient presents with secondary infertility for which no other cause can be identified.

Treatment consists in resectoscopic correction by means of hysteroscopy in order to reduce the size of the defect and close the site of the incision. When it is too wide and deep to be resolved via hysteroscopy, the appropriate surgical intervention is laparoscopy and the procedure consists in closing the defect inside a sutured sac containing the uterine scar.

There are very few cases reported in the literature where this technique was used, but the initial results are promising. Most women were able to obtain spontaneous pregnancies only months after surgical correction, provided no other causes of infertility were present.
Although the surgical intervention can successfully resolve the defect, patients are advised to wait for approximately three months after hysteroscopy and six months after laparoscopy before attempting to conceive again. This gives the uterine wall the necessary time to fully heal in order to minimize risks.

Dr Theodora Armeanu, junior doctor, Obstetrics-Gynaecology