What Is Isthmocele?

Overview

Isthmocele (its other names include niche or defect of caesarean scar) is scar tissue that grows after caesarean section (C-section) delivery in the myometer (on the previous caesarean section location). This anomaly has long-term complications and health implications for the birthing parent mothers, causing persistent pelvic pain, infertility, menorrhagia (continued bleeding) or postmenstrual spotting. Since the number of C-sections is constantly growing, it is essential to be aware of this entity to make an early diagnosis.^1,2 

The number of cesarean sections has increased globally over the past three decades. The incidence of C-sections in developed countries ranges from 6.2% to 36%, with an average value of 21.1% between 2002 and 2006, the proportion of C-sections in the United States increased to 30.5%, reaching 32% in 2007.^3,4,5

Rupture of the uterus, placenta previa, abnormal adherence of the placenta to future pregnancy, and pregnancy implanted at the level of post-C-section scar, among isthmocele, are the known long-term complications of cesarean section.⁶

The isthmocele involves a lack of myometrial substance in the scar resulting from a previous C-section that will deform the anatomy of the lower portion of the uterus.⁷ Caesarean sections are the most common uterine surgery for birthing people of childbearing age.⁸

Causes of isthmocele

For an isthmocele to occur, the birthing person must have undergone a caesarean section. While the mechanism responsible for this complication is unknown, its incidence is related to the number of previous C-sections. Therefore, some recent studies have estimated that an isthmocele could appear after the first C-section in 60% of cases, and after three C-sections this incidence could even reach 90-100%.

Known risk factors for an isthmocele include:

• Receiving a C-section after the onset of labour
• Large dilation of the cervix( greater than 5 cm) and low baby head position at the time of operation
• Number of  C-sections (the risk increases exponentially after each procedure)
• Retroverted uterus
• Obesity
• Diabetes; 
• Using tobacco/ cigarettes
• Intraoperative complications

Signs and symptoms of isthmocele

Isthmoceles are not always associated with clinical symptoms. Often the diagnosis occurs during a routine consultation. If it is symptomatic, the most common symptoms include post-menstrual bleeding, especially in the form of a brownish discharge that persists after the actual menstrual period, dyspareunia (pain during intercourse), and sometimes abdominal pain.

There is also evidence that isthmocele is included in the causes of secondary infertility.

Management and treatment for isthmocele

Isthmoceles should be treated in cases of symptoms or secondary infertility. Patients who do not wish to conceive again may be treated conservatively by administering oral contraceptives or radically by total hysterectomy (removal of reproductive organs). In the case of patients with secondary infertility who want a new pregnancy, surgical treatment is the first choice and involves the excision of the swollen tissue at the level of the uterine defect, an intervention that also improves the clinical symptoms.

The goal of conservative surgical treatment is to correct the defect at the level of the uterine scar, through an intervention called isthmoplasty.⁹ Isthmoplasty can be performed through several surgical procedures: the classic laparotomy technique, laparoscopic isthmoplasty, vaginal isthmoplasty or combined laparoscopic-vaginal procedure, laparoscopic technique through robotic surgery and hysteroscopic isthmoplasty.^9,10,11,12

Diagnosis

The process of diagnosing an isthmocele involves an extensive clinical examination and requires the use of imaging techniques such as endovaginal ultrasound and diagnostic hysteroscopy.

During an endovaginal ultrasound, the size of the defect is measured: it is seen as an ellipsoidal or triangular hypoechoic image, so both diameters can be measured and then the area of ​​the defect can be calculated.

Diagnostic hysteroscopy provides clear evidence of the defect, determines its severity, and determines the correct course of action needed to resolve it (interventional hysteroscopy or even laparoscopic).

Occasionally, magnetic resonance imaging (MRI), because of its investigative accuracy, has been used to decide which surgical approach to use to correct the defect based on the size, in millimetres, of the thickness of the previous surgical margin.

Complications

Complications include:

• Greater risk of complications during gynaecological procedures
• Placenta accrete (the placenta attaches too deep to the uterine wall)
• Placenta previa (the placenta covers the cervical tract)
• Scar pregnancy (an extrauterine pregnancy in which the egg grafts to a scar)
• Secondary infertility (infertility following a successful pregnancy in the past)
• Uterine dehiscence (laceration or rupture at the location of a uterine scar)

Isthmocele is an underdiagnosed reason for secondary infertility.¹ The mechanisms by which the isthmocele can affect fertility can be: the retained blood mixed with the mucus changes the quality of the endometrium, which disrupts the transport of sperm; implantation problems of the embryo, determined by chronic endometritis and hematometry, myometrial contractility deficits. The typical bleeding is light, and brown, with postmenstrual onset and a variable duration of 2 to 12 days, and may be due to in situ production, retention of menstrual blood, poor contractility, and endometrium congestion.¹³

FAQs

How can I prevent an isthmocele?

The only way to completely prevent the isthmoceles is to have no cesarean section. If you are pregnant and planning a C-section, discuss with your healthcare provider the risks of C-section scars (isthmoceles). You may have the ability to reduce your risk by:

• Keep a healthy weight before and during pregnancy
• Managing diabetes
• Do not smoking or use tobacco

How common is an isthmocele?

The incidence of an isthmocele at 6 months post-caesarean section was 44.4%. In addition, lower scar and abdominal pain were more intense when an isthmocele was also noted.¹⁴

Who is at risk of an isthmocele?

The American Journal of Obstetrics and Gynecology states that according to the sonohysterographic exam, the birthing person’s body mass index, gestational diabetes, and prior  C-sections are related to an increased risk of incomplete healing of the uterine incision.

What can I expect if I have an isthmocele?

When you have an isthmocele, it is important to closely monitor certain signs and symptoms.

You should consult a doctor if you have had a cesarean section and subsequently develop symptoms that cause discomfort, such as persistent pain, bleeding, or spotting.

If you are trying for a new pregnancy after a caesarean section, it is advisable to consult with a gynaecologist to determine together if there are associated risks, what they are, and what solutions there are. On the other hand, if you do not succeed in conceiving again there is the possibility of developing an isthmocele and that can lead to secondary infertility.

If you are pregnant, have a history of cesarean section (scarred uterus), and any symptoms causing serious discomfort appear, consult an emergency physician.

A pregnancy can be carried to term even in the case of an isthmocele. However, the risk of uterine rupture or other complications increases directly in proportion to the number of caesarean sections.

When should I see a doctor?

Being a relatively new and incompletely clarified pathology,  isthmoceles is frequently underdiagnosed, and the application of the very best treatment is often delayed. 

If you get pregnant with an isthmocele, you risk a rupture of the uterus. This is a surgical emergency. This happens when the uterine wound (scar) separates and your uterus tears. It can put you and your baby at significant risk. Consult a doctor immediately if you experience acute pelvic pain, pain at the place of a cesarean section scar, or significant vaginal bleeding. It might be a sign of a ruptured uterus.

Summary

An isthmocele is a defect that occurs after a C-section. Isthmoceles can cause abnormal uterine bleeding, chronic pelvic pain, and secondary infertility. Consult a doctor if you have had a cesarean section and subsequently develop symptoms that cause discomfort, such as persistent pain, bleeding, or spotting. If you are pregnant, have a history of cesarean section (scarred uterus), and any symptoms causing serious discomfort appear, consult an emergency physician.