Isthmus

Uterine wall defect after cesarean delivery

The definition

An isthmocele is a structural defect in the anterior wall of the uterus, at the site of a cesarean section. This defect forms a depression (invagination) that often accumulates menstrual blood or secretions, causing various gynecological symptoms.

It may be referred to as:

Caesarean section

Uterine diverticulum

Lower uterine segment defect

Uterine scar defect

Epidemiology

The incidence ranges from 24–70% in women who have had at least one cesarean delivery.

Only 7–15% of cases are symptomatic and require treatment.

It is most often diagnosed in women seeking help for secondary infertility or unusual bleeding.

Risk factors

factor	Explanation
Number of cesarean births	The risk increases with each additional cesarean delivery.
Incomplete closure of the uterine incision	Surgical technique or inadequate tissue perfusion
Postpartum infection	Prevents complete wound healing
Uterine position (retroversion)	Makes it difficult to make full contact of surfaces for good sealing
Incomplete removal of the placenta or intrauterine manipulations	Increases healing tissue damage

4. Pathophysiology

Isthmocele results from uneven or incomplete closure of the uterine wall during healing from a cesarean section. This leads to:

Accumulation of blood at the site of the defect (local hematometra)

Local irritation of the endometrium

Chronic inflammation

Changes in the pH and quality of uterine mucus

Interruption of sperm motility or embryo implantation

5. Clinical signs

Symptoms	Explanation
Postmenstrual bleeding (spotting)	Usually a few days after the end of menstruation
Prolonged menstruation	With irregular or heavy bleeding
Chronic pelvic pain	Usually located at the bottom of the abdomen
Secondary infertility	Usually after a pregnancy with a cesarean section
Odorous secretions or infections	Overlapping infection

6. Diagnosis

Transvaginal ultrasound

The most used and easiest method to implement

Isthmocele appears as a triangular hypoechoic area in the lower uterine segment.

Sonohysterography (with saline)

Used to highlight the communication of the isthmocele with the uterine cavity

Provides a clearer view of the size, volume, and remaining thickness of the uterine wall above the defect

Diagnostic hysteroscopy

Allows direct inspection of the uterine cavity and assessment of the depth and contours of the defect

MRI (magnetic resonance imaging)

Indicated in cases where significant surgical intervention is planned or in the presence of multiple defects.

7. Classification

Assesses the thickness of the residual myometrium in relation to further follow-up:

3 mm → usually safe for pregnancy

<3 mm → higher risk of uterine rupture in pregnancy

<2.5 mm → surgical treatment is usually indicated

8. Treatment

No symptoms → periodic observation and follow-up

With symptoms or desire for pregnancy → active treatment

Surgical hysteroscopy

Reserved for minor defects

Minimally invasive intervention

Risk: further thinning of the wall in some cases

Laparoscopy (with or without hysteroscopy)

Most advanced technique for complete reconstruction

Allows restoration of uterine wall thickness

Full-layer closure with careful technique

Recommended for women who want to get pregnant

9. Complications

Chronic bleeding

Reduced fertility

Increased risk of placenta accreta (placenta previa)

Uterine rupture during pregnancy or childbirth

10. Planning pregnancy after treatment

Pregnancy can be planned 3–6 months after surgery, according to clinical assessment.

Cesarean delivery is recommended.

11. Advice for patients

If you have had a cesarean section and are experiencing:

Unusual bleeding

Pain in the lower abdomen

Difficulty getting pregnant after cesarean deliveries or repeated miscarriages