Cesarean Scar Defect (Isthmocele): Symptoms, Risks, and Recovery
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 17, 2026
Quick answer
A cesarean scar defect, or isthmocele, is a pouch or dent of scar tissue in the uterine wall at the site of a past C-section incision. [1] Symptoms include bleeding between periods, pelvic pain and difficulty getting pregnant, though many women have none. [1] It is diagnosed with transvaginal ultrasound, and not everyone needs treatment. [1]
What the research says
According to PubMed:
Isthmocele is common, and risk rises with prior C-sections, gestational diabetes and BMI. In a prospective study of 401 women, 371 were examined with sonohysterography six months after cesarean delivery, and the prevalence of isthmocele was 45.6%. Independent risk factors were a previous cesarean delivery (odds ratio 3.14, 95% CI 1.90–5.17), a history of gestational diabetes (odds ratio 1.73, 95% CI 1.02–2.92), and higher body mass index (each extra unit raised the risk by 6%). (Antila-Långsjö et al., American Journal of Obstetrics and Gynecology, 2018) [2].
A niche may lower live-birth rates after assisted reproduction. A systematic review of six retrospective cohort studies (1,083 people with a niche and 3,987 without) found a lower live birth rate with a niche (pooled adjusted odds ratio 0.58, 95% CI 0.48–0.69), but the authors rated the evidence as low-grade. (van den Tweel et al., Journal of Obstetrics and Gynaecology, 2024) [4].
Surgery relieves bleeding in most symptomatic women. In a systematic review and meta-analysis of 33 publications, symptoms improved in 85.0% of women after hysteroscopic correction, 92.8% after laparoscopic or robotic correction, and 82.5% after vaginal correction; hysteroscopic surgery had the lowest complication risk (0.76%). The authors found a lack of evidence that surgery improves fertility or reduces obstetric complications in women with no symptoms. (Vitale et al., Archives of Gynecology and Obstetrics, 2020) [5].
What is an isthmocele?
An isthmocele (also called a cesarean scar defect or niche) is a small pouch or dent of scar tissue that can form in the front wall of your uterus after a C-section. [1] It develops when the incision made in your uterus during the C-section doesn't heal completely. [1]
Severity varies widely. Some women have a mild indentation that never causes a problem. Others have a deeper defect that thins the uterine wall and causes symptoms. [1] Studies suggest that about 2 to 7 out of 10 women who have had at least one C-section develop some degree of isthmocele (a range of 20% to 70% appears in the medical literature). [1] [3]
Because the pouch can collect blood and fluid, it can become a site of inflammation or infection and may interfere with normal reproductive function. An isthmocele won't go away on its own, but many women don't need treatment unless they have symptoms or plan another pregnancy. [1]
At a glance | Details |
|---|---|
What it is | A pouch or dent of scar tissue in the uterine wall [1] |
Also called | Cesarean scar defect, niche |
Cause | A C-section incision in the uterus that doesn't heal completely [1] |
How common | |
Main symptoms | Bleeding between periods, painful periods, pelvic pain, trouble getting pregnant [1] |
Goes away on its own? | No, but not everyone needs treatment [1] |
What are the symptoms of a cesarean scar defect?
Cesarean scar defect symptoms may not appear for months or even years after a C-section. [1] Many women only discover the defect when they have trouble getting pregnant again, a problem known as secondary infertility. [1] Symptoms can include:
Irregular periods or bleeding between periods — often dark brown spotting that continues after your period ends, because the pouch traps blood and releases it slowly.
Painful periods (dysmenorrhea). [1]
Pelvic pain, including pain during sex. [1]
Difficulty getting pregnant. [1]
Signs of infection, such as fever or foul-smelling vaginal discharge, if the trapped fluid becomes infected. [1]
Seek medical care right away if you have severe pelvic pain, pain directly over your C-section scar, or heavy vaginal bleeding. These can be signs of a ruptured uterus, which is an emergency. [1]
What causes an isthmocele, and who is at risk?
An isthmocele, or cesarean scar defect, forms when the uterine incision doesn't heal completely or when several incisions in the same area leave the tissue thin. [1] Anyone who has a C-section can develop one, but some factors raise the risk:
Multiple C-sections. Repeated incisions in the same area thin the uterine wall. [1]
An incision very low on the uterus. Cuts made very low tend to leave larger scars, especially if you were in labor before surgery. [1]
Single-layer stitching. Closing the uterus with one layer of stitches instead of two can raise the risk. [1]
An unplanned C-section late in labor. [1]
Weight and metabolic health. Overweight or obesity, diabetes or gestational diabetes, and any condition that prevents wounds from healing well. [1]
Research adds some nuance. In one prospective study, a previous cesarean delivery, gestational diabetes and higher BMI were independent risk factors, and overall prevalence did not differ significantly between planned and emergency C-sections. Among emergency C-sections, though, a longer active labor raised the risk (Antila-Långsjö et al., 2018). [2]
What are the complications of an untreated isthmocele?
Most small isthmoceles cause no harm, but an untreated deeper defect can contribute to infertility, scar pregnancy, placental problems, uterine rupture and infection.
Secondary infertility — fluid and inflammation in the pouch can make it harder to get pregnant. [1]
Ectopic pregnancy in the scar — an embryo implants in the defect instead of the uterine cavity. [1]
Placental problems in a later pregnancy. [1]
Uterine rupture — a weakened scar can tear during a later pregnancy or labor. [1]
Infection — trapped blood and fluid give bacteria a place to grow. [1]
A systematic review of six retrospective cohort studies also linked a niche to lower live-birth rates after assisted reproduction, although the evidence was low-grade and the effect is still being studied (van den Tweel et al., 2024). [4]
How is an isthmocele diagnosed?
Imaging tests, usually starting with a transvaginal ultrasound, are used to diagnose an isthmocele. [1] The best time is right after your period, when the niche is likely to be full of blood and easiest to see. [1] Your provider may use:
Transvaginal ultrasound. An ultrasound wand is placed in the vagina, and the defect may show up as a darker area. This is usually the first test. [1]
Sonohysterogram. The uterus is filled with saline before a transvaginal ultrasound, which makes the size and depth of the niche easier to see. [1]
Hysteroscopy. A thin camera passes through the cervix into the uterus. [1] It shows the size and depth most clearly and is usually done when surgery is needed.
Providers also look at the residual myometrial thickness — how much healthy muscle is left over the defect — because it helps guide the choice of treatment. [3] [5]
How is an isthmocele treated?
Not everyone needs treatment. The decision depends on your symptoms, the size of the defect, and your plans for future pregnancies.
Option | What it involves | Good to know |
|---|---|---|
Hormone medication | Birth control or other hormones regulate periods and lighten bleeding | Helps bleeding but doesn't repair the defect [1] |
Hysteroscopic repair | Scar tissue is removed through the vagina and the sides of the niche are opened so blood and fluid can drain | |
Laparoscopic repair | One or more small cuts in the belly; a lighted tube is used to remove scar tissue and extra tissue around the niche | |
Hysterectomy | Removal of the uterus | Rarely needed; considered for a large defect with severe symptoms in someone who doesn't want another pregnancy [1] |
In a systematic review and meta-analysis, surgery improved bleeding symptoms in more than 80% of symptomatic women. Hysteroscopic correction appeared safest and most effective when enough muscle remained over the defect, while laparoscopic or vaginal surgery may be preferred when the remaining wall is thinner than about 2.5 mm. The authors found a lack of evidence that surgery improves fertility or reduces obstetric complications in women who have no symptoms (Vitale et al., 2020). [5]
What is the outlook, and what about future pregnancies?
Everyone's experience is different. Some women have a small pouch for the rest of their lives with no problems. Others have pain or difficulty getting pregnant, and many find relief from symptoms after treatment while keeping their ability to get pregnant. [1]
If you plan another pregnancy, talk with your obstetrician early. A weakened scar raises the risk of complications such as uterine rupture and placental problems, so your provider can help you plan the safest way to deliver.
When should I see my healthcare provider?
Contact your provider about a possible cesarean scar defect if you notice spotting between periods, difficulty getting pregnant, pelvic pain or signs of infection after a C-section.
Spotting between periods.
Difficulty getting pregnant.
Pelvic pain or pain during sex.
Signs of infection, such as fever or foul-smelling vaginal discharge.
Get medical attention right away for severe pelvic pain, pain on your C-section scar, or heavy vaginal bleeding.
What's the bottom line?
A cesarean scar defect is a common but often overlooked result of C-section delivery: a small pouch in the uterine wall where the incision didn't heal fully. Many women have no symptoms, but bleeding between periods, pelvic pain, and difficulty getting pregnant again are signals worth raising with your provider. Imaging gives the diagnosis, and treatment — from hormone medication to minimally invasive repair — is matched to your symptoms, the thickness of the remaining uterine wall, and your plans for pregnancy.
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Conclusion
Noticing changes in your cycle after a C-section can feel unsettling, but an isthmocele is well understood and manageable. Knowing the symptoms helps you ask for the right imaging, and today's treatment options mean that most women can find relief while protecting their chances of a healthy future pregnancy. If something doesn't feel right, don't wait — talk with your healthcare provider.
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Frequently Asked Questions
Can an isthmocele go away on its own?
No. A cesarean scar defect is a physical change in the uterine wall and doesn't go away on its own. But you don't always need treatment, especially if it causes no symptoms and you aren't planning another pregnancy.
Does every C-section cause an isthmocele?
No. Studies suggest about 2 to 7 out of 10 women who have had at least one C-section develop some degree of isthmocele, and many of them have no symptoms. Many other women heal completely.
What is a niche in the uterus?
"Niche" is another medical term for the pouch or dent formed by a cesarean scar defect, also called an isthmocele.
How soon after a C-section can symptoms start?
Symptoms may start once your periods return, but some women don't notice any problem for months or even years.
Why does an isthmocele cause dark brown spotting?
The pouch can trap menstrual blood, which then drains slowly after your period ends. Older blood looks dark brown.
Can an isthmocele cause an infection?
Yes. Trapped blood and fluid in the pouch can create a place for bacteria to grow, which can lead to infection. Fever or foul-smelling vaginal discharge are warning signs.
Can a pregnancy implant in an isthmocele?
Rarely, yes. An ectopic pregnancy can implant in the scar defect, which is a serious condition that needs urgent medical care.
Is an isthmocele the same as a uterine fibroid?
No. A fibroid is a noncancerous growth in or on the uterus, while an isthmocele is a pouch or dent in the existing uterine wall at the site of a scar.
Does birth control fix an isthmocele?
No. Birth control and other hormone medications can regulate periods and lighten bleeding, but they don't repair the physical defect.
How is an isthmocele diagnosed?
Imaging is used, usually starting with a transvaginal ultrasound. A sonohysterogram or hysteroscopy may be added for more detail. The best time for imaging is right after your period.
Can obesity or diabetes cause an isthmocele?
Obesity and diabetes raise the risk. Overweight or obesity, diabetes, gestational diabetes, and conditions that slow wound healing are linked to a higher chance of incomplete healing of the uterine incision. In one study, each extra unit of BMI raised the risk by 6%.
What is residual myometrial thickness?
Residual myometrial thickness is the amount of healthy uterine muscle left over the defect, measured on imaging. It helps your provider choose between hysteroscopic and laparoscopic repair.
Is surgery to repair an isthmocele painful?
Hysteroscopic repair is done through the vagina with no cuts in the belly, and laparoscopic repair uses small cuts. Your surgeon will explain the type of anesthesia, pain control, and recovery for your procedure.
Can an isthmocele affect IVF?
A systematic review of six retrospective cohort studies linked a niche to lower live-birth rates after assisted reproduction, but the evidence was low-grade and more research is needed.
Can I get pregnant after isthmocele repair?
Many women keep their ability to get pregnant after treatment, but evidence that surgery improves fertility in women without symptoms is limited. Talk with your provider about your goals before choosing treatment.
Can I have a vaginal birth if I have an isthmocele?
Vaginal birth with an isthmocele is a decision to make with your obstetrician. A weakened scar raises the risk of complications such as uterine rupture, so your provider will help you plan the safest delivery.
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the guidance of your physician or other qualified health provider with any questions about a medical condition. Never disregard professional medical advice or delay seeking care because of something you have read here. If you have severe pelvic pain, pain over your C-section scar, or heavy vaginal bleeding, seek urgent medical care.
Related Reading
C-Section (Cesarean Delivery): Reasons, Procedure, Risks, and Recovery explains the surgery that can leave a uterine scar defect.
Ectopic Pregnancy: Symptoms, Causes, and Treatment covers pregnancies that implant outside the normal spot, including scars.
Hysteroscopy: Procedure, Recovery, Risks and What to Expect describes the scope procedure used to view and repair the uterus.
Adenomyosis: Complete Guide to Symptoms, Causes, Diagnosis & Treatment explains another uterine condition that causes abnormal bleeding and pain.
References
Cleveland Clinic. Isthmocele (Cesarean Scar Defect). Cleveland Clinic. Last updated May 21, 2026. https://my.clevelandclinic.org/health/diseases/23351-cesarean-scar-defect
Antila-Långsjö RM, Mäenpää JU, Huhtala HS, Tomás EI, Staff SM. Cesarean scar defect: a prospective study on risk factors. Am J Obstet Gynecol. 2018;219(5):458.e1-458.e8. PMID 30240650. https://doi.org/10.1016/j.ajog.2018.09.004
Baldini GM, Lot D, Malvasi A, et al. Isthmocele and infertility. J Clin Med. 2024;13(8):2192. PMID 38673465. https://doi.org/10.3390/jcm13082192
van den Tweel MM, van der Struijs S, Le Cessie S, Boers KE. The impact of caesarean scar niche on fertility - a systematic review. J Obstet Gynaecol. 2024;44(1):2349714. PMID 38775009. https://doi.org/10.1080/01443615.2024.2349714
Vitale SG, Ludwin A, Vilos GA, et al. From hysteroscopy to laparoendoscopic surgery: what is the best surgical approach for symptomatic isthmocele? A systematic review and meta-analysis. Arch Gynecol Obstet. 2020;301(1):33-52. PMID 31989288. https://doi.org/10.1007/s00404-020-05438-0
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