May 15, 2026
According to the Centers for Disease Control and Prevention, cesarean section rate, also called C-section rate, rose to 32.5% in 2025 — the highest annual rate in the U.S. since 2013. As the rate of C-section births increases, C-section scar defects, also called isthmoceles, are becoming a more commonly recognized cause of abnormal uterine bleeding and secondary unexplained infertility. Increased awareness of the diagnostic criteria, imaging protocols and defined surgical options can improve outcomes for patients.
A recent Mayo Clinic case review, published in the November 2025 issue of Fertility and Sterility, analyzed the clinical presentation, diagnosis and management of uterine isthmoceles. It features relevant patient cases that demonstrate the principles of surgical management of isthmocele repair via robot-assisted laparoscopy or hysteroscopy, as well as the associated surgical management of scar variations and possible complications.
Isthmoceles form when a uterine scar from a prior cesarean delivery fails to heal as a smooth, continuous layer. Instead, it forms a pocket that traps menstrual blood. "In some cases, an isthmocele can interfere with conception," says Zaraq Khan, M.D., a gynecologic surgeon and reproductive endocrinologist at Mayo Clinic in Rochester, Minnesota.
"More and more, we're seeing patients with previous cesarean births presenting with secondary unexplained infertility," says Michael F. Neblett II, M.D., an obstetrician-gynecologist and reproductive endocrinologist at Mayo Clinic in Rochester, Minnesota. "We have to consider whether a C-section scar defect is playing a role in the patient's ability to get pregnant and also determine what additional symptoms an isthmocele could be causing."
Patients typically present in two ways: gynecologic symptoms and reproductive concerns. Isthmocele symptoms commonly include abnormal bleeding, irregular menstrual cycles, chronic pelvic pain and unexplained secondary infertility after a previous cesarean birth.
"Gynecologic complaints include prolonged spotting after menses and persistent brown discharge that continues until ovulation or even later in the cycle — a pattern explained by blood accumulating in the scar niche and then slowly draining," Dr. Neblett says. "Reproductive presentations range from unexplained secondary infertility to rare but serious complications such as an ectopic pregnancy implanted within the defect." Many patients, however, remain asymptomatic, which contributes to underrecognition and insufficient treatment.
"Currently, there isn't much consensus on when an isthmocele should be repaired, and for that matter, how it should be repaired," Dr. Khan says. "It was important for us to contribute towards a publication that would demonstrate principles of surgical management of isthmoceles, both laparoscopically and hysteroscopically."
Diagnosis relies on a high index of suspicion and targeted imaging. Transvaginal ultrasound that highlights the lower uterine segment is particularly useful. The defect often appears as a localized indentation or cul‑de‑sac at the site of the prior hysterotomy.
"We used surgical videos to highlight three different surgical approaches for isthmocele, including vaginal, laparoscopic and hysteroscopic repair," Dr. Khan says. "The recommended approach depends on several factors, including the severity of the isthmocele and its minimal residual distance — the distance between the dome of the isthmocele to the urinary bladder in front of it. Because robust outcome data is limited, our team is focused on compiling our outcomes to better define pregnancy rates and repair success."
While isthmocele is not a new pathology, the incidence continues to grow with the increase of cesarean deliveries and is commonly undetected. "Adding isthmocele to the differential for postmenstrual spotting and secondary unexplained infertility, using targeted imaging to identify the defect, and considering outreach or referral when indicated can accelerate recognition and ensure patients receive appropriate, fertility‑preserving care," Dr. Neblett says.
For more information
Aase DA, et al. Isthmocele: One problem, many faces. Fertility and Sterility. 2025;124(suppl):1132.
Refer a patient to Mayo Clinic.