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One in 3 babies<\/a> in the U.S. are born via C-section. Despite their prevalence, C-sections are still major abdominal surgeries, with attendant risks. If you\u2019ve had a C-section in the past and are struggling to conceive now, it\u2019s possible your scar could be playing a role. Here\u2019s what to know about the connection between uterine isthmocele, aka C-section surgical scar defect or Cesarean scar defect, and secondary infertility. <\/p>\n\n\n\n A C-section requires cutting through or separating a whopping seven<\/em> layers of tissue. Once the surgeon is down to the uterus\u2014the pear-shaped muscle that grows exponentially over the course of pregnancy to hold the baby inside his or her amniotic sac\u2014he or she must cut through the uterine muscle wall to access the amniotic sac. After the baby is removed, the uterus is sewed back together with either one or two layers of sutures.\u00a0<\/p>\n\n\n\n But sometimes, the three standard stages of wound healing<\/a> (beginning immediately after C-section surgery and formally concluding a year or two later), don\u2019t occur properly for the incision in the uterine muscle wall [1]. The end result can be a too-thin muscle layer. <\/p>\n\n\n\n In a 2025 Instagram reel,<\/a> St. Louis-based restorative reproductive medicine (RRM)-trained OB\/GYN, Dr. Gavin Puthoff, summed up: \u201cA uterine isthmocele is a small pouch or defect in the wall of the uterus where the muscle simply didn\u2019t heal after your C-section.\u201d Infection<\/a> may be a main reason uterine isthmocele form [2]. <\/p>\n\n\n\n As C-sections are on the rise here in the U.S. and globally, so are Cesarean scar defects. Uterine isthmocele is almost shockingly common, occurring<\/a> in as many as 2 of 3 C-section cases<\/a> [2] [3]. In up to 30% of these women, Cesarean scar defect can cause abnormal vaginal bleeding separate from menstrual period bleeding, painful periods, pelvic pain, and\/or secondary infertility. <\/p>\n\n\n\n The connection between uterine isthmocele and secondary infertility (infertility after successfully carrying one or more pregnancies) is fairly straightforward. Dr. Puthoff explained, \u201c[The isthmocele] area can trap blood, which causes inflammation that leads to infertility and miscarriages.\u201d Fluid can also accumulate along with the blood, worsening inflammation. <\/p>\n\n\n\n This YouTube video<\/a> by Texas-based double board-certified OB\/GYN and reproductive endocrinologist Dr. Natalie Crawford breaks down several research studies on rates of secondary infertility for women who previously gave birth vaginally versus via C-section. In general, women were about twice as likely<\/em> to experience secondary infertility after one or more previous C-sections compared to women who had only ever given birth vaginally. <\/p>\n\n\n\n Crawford further specified that secondary infertility after C-section may be caused by one or more of five different factors (of which uterine isthmocele is one). The four other factors could include: 1) previous birth trauma leading to delaying future pregnancy; 2) factors such as age or underlying fertility issues leading women to undergo IVF or other ART procedures (C-section rates are higher in women who are older and\/or have had IVF); 3) previous C-section that healed normally but still contributed to future placenta implantation issues for unknown reasons; and 4) scarring of the uterus. <\/p>\n\n\n\n Secondary infertility after C-section may be caused by one or more of five different factors (of which uterine isthmocele is one). The four other factors could include: 1) previous birth trauma leading to delaying future pregnancy; 2) factors such as age or underlying fertility issues leading women to undergo IVF or other ART procedures (C-section rates are higher in women who are older and\/or have had IVF); 3) previous C-section that healed normally but still contributed to future placenta implantation issues for unknown reasons; and 4) scarring of the uterus. <\/p><\/blockquote><\/figure>\n\n\n\n C-section surgical scar defects can cause or contribute to two rare pregnancy complications. <\/p>\n\n\n\n One is C-section scar ectopic pregnancy<\/a> (also called C-section scar pregnancy), where a newly conceived life implants into the wall of the uterus at the location of scar tissue from a previous C-section. While a C-section scar ectopic pregnancy is not <\/em>the same as a traditional ectopic pregnancy (because it occurs in the uterus and not in the fallopian tubes), it is<\/em> dangerous for both mother and baby because it can lead to uterine rupture and\/or hemorrhage. Women with a C-section scar pregnancy are often counseled to undergo abortion, but it is possible to carry the pregnancy safely with adequate medical oversight and care. A C-section between 34 and 36 weeks gestation is recommended for the safety of both mother and child.<\/p>\n\n\n\n Even if a newly conceived life implants in a different, healthy part of the uterine wall, a surgical scar defect from a previous C-section can still increase risk of uterine rupture<\/a> during labor. This is the second rare pregnancy complication Cesarean scar defects can cause. <\/p>\n\n\n\n Uterine isthmocele is easily diagnosed via a specific type of ultrasound called saline infusion sonohysterogram<\/a>. This procedure is done transvaginally, meaning that the ultrasound probe is inserted vaginally.<\/p>\n\n\n\n How would a doctor know to perform a saline infusion sonohysterogram? Generally, a traditional ultrasound would show an abnormality in the uterine wall, and the saline infusion sonohysterogram would be done to confirm and definitively diagnose Cesarean scar defect. <\/p>\n\n\n\n C-section surgical scar defects are<\/em> treatable, via laparoscopic or robotic laparoscopic surgery or<\/em> hysteroscopy. Laparoscopic surgery involves use of a tiny video camera and scope inserted through several small incisions in the abdomen, and then either direct or robotic-assisted cutting out (excision) of the damaged tissue and suturing to repair the surrounding tissue. Hysteroscopy utilizes a video scope also, but the uterus is accessed via the vagina and cervix, not through the abdomen. The abnormal pouch is drained of fluid and blood and then the tissue is shaved or burned out. <\/p>\n\n\n\n According to Dr. Puthoff\u2019s website<\/a>, the size of the Cesarean scar defect, combined with the woman\u2019s intentions to conceive (or not) in the future, often determines whether hysteroscopy (for smaller isthmocele) or laparoscopy (for larger isthmocele) is recommended. In some cases, both<\/a> hysteroscopy and laparoscopy may be necessary [3]. <\/p>\n\n\n\n The most obvious way to prevent C-section surgical scar defects is to only perform medically necessary C-sections<\/a>, followed by promoting and facilitating vaginal birth after Cesarean <\/a>(VBAC). No longer rare, one study summarizes, \u201cVaginal birth after a cesarean section (VBAC) is now an integral part of modern obstetrics\u201d [1].<\/p>\n\n\n\n Additionally, Dr. Crawford mentioned waiting at least one year, perhaps eighteen months, after giving birth via C-section to allow proper healing of all layers of the uterus. <\/p>\n\n\n\nWhat is a uterine isthmocele and why do they form?<\/span><\/h2>\n\n\n\n
How often do C-section scar defects occur?<\/span><\/h2>\n\n\n\n
How can a Cesarean scar defect impact future fertility?<\/span><\/h2>\n\n\n\n
C-section surgical scar defects can also cause two very rare pregnancy complications<\/span><\/h2>\n\n\n\n
How do you know you have a uterine isthmocele?<\/span><\/h2>\n\n\n\n
Is a C-section surgical scar defect fixable?<\/span><\/h2>\n\n\n\n
Can uterine isthmocele be prevented?<\/span><\/h2>\n\n\n\n
Only perform medically necessary C-sections<\/span><\/h3>\n\n\n\n
Wait longer to conceive again<\/span><\/h3>\n\n\n\n