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Clinical implications of cesarean-induced isthmoceles

Researchers studying uteri removed via hysterectomy found a variety of wall thicknesses at the cesarean incision site indicating nonunion healing



In a presentation of the Golden Hysteroscope Award Best Paper on Hysteroscopy at the 46th AAGL Global Congress on Minimally Invasive Surgery in National Harbor, Maryland, James Coad, MD, described a study that he and colleagues from West Virginia University School of Medicine in Morgantown, and Universidad Autónoma de Nuevo León in Monterrey, Mexico, conducted concerning the healing differences of cesarean incisions and the development of isthmoceles (cesarean scar defects).1

Detecting isthmoceles

Isthmoceles are variably sized evaginations into the anterior lower uterine segment at a previous cesarean delivery incision due to suboptimal myometrium healing. This leads to thinning of the anterior uterine wall, which creates an indentation and fluid-filled pouch at the cesarean scar site.1,2

Recent findings, say Coad and colleagues, associate isthmoceles with adverse reproductive and gynecologic conditions such as infertility, postmenstrual spotting, dysmenorrhea, and chronic pelvic pain. Patients who have undergone multiple cesarean deliveries tend to have larger isthmoceles with widths correlating to increased symptoms.1

While the presence of inner nonunion healing can be hysteroscopically visualized, it is difficult to detect outer nonunion healing. The reported incidence of isthmoceles differs by imaging technique used: up to 70% are found with transvaginal ultrasound, and up to 84% are detected by sonohysterography.3,4 This study found that 98% of isthomoceles can be detected by gross examination.1

Related article:
Cesarean scar defect: What is it and how should it be treated?

Study details

Researchers designed a prospective de-identified anatomic pathology study to evaluate the anatomy of uteri from 204 premenopausal women who underwent hysterectomy for benign disease due to abnormal uterine bleeding, fibroids, and/or adenomyosis. Uteri were midline sagittally sectioned and the area of cesarean section anatomy was documented, including the presence of inner and outer nonunion healing.1

Of the 204 uteri, 134 (66%) had at least 1 identifiable cesarean scar (22% had 1 scar, 19% had 2 scars, and 25% had 3 or more scars). Of these, 2 uteri (1.5%) had intact incisional healing with minimal wall narrowing showing complete union healing. Isolated inner nonunion healing with the formation of prominent isthmoceles was found in 111 uteri (82.8%). Five uteri (3.7%) showed isolated outer nonunion healing without the formation of isthmoceles. Fourteen uteri (10.5%) had both inner and outer nonunion healing. Two uteri (1.5%) had complete transmural union healing with localized loss of anterior lower segment wall integrity. No isthmoceles were detected in women who had not undergone cesarean delivery.1

Study results

When present, inner nonunion healing involved a mean (SD) 39% (23%; range, 5% – 90%) of the wall thickness and outer nonunion healing involved a mean (SD) 27% (17%; range, 10% – 60%). Due to nonunion healing, the resultant wall thicknesses at cesarean scar site were a mean (SD) 5.6 mm ( 2.60 mm; range, 0.0 mm – 14.2 mm). When compared with the adjacent uterine wall, the nonunion healing resulted in an approximate mean (SD) of 70% (16%) thinner wall. 1

Conclusions and a warning

The authors concluded that, following cesarean delivery, there is a high incidence of architectural healing–related change, including significant inner and outer wall thinning. While inner nonunion healing can be hysteroscopically visualized, outer-wall healing cannot be visualized and may result in finding a thinner wall than expected during procedures in this region, including isthmocele repairs.1

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