A Histopathologic Approach to Uterine Niche: What to Expect and to Report in Hysteroscopy-Resected Isthmocele Specimens

Abstract

As one of the emerging complications of caesarean sections (CSs), pathologists will have an important role in handling samples of uterine niches. An isthmocele is a defect at the site of a previous CS scar resulting in a variety of symptoms and niche-related subfertility. There is a deficiency in the literature of the histopathologic features of hysteroscopy-resected isthmocele ridges. Our aim is to fill this gap to highlight what to expect to see and what important findings to report to guide gynecologists to the results of hysteroscopic isthmoplasty in relation to symptoms improvement, fertility restoration, and potential complications. We found 22 cases of hysteroscopy-resected isthmoceles by performing a retrospective review study. The majority of the women were symptomatic with secondary infertility. The resected isthmocele edges were lined by endocervical, endometrial, and isthmic mucosa either combined or isolated depending on each case. Isthmoceles could be classified depending on the predominant lining mucosa into endocervical-isthmoendocervical (low) and endometrial-isthmic (high-intermediate) niches. This could be correlated with certain symptoms. The edges showed variably thickened fibrous and fibromuscular stromal tissue with characteristic thick-walled blood vessels. Some cases showed miscellaneous findings such as hemosiderin pigments with foreign body giant cell reaction and placental implantation site tissue reflecting a previous history of surgical repair and scar pregnancy. Cauterization artifacts may impose interpretation challenges for pathologists. Utility of certain special stains helps delineate the nature of badly cauterized tissues. It is important to report certain histologic findings in isthmocele samples to correlate with clinical findings and guide gynecologists.

Cesarean scar niche: An evolving concern in clinical practice

“…3 A small case series examining the histology of resected scar niche (either hysteroscopically because of secondary fertility or hysterectomy because of abnormal uterine bleeding) found that six of eight of the cases contained endocervical type mucosa. 27 Niche formation may also be related to ischemia as, even after adequate elective repair, at least 5% of women will develop a recurrent niche, suggesting inadequate wound healing as a possible contributor. 3 This theory is further supported by the fact that incidence and severity of cesarean scar niche increase with each subsequent cesarean section.…”

“…It has been hypothesized that a lower incision through cervical tissue leads to the formation of a larger scar niche caused by accumulation of mucus in communicating spaces therefore impairing wound healing 3 . A small case series examining the histology of resected scar niche (either hysteroscopically because of secondary fertility or hysterectomy because of abnormal uterine bleeding) found that six of eight of the cases contained endocervical type mucosa 27 …”

Comparison of the Histopathologic Features of Uterine Niches Between Hysterectomy Specimens and Hysteroscopy-Resected Isthmoceles

“…The recent online publication of the article entitled "A histopathologic approach to uterine niche: What to expect and to report in hysteroscopy-resected isthmocele specimens" in the "International Journal of Surgical Pathology", has shown some absent or scarce histopathologic features in hysteroscopy-resected isthmocele specimens compared to previously reported cases of isthmoceles in hysterectomy specimens. [1][2][3][4][5] We became interested in the histopathologic features in isthmoceles that can be identified in hysterectomy specimens which might have been absent or obscured in hysteroscopy-resected isthmoceles. Our aim this time is to compare and contrast the clinicopathologic features of isthmoceles procured from hysterectomy and isthmoplasty specimens.…”

“…6 Some of the clinicopathologic differences might indicate two groups of patients with Caesarean section-related isthmoceles depending on their levels, sizes, shapes, contents, and histologic properties of their mucosa, edge wall, surrounding tissue, residual myometrial and scar tissues. 1,6 Some findings may have potential pathologic and clinical implications. For example, the surface epithelial atypia and sloughed degenerate epithelial cells might have interpretation pitfalls when examining cervical smears and biopsies.…”