Incisional/Scar Endometriosis: A Scoping Review

Endometriosis is a chronic, progressive disease where uterine endometrial-like tissue, grows outside of the uterus. It is estimated to affect at least 1 in 9 girls/women and those assigned female at birth (AFAB). Symptoms include severe abdominal/pelvic pain (especially during menstruation), dyspareunia, menorrhagia, fatigue, depression and/or anxiety, and infertility. This condition results in inflammation and scar tissue formation in the pelvic region, with the potential for the scar tissue leading to ‘adhesions’ and resulting in a range of complications. The cause is unknown with no preventive measures or curative interventions are available, however a family history of endometriosis appears to increase the risk of developing this disease. Classification of endometriosis is based on location and/or pathophysiology. Abdominal wall endometriosis (AWE) describes endometrial-like tissue present in the subcutaneous fat and muscles of the abdominal wall, it can occur spontaneously or secondary to a surgical scar and is considered a rare condition. The reported incidence of AWE following obstetric and/or gynaecological surgeries has been reported to range from 0.03-3.5%, with the time between surgery and diagnosis of secondary AWE ranging from 3 months to 2 decades. Currently, wide surgical excision (WSE) is the only curative therapy for AWE, and histological analysis of the nodule is the only way to provide a definitive diagnosis. Within the AWE umbrella is a subtype of endometriosis known as incisional (or scar) endometriosis – an extra-pelvic form of endometriosis that forms in scar tissue following obstetric and gynaecological procedures (e.g., caesarean section, hysterotomy, salpingectomy, episiotomy, etc.). Whilst the potential surgical causes are broad, the available literature appears to indicate that the most common surgical link to development of AWE is caesarean section (sometimes referred to as caesarean section endometriosis [CSE]). Despite this being the most attributed cause of AWE, other obstetric and gynaecological procedures (such as previously listed) have been identified in published case studies. The Australian Institute of Health and Welfare (AIHW) reported 39% of mothers had a caesarean in 2022, a 7% increase from 2010, and current literature indicates that incisional endometriosis, under AWE/CSE, may already be increasing in incidence. However, AWE, particularly incisional endometriosis, is still not well understood and we have not been able to identify particular risk factors which would aid in earlier risk management, diagnosis, and treatment. Another potential contributing factor to reported low incidence rates and/or delay in diagnosis is that incisional endometriosis can be clinically mistaken for other surgical conditions such as inguinal hernia, incisional hernia, abdominal wall tumour, or stitch granulomas. Some literature reported an average of an 8-year delay in receiving a formal diagnosis of endometriosis. This delay is reported to result from an affected individual waiting up to 3 years before seeking medical advice and up to 5 years from the initial consultation to surgical diagnosis. The diagnostic complexities of non-specific endometriosis symptoms, lack of sensitive and specific biomarkers, and lack of awareness of both the public and practitioners have been reported to contribute to the delays in diagnosis. In 2020-21, $247.2 million was spent on endometriosis in the Australia healthcare system, and one publication reported a total yearly cost of $20,898 for each woman of any age with a diagnosis of endometriosis (which included health costs, carer costs, and productivity loss costs). Although these figures are discussing endometriosis collectively, incisional endometriosis could still be considered a contributing factor to these costs. Endometriosis has also been shown to be associated with ovarian clear cell carcinoma and endometroid ovarian carcinoma (EOVC). One study demonstrated that women with endometriosis are 4.20 times more likely to develop ovarian cancer – 7.48 times more likely to develop a Type I ovarian cancer (e.g., endometroid, clear cell) and 2.70 times more likely to develop a Type II ovarian cancer (high-grade serous) – than women without endometriosis. At present, there is no screening or surveillance tests that can accurately detect early ovarian cancer, so detection and diagnosis is dependent upon patients recognizing changes/symptoms and being aware of their risk factors (e.g., endometriosis). Due to the nature of ovarian cancer, the relative 5-year survival rate in Australia between 2016-2020 was only 48.1% (45% observed 5-year survival rate), with 1,355 new ovarian cancer cases in 2020. With the potential for an increase in incisional endometriosis incidence due to rising obstetric and gynaecological surgeries, it is imperative that mapping of the available literature is done. This will provide an overview of current knowledge of the condition which will aid with medical, and public, education, as well as highlight areas of need for future research directions. The primary aim of this review is to establish the current landscape of evidence for incisional/scar endometriosis and mapping published case reports to provide a potential population for targeted future research into literature/knowledge gaps. Secondary aims are to provide an overview of current and potential treatments, as well as the risk of malignant sequelae.