Introduction:
Endometriosis is a chronic condition affecting women of reproductive age characterised by extra-uterine deposits of endometrial tissue with a prevalence of up to 10%.1-3 It can be found in peritoneal deposits, ovarian endometriomata and invasive disease, with sufferers experiencing pain and sub-fertility.2,4-6There is currently a 7-12 years delay between symptom onset and definitive diagnosis, by laparoscopy and biopsy.7-9Reducing this has long been a research priority. 10,11Up to 58% of sufferers present to primary care 10 or more times before diagnosis, demonstrated across a variety of healthcare systems and geographies.4,7,12-14 A better understanding of the accuracy with which symptoms, clinical history and non-invasive tests diagnose pelvic endometriosis would aid triage and referral.
Many studies have attempted to find replacement tests for diagnostic laparoscopy.15-17 These are often invasive or otherwise not applicable to primary care.16,18Previous meta-analyses have been restricted by a narrow inclusion criteria yielding a small number of eligible studies, limiting findings.19 Meta-analyses assessing imaging and biomarkers showed that no individual test met their criteria as a replacement or triage test alone, but findings on trans-vaginal ultrasound and serum CA-125 showed a high specificity for disease.20,21 These studies did not include assessment of other clinical factors. A 2019 narrative review demonstrated the importance of clinical factors in prediction of disease, but primary studies were not assessed for quality and absence of meta-analysis limited quantitative assessment of test performance.22
A 2021 case-control study reporting on the accuracy of a simple patient-completed questionnaire identified those at high or low risk of disease with good accuracy reflecting the utility of assessment of patient reported symptoms at a primary care level.24
Research related to endometriosis is increasing in volume, with 75% of primary studies published in the last decade.25,26Given this, and due to the limitations of previous reviews a new comprehensive systematic review and meta-analysis is required. We performed such an evidence synthesis and determined the accuracy of symptoms, clinical history, a simple low-cost biomarker and first line ultrasound for the diagnosis of pelvic endometriosis by means of a comprehensive systematic review and accuracy meta-analysis.