Performance of ultrasound-based endometriosis staging system (UBESS) for predicting level of complexity of laparoscopic surgery for endometriosis

Objective: To develop and assess the performance of a preoperative ultrasound-based endometriosis staging system (UBESS) to predict the level of complexity of laparoscopic surgery for endometriosis. Methods: This was a multicenter prospective and retrospective cohort study on consecutive women with suspected endometriosis who underwent laparoscopy between June 2009 and July 2013. Each woman underwent a systematic transvaginal ultrasound evaluation to assess the pelvis for different phenotypes of endometriosis, and the diagnostic performance of ultrasound for these different phenotypes was evaluated relative to the gold standard, laparoscopy. A three-stage preoperative UBESS was developed to assess the severity of pelvic endometriosis, based on the histological phenotypes of endometriosis, the anatomical locations of deep infiltrating endometriosis and their sonographic markers of local invasiveness. The three stages of UBESS (I–III) were then correlated with the three levels of complexity of laparoscopic surgery for endometriosis described by the Royal College of Obstetricians and Gynaecologists (Levels 1–3). The end-points were the diagnostic performance of UBESS to predict the level of complexity of laparoscopic surgery for endometriosis, i.e. UBESS stage I to predict Level-1 laparoscopic surgery, UBESS stage II to predict Level-2 laparoscopic surgery and UBESS stage III to predict Level-3 laparoscopic surgery. Results: The analysis included 192 women, with a mean ± SD age at diagnosis of endometriosis of 23.7 ± 9.3 years and a mean duration of symptoms prior to presentation of 42 months. Predominant reported locations of pelvic pain were left iliac fossa (32%), right iliac fossa (29.5%) and lower abdomen (61%) and predominant symptoms included dyspareunia (57.5%), dysmenorrhea (58.5%) and dyschezia (41.5%). The accuracy, sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios of UBESS I for predicting a requirement for Level-1 laparoscopic surgery were: 87.5%, 83.3%, 91.7%, 90.9%, 84.6%, 10 and 0.182; those of UBESS II for predicting Level-2 surgery were: 87.0%, 73.7%, 90.3%, 65.1%, 93.3%, 7.6 and 0.292; and those of UBESS III for predicting Level-3 surgery were: 95.3%, 94.8%, 95.5%, 90.2%, 97.7%, 21.2 and 0.054, respectively. Conclusion: UBESS could be utilized to predict the level of complexity of laparoscopic surgery for endometriosis. It has the potential to facilitate the triage of women with suspected endometriosis to the most appropriate surgical expertise required for laparoscopic endometriosis surgery. UBESS needs to be validated externally in multiple centers to assess its general applicability.