Abstract Introduction Ultrasound assessment of superficial endometriosis (SE) is difficult, and it is still mainly diagnosed via surgery. We hypothesized that a thickening of the subperitoneal layer of tissue overlying the anterior pouch of Douglas (POD), labeled the “White line sign” (WLS), could indicate the presence of SE. The aim of the study was to investigate the association between the WLS and the finding of endometriosis at histology. Material and Methods This prospective diagnostic accuracy study included 100 premenopausal women with chronic pelvic pain who underwent transvaginal ultrasound (TVS) by a single expert operator and subsequent laparoscopy by a specialist surgeon between January 2021 and January 2023. To assess intra‐ and inter‐observer reproducibility of the WLS, 36 consecutive ultrasound scans were recorded and re‐evaluated 6 months later by the first operator and an independent, second operator, both blinded to the original and each other's findings. Outcomes of interest were the diagnostic accuracy of the WLS for predicting the presence of SE and deep endometriosis (DE) at histopathology, and the reproducibility of the WLS at TVS. The former was assessed by calculating specificity, sensitivity, and accuracy, and the latter by determining proportions of agreement and Cohen's kappa coefficient ( κ ), respectively. Results The WLS had high specificity 100% (95% CI, 2.5–100%), but low sensitivity and accuracy for the detection of SE 30.6% (95% CI, 20.2–42.5%) and 31.5% (95% CI, 21.1–43.4%), respectively. The WLS was highly sensitive, specific, and accurate for the identification of DE 79.7% (95% CI, 67.8–88.7%), 100% (95% CI, 66.4–100%), and 82.2% (95% CI, 71.5–90.2%), respectively. The WLS was reproducible, demonstrated by good inter‐ and intra‐rater agreement and reliability for its diagnosis on TVS proportions of agreement 0.86 (95% CI, 0.69–0.95) and 0.83 (95% CI, 0.66–0.93), κ 0.72 (95% CI 0.49–0.94) and 0.64 (95% CI, 0.38–0.89), respectively. Conclusions Our study demonstrated that the WLS could be a valuable soft marker of both SE and DE. This is particularly useful in cases where no other or only subtle signs of endometriosis are present on scan.
Chaggar et al. (Sun,) studied this question.