Ultrasonographic characterization of parametrial endometriosis: a prospective study

Abstract

ObjectiveTo study the ultrasonographic diagnostic accuracy and characteristics of parametrial endometriosis comprehensively. DesignThis prospective study enrolled patients with suspected deep endometriosis scheduled for laparoscopic surgical treatment. Preoperative ultrasonographic examinations were performed following the International Deep Endometriosis Analysis criteria. The study aimed to evaluate the presence of parametrial endometriosis and its ultrasonographic characteristics, using surgical diagnosis as the reference standard. Additionally, indirect signs of deep endometriosis and concomitant deep endometriosis nodules associated with parametrial involvement were identified, assessing their predictive significance in anterior, lateral, and posterior parametrial areas. SubjectsPatients with suspected deep endometriosis scheduled for surgical treatment. Intervention/ExposureStandardized preoperative ultrasonographic examination. Main Outcome MeasuresThe diagnostic accuracy of transvaginal ultrasound in identifying parametrial endometriosis, including sensitivity and specificity. Ultrasonographic characteristics of parametrial nodules, prevalence in distinct parametrial areas, and associations with indirect deep endometriosis signs and concomitant nodules. ResultsSurgical confirmation of parametrial nodules was observed in 105 out of 545 patients (18.5% left, 17.0% right). Transvaginal ultrasound demonstrated a sensitivity of 77.1% (95% CI 68.0–84.8%) and specificity of 99.1% (95% CI 67.7–99.8%). Parametrial nodules typically exhibited characteristics such as a mild hypoechoic appearance (83.6%), starry morphology (74.7%), irregular margins (70.2%), and low vascularization. The posterior parametrium was the most common location (52.2%), followed by the lateral (41.0%) and anterior parametrium (6.8%). Concomitant deep nodules in the rectum (63.5%) and infiltrating the rectovaginal septum (56.5%) were significantly more prevalent in patients with parametrial involvement (both p<0.001). Indirect signs of deep endometriosis, such as ovaries fixed to the uterine wall (71.8%) and the absence of a posterior sliding sign (51.8%), were also more common in women with parametrial DE nodules (both p<0.001). Hydronephrosis, though relatively uncommon in patients with parametrial involvement (8.2%), was largely detected in lateral parametrial nodules (70.0%). ConclusionThis study represents a systematic ultrasonographic characterization of parametrial endometriosis, comprehensively assessing the diagnostic accuracy of transvaginal ultrasound in identifying parametrial involvement within a sizable cohort of patients with preoperative suspicion of deep endometriosis.