High Accuracy of Ultrasound with Bowel Preparation in Detecting Ileum, Cecum, and Appendix Endometriosis: A Prospective Cohort

Abstract

Study Objective

To evaluate the diagnostic accuracy of ultrasound with bowel preparation (USBP) in identifying endometriosis in the right iliac fossa (RIF) structures—namely the ileum, cecum, and appendix.

Design

a prospective study conducted between 2011 and 2024.

Setting

two tertiary hospitals in Brazil

Patients or Participants

patients with suspected endometriosis

Interventions

all patients underwent USBP and laparoscopic surgery with histological confirmation within three months. For appendix lesions, only those without prior appendectomy were considered. Sensitivity, specificity, positive and negative predictive values, and Kappa coefficients were calculated for each site (ileum, cecum, appendix) and for overall RIF involvement.

Measurements and Primary Results

Of 992 cases, 182 (18.3%) had histologically confirmed RIF endometriosis. Overall sensitivity and specificity of USBP for any RIF lesion were 86.0% (CI: 78.8-91.5) and 98.8% (CI: 97.8-99.4), respectively (κ = 0.87). Sensitivity was highest for the ileum (88.2%,[CI: 72.5-96.7], κ = 0.92), followed by the cecum (86.2%,[CI: 72.5-96.7], κ = 0.91), and appendix (70.5%,[(CI: 72.5-96.7], κ = 0.75). Diagnostic performance was not significantly affected by BMI or prior surgery. Lesions ≥0.5 cm were more readily detected.

Conclusion

USBP offers a non-invasive, highly accurate method for detecting RIF endometriosis, potentially reducing the need for diagnostic laparoscopy and enabling better surgical planning.