Can transvaginal sonography predict infiltration depth in patients with deep infiltrating endometriosis of the rectum?

BACKGROUND Patients with deep infiltrating endometriosis (DIE) of the rectum often benefit from surgical treatment, including disc or segmental bowel resection, in terms of pain relief and treatment of infertility. The aim of the present study was to evaluate the diagnostic accuracy of transvaginal sonography (TVS) for preoperative detection of rectal DIE. Furthermore, we aimed to investigate whether TVS can predict infiltration depth based on the distortion of characteristic sonomorphologic features of the rectal wall. METHODS Two-hundred patients with symptoms of endometriosis were prospectively assessed by TVS for the presence of rectal DIE before undergoing laparoscopic radical resection of endometriosis including segmental resection of the bowel in affected cases. Sensitivities, specificities, positive and negative predictive values (PPV and NPV), positive and negative likelihood ratios (LHR) and test accuracies were then calculated for the presence of infiltration of the serosal/smooth muscle (S/M) layer and submucosal/mucosal (MUC) layer as demonstrated by TVS and confirmed by histopathological analysis. RESULTS Rectal endometriosis was confirmed in 43 out of 195 (22%) cases. The sensitivity, specificity, PPV, NPV, test accuracy and positive and negative LHR of TVS on S/M infiltration were 98%, 99%, 98%, 99%, 99%,150.24 and 0.02, respectively, whereas respective data on MUC involvement were 62%, 96%, 53%, 97%, 93.8%, 16 and 0.4. CONCLUSIONS TVS is a highly valuable tool in detecting rectal endometriosis preoperatively. Within this, S/M endometriotic infiltration can be accurately predicted, whereas TVS is less valuable for detection of MUC involvement.