The value of transvaginal sonography in the preoperative assessment of myometrial invasion in high and low grade endometrial cancer and in comparison to frozen section in grade 1 disease

OBJECTIVE: To evaluate the diagnostic accuracy of preoperative transvaginal sonography (TVS) in the detection of deep myometrial invasion in endometrial cancer cases classified by the grade of disease, and in comparison to frozen section analysis in grade 1 cases. METHODS: In a prospective study, 91 patients with confirmed endometrial carcinoma underwent preoperative TVS for evaluation of myoinvasion. Sonographic results were categorized as superficial (less than or equal to 1/2 myometrial depth) and deep invasion (greater than 1/2 myometrial depth). TAH-BSO followed by retroperitoneal lymph node sampling were performed in all patients with grade 2-3 tumors. In patients with grade 1 disease, the surgical specimen was intraoperatively evaluated by frozen section, and lymph node sampling was carried out if deep invasion was determined. The preoperative sonographic findings and the frozen section results were compared to the final histopathology report of myoinvasion. RESULTS: In 77 of the 91 (84.6%) patients, the sonographic assessment of the depth of myoinvasion was in accord with the final histopathologic findings. TVS demonstrated a sensitivity of 87.8% and a specificity of 82.7% in detecting deep invasion in the entire study group (grade 1-3), with positive and negative predictive values (PPV, NPV) of 74.3% and 92.3%, respectively. TVS in grade 1 cases (n=47) showed a sensitivity of 77.7%, a specificity of 79%, PPV of 46.6% and NPV of 93.7%. TVS in cases with grade 2-3 tumors (n=44) showed a sensitivity of 90%, specificity of 91.6%, PPV of 90% and NPV of 91.6%. Thus, the accuracy of TVS in grade 2-3 cases was superior to that achieved in grade 1 cases (91% vs 78.7%; p=.002). The myometrial invasion was assessed by frozen section in 41 out of 47 patients with grade 1 disease and demonstrated a sensitivity of 85.7%, a specificity of 100%, PPV of 100% and NPV of 97.1%. The specificity (100%) and accuracy (97.5%) of the frozen section were found to be superior compared to that of the TVS (79% and 78.7%) in detecting deep invasion in grade 1 cases (p=.008, p=.005, respectively). No statistically significant difference was found between the sensitivity of either technique. CONCLUSIONS: TVS appeared to be a more accurate method for preoperative assessment of myoinvasion in grade 2-3 endometrial cancer patients compared to grade 1 patients. In grade 1 cases, this method achieved lower accuracy in detecting deep invasion compared to the frozen section analysis. Based on these data, the value of preoperative TVS results as the sole criterion in the decision to perform extensive surgical procedures in grade 1 endometrial cancer is questionable and warrants further evaluation.