Abstract:Objective: To compare the application value of endorectal ultrasonography (ERUS) with two kinds of probe in preoperative T staging of rectal cancer and the value of the two probes in the staging of rectal cancer at different positions. Methods: The data of 440 patients with rectal cancer in our hospital from January 2014 to September 2021 were collected (277 cases of straight convex probe and 163 cases of circumferential scanning probe), and 301 patients with preoperative ERUS and postoperative pathological findings were screened out. Then the results of preoperative ultrasound T-staging (uT) and pathological staging (refer to the eighth edition of AJCC) were compared to calculate the sensitivity, specificity and accuracy of preoperative ultrasound staging. Results: The results of ultrasonography and pathology of 180 cases of rectal cancer (straight convex probe) were compared, and the total accuracy of uT by ERUS was 73%. The accuracy of each stage was T1 97%; T2 91%; T3 79%; T4 79%. The results of ultrasonography and pathology of 121 cases of rectal cancer (circumferential scanning probe) were compared, and the total accuracy of uT by ERUS was 74%. The accuracy of each stage was: T1 93%; T2 84%; T3 83%; T4 88%. The accuracy of the two probes in the diagnosis of rectal cancer at different positions were as follows: that of straight convex probe at the upper position was 60%, the middle positon was 75%, and the lower position was 73%. And that of circumferential scanning probe at the upper position was 73%, the middle positon was 75% and the lower position was 75%. Conclusion: The two probes are both of great importance for preoperative uT of rectal cancer. For the preoperative diagnosis of rectal cancer at different positions, the accuracy rate of circumferential scanning probe is slightly higher than that of straight convex probe. Based on the actual situation, choosing the appropriate probe or using two probes in combination can improve the accuracy of preoperative staging and provide a good basis for the treatment.