Abstract: Background and purpose: Rectal cancer is one of the most common digestive tract malignancies, and treatment is selected according to tumor staging. The accurate preoperative staging is the precondition in guiding rectal cancer surgery. 3D-transrectal ultrasound (3D-TRUS) can clearly show the 5 layer structures of the intestinal wall, the organs adjacent to the rectum and the lymph nodes in the bowel. At present, it is one of the most accurate methods for preoperative staging of rectal cancer. The primary objective of the present study was to evaluate the diagnostic value of 3D-TRUS in the assessment of preoperative staging of rectal carcinoma. Methods: Fifty-nine cases of rectal carcinoma diagnosed clinically were staged preoperatively by 3D-TRUS, and compared with postoperative pathologic staging respectively. Results: The accuracy of 3D-TRUS for T staging was 93.2%. The kappa value was 0.814, which showed considerable consistency (P<0.005). The accuracy of 3D-TRUS for N staging was 76.3%. The kappa value was 0.219, which showed considerable inconsistency (P>0.05). Conclusion: 3D-TRUS is a practical and accurate tool in assessment of preoperative staging of rectal tumors in regard to tumor invasion depth (T) with advantages of simple operation, less pain and high accuracy. However, it is inaccurate in assessing regional lymph node status (N).

Key words: Rectal carcinoma, 3D-transrectal ultrasound, Preoperative staging