Staging of rectal carcinoma with transrectal ultrasonography

Transrectal ultrasonography (TRUS) has proven useful for loco-regional staging of rectal carcinoma in specialised centres, but the investigation is not widely used. The aim of this study was to audit the introduction of TRUS performed by surgeons without previous experience with ultrasonography.

All patients admitted with rectal carcinoma in the period 1996-2002 entered this prospective, comparative study. TRUS with a stiff endorectal probe was performed preoperatively in 118 consecutive patients, 91 of whom subsequently had rectal resection without preoperative radiotherapy (PRT), and seven who had rectal resection after PRT. Twenty patients did not have resection. The main outcome measures was the feasibility of TRUS in staging of rectal cancer, and the accuracy of T- and N-staging, comparing TRUS with the histopathological examination of resected specimens.

TRUS was successful in 81/91 patients who underwent rectal resection without PRT. The accuracy of T-staging was 74% overall; 40% in five pT1 tumours, 81% in 26 pT2 tumours, 80% in 45 pT3 tumours and 25% in four pT4-tumours. With regard to perirectal tissue invasion, the sensitivity and specificity of TRUS was 82% and 84%, respectively, and the positive and negative predictive values were 89% and 71%, respectively. The accuracy of TRUS for N-staging was 65%. The sensitivity for detection of lymph node metastases was 41% and the specificity 68%. TRUS was unsuccessful in 21/118 patients, in 12/98 who had rectal resection, and in 9/ 20 who did not have resection, because of stenosis or high location of the tumour precluding correct placing of the probe.

TRUS is often unsuccessful in patients with advanced tumours, especially when the tumour is located in the upper rectum. The predictive values for perirectal tumour invasion were acceptable, but the sensitivity for detection of lymph node metastases was low. These results were obtained by surgeons without previous experience with ultrasonographic examinations.