To explore the preoperative precise predictive value of multi-parameter combined detection of transrectal ultrasound (TRUS) for lymph node metastasis of middle and low rectal cancer.

The medical records of 200 patients with middle and low rectal cancer who were treated in Hanzhong People's Hospital from March 2022 to March 2024 were retrospectively collected, according to the postoperative pathological results, they were divided into the metastasis group (89 cases) and the non-metastasis group (111 cases). All patients underwent TRUS examination before the operation, and TRUS-related parameters were collected, the predictive efficacy of each parameter and combined detection was analyzed using the receiver operating characteristic (ROC) curve.

The long diameter of lymph nodes, short diameter of lymph nodes, and the ratio of long to short diameter in the metastasis group were significantly larger than those in the non-metastasis group, and the number of cases where rectal masses accounted for more than 1/2 of the intestinal lumen circumference and the number of cases with ultrasound T₃ or above stages were significantly higher than those in the non-metastasis group (P<0.05). ROC curve analysis showed that the AUC, sensitivity and specificity of combined detection of long diameter of lymph nodes, short diameter of lymph nodes, ratio of long to short diameter, rectal mass accounting for more than 1/2 of the intestinal lumen circumference, and ultrasound T₃ and above stages were significantly higher than those of individual detection of each index (P<0.05).

The joint prediction model constructed based on TRUS multi-parameters can effectively improve the preoperative prediction accuracy of lymph node metastasis in middle and low rectal cancer, combined with the nomogram, it can provide reliable references for clinical condition assessment and individualized treatment plan formulation.