Endoluminal transrectal ultrasonography: accuracy, reliability, and validity.

The significant risk of local recurrence after curative resection and the relative inaccuracy of preoperative clinical assessment justify a more sophisticated assessment for carcinoma of the rectum. Endoluminal rectal ultrasonography (EU) can directly visualize the degree of rectal wall penetration by tumor and the immediate pararectal lymph nodes. Despite several reports reporting excellent accuracy of EU compared with pathology in detecting the degree of tumor penetration, EU remains restricted in terms of widespread availability. A review of the literature was performed to determine the accuracy, reliability, and current validity of EU. Raw data were collected from cross-sectional surveys assessing the degree of tumor penetration in 873 patients and lymph node involvement in 571 patients with primary rectal cancer. EU is very accurate at determining tumor penetration (kappa = 0.85) but is only moderately accurate at detecting lymph node involvement (kappa = 0.58). The reliability of EU has not been assessed, and a simple protocol is proposed. The validity of EU was assessed in only a few studies. EU is credible and feasible, makes intuitive biologic sense, and is, perhaps, sensitive to change. The ability to make clinical decisions based on EU (content validity) will decide whether widespread implementation is applicable.