Esophageal ultrasound and the preoperative staging of carcinoma of the esophagus. Esophageal ultrasound allows the esophageal wall to be viewed as five discrete layers. Lymph nodes are easily identified, and their size, shape, margin, and internal structure can be assessed. This provides an alternative method of preoperative (clinical) evaluation of the primary tumor [T] and the regional lymph nodes [N] of patients with carcinoma of the esophagus. Esophageal ultrasound was attempted in the clinical staging of 28 patients with carcinoma of the esophagus. Six patients (21%) were not assessed because of the inability to pass the esophageal ultrasound probe through the malignant stricture. The staging system for carcinoma of the esophagus developed by the International Union Against Cancer and the American Joint Committee on Cancer was used. Twenty-two patients had the true T determined by pathologic review of the resected esophagus. Esophageal ultrasound correctly identified T in 13 patients (59% accuracy). In four patients (18%) the disease was overstaged by esophageal ultrasound; all these patients had early T1 tumors confined to the submucosa. In five patients (23%) the disease was understaged by esophageal ultrasound; all of these patients had advanced tumors (four T3 and one T4) that invaded beyond the esophageal wall. Seven of the nine incorrect esophageal ultrasound determinations were called T2 (three T1, three T3, one T4), which suggests that the borders of the muscularis propria require careful attention when evaluated by esophageal ultrasound. Twenty patients had the true N determined by pathologic review of the resected specimen. Esophageal ultrasound correctly identified N in 14 patients (70% accuracy). Three patients were falsely identified as having N1 disease and three were falsely identified as having N0 disease. The sensitivity, specificity, positive predictive value, and negative predictive value for N assessment by esophageal ultrasound were 70%. Esophageal ultrasound provides an alternative method of visualization of the esophageal wall and regional lymph nodes. Our early experience shows promise for esophageal ultrasound in the clinical staging of carcinoma of the esophagus. 