[Hydrocolonic sonography in the study of colonic diseases. Comparison with double-contrast enema]

This study was aimed at assessing the diagnostic value of hydrocolonic sonography (HS), a new technique of US examination of the colon during water enema, in colonic diseases. HS was performed on 120 clinically selected patients and was followed by double contrast barium enema (DCBE) in all patients, by endoscopy in 85, by pathology in 50 and by surgery in 36 patients. We obtained good quality images in 86% of cases, middle quality findings in 10% and poor results in 4% of cases. HS allowed the 5 layers of the colonic wall to be visualized. Forty of 50 polyps bigger than 1 cm, 9/10 cases of granulomatous colitis and diverticulitis were recognized and distinguished from cancer and 31/32 carcinomas were found--3 of them were locally invasive tumors, even though endoscopic biopsy had diagnosed them as adenomas. Compared with DCBE, HS exhibited lower sensitivity in recognizing small polyps (80% vs. 92%) but higher specificity (100% vs. 92.8%); in the diagnosis of carcinoma, HS exhibited higher sensitivity (96.8% vs. 90.6%) and the same specificity (about 100%); the depiction of parietal layers allowed also tumor staging. At present, HS cannot be proposed as the examination of choice to study polyps because of its limitations in recognizing them; nevertheless, HS appears to exhibit some advantages over DCBE in tumor detection and staging. HS is a simple, fast and safe technique which is well tolerated and easily repeatable, which calls for further investigation of its potentials, also because improved operator's experience is sure to increase HS reliability.