[Sonographic diagnosis of colon cancer]

In a prospective study a total of 155 patients were investigated, 72 of whom had carcinoma of the colon confirmed by colonoscopy and biopsy, while 83 had no bowel disease. Among the patients with carcinoma of the colon, pathological changes of the bowel wall were reliably detected by ultrasound in 81.9% of the cases. Among the patients without bowel disease, 91.6% of the cases were interpreted as being unremarkable. In 7.1% of all cases the finding was classified as uncertain. In the cases of carcinoma detected by ultrasound, the localization of the lesion was correctly determined in 91.5%. The ultrasonographic appearance of the carcinoma of the colon depends on the stage of progression. In an early stage it reveals a circumscribed non-circular thickening of the bowel wall. The typical feature of a late stage is a hypoechoic tumour with a narrow ribbon of echoes. This ribbon of echoes is either located in the center of the tumour or more frequently eccentric. It is a hint on the intestinal origin of the tumour and represents a stenosis of the lumen. Ultrasonography is useful as a supplementary method in the investigation of the large bowel. However a carcinoma of the colon cannot be excluded on the basis of the ultrasonographic image.