Ultrasonographic diagnosis of clinically non-palpable primary colonic neoplasms.

Over a 2-year period, more than 1700 abdominal ultrasound scans were performed which included a search for bowel disease in the scanning routine. Features consistent with a primary colonic neoplasm were reported in 35 patients. In 14 patients, ultrasound indicated the possibility of a colonic neoplasm in the absence of a clinically palpable mass. An intraabdominal mass was confirmed in 12 patients (86%), and was a primary colonic neoplasm in 11 patients (79%). In one patient a metastatic malignant mass had been misinterpreted as arising from the colon. In two patients no lesion could be demonstrated to account for the ultrasonographic abnormality. In a further 21 patients in which an abdominal mass had been evident on clinical examination, ultrasound was performed for further elucidation and indicated the mass to be arising from the colon. In this group, a primary colonic neoplasm was the cause in 11 patients (52%), while other primary or metastatic malignancy was found in six patients (29%) and benign disease in four patients (19%). We conclude that ultrasound is a useful primary diagnostic technique for colonic neoplasms, with a predictive value of 79% in detecting clinically non-palpable lesions. In our experience, false positive results due to scanning artefacts are rare. We consider that examination of the bowel is a worthwhile addition to the routine scan in patients with non-specific abdominal complaints.