INFLAMMATORY BOWEL CONDITIONS

Inflammatory bowel conditions
Both barium studies and ultrasound have a useful role to play in the management of patients with inflammatory bowel disease. Diagnosis is generally made with conventional barium X-ray studies, while ultrasound may be used to monitor disease and identify extraluminal complications of the disease. Crohn’s disease is a common cause of inflammation affecting the small bowel and particularly the terminal ileum. It usually presents with pain, diarrhoea and weight loss. The terminal ileum/ileocaecal junction is involved in the majority of cases, and thickened, hypoechoic bowel wall can often be demonstrated in this area.

Ultrasound may be used to identify complications of Crohn’s disease, screen patients at risk, and monitor patients for recurrence of disease following surgery. Crohn’s disease affects the entire thickness of the bowel wall, and one of the common complications is that of intramural abscesses. These can sometimes be seen within the thickened wall as gas-containing, highly echogenic areas. When large, they may perforate, resulting in an ill-defined collection of pus, which may be drained percutaneously.

Fistulae are another complication of Crohn’s, and are easier to demonstrate with contrast radiography. Ulcerative colitis affects the mucosa, rather than the whole wall. On ultrasound it produces a thickened, stratified hypoechoic wall, unlike Crohn’s, in which the entire thickness of the wall is affected. A wall thickness greater than 3 mm is considered abnormal. Like Crohn’s, small ulcer craters within the wall of the colon in ulcerative colitis may appear as hyperechoic gas-filled foci. Inflammatory bowel diseases increase the perfusion of the intestine, decreasing vascular resistance.

Hypervascularized bowel wall has been identified in both Crohn’s and ulcerative colitis24 compared with normal subjects. Doppler of the SMA has revealed an increase in flow velocities (both peak systolic and end diastolic) and a decrease in resistance index in numerous types of pathological bowel, including Crohn’s. However the lack of specificity limits its use in clinical work. Changes in resistance index have been found to be related to the activity of Crohn’s disease, which could prove valuable in monitoring patients with known disease.

Diverticulitis may also be recognized on ultrasound as outpouchings from the bowel wall, most commonly affecting the sigmoid colon. Perforation of a diverticulum may give rise to a diverticular abscess, although the presence of air makes ultrasound limited in its evaluation of this condition.