Introduction Diagnoses and monitoring of small bowel Crohn's disease can often present a challenge. Tests for aiding decision making are often not available readily and involve radiation. This can potentially results in uncertainty in diagnosis and reluctance and delay in treatment.

We studied the role of ultrasound scan (USS) in diagnosis of small bowel Crohn's disease. We compared the results of USS with Magnetic Resonant Imaging (MRI).

Methods This was a prospective study of use of USS followed by a MRI small bowel. Patients who were clinically suspected to have a first diagnosis of small bowel Crohn's/recurrence after surgery/exacerbation of known Crohn's disease were referred from Gastroenterology clinics and inpatients. USS were performed by experienced Radiology consultant. All the patients first had an USS performed and reported, followed by MRI scan.

Results A total of 30 patients were identified for this study. Age range was from 17 to 78 years and median age of 30 years. 50% of patients were males and 50% females. 20% of the patients were known to have Crohn's disease, 10% had known post surgical recurrence, 17% suspected post surgical recurrence and 53% were clinically suspected to have small bowel Crohn's.

USS was reported as normal or no active disease in 70% of all scans. Out of the remaining 30%, 10% of post resection, 7% of clinically suspected and 13% of the known Crohns disease patients were found to have active disease and stricturing in small bowel on USS.

Subsequent MR scans showed very good sensitivity of USS in diagnosis. In 96.2% patients MRI scan showed same or very similar findings as on USS. All Abnormal USS were confirmed with same abnormality on MRI scans (positive predictive value 100%). Of the Normal USS only one MRI scan (3%) showed a stricture in proximal small bowel (Negative predictive value 95.2%). Of the remaining, two MRI scans (7%) could not be performed, as patients were unable to tolerate procedure. One (3%) MRI scan was cancelled after USS, as no longer indicated. One further MRI scan showed a primary small bowel volvulus, but no Crohns disease, where USS was normal.

Conclusion With emergence of new modalities the role of ultrasound in small bowel disease has diminished. This study shows that ultrasound scan can still play a very important role in monitoring and diagnosis of Crohn's disease. USS can aid in planning management of patients in acute settings, where other investigations may cause delay. It has the advantages of ready availability, less time to perform, well tolerated and no radiation exposure.

In our study it proved to be very sensitive and accurate in comparison to MRI scan and may be usefully employed in assisting clinical decision making before other investigations are performed.