The Role of Endoscopic Ultrasound in Periano-Rectal Crohn’s Disease

INTRODUCTION Crohn’s disease is a chronic inflammatory disease of unknown etiology that may involve any part of the gastrointestinal tract. In addition patients may have extra intestinal symptoms. Perianal fistulae and abscesses may occur in as many as 20%–40% of patients with CD and are a significant cause of morbidity. Imaging modalities include fistulography, CT and MRI. Fistulography involves injection of radiographic contrast directly into a fistulous tract followed by plain radiographs. Fistulography may be painful, with limited ability to determine anatomic relationship of the fistulae with the sphincteric musculature, and has been found to be relatively inaccurate when compared to surgical findings. CT is valuable for detecting and guiding drainage of periano-rectal abscesses, but has a limited role in evaluating patients with perianal fistulae. CT may not be able to differentiate between inflammatory stranding and a true fistulous tract. Also the exact anatomic classification of fistulae may be difficult with CT. Both fistulography and CT expose the patient to ionizing radiation. Since MRI provides the ability for detailed high resolution imaging of the perianal musculature it is a sensitive and accurate modality to detect pathologic processes and delineate anatomy of fistulae in perianal CD. The use of a pelvic phased array coil increases the sensitivity and accuracy of MRI in perianal CD when compared to using a body coil. Although EUA is generally considered the gold standard for evaluating perianal fistulae and abscesses, endoscopic ultrasound, has an emerging role in the evaluation of perianal complications of CD. EUS may also be helpful in assessing response to medical or surgical therapy. Not only does EUS provide accurate imaging of the perianal region, but it is also safe and lacks exposure to ionizing radiation. INFLAMMATORY BOWEL DISEASE: A PRACTICAL APPROACH, SERIES #32