A 20 year old male presents with mucus and repeated gastrointestinal bleeding. Patient is positive for ANCA. The most likely diagnosis is:

Answer is A (Ulcerative Colitis) Presence of mucus and blood in stool along with positive ANCA antibodies suggests a diagnosis of ulcerative colitis Different Clinical, Endoscopic and Radiographic Features Clinical Ulcerative Colitis Crohn's Disease Gross blood in stool Yes Occasionally Occasionally Mucus Yes Systemic symptoms Occasionally Frequently Pain Occasionally Frequently. Abdominal mass Rarely Yes Significant perineal disease No Frequently Fistulas No Yes Small-intestinal obstruction No Frequently Colonic obstruction Rarely Frequently Response to antibiotics No Yes Recurrence after surgery No Yes ANCA-positive Frequently Rarely ASCA --positive Rarely Frequently Endoscopic Rectal sparing Rarely Frequently Continuous disease Yes Occasionally Cobblestoning No Yes Granuloma on biopsy No Occasionally Radiographic Small bowel significantly abnormal No Yes Abnormal terminal ileum Occasionally Yes Segmental colitis No Yes Asymmetric colitis No Yes Stricture Occasionally Frequently Epidemiology of 1BD Age of onset 15-30 and 60-80 15-30 & 60-80 Male : Female ratio 1:1 "4.5 : 1 Smoking May prevent disease May cause disease Oral contraceptives No increased risk Odds ratio 1.4 Appendectomy Protective Not protective Monozygotic twins 6% concordance 58% concordance Dizygotic twins 0% concordance 4% concordance