<prompt> A plain X ray abdomen is performed in case of small bowel obstruction. Small bowel would be called dilated if its diameter is more than:2 cm3 cm4 cm5 cm  <response>: Normal bowel caliber: Small bowel- 3 cm Large bowel- 6 cm Caecum- 9 cm Thus, small bowel is called dilated if its caliber is 3 cm. 