X-ray
What is the upper limits of normal for colonic diameter?
A rough rule of thumb is colon > 6 cm in diameter is considered dilated, except at the caecum, where > 9 cm is considered dilated.
The caecum is dilated measuring up to 11.1 cm with large air fluid level. Air is seen throughout the remainder of the colon and down to the rectum. No dilated loops of small bowel identified. Pneumobilia is noted.