The following radiograph performed 3 days later demonstrates that there is now dilatation of the distal descending colon and sigmoid. The thickening of the distal sigmoid and of the proximal aspect of the sigmoid can be noted overlapping over the left iliac wing. There is now more significant proximal small bowel dilatation which is likely due to ileus.
These appearances are suggestive of a colitis. Initial mural thickening, often termed "thumbprinting" as in this case, reflect bowel wall oedema. It is then followed by bowel atony and gaseous distended ileus. Many similar etiologies of colitis can result in similar appearance including inflammatory bowel disease (usually ulcerative colitis), but also pseudomembranous or other infectious colitis. In this case the disease process was due to ulcerative colitis and serial daily imaging was performed to assess the possibility of a toxic megacolon. Maximal dilatation was at the 3 day film. Toxic megacolon, typically affects the transverse colon which may develop pronounced lung printing, loss of haustration and formation of inflammatory polyps. As the colon distends to 6 cm in greater there is a perforation is significantly increased. Perforation clearly is associated with high morbidity and mortality.