LearningRadiology - Diverticulitis

Diverticulosis/Diverticulitis

of the Colon

Findings: There are two extraluminal collections of barium arising from the medial border of the sigmoid colon. There is a mass effect (pad sign) on the superior border of the sigmoid.

• Herniation of mucosa and submucosa through muscular layers– pseudodiverticulum=false diverticulum=pulsion type

• Diverticula are reducible; they may be seen on one but not another BE

• Only proven association is with Marfan’s syndrome (20% get diverticulitis)

• Location

• Almost always involves sigmoid; never rectum; more common on left

• In about 17%, the tics cover the entire colon

• In another 12%, they are isolated to right colon

Prediverticular Disease

• Saw-tooth appearance to the colon, usually sigmoid, with shortening of bowel, crowding of haustra and picket-fencing of folds

• Muscle spasm is present-may be relieved with glucagon

• Controversial as to whether this form can be symptomatic, i.e. pain

Diverticulosis

• May be due to low roughage, high refined-fiber diet

• More common in industrialized nations

• Arise between the mesenteric and anti-mesenteric teniae of the colon and project between circular muscle rings–not through them

• May vary in size from tiny projections to several cm in size

• Have variable filling

• Associated spasm and numerous tics in sigmoid may make it impossible to see polyp in this region–even difficult with colonoscopy

• On AC BE tics have sharp outer and fuzzy inner margins viewed en-face

• Giant sigmoid diverticulum–huge gas-containing cyst-like structure arising in left iliac fossa

Diverticulitis

• Perforation of diverticulum with pericolic abscess of varying size; not simply inflammation of a tic

Clinical

• Pain and tenderness, mass in LLQ

• Fever, leucocytosis

Plain Film X-ray

• Sentinel loop or, less likely, LBO

• Air bubbles in abscess

• Pneumoperitoneum (rare)

• Extraluminal contrast

• Pericolonic abscess produces mass effect

• Double-tracking=barium in longitudinal sinus tract in wall

• Spasm is an indirect sign of diverticulitis

• Fistula to bladder (diverticulitis is most common cause of non-traumatic fistula here) or small bowel or vagina (diverticulitis causes 1/3 of fistulae to vagina)

• Infiltration of pericolonic fat

• Bowel wall thickening >1cm

• Abscess

• Fluid or free air in peritoneal cavity

• Colovesicle or colovaginal fistula

• Intramural sinus tracts

DDX

• Colon ca-but mucosa is left intact in diverticulitis

• Crohn’s disease-may be indistinguishable if TI not involved in Crohn’s

• Ischemic colitis–only if sigmoid is involved

• Radiation colitis

Complications

• Peritonitis–usually the perforation is walled off but it may spread throughout the peritoneal cavity or the retropertineum

• If a ruptured diverticulum is a strong clinical consideration prior to contrast study, water soluble contrast should be used rather than barium

• Obstruction–is rare

• Bleeding–see below

Hemorrhage from Diverticulosis

• Doesn’t involve Diverticulitis

• 75% of those that bleed are in right colon

• Clinically, massive rectal hemorrhage without pain

• May be diagnosed with nuclear med bleeding scan or angiography

WH/93