Multiple colonic diverticula and colonic wall thickening

image Inflammation of pericolonic fat (stranding)

image Thickened base of sigmoid mesocolon

image Engorged mesocolic blood vessels

image “Microperforation”: Small bubbles of pericolonic gas

• More complicated diverticulitis
image More extensive extraluminal collections of gas and fluid

image Free intraperitoneal spread of gas or fluid

image Fistulas to skin or hollow viscera

image Infectious thrombophlebitis (pylephlebitis)


• Colon carcinoma

• Radiation colitis

• Ischemic colitis

• Pseudomembranous colitis


• Most common colonic disease in Western world

• Average age at onset is dropping
image Related to obesity, metabolic syndrome, poor diet

• Percutaneous abscess drainage can obviate surgery or allow elective 1-step procedure in most cases


• Long segment colonic involvement, extensive inflammatory changes, and absence of nodes or metastases favor diverticulitis over colon cancer

• In some patients, it is difficult to distinguish diverticulitis from colon cancer; these should have follow-up endoscopy following resolution of acute symptoms

(Left) Graphic illustrates sigmoid diverticula, luminal narrowing, and wall thickening (circular muscle hypertrophy). There is a pericolic abscess due to the perforated diverticulum, but the rectum is spared.

(Right) Axial CECT shows uncomplicated sigmoid diverticulitis with irregular luminal narrowing and wall thickening, numerous gas-filled diverticula image, and relatively mild infiltration of the pericolonic fat image.

(Left) Axial CECT in a 60-year-old woman presenting with lower abdominal pain, fever, and tenderness demonstrates extensive free intraperitoneal gas image.

(Right) Axial CECT in the same patient shows fluid that has loculated into abscesses image. At surgery extensive sigmoid diverticulosis image was discovered to be the source of the free air and abscesses. This amount of free intraperitoneal air is unusual as the omentum usually walls off the perforated diverticulum.



• Intramural and pericolonic infectious/inflammatory process resulting from perforation of colonic diverticula.


General Features

• Best diagnostic clue
image Diverticula, infiltrated pericolonic fat and engorged vessels, ± extraluminal gas and fluid

• Location
image Most common in sigmoid colon (> 90% of cases)

image Diverticula occur mainly where vasa recta vessels pierce muscularis propria, between mesenteric and antimesenteric taeniae

• Size
image Diverticula usually 0.5-1.0 cm

• Morphology

• Colonic diverticula are pseudodiverticular
image Saccular outpouchings of mucosa and submucosa, 5-10 mm in diameter

Fluoroscopic Findings

• Single contrast barium enema
image Generally contraindicated in acute setting

image Numerous diverticula are usually present as outpouchings from lumen

image Colonic lumen is narrowed with serrated or “cog wheel” appearance
– Latter may represent spasm or result of circular muscle hypertrophy (not necessarily indicative of active inflammation)

CT Findings

• Diverticulosis
image Multiple air-, contrast-, or stool-filled outpouchings (diverticula)

image Colonic wall is often thickened 
– May be due to circular muscle hypertrophy, not necessarily acute diverticulitis

• Diverticulitis
image Simple or uncomplicated diverticulitis
– Multiple colonic diverticula and colonic wall thickening
image Long segmental (> 10 cm)  colonic involvement

– Inflammation of pericolonic fat (stranding)
image Inflammation is usually localized by adherence of omentum

– Thickened base of sigmoid mesocolon; curvilinear line in left iliac fossa

– Engorged mesocolic blood vessels

– “Microperforation”: Small bubbles of pericolonic gas

image More complicated diverticulitis
– More extensive extraluminal collections of gas &/or fluid (“macroperforation”)
image May loculate as abscess with contrast-enhancing wall

– Free intraperitoneal spread of gas or fluid
image Represents failure of omentum to wall off perforation

image Generally requires surgical intervention for peritoneal soiling

– Fistulas to skin or hollow viscera
image Enhancing tract with gas &/or enteric contrast material evident within bladder, vagina, etc.

– Infectious thrombophlebitis
image Mesenteric vein becomes contaminated with colonic bacteria

image May be evident as venous wall enhancement, luminal gas, or thrombosis

image May carry gas and bacteria to portal vein and liver (potentially causing pyogenic hepatic abscess)

Ultrasonographic Findings

• Grayscale ultrasound

• Pericolic inflammation
image Increased echogenicity ± ill-defined hypoechoic areas

• Pericolic abscess
image Hypoechoic ± internal echoes

• Color and power Doppler
image Hyperemia of pericolonic fat

Imaging Recommendations

• Best imaging tool
image Multiplanar CECT
– Rectal contrast may be useful to demonstrate colonic fistulas


Colon Carcinoma

• Short segment involvement (< 10 cm), wall thickness > 2 cm, mesenteric lymphadenopathy, metastases

• Asymmetric bowel wall thickening ± irregular surface

• Less pericolonic infiltration and vessel engorgement

Radiation Colitis

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Diverticulitis

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