This document provides information about acute colonic diverticulitis (ACD) including: - ACD is a complication of colonic diverticulosis where diverticula in the colon become inflamed or infected. - CT scan is the preferred imaging method to diagnose and stage ACD. Findings on CT scan include colon wall thickening, pericolic stranding, and abscess formation in severe cases. - ACD is classified as uncomplicated or complicated, with complicated ACD further divided into stages depending on the extent of inflammation and abscess formation. Potential complications of ACD include abscess, fistula formation, and perforation.

1. Acute Colonic Diverticulitis
Hisham AlKhatib, M.D.
Consultant Radiologist

2. •‫اله‬ ‫وعلى‬ ‫هللا‬ ‫رسول‬ ‫على‬ ‫والسالم‬ ‫والصالة‬ ‫هلل‬ ‫الحمد‬
‫اجمعين‬ ‫م‬ّ‫ل‬‫وس‬ ‫وصحبه‬
•، ‫علما‬ ‫وزدني‬ ‫ينفعني‬ ‫بما‬ ‫وعلمني‬ ‫علمتني‬ ‫بما‬ ‫انفعني‬ ‫اللهم‬
‫الحكيم‬ ‫العليم‬ ‫انك‬
• Praise be to Allah and prayers be upon the
Messenger of Allah and his family and
companions.
• Oh God, give me the benefit of what you
have taught me and teach me what benefits
me.

3. Definition
• is one of the presentations of diverticular
disease and is most often a complication of
colonic diverticulosis .
• uncomplicated diverticulosis is mostly
asymptomatic and acute diverticulitis is a
potentially life-threatening illness.

4. Imaging
• CT is the modality of choice for the diagnosis
and staging of diverticulitis
• dedicated ultrasound study may be able to
confidently characterize this condition.

5. CT SCAN
• pericolic stranding, often disproportionately
prominent compared to amount of bowel wall
thickening
• segmental thickening of bowel wall
• enhancement of colonic wall
– usually has inner and outer high-attenuation
layers, with a thick middle layer of low attenuation

9. • diverticular perforation
– extravasation of air and fluid into pelvis and
peritoneal cavity
• abscess formation (seen in up to 30% of cases)
– may contain fluid, gas or both
• fistula formation (usually a chronic
complication)
– gas in the bladder
– direct visualisation of a fistulous tract
CT SCAN

10. The CT diagnosis of AD
• Diverticulitis which has a sensitivity of 43%
and a specificity of 100%
• Intestinal wall thickening which has a
sensitivity of 96% and a specificity of 91% .
• Signs of inflammation in the pericolonic fat
and thickening of the lateroconal fascia ,
which have a sensitivity of 95% and 50%,
respectively, and a specificity of 90%
• and 100%, respectively

11. The CT diagnosis of AD
• Signs of intestinal perforation (Figure 4), which
have a sensitivity of 30% and a specificity of
100%.
• Pericolonic or distant abscess , which has a
sensitivity of 58% and a specificity of 99%
• Fistulas with adjacent organs .
• Vascular engorgement (the comb sign), which has
a sensitivity of 29% (increasing to 59% if
associated with fluid) and a specificity of 100%

18. • The most recent classification systems divide
ACD into two groups:
– complicated and
– uncomplicated

19. • Uncomplicated AD is characterized only by
– thickening of the wall of the diverticula,
– with increased pericolonic fat density.

21. • Complicated AD is divided into stages:
– In stage 1A, pericolonic air bubbles, with little
fluid, can be seen, and there is no abscess.
– stage 1B if the diameter of the abscess is ≤ 4 cm
and
– as stage 2A if it is > 4 cm.
– In stage 2B there may be distant air (> 5 cm from
the inflamed loop);
– in stages 3 and 4, there is diffuse fluid, without
and with distant free air, respectively

29. Complications
• abscess formation
• fistula formation
– bladder: colovesical fistula
– vagina: colovaginal fistula
– bowel: coloenteric fistula or colocolic fistula
– skin: colocutaneous fistula
• small bowel obstructions from adhesions
• perforation resulting in pneumoperitoneum
• pylephlebitis

30. Differential diagnosis
• colorectal carcinoma
– less inflammatory change
– usually shorter segment
• acute appendicitis (for right-sided disease)
– younger patients
– no predilection for Asian patients
• epiploic appendagitis

32. Differential diagnosis
• ischaemic colitis
• pseudomembranous colitis
– bowel wall thickening more pronounced than the
amount of stranding
• inflammatory bowel disease
– bowel wall thickening more pronounced than the
amount of stranding
• tuboovarian abscess

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