Diverticulitis

Images and Text Genevieve Carbonatto

A 45 year old man presents with a 3 day history of diarrhea and increasing LIF pain. He is afebrile. His diarrhea has tapered off. On examination he is tender in his LIF. A point of care ultrasound is performed using a curvilinear probe. He is able to localise with precision his area of tenderness.

This is his scan

At his area of maximum tenderness there is a diverticulum which is clearly visible. The colon is thickened and stands out against the  surrouning hyperechoic inflammed mesentary. A CT confirms the diagnosis

 Discussion

Diverticulitis is a common presentation to the Emergency department. It is a herniation of the mucosa and submucosa, corresponding to a weak point where the vasa recti penetrate the tunica muscularis, so most colonic diverticula are “false diverticula”containing no muscularis propria.

Imaging technique

  • Transducer : Curvilinear transducer first to “scout the area”. May change to linear high frequency transducer if patient slim.
  • Sweep over the area of tenderness  and ask the patient to put the transducer over the maximal area of tenderness.
  • Identify the thickened loop of colon and assess in it’s long axis first then scan through the entire length in the short axis
  • Look for
  1. At least one diverticulum
  2. Local thickening of the bowel wall > 4 -5 mm
  3. A faecolith may be visible
  4. Echogenic non compressible fat surrounding one or more diverticula suggesting an acute inflammatory process
  5. Identification of a “target sign”  A hyoechoic wall surrounding a hyperechoic center.

Longitudinal view

2. 

By scanning distally along the colon, the relatively short length of colon inflammation and the diverticulum are visible. It lies precisely under the area of tenderness.

Ultrasound in Diverticulitis (1)

  1. Not as good as CT for the diagnosis of diverticulitis . CT is superior in
  • Obese patients
  • Area obscured by gas
  • Distal sigmoid involvement
  • Complicated diverticulitis associated with free air, faecal peritonitis, deep abscesses
  • Detecting alternative diagnoses to diverticulitis such as ureterolithiasis, pyelonephritis, perforated peptic ulcer, appendicitis, Crohn’s disease, epiploic appendagitis, gynecological conditions, colonic malignancy, pancreatitis
  • Ultrasound is a good first imaging technique in the Emergency department for diverticulitis but should be followed up by a CT scan.

2. Ultrasound has a  role in patients who are not obese

3. Ultrasound has a role in early uncomplicated diverticulitis

4. Repeated daily ultrasound shows that diverticulitis runs a  predictable and benign course

  • Local wall thickening of the colon with preservation of the US layer structure. Within the inflamed diverticulum a fecolith is present. The diverticulum is surrounded by hypoechoic , non       compressible tissue
  •  Evacuation of the faecolith to the colonic lumen with or without the development of a small paracolic abscess, sometimes with the disintergration of the faecolith within 1 -2 days
  •  Remaining inflammatory changes remain present for several days after the evacuation of the faecolith

Diverticulitis may be right sided (left : right 15:1) Diverticula of the right colon are usually solitary, congenital, true diverticula containing all bowel layers. The faecoliths are larger and the diverticula neck wider. There is no hypertrophy of the muscularis of the right colonic wall

References:

  1. Dig Dis 2012;30:56–59 (DOI:10.1159/000336620)Ultrasound of Colon DiverticulitisPuylaert J.B.C.M
  2. World J Emerg Med. 2016; 7(1): 74–76. Ultrasound diagnosis of diverticulitis Michael E. Abboud, Sarah E. Frasure, and Michael B. Stone

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