CT hypotension complex

CT hypotension complex refers to the predominantly abdominal imaging features that occur in the context of profound hypotension. Multiple abdominal organs can display atypical appearances not related to the initial trauma, but reflect alterations in perfusion secondary to hypovolemia which affects the sympathetic splanchnic simulation. The small bowel is more commonly affected than the large bowel

The term CT hypoperfusion complex is now preferred over the older and more direct term shock bowel 2,9

Aetiology

CT hypoperfusion complex is most commonly described in the context of post-traumatic hypovolaemic shock but can also occur in 1-2:

  • septic shock
  • severe head or spinal injury
  • cardiac arrest
  • bacterial endocarditis
  • diabetic ketoacidosis
CT

Features of CT hypoperfusion complex have been defined as (some or all of these features may be present):

  • thickened bowel loops (>3 mm) with enhancing walls (the reason the condition was previously known as "shock bowel")
    • on non-contrasted images, hyperdense walls compared to the psoas muscle 2, 6
    • wall thickening is due to submucosal oedema
    • hyperenhancing mucosa
  • collapsed inferior vena cava: AP diameter <9 mm in three consecutive segments; i.e. 20 mm both above and below the renal veins and the perihepatic portion 2,6
    • sometimes not appreciated due to massive fluid resuscitation 
  • halo sign:
    • low density (<20 HU) fluid surrounding the IVC 6
    • this occurs in ~80% of patients with severe hypovolaemia 8
  • small calibre abdominal aorta: AP diameter <13 mm both 20 mm above and below the renal arteries 2; this occurs in ~30% of patients with hypovolaemia, and is not specific
  • shock pancreas: heterogeneous enhancement with peripancreatic fluid (<20 HU) 2,6; this is a controversial finding 10
  • hypoenhancement of the spleen (subjective) 2
  • hypoenhancement of the liver: 25 HU less than the spleen 6
  • bilateral adrenal gland hyperenhancement may be a feature 7 mainly in paediatrics and is controversial in adults 10

The small bowel findings are the most commonly observed feature in CT hypotension complex. Note that the frequency of most associated findings does not differ between trauma and non-trauma patients with shock bowel, except in case of a collapsed IVC which occurs in the majority of trauma patients, but in <40% of non-trauma patients with shock bowel.2

CT findings tend to be reversible with appropriate fluid management 3 although severe hypotension and shock have a significant mortality rate. 

The clinical context is extremely valuable for image interpretation. The differential for thickened enhancing bowel includes 4-5:

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Article Information

rID: 9779
Section: Pathology
Synonyms or Alternate Spellings:
  • CT (bowel) hypoperfusion complex
  • Shocked bowel
  • Shock bowel
  • CT hypoperfusion complex

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