CT hypoperfusion complex

Last revised by Ciléin Kearns on 4 Jul 2024

CT hypoperfusion 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 hypovolaemia which affects the sympathetic splanchnic stimulation. The small bowel is more commonly affected than the large bowel. 

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The term CT hypoperfusion complex is now preferred over the older and less accurate term shock bowel 2,9.

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

Features of CT hypoperfusion complex can include:

  • vascular

    • small calibre abdominal aorta

      • AP diameter <13 mm, measured 20 mm above and below the level of renal arteries 2

      • occurs in ~30% of patients with hypovolaemia and is not specific

    • collapsed inferior vena cava

      • AP diameter <9 mm in three consecutive segments; i.e. measured at 20 mm both above and below the level of renal veins and at the perihepatic portion 2,6

      • sometimes not appreciated due to massive fluid resuscitation

    • halo sign

      • low density (<20 HU) fluid surrounding the IVC 6

      • occurs in ~80% of patients with severe hypovolaemia 8

  • bowel

    • thickened bowel wall (>3 mm) 2

      • typically involves the jejunum

      • wall thickening is due to submucosal oedema

    • hyperenhancing mucosa

      • relative to the psoas muscle on contrast enhanced images 2,13

  • hepatobiliary

    • shock pancreas

      • heterogeneous enhancement with peripancreatic fluid (<20 HU) 2,6 is controversial 10

    • hypoenhancement of the liver relative to the spleen by 25 HU 6

  • spleen

    • hypoenhancement (subjective) 2

    • decreased volume 14

  • bilateral adrenal gland hyperenhancement 7

    • established sign in paediatrics but controversial in adults 10

  • hyperenhancing kidneys 13

  • ascites 13

  • shock thyroid

    • heterogenous contrast enhancement, enlargement and surrounding fluid 11,12.

The small bowel findings are the most commonly observed feature in CT hypoperfusion complex, and may be seen to reverse on repeat imaging following resuscitation. A collapsed IVC occurs in the majority of trauma patients with CT hypoperfusion complex, but in <40% of non-trauma patients with CT hypoperfusion complex 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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