Crohn's disease

Complications + Associations

Appropriate Tests

Faeces MCS and antigen detection, Ova cysts parasites faeces, to exclude infection as the cause of prolonged diarrhoea.

Biopsy of the involved area.

Colorectal biopsy, Faecal calprotectin, Full blood count, Blood film. Protein, and Albumin; plasma or serum are useful for monitoring disease activity.

Crohn’s disease may present with a gastrointestinal or systemic complication.

Gastrointestinal complications






Bowel obstruction


Peri-anal fistula/abscess

Lesion biopsy to establish diagnosis and to exclude other conditions.

Systemic complications + associations




Anaemia, related to


  • Iron deficiency


  • Anaemia of chronic disease


  • Vitamin B12 deficiency




Ankylosing spondylitis


Erythema nodosum


Hepatobiliary disease, including


  • Sclerosing cholangitis

See Cholestasis.

  • Autoimmune hepatitis

See under Hepatitis.

  • Cirrhosis


Splenic atrophy/absence


Treatment complications


Anaemia, especially


  • Salicylazosulphapyridine


  • Drug-induced oxidative haemolysis under Haemolysis.
  • Drugs (may impair folate absorption) under Folate deficiency.

Corticosteroid excess