22nd April 2024

Disorders of the bowel and absorption

Background

Disorders of the large and small bowel can vary in terms of presentation, as well as severity. Patients may present with benign diarrhoea or constipation, or this can be a portent of a more malignant underlying disorder.

Clinical manifestation

Diarrhoea, the increased frequency of loose or watery stools, can be acute or chronic. Acute lasts generally less than 14 days. It is typically self-limiting and may not require investigation. Chronic or persistent diarrhoea tends to require investigation and constipation is common. It is often related to lifestyle factors and diet, though it can be a signal of an underlying condition. Weight loss and abdominal pain can also signify underlying bowel disorders. Inflammatory bowel disease forms the major topic within disease of the large and small bowel. Crohn’s disease and ulcerative colitis are chronic relapsing conditions which tend to be immunologically mediated. It is thought that an overly aggressive T-cell immune response to commensal bacteria in the gut leads to IBD, precipitated by genetic and environmental factors. Absorption and nutrition are closely linked to this, with impaired absorption of nutrients resulting from defects in the small intestines membrane transport system, as well as from acquired defects.

Investigations

In addition to history, examination and basic blood tests, there are a number of investigations specific to disorders of the large and small bowel. Endoscopy, in the form of oesophago-gastro-duodenoscopy (OGD) or colonoscopy, are the mainstay of investigation. Antineutrophil cytoplasmic antibodies (pANCA) can also be useful in the investigation of patients with suspected IBD. This permits visualisation of the bowel, as well as biopsy. In cases of suspected fat malabsorption, faecal elastase is most often used. This allows differentiation between pancreatic and intestinal causes of steatorrhea.

Management

Management of diseases of the bowel tends to depend on the underlying cause. In the case of IBD, immune suppression is the strategy, whilst those with malignancy are managed in conjunction with the surgical team. Patients with absorptive disorders are managed depending on the underlying cause of the malabsorption.

References

• Lamb CA, Kennedy NA, Raine T, Hendy PA, Smith PJ, Limdi JK, Hayee B, Lomer MCE, Parkes GC, Selinger C, Barrett KJ, Davies RJ, Bennett C, Gittens S, Dunlop MG, Faiz O, Fraser A, Garrick V, Johnston PD, Parkes M, Sanderson J, Terry H; IBD guidelines eDelphi consensus group; Gaya DR, Iqbal TH, Taylor SA, Smith M, Brookes M, Hansen R, Hawthorne AB. British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut. 2019 Dec;68(Suppl 3):s1-s106. doi: 10.1136/gutjnl-2019-318484. Epub 2019 Sep 27. Erratum in: Gut. 2021 Apr;70(4):1. PMID: 31562236; PMCID: PMC6872448.
• Arasaradnam RP, Brown S, Forbes A, Fox MR, Hungin P, Kelman L, Major G, O’Connor M, Sanders DS, Sinha R, Smith SC, Thomas P, Walters JRF. Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition. Gut. 2018 Aug;67(8):1380-1399. doi: 10.1136/gutjnl-2017-315909. Epub 2018 Apr 13. PMID: 29653941; PMCID: PMC6204957.