Why do patients with Crohn's disease (CD) develop small bowel obstruction (SBO)?

From the Guidelines

Patients with Crohn's disease develop small bowel obstruction (SBO) primarily due to intestinal inflammation that leads to stricture formation, with up to 54% of patients being affected by this complication 1. The chronic inflammatory process in Crohn's disease causes repeated cycles of tissue damage and healing, resulting in fibrosis and thickening of the intestinal wall. These strictures narrow the intestinal lumen, impeding the normal passage of intestinal contents. Additionally, Crohn's patients may develop adhesions from previous surgeries, as approximately 70-80% of patients require surgical intervention at some point in their disease course. The transmural inflammation characteristic of Crohn's disease can also lead to fistula formation and abscesses, which may cause external compression of the bowel. Furthermore, the disease can cause significant bowel wall edema during acute flares, temporarily narrowing the lumen. Long-standing inflammation may also result in fibrostenosing disease, a complication where the intestine becomes increasingly rigid and narrow. Management typically involves treating the underlying Crohn's disease with anti-inflammatory medications, immunomodulators, or biologics, while severe or recurrent obstructions may require endoscopic dilation or surgical intervention such as strictureplasty or bowel resection, with deferred surgery being the preferred option in adult patients with Crohn's disease presenting with acute small-bowel obstruction without bowel ischaemia or peritonitis 2. Some key points to consider in the management of SBO in Crohn's disease include:

• Endoscopic balloon dilation has a technical success rate of 89 to 92% for fibrotic strictures, with 70 to 81% of patients experiencing short-term relief of symptoms 1
• Surgery is warranted for small bowel CD stenosis that causes an intestinal obstruction with potential impending perforation, with long or multiple strictures, when the stricture is not endoscopically accessible and when medical and/or endoscopic treatment fails to adequately improve the patient’s symptoms or when there is concern about concomitant malignancy 1
• Conservative management is the preferred option in the absence of peritonitis, including bowel rest, gastric decompression, and intravenous fluid therapy, with intravenous steroids being considered in the presence of active inflammatory disease 2

From the Research

Causes of Small Bowel Obstruction (SBO) in Crohn's Disease

• Crohn's disease is a chronic gastrointestinal inflammatory disease that can lead to long-term complications, including fibrotic strictures, enteric fistulae, and intestinal neoplasia 3.
• Uncontrolled inflammation in Crohn's disease can cause transmural inflammation of the intestine, leading to strictures, fistulas, and abscesses, which can result in small bowel obstruction (SBO) 4.
• The risk factors implicated in Crohn's disease, such as smoking, low fiber-high carbohydrate diet, altered microbiome, and medications like non-steroidal anti-inflammatory drugs, can also contribute to the development of SBO 4.

Pathophysiology of SBO in Crohn's Disease

• The pathophysiology of SBO in Crohn's disease involves a combination of inflammation, fibrosis, and luminal narrowing, which can cause bowel obstruction 5.
• CT findings in patients with SBO and Crohn's disease often show a markedly stenotic bowel segment or a thickened-wall small bowel segment with luminal narrowing, which can be caused by active or chronic disease 5.

Treatment and Management of SBO in Crohn's Disease

• The treatment of SBO in Crohn's disease depends on the severity of the obstruction and the patient's overall condition, and may involve conservative management, surgery, or a combination of both 5, 6.
• Intravenous steroids are commonly used to treat acute flares of Crohn's disease, but their effectiveness in improving short-term outcomes in patients with uncomplicated SBO is unclear, with one study suggesting that they do not improve outcomes 6.
• Other treatments, such as probiotics, antibiotics, 5-aminosalicylates, immunomodulators, and antibodies to tumor necrosis factor, may be used to prevent postoperative recurrence of Crohn's disease and SBO 7.