Differential Diagnosis

The patient's presentation on CTAP with interval development of moderate distention in fluid retention throughout the majority of the small bowel and new right side segment colitis extending from the cecum to the mid transverse colon in an elderly adult suggests several potential diagnoses. These can be categorized as follows:

• Single Most Likely Diagnosis
  • Small Bowel Obstruction (SBO): The description of moderate distention in fluid retention throughout the majority of the small bowel is highly suggestive of a mechanical obstruction. The presence of new segment colitis could be secondary to the obstruction or an unrelated process but is less likely to be the primary cause of the small bowel findings.
• Other Likely Diagnoses
  • Inflammatory Bowel Disease (IBD): The new onset of segment colitis could suggest Crohn's disease or ulcerative colitis, especially if the patient has a history of IBD. However, the primary finding of small bowel distention would need to be explained by complications of IBD such as strictures.
  • Ischemic Bowel Disease: This could cause both small bowel distention due to ileus and colitis, especially in an elderly patient with potential vascular disease.
• Do Not Miss Diagnoses
  • Mesenteric Ischemia: Although less likely given the colitis, mesenteric ischemia can cause small bowel distention and is a medical emergency. The presence of colitis might be a late sign of ischemia affecting the colon.
  • Volvulus or Intussusception: These are mechanical causes of obstruction that can present with the described findings and require urgent intervention.
  • Neutropenic Colitis (Typhlitis): In an immunocompromised patient, this could be a consideration, especially with the new onset of colitis, but the primary finding of small bowel distention would be unusual.
• Rare Diagnoses
  • Eosinophilic Gastroenteritis: This rare condition can cause small bowel obstruction and could potentially involve the colon, but it would be an unusual cause of the described findings.
  • Lymphoma or Other Malignancies: These could cause both obstruction and colitis, either through direct invasion or through complications like intussusception, but would be less common and might have other associated findings.