Differential Diagnosis for Patient with Diarrhea after Hip Replacement
Single most likely diagnosis
- Medication-induced diarrhea: The patient has had diarrhea since hip replacement surgery 9 weeks ago. Many medications used post-surgery, such as antibiotics, can cause diarrhea. Given the timeline and the fact that C. diff was ruled out, medication side effects are a plausible cause.
Other Likely diagnoses
- Infection (other than C. diff): Although C. diff was negative, other infectious causes of diarrhea should be considered, especially in an immunocompromised patient or one who has recently undergone surgery.
- Gastrointestinal motility issues: Postoperative ileus or other motility issues could lead to diarrhea, especially if the patient has been on medications that affect gut motility.
- Malabsorption: Post-surgical changes in gut anatomy or function could lead to malabsorption, resulting in diarrhea.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Ischemic colitis: Reduced blood flow to the colon can cause diarrhea, abdominal pain, and potentially life-threatening complications if not addressed promptly.
- Sepsis: Any sign of infection in a post-surgical patient should prompt consideration of sepsis, a potentially fatal condition if not treated immediately.
- Hemolytic uremic syndrome (HUS): Given the abnormal RBC morphology, HUS, which can be triggered by certain infections or medications, should be considered due to its severe consequences.
Rare diagnoses
- VIPoma or other neuroendocrine tumors: These rare tumors can cause chronic, watery diarrhea due to the secretion of vasoactive intestinal peptide (VIP) or other substances.
- Short bowel syndrome: Although less likely without a history of significant bowel resection, this condition can lead to malabsorption and chronic diarrhea.
- Lymphocytic colitis or collagenous colitis: Part of the microscopic colitis group, these conditions can cause chronic, non-bloody diarrhea and are often diagnosed after other causes have been ruled out.