Differential Diagnosis for Sepsis Secondary to Stool Impaction

The patient's presentation with possible sepsis secondary to stool impaction, negative blood cultures, an initial lactic acid level of 4.5, and a subsequent increase in lactic acid after desimpaction and initiation of antibiotics, suggests a complex clinical scenario. The following differential diagnoses are categorized for clarity:

• Single Most Likely Diagnosis

  • Ongoing or Unresolved Sepsis: Despite the initial intervention, the rising lactic acid level suggests that the septic process may not be fully controlled. This could be due to inadequate antibiotic coverage, a resistant organism, or an unresolved source of infection, such as an abscess or persistent bowel ischemia.

• Other Likely Diagnoses

  • Bowel Ischemia: The increase in lactic acid could indicate bowel ischemia, either as a complication of the impaction or due to another cause such as embolism or thrombosis. Ischemia could lead to bowel necrosis and worsen the septic picture.
  • Abscess Formation: An abscess could have formed as a complication of the stool impaction, which may not have been fully addressed by the desimpaction procedure. An abscess would serve as a persistent source of infection.
  • Antibiotic-Associated Diarrhea or Clostridioides difficile Infection: The initiation of antibiotics increases the risk of antibiotic-associated diarrhea or Clostridioides difficile infection, which could complicate the patient's course and contribute to the rising lactic acid level.

• Do Not Miss Diagnoses

  • Toxic Megacolon: Although less common, toxic megacolon is a life-threatening condition that can occur in the setting of severe colonic distension, such as with stool impaction. It requires prompt recognition and treatment.
  • Perforation: Bowel perforation, either due to the impaction itself or as a complication of ischemia, is a critical diagnosis that must not be missed. It would require immediate surgical intervention.
  • Septic Shock: The progression to septic shock, characterized by persistent hypotension despite fluid resuscitation and evidence of organ dysfunction, is a critical condition that necessitates aggressive management.

• Rare Diagnoses

  • Hirschsprung’s Disease: Although rare in adults, undiagnosed Hirschsprung’s disease could lead to chronic constipation and potentially to complications like stool impaction. However, it would be an unusual cause of sepsis in this context.
  • Colonic Volvulus: This is a rare condition where the colon twists around itself and its mesentery, leading to obstruction and potentially ischemia. It could present with abdominal pain and constipation but is less likely to be directly related to the sepsis picture described.