What is the diagnosis for a patient with a CT abdomen showing no hydronephrosis, no ureteral stones, fluid in the small bowel and colon, diverticulosis without diverticulitis, and no appendicitis, along with laboratory results indicating mild leukopenia (low white blood cell count), metabolic acidosis (low CO2), elevated C-reactive protein (CRP) indicating inflammation, and urinalysis showing hematuria (blood in urine), proteinuria (protein in urine), and bacteriuria (bacteria in urine)?

Differential Diagnosis

• Single most likely diagnosis
  • Pyelonephritis: The presence of moderate blood, protein, and bacteria in the urine, along with an elevated CRP indicating inflammation, points towards a urinary tract infection involving the kidneys. The absence of hydronephrosis and ureteral stones makes an obstructive cause less likely, but the clinical and laboratory findings are consistent with pyelonephritis.
• Other Likely diagnoses
  • Diverticulitis: Although the CT scan mentions diverticulosis without diverticulitis, the presence of inflammation (elevated CRP) and mild ileus or nonspecific gastroenteritis could be indicative of early or mild diverticulitis not yet apparent on imaging.
  • Gastroenteritis: The fluid in portions of the small bowel and colon could be due to a viral or bacterial gastroenteritis, which might also explain the mild elevation in inflammatory markers.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: The elevated CRP, bands on the CBC, and evidence of infection (bacteria in urine) could indicate the beginnings of sepsis, especially if the patient shows signs of systemic response to infection. Early recognition and treatment are crucial.
  • Perforated viscus: Although the CT does not show evidence of free air or perforation, any condition that leads to peritonitis (such as a perforated ulcer or diverticulum) could present with nonspecific findings initially and is a medical emergency.
• Rare diagnoses
  • Vasculitis: Certain types of vasculitis (like ANCA-associated vasculitis) could present with renal involvement (protein and blood in urine), gastrointestinal symptoms, and elevated inflammatory markers. However, this would be less common and typically associated with other systemic symptoms.
  • Inflammatory bowel disease (IBD) flare: While IBD could explain some gastrointestinal findings and elevated inflammatory markers, the acute presentation and specific findings (like moderate bacteria in urine) are less typical for an IBD flare as the primary diagnosis.