What is the diagnosis for a patient with a computed tomography (CT) scan of the abdomen showing no hydronephrosis, no ureteral stones, fluid in the small bowel and colon, diverticulosis without diverticulitis, no appendicitis, leukopenia with bandemia and lymphopenia, metabolic acidosis with elevated C-reactive protein (CRP), and a urinalysis (UA) showing hematuria, proteinuria, and bacteriuria?

Differential Diagnosis

• Single most likely diagnosis
  • Pyelonephritis: The presence of moderate blood, protein, and RBCs in the urine, along with moderate bacteria, suggests a urinary tract infection. The elevated CRP (41.2) also indicates a significant inflammatory response, which is consistent with pyelonephritis. The absence of hydronephrosis and ureteral stones makes a obstructive cause less likely, but the clinical presentation and lab results point towards an upper urinary tract infection.
• Other Likely diagnoses
  • Urinary Tract Infection (UTI) with cystitis: While the presence of bacteria and blood in the urine could suggest a lower urinary tract infection, the elevated CRP and the absence of other clear sources of infection (e.g., appendicitis, diverticulitis) make pyelonephritis more likely. However, a UTI with cystitis cannot be ruled out without further evaluation.
  • Gastroenteritis: The fluid in portions of the small bowel and colon, as well as the mild ileus or nonspecific gastroenteritis, could suggest a gastrointestinal infection. However, the lack of other symptoms (e.g., diarrhea, vomiting) and the presence of urinary findings make this diagnosis less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: The elevated CRP and the presence of bands (absolute 1.2) on the CBC suggest a significant inflammatory response, which could be indicative of sepsis. While the patient's presentation does not clearly indicate sepsis, it is a potentially life-threatening condition that must be considered.
  • Perforated viscus: Although the CT abdomen does not show clear evidence of a perforated viscus, the presence of free fluid in the abdomen and the mild ileus or nonspecific gastroenteritis could suggest a perforation. This diagnosis would require prompt surgical intervention.
• Rare diagnoses
  • Vasculitis: The presence of blood and protein in the urine, along with the elevated CRP, could suggest a systemic vasculitis. However, this diagnosis would be uncommon and would require further evaluation (e.g., ANCA testing, biopsy).
  • Tubulointerstitial nephritis: This condition could present with similar urinary findings, but it would be an uncommon diagnosis and would require further evaluation (e.g., renal biopsy).