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 evidence of appendicitis, with lab results indicating mild leukopenia (low white blood cell count), metabolic acidosis (low CO2), elevated C-reactive protein (CRP), 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 reduces the likelihood of an obstructive cause, making pyelonephritis a more likely diagnosis given the clinical and laboratory findings.
• Other Likely diagnoses
  • Urinary Tract Infection (UTI) with cystitis: While the findings are more suggestive of an upper urinary tract infection, a lower urinary tract infection (cystitis) could also present with similar urinary findings and should be considered, especially given the presence of bacteria and blood in the urine.
  • Gastroenteritis: The CT findings of fluid in portions of the small bowel and colon, suggestive of mild ileus or nonspecific gastroenteritis, along with the laboratory findings of bands and lymphocytes, could indicate a gastrointestinal infection.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: Although the patient's presentation does not overtly suggest sepsis, the elevated CRP, presence of bands, and evidence of infection (bacteria in urine) necessitate consideration of this potentially life-threatening condition.
  • Perforated viscus: Despite the CT report not indicating appendicitis or diverticulitis, any sign of free fluid or abnormal bowel findings should prompt consideration of a perforated viscus, which is a surgical emergency.
• Rare diagnoses
  • Interstitial nephritis: This condition could present with similar urinary findings (blood, protein) and systemic signs of inflammation (elevated CRP). However, it is less common and typically associated with specific medications or infections.
  • Vasculitis: Certain types of vasculitis can affect the kidneys and gastrointestinal tract, presenting with a wide range of symptoms. However, this diagnosis is less likely without additional specific findings such as skin rash, joint pain, or more significant renal impairment.