Differential Diagnosis for a 50-year-old man with foul-smelling urine, positive nitrites, positive blood, one month after falling on RUQ

• Single most likely diagnosis
  • Urinary Tract Infection (UTI): The presence of foul-smelling urine, positive nitrites, and positive blood in the urine are classic signs of a UTI. The recent trauma to the right upper quadrant (RUQ) could be coincidental or might have led to a urinary retention or other urinary issues that predisposed him to infection.
• Other Likely diagnoses
  • Kidney Stone: The trauma could have caused a kidney stone, and the infection could be secondary to the obstruction caused by the stone. The presence of blood in the urine (hematuria) supports this possibility.
  • Pyelonephritis: An infection of the kidney, which could be a complication of a UTI, especially if the bacteria have ascended to the kidneys. The symptoms and positive urine test support this diagnosis.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: If the infection is severe and has entered the bloodstream, it could lead to sepsis, a life-threatening condition. Although less likely, given the one-month timeline post-trauma, it's crucial not to miss.
  • Perinephric Abscess: A collection of pus around the kidney that can occur as a complication of pyelonephritis. It's a serious condition that requires prompt treatment.
• Rare diagnoses
  • Emphysematous Pyelonephritis: A rare but severe infection of the kidney where gas is produced in the tissue, often associated with diabetes or urinary obstruction. It's rare but could be considered given the severity of symptoms and the potential for complications from the initial trauma.
  • Renal Infarction: Although less likely given the symptoms, a renal infarction (death of kidney tissue due to lack of blood supply) could potentially present with hematuria and pain, especially if the trauma caused a vascular injury.