Differential Diagnosis

The patient presents with symptoms of back pain, burning pain with urination, hematuria, fever, chills, and urgency with small amounts of urine output. Based on the provided information, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Pyelonephritis: This is the most likely diagnosis given the patient's symptoms of back pain, fever, chills, and burning pain with urination, along with laboratory findings of elevated WBCs in the urine, positive leukocyte esterase, and a high WBC count on the CBC. The presence of an IUD could be a contributing factor, but it is not the primary cause of her symptoms.

• Other Likely Diagnoses

  • Kidney Stone: Although the patient denies a history of kidney stones, the symptoms of back pain, hematuria, and burning pain with urination could be consistent with a kidney stone. The absence of nausea and vomiting does not rule out this diagnosis.
  • Urinary Tract Infection (UTI): While pyelonephritis is a type of UTI, a lower UTI could also present with similar symptoms, especially given the patient's complaints of urgency and small amounts of urine output.

• Do Not Miss Diagnoses

  • Sepsis: Given the patient's fever, chills, and elevated WBC count, sepsis is a potential diagnosis that must be considered, especially if the patient's condition worsens or if she shows signs of organ dysfunction.
  • Obstructive Uropathy: The patient's symptoms of small amounts of urine output and urgency could suggest an obstruction in the urinary tract, which could be caused by a variety of factors, including kidney stones or other masses.
  • Ectopic Pregnancy: Although the patient's beta-hCG is negative and she has an IUD, ectopic pregnancy is a diagnosis that must be considered in any female patient of childbearing age presenting with abdominal or back pain, especially if there is any possibility of pregnancy.

• Rare Diagnoses

  • Tuberculosis of the Urinary Tract: This diagnosis could present with chronic symptoms of back pain, hematuria, and burning pain with urination, but it is less likely given the acute presentation and the absence of other systemic symptoms.
  • Interstitial Cystitis: This condition could cause symptoms of urgency, frequency, and burning pain with urination, but it is less likely given the patient's acute presentation and the presence of systemic symptoms such as fever and chills.