Differential Diagnosis of Pyelonephritis in Pregnancy

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis

  • Urinary Tract Infection (UTI) with ascent to the kidneys: This is the most likely diagnosis due to the common occurrence of UTIs in pregnancy, which can ascend to the kidneys and cause pyelonephritis, especially in the presence of urinary stasis and ureteral dilation that occur during pregnancy.

• Other Likely Diagnoses

  • Kidney stones: Pregnancy increases the risk of kidney stones due to urinary stasis and hypercalciuria, which can cause obstructive uropathy and lead to pyelonephritis.
  • Sepsis from other sources: Pregnancy can predispose to sepsis from various sources, including respiratory, gastrointestinal, or other infections, which can mimic pyelonephritis.
  • Pre-eclampsia: This condition can cause renal dysfunction and symptoms that may overlap with pyelonephritis, such as flank pain and hypertension.

• Do Not Miss Diagnoses

  • Appendicitis: Although less common in pregnancy, appendicitis can present with atypical symptoms, including flank pain, and can be life-threatening if missed.
  • Placental abruption: This condition can cause severe abdominal pain and may mimic the symptoms of pyelonephritis, but it requires immediate attention to prevent maternal and fetal morbidity.
  • Ruptured ectopic pregnancy: Although rare, a ruptured ectopic pregnancy can present with acute abdominal pain and may be mistaken for pyelonephritis, but it is a life-threatening emergency.

• Rare Diagnoses

  • Renal infarction: This is a rare condition that can cause acute flank pain and may mimic pyelonephritis, but it requires prompt diagnosis and treatment to prevent long-term renal damage.
  • Renal vein thrombosis: This condition is rare in pregnancy but can cause acute renal failure and may present with symptoms similar to pyelonephritis.
  • Perinephric abscess: Although rare, a perinephric abscess can cause severe flank pain and may be mistaken for pyelonephritis, but it requires prompt drainage to prevent complications.