What is the initial workup for hematuria (presence of blood in urine) in pregnancy?

Initial Workup for Hematuria in Pregnancy

Ultrasound of the kidneys and bladder is the recommended first-line imaging for evaluation of hematuria in pregnancy, with more comprehensive workup deferred until after delivery once benign causes have been excluded. 1

Initial Assessment

• Begin with thorough history, physical examination, urinalysis, and serologic testing before any imaging 1
• Rule out common benign causes specific to pregnancy:
  • Urinary tract infection (obtain urine culture) 1, 2
  • Gynecologic bleeding (perform pelvic examination) 1, 3
  • Recent vigorous exercise 1
  • Viral illness 1

Epidemiology and Risk Assessment

• The incidence of asymptomatic microhematuria in pregnant women is similar to non-pregnant women (approximately 20%) 1, 2
• The risk of malignancy in pregnant women with hematuria is low 1
• Dipstick hematuria is very common during pregnancy (20% in one study) but rarely indicates a condition that will impact pregnancy outcome 2

Diagnostic Algorithm

For Microhematuria in Pregnancy:

1. Initial laboratory evaluation:

   • Complete urinalysis with microscopic examination 1
   • Urine culture to rule out infection 1, 2
   • Serum creatinine to assess renal function 2
   • Protein-to-creatinine ratio to evaluate for proteinuria 4

2. First-line imaging:

   • Ultrasound of kidneys and bladder is the recommended initial imaging modality 1
   • Avoids radiation exposure to the fetus 1
   • Can identify most structural abnormalities of the urinary tract 1

3. Additional imaging considerations:

   • MRU (magnetic resonance urography) without IV contrast may be reasonable in select cases 1
   • CT, CTU, and MRI with IV contrast should be avoided due to fetal radiation exposure or uncertain effects of gadolinium 1
   • Conventional radiographs, IVU (intravenous urography), and arteriography are not recommended 1

For Gross Hematuria in Pregnancy:

• Requires more urgent evaluation due to higher association with malignancy (30-40% in general population) 1
• Same initial workup as microhematuria, but with more expedited ultrasound 1
• Consider urology consultation if no benign cause is identified 3, 5

Follow-up Recommendations

• If benign cause identified (infection, gynecologic bleeding): treat appropriately and repeat urinalysis in 6 months 5
• If no cause identified and initial evaluation is reassuring: defer comprehensive workup until after delivery 1
• Postpartum follow-up is recommended as microscopic hematuria persists in approximately 50% of women after delivery 2

Important Caveats

• Avoid unnecessary radiation exposure during pregnancy; ultrasound should be the first imaging modality 1
• Avoid gadolinium-based contrast agents during pregnancy due to uncertain fetal effects 1
• Dipstick testing alone is insufficient for diagnosis of hematuria and should be confirmed with microscopic examination 4
• Consider the possibility of preeclampsia when hematuria is accompanied by hypertension, though isolated hematuria is not strongly associated with development of preeclampsia 2, 4