What investigations would you perform on a 38-year-old pregnant woman at 17 weeks gestation with a history of joint pain, elevated serum Antinuclear Antibody (ANA) and Double-Stranded Deoxyribonucleic Acid (DS DNA), and a pregnancy weight of 92 kilograms?

Investigations for Pregnant Patient with Elevated ANA and Anti-dsDNA

This 38-year-old pregnant woman at 17 weeks gestation with elevated ANA and anti-dsDNA antibodies requires immediate comprehensive serological testing, renal function assessment, and disease activity monitoring to confirm suspected SLE and stratify pregnancy risk.

Immediate Serological Testing

Complete the autoantibody profile to confirm SLE diagnosis and assess pregnancy-specific risks:

• Antiphospholipid antibodies (aPL): Test once for lupus anticoagulant (LAC), anticardiolipin antibodies (aCL IgG/IgM), and anti-β2-glycoprotein I antibodies (anti-β2GPI IgG/IgM) 1, 2

  • These antibodies predict thrombotic events (OR 12.1), preeclampsia (OR 2.3), and pregnancy loss 1
  • Do not repeat during pregnancy as these antibodies remain stable 1

• Anti-Ro/SSA and anti-La/SSB antibodies: Test once to assess risk of neonatal lupus and congenital heart block 1, 2

  • Positive anti-Ro carries 0.7-2% risk of congenital heart block, requiring serial fetal echocardiography 1
  • Do not repeat during pregnancy as titers remain stable 1

• Complement levels (C3 and C4): Establish baseline and monitor serological activity 1, 2

  • Declining complement levels during pregnancy predict disease flares (OR 5.3) and pregnancy loss 1

• Anti-dsDNA antibody titers: Quantify using Farr assay or CLIFT for high specificity 1

  • Rising titers differentiate SLE flare from preeclampsia 1

Renal Function Assessment

Evaluate for lupus nephritis, which strongly predicts poor maternal (RR 9.0 for renal flare) and fetal outcomes (OR 18.9 for preterm delivery):

• Urinalysis with microscopy: Check for glomerular hematuria and urinary casts 1
• 24-hour urine protein or spot protein:creatinine ratio: Quantify proteinuria 1, 2
• Serum creatinine and calculated GFR: Assess baseline renal function 1

Baseline Hematologic Assessment

• Complete blood count with differential: Detect cytopenias associated with active SLE 2
• Erythrocyte sedimentation rate (ESR): Monitor disease activity, though physiologically elevated in pregnancy 1

Disease Activity Assessment

Document baseline SLE activity using validated pregnancy-specific indices:

• Clinical assessment for active manifestations: arthritis, serositis, rash, neurologic symptoms 1
• Active disease at conception increases risk of flares during pregnancy (RR 2.1) and adverse outcomes (OR 5.7 for pregnancy loss, 6.5 for preterm delivery) 1

Fetal Surveillance Planning

Based on antibody results, establish appropriate monitoring:

• If anti-Ro/SSA or anti-La/SSB positive: Plan serial fetal echocardiography from weeks 16-26 1, 2
• If history of neonatal lupus: Plan weekly fetal echocardiography weeks 16-26 1, 2
• Baseline obstetric ultrasound with Doppler at 20-24 weeks 1

Additional Considerations

Thyroid function testing: Screen for autoimmune thyroiditis, which associates with obstetric complications in autoimmune disease 3

Blood pressure monitoring: Establish baseline as SLE patients have increased preeclampsia risk (OR 1.8) 1

Critical Pitfalls to Avoid

• Do not delay testing: Early pregnancy testing (before 16 weeks) is essential for risk stratification and intervention planning 1, 2
• Do not repeat stable antibodies: Anti-Ro/La and aPL testing should be performed once only, not serially 1
• Do not use ANA for monitoring: ANA testing is for diagnosis, not disease activity monitoring 1
• Do not confuse preeclampsia with lupus nephritis: Both present with proteinuria and hypertension; declining complement and rising anti-dsDNA favor SLE flare 1, 4

Immediate Therapeutic Considerations Based on Testing

Once results available:

• If not on hydroxychloroquine: Initiate immediately as it reduces flares and improves pregnancy outcomes 1, 2, 5
• If aPL positive: Add low-dose aspirin (81-100 mg daily) ± heparin based on APS classification 1, 2
• Establish trimester-based monitoring schedule: Repeat complement, anti-dsDNA, CBC, and renal function at least once per trimester 1, 2