Diffuse Alveolar Hemorrhage (DAH)

Bleeding into the alveolar space from pulmonary capillaritis or diffuse alveolar damage — ANCA vasculitis, anti-GBM disease, lupus; rare but life-threatening

Symptoms / Associated Sx

  • Hemoptysis (may be absent in up to 33% — "dry DAH")

  • Rapidly progressive dyspnea, hypoxia

  • Bilateral pulmonary infiltrates (diffuse; new or worsening)

  • Falling hemoglobin without obvious external blood loss

  • Fever (less consistent)

  • Signs of systemic vasculitis: sinusitis, saddle nose deformity (GPA), rash, arthritis, renal failure (pulmonary-renal syndrome)

  • Hematuria, red cell casts on urinalysis (glomerulonephritis — pulmonary-renal syndrome)

Denies

  • Fever + purulent sputum + focal consolidation (rules out pneumonia as primary — though can coexist and BAL distinguishes)

  • BNP elevation + cardiomegaly + edema (rules out cardiogenic pulmonary edema as primary)

  • Prior known malignancy (rules out diffuse tumor infiltration)

  • Recent new medication (rules out drug-induced DAH if absent)

Social History (SHx)

Autoimmune disease history (SLE, RA, GPA, MPA, anti-GBM — Goodpasture), prior renal disease (glomerulonephritis), drug history (propylthiouracil, hydralazine, cocaine — ANCA-associated; mitomycin C; amiodarone), bleeding disorder or anticoagulation, bone marrow transplant (allogeneic HSCT — DAH from graft conditioning).

Main Etiology

  • Pulmonary capillaritis (most common — inflammation of alveolar capillaries):

    • ANCA-associated vasculitis: GPA (granulomatosis with polyangiitis — c-ANCA/PR3), MPA (microscopic polyangiitis — p-ANCA/MPO)

    • Anti-GBM disease (Goodpasture syndrome) — linear IgG deposits on GBM; pulmonary hemorrhage + rapidly progressive GN; anti-GBM antibody

    • SLE (lupus pneumonitis + capillaritis)

    • Antiphospholipid syndrome

    • Isolated pauci-immune capillaritis (ANCA negative)

  • Diffuse alveolar damage (non-capillaritis): ARDS, AIP, drug-induced

  • Bland hemorrhage (no inflammation): Mitral stenosis, coagulopathy, anticoagulation

  • Other: Bone marrow transplant (idiopathic; typically post-engraftment), cocaine inhalation, inhaled toxins

Most Common DDx

  • Bilateral pneumonia / ARDS (fever + leukocytosis + cultures positive; BAL shows infection not hemorrhage; P/F ratio low; treat with antibiotics)

  • Cardiogenic pulmonary edema (elevated BNP; JVD; bilateral effusions; responds to diuretics; BAL pink frothy — not progressively bloody)

  • Pulmonary embolism with bilateral infarcts (pleuritic pain; tachycardia; D-dimer + CTPA; unilateral or patchy — not diffuse bilateral)

  • Drug-induced pneumonitis (bilateral infiltrates; new drug exposure; eosinophilia on BAL; responds to drug withdrawal + steroids)

  • Acute eosinophilic pneumonia (bilateral infiltrates; eosinophilia on BAL >25%; peripheral eosinophilia; responds to steroids; no capillaritis)

  • Lymphangitic carcinomatosis (bilateral reticular infiltrates; known malignancy; dyspnea; BAL may show malignant cells)

DATA

  • CBC (falling Hgb without external blood loss — key finding; anemia; thrombocytopenia in vasculitis)

  • BMP (creatinine — AKI; renal involvement in pulmonary-renal syndrome)

  • Urinalysis + microscopy (red cell casts — glomerulonephritis; proteinuria)

  • ANCA panel: c-ANCA (PR3-ANCA) → GPA; p-ANCA (MPO-ANCA) → MPA (send both by immunofluorescence AND ELISA)

  • Anti-GBM antibody (Goodpasture — urgent; test immediately; linear GBM deposits on renal biopsy)

  • ANA, anti-dsDNA, anti-Sm, complement (SLE — anti-dsDNA most specific; low C3/C4 in active lupus nephritis)

  • Antiphospholipid antibodies (APLA syndrome — anti-cardiolipin, anti-β2GP1, lupus anticoagulant)

  • Coagulation panel (coagulopathy contributing)

  • CXR (bilateral diffuse alveolar infiltrates — "bat-wing" pattern; rapid progression over hours)

  • CT chest (bilateral ground-glass opacities; consolidation; tree-in-bud in capillaritis; distinguish from infection)

  • Bronchoscopy + BAL (most important diagnostic procedure — progressively hemorrhagic BAL from sequential segments confirms DAH; cell differential; cultures to exclude infection)

  • Renal biopsy (gold standard for diagnosis in pulmonary-renal syndrome — pauci-immune GN in ANCA; linear IgG in anti-GBM; immune complex in SLE)

  • Echocardiogram (mitral stenosis exclusion)

Home Meds

  • Anticoagulants (hold if major DAH — reversal; restart timing per indication)

  • Medications causing DAH: propylthiouracil (ANCA), hydralazine (ANCA), cocaine (drug-induced ANCA); stop immediately

  • Immunosuppressants if on for autoimmune disease (may need to escalate)

Plan

  • ICU (DAH is almost always an ICU-level emergency)

  • Supplemental O2; escalate to HFNC → BiPAP → intubation as needed; avoid high PEEP (worsens bleeding from increased pulmonary venous pressure)

  • Immediate diagnostic bronchoscopy + BAL (confirms DAH, excludes infection, sends cultures) — perform as soon as hemodynamically stable; do not delay for all serologies

  • Send ANCA + anti-GBM antibody IMMEDIATELY — these results drive treatment; do not wait for biopsy

  • Empiric broad-spectrum antibiotics (Piperacillin-tazobactam 3.375 g IV q6h) while excluding infection — stop when BAL cultures negative and clinical picture suggests vasculitis

  • ANCA-associated vasculitis (GPA/MPA) — treatment:

    • Methylprednisolone 500–1000 mg IV daily × 3 days (pulse steroids — induction)

    • Then prednisone 1 mg/kg/day PO × 4 weeks → slow taper

    • Cyclophosphamide 15 mg/kg IV q2–3 weeks (severe organ-threatening disease) OR Rituximab