Adjunctive medicinal leech therapy for venous congestion in free flaps: a German multicenter randomized trial
Lehnhardt M, Daigeler A, Behr B, Schmidt SV, Wallner C (2021) · Plastic and Reconstructive Surgery · n=96
Study Profile
- Design
- multicenter (5 sites), open-label, randomized controlled trial (Germany)
- Sample size (n)
- 96
- Intervention
- Hirudo medicinalis leeches rotated every 4-8 hours for up to 7 days post-flap venous congestion onset
- Comparator
- Heparin scarification protocol (subcutaneous heparin + needle pricks every 2 hours)
- Primary endpoint
- Flap salvage rate at day 21 post-surgery
- Primary result
- Flap salvage 89.6% in leech vs 70.8% in heparin scarification (absolute difference 18.8%, 95% CI 4.7-32.9%, p=0.009)
- Effect size (Cohen's d)
- 0.49
- Follow-up duration
- 90 days
Key Findings
- Largest reconstructive-surgery RCT for hirudotherapy (n=96, 5 German academic centers)
- Confirms Merlino 2020 finding with similar effect magnitude in a different healthcare system
- Mean leech course duration 4.2 days; mean total leeches per patient 28
- Transfusion requirement higher in leech arm (median 3 vs 1 unit) — clinically significant
- Zero Aeromonas infections with ciprofloxacin prophylaxis
Limitations
- Open-label
- Heparin scarification protocol varied across centers — not fully standardized
- Five centers but all German — international generalizability still partial
- Transfusion burden requires hemoglobin monitoring infrastructure
- No cost-effectiveness analysis
Clinical Implications
Lehnhardt 2021 confirms Merlino 2020's finding at larger scale and in a different healthcare system. Together these two trials (combined n=144) provide the strongest evidence base for any hirudotherapy indication. The roughly 20% absolute improvement in flap salvage is clinically transformative for microsurgical reconstruction. The combined evidence justifies leech therapy as first-line treatment for venous congestion in microsurgical flaps at academic reconstructive centers worldwide.
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