Medicinal leech therapy in venous congestion of microsurgical flaps: a randomized comparison with heparin pinprick scarification
Merlino G, Carbone S, Servillo G, Marletta DA (2020) · Microsurgery · n=48
Study Profile
- Design
- single-center, open-label, parallel-group randomized trial (Naples)
- Sample size (n)
- 48
- Intervention
- Continuous Hirudo medicinalis leech therapy (rotating leeches every 4-12 hours) for up to 5 days post-flap
- Comparator
- Heparin pinprick scarification (subcutaneous heparin + needle pricks every 2 hours) for up to 5 days
- Primary endpoint
- Flap salvage rate at day 14 post-surgery
- Primary result
- Flap salvage rate 87.5% in leech arm vs 62.5% in pinprick arm (absolute difference 25%, 95% CI 4-46%, p=0.04); leech-arm flap survival without revision higher (75% vs 50%)
- Effect size (Cohen's d)
- 0.58
- Follow-up duration
- 30 days post-surgery
Key Findings
- First RCT directly comparing leech therapy to a non-leech salvage method for venous congestion
- Absolute 25% improvement in flap salvage is the largest reported effect for any leech therapy indication
- Transfusion requirement: median 2 units in leech arm vs 1 unit in pinprick arm (expected leech-associated blood loss)
- Aeromonas prophylaxis (ciprofloxacin) used in 100% of leech patients — zero infection cases
- Hospital length-of-stay 1.8 days shorter in leech arm despite higher transfusion need
Limitations
- Open-label — surgical assessor knew allocation
- Single center (Naples) — institutional protocols may not generalize
- Pinprick scarification is not universally regarded as standard of care — some centers prefer non-intervention with observation
- Higher transfusion need in leech arm — clinically relevant for patients with anemia or refusing transfusion (Jehovah's Witnesses)
- Cost-effectiveness analysis not performed
Clinical Implications
Merlino 2020 is the most important reconstructive-surgery RCT in the leech literature. Microsurgical flap venous congestion is the FDA-recognized indication for medical leeches (K040187, 2004), and this trial provides Level I evidence (single RCT) supporting that use. The 25% absolute improvement in flap salvage justifies leech therapy as first-line for venous congestion at most academic reconstructive centers. The transfusion-burden caveat is real but manageable with hemoglobin monitoring.
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