Clinical Knowledge Support
Tier-based framework for clinicians considering hirudotherapy.
Boundary disclaimer
This is an educational protocol-retrieval and evidence-navigation tool. It does not diagnose, determine eligibility, recommend treatment, or replace clinician judgment, institutional policy, infectious disease consultation, or emergency care. Per FDA January 2026 guidance on Clinical Decision Support Software, this page is not intended as device software, is not patient-directed, and does not drive treatment selection. Clinicians remain solely responsible for clinical decisions.
This page is for clinicians and researchers. It provides a structured educational framework summarizing how ASH organizes evidence about hirudotherapy indications by regulatory tier and evidence depth. The framework is descriptive, not prescriptive.
Clinical decisions require individualized assessment, informed consent, institutional protocol approval, and consideration of patient comorbidities. This page does not substitute for any of those.
Decision framework
Identify the indication tier
ASH classifies every indication into one of three tiers based on regulatory and evidence status:
FDA-cleared (3 indication)
Use is within the FDA-cleared device pathway (K040187, June 2004 — venous congestion in microsurgical reconstruction). No off-label regulatory rationale is required when used within this cleared pathway; clinical indication, informed consent, infection-control plan, monitoring, and institutional protocol remain required.
Off-label with RCT support (10 indications)
At least one RCT or systematic review supports use. Requires off-label consent, individualized risk-benefit assessment, and institutional protocol approval.
Investigational (186+ indications)
Tier C content is catalogued for research and educational review. Clinical use outside established pathways requires formal institutional governance, documented rationale, informed consent, and where appropriate, research oversight (IRB). ASH does not recommend Tier C treatment.
Screen absolute contraindications
Apply across all tiers. Any single absolute contraindication is sufficient to defer treatment.
- Active anticoagulant therapy (warfarin INR >2.0, DOACs, heparin)
- Hemophilia or other bleeding disorder
- Severe anemia (Hb <10 g/dL)
- Active bacteremia or sepsis
- Known hypersensitivity to leech salivary proteins
- Pregnancy (relative \u2014 first/third trimester)
- Immunocompromised state with severe neutropenia
- Critical limb ischemia (ABI <0.4) for vascular indications
- Active deep vein thrombosis (acute phase <2 weeks) for vascular indications
See full contraindication list and modifications: Contraindications reference
Confirm appropriate setting
Hirudotherapy requires the right clinical setting based on indication tier:
- Tier A (microsurgery flap salvage): Hospital with microsurgery team, transfusion availability, IRB-approved protocol, 24-hour monitoring, antibiotic prophylaxis (typically ciprofloxacin + TMP-SMX).
- Tier B (off-label): Outpatient or short-stay possible if no vascular compromise. Requires informed consent for off-label use, monitoring protocols, and pre/post-treatment labs (Hb, coagulation panel if multi-session).
- Tier C (investigational): Specialist clinic with documented training. Patient discussion must explicitly cover evidence limits. Single-leech sessions for first exposure; escalate cautiously.
Informed consent essentials
Document patient understanding of:
- Regulatory status of the specific indication (Tier A/B/C)
- Expected bleeding (typically 6-24h post-detachment)
- Aeromonas infection risk (1-20% historically; mitigated by prophylaxis)
- Allergic reaction possibility (rare, anaphylaxis exceptional)
- Transfusion risk in multi-session protocols
- Patient-specific contraindications screened
- Alternative treatments considered and discussed
Template available: Consent forms library
Monitoring & follow-up
- Pre-treatment: CBC, coagulation panel (PT/INR, PTT), basic metabolic panel
- Intra-treatment: vital signs, application site assessment, leech behavior
- Post-detachment: bleeding duration, dressing changes, patient education
- 24-72h follow-up: Hb if multi-leech, application site (Aeromonas surveillance)
- Adverse event reporting to ASH adverse event atlas
Monitoring algorithms: Complication algorithms
Tier A quick reference (FDA-cleared)
The FDA-cleared indication is venous congestion in surgical flaps and digit/ear replantation. This is the highest-evidence use and follows established microsurgery protocols.
- Venous Congestion in Surgical Flaps \u2014 FDA-cleared application: medicinal leech therapy to relieve venous congestion in compromised tissue flaps awaiting vascular ingrowth.
- Microsurgical Replantation (Digit / Ear / Scalp) \u2014 FDA-cleared application: post-replantation venous decompression in digits, ears, scalp, and partial avulsion injuries.
- Breast Reconstruction Flap Salvage \u2014 FDA-cleared application: venous decompression of compromised DIEP, TRAM, and latissimus dorsi flaps in post-mastectomy reconstruction.
Tier B quick reference (off-label with RCTs)
Off-label uses with at least one RCT or systematic review. Requires individualized risk-benefit assessment and off-label consent.
Tier C considerations (investigational)
186+ conditions are catalogued as investigational. Use only when:
- Conventional treatment options have been tried or are contraindicated
- Patient understands the mechanistic-rationale-only evidence basis
- Setting is specialist clinic with documented training
- Initial session is single-leech to assess tolerability
- Outcome reporting contributes to the evidence base (consider registry enrollment)
Browse full Tier C list on the conditions atlas or the coverage map.
Related resources
Clinician FAQ
Common questions from microsurgeons, integrative medicine physicians, and nurses.
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