What is hydrodissection?

What is Hydrodissection?

Hydrodissection is a procedural technique that involves injecting fluid under pressure into tissue planes to create physical separation between anatomical structures, facilitating safer dissection and protecting vital structures during interventional procedures. 1

Mechanism and Purpose

Hydrodissection works by injecting isolation fluid (typically saline, sterile water, or glucose solutions) between tissue layers to:

• Create a safe separation zone between the treatment area and adjacent vital structures such as nerves, blood vessels, and organs 1
• Establish and display the correct anatomical plane between adherent or difficult-to-separate tissues 2
• Provide a protective barrier during thermal ablation procedures to prevent collateral thermal injury 1

Clinical Applications

Thermal Ablation Procedures

In thyroid nodule ablation, hydrodissection is a standard recommended technique to protect the recurrent laryngeal nerve, trachea, esophagus, and major neck vessels from thermal injury 1:

• For microwave ablation (MWA): 0.9% sodium chloride injection is typically used 1
• For radiofrequency ablation (RFA): sterile distilled water or 5% glucose injection is preferred 1
• Injection is performed using PTC needles or syringes 1

Hydrodissection minimizes nerve damage and is specifically recommended to reduce the risk of permanent vocal cord paralysis (0.04%-0.17% incidence) during thyroid thermal ablation 1

Hepatobiliary Ablation

In liver tumor ablation, hydrodissection enables treatment of lesions near critical structures:

• Allows safe ablation of tumors adjacent to bile ducts, stomach, bowel, gallbladder, or diaphragm 1
• Techniques have been described to improve technical success rates for challenging anatomical locations 1

Percutaneous Drainage

Hydrodissection improves safety during percutaneous catheter drainage of abdominal collections by creating safe access windows 1

Surgical Applications

In laparoscopic and open surgery:

• Reduces bleeding, tissue damage, and operative time during adhesiolysis and dissection of adherent tissues 3, 4, 2
• Creates a 1-1.5 cm edematous separation zone that facilitates both prograde and retrograde dissection 3

Technical Considerations

Fluid Selection

The choice of hydrodissection fluid affects heat transfer dynamics during thermal procedures 5:

• Liquid solutions (saline, D5W) dissipate heat primarily through convection 5
• Gel materials (poloxamer 407) dissipate heat through conduction and may provide more stable tissue separation without peritoneal migration 5

Injection Technique

• Fluid is injected under pressure into the desired dissection plane 4, 2
• May be combined with local anesthetic (lidocaine with epinephrine) to provide hemostasis and analgesia 4
• Real-time ultrasound or CT guidance ensures accurate fluid placement 1

Safety Profile

Hydrodissection is considered a safe technique with minimal complications when performed correctly:

• Reduces risk of thermal injury to adjacent structures during ablation 1
• Decreases bleeding and tissue damage during surgical dissection 3, 4
• Very low risk of local anesthetic toxicity when using dilute anesthetic solutions 6

Common Pitfall

The primary limitation is fluid migration, particularly with liquid solutions that can disperse into the peritoneum, reducing protective efficacy 5. Gel-based materials may provide more stable barriers but alter heat dissipation mechanics 5.