In an adult with portal hypertension and acute bleeding from large gastric varices (GOV2 or IGV1) not suitable for band ligation, how should endoscopic injection of N‑butyl‑2‑cyanoacrylate (Histoacryl) be performed, including preparation, dosage, technique, and post‑procedure monitoring?

Endoscopic Histoacryl Injection for Gastric Varices (GOV2/IGV1)

For acute bleeding from large cardiofundal varices (GOV2 or IGV1), TIPS is the treatment of choice, but when TIPS is not technically feasible, endoscopic N-butyl-2-cyanoacrylate (Histoacryl) injection should be performed only in centers with expertise, as it is not FDA-approved in the United States. 1

Pre-Procedure Preparation

Initial Medical Management

• Start vasoactive drugs immediately: octreotide 50 µg IV bolus followed by 50 µg/hour continuous infusion for 3-5 days 2
• Administer prophylactic antibiotics: ceftriaxone 1 g IV every 24 hours for up to 7 days 2
• Use restrictive transfusion strategy targeting hemoglobin 7-9 g/dL to avoid increasing portal pressure 2
• Perform endoscopy within 12 hours once hemodynamically stabilized 2

Equipment Preparation

• Mix N-butyl-2-cyanoacrylate with Lipiodol in a 1:1 ratio 3, 4
• Alternative: Use undiluted cyanoacrylate followed by 0.7 mL distilled water flush to rinse the injection catheter 5
• Prepare standard injection catheter (avoid hand-made probes in modern practice) 6
• Have immediate access to equipment for needle withdrawal to prevent impaction 5

Injection Technique

Dosage and Administration

• Inject 0.5-1 mL per injection site directly into the varix (intravariceal injection) 5
• Use 1-3 injections per session until all gastric varices become hard 5
• Average total volume per session: 1.43-1.5 mL (range 0.6-5 mL) 4, 7
• Typical range: 1-9 ampoules of cyanoacrylate may be needed per session 6

Critical Technical Points

• Withdraw the needle immediately after injection to prevent impaction into the tissue adhesive—failure to do so can result in fatal bleeding 5
• Inject directly into the varix, not perivariceally 3, 5
• Continue injections until varices are obliterated and feel hard on palpation 5
• Flush injection catheter with distilled water immediately after each injection if using undiluted cyanoacrylate 5

Expected Outcomes

Hemostasis Rates

• Initial hemostasis: 94-98.6% within 1 week 3, 4, 6
• Definitive hemostasis: 93.3% 3
• Cyanoacrylate achieves 94% control of active bleeding versus 80% with band ligation 2

Rebleeding Rates

• Early rebleeding (within 24 hours): 10-14.4% 7, 6
• Overall rebleeding: 23.3-29.2% occurring from 3 days to 16 months after initial injection 3, 4
• Most rebleeding (76.2%) occurs within 1 year of initial injection 4
• Cyanoacrylate significantly reduces rebleeding compared to band ligation: 18-26% versus 48-86% 2

Post-Procedure Monitoring

Immediate Monitoring (First 24 Hours)

• Monitor for signs of rebleeding: hematemesis, melena, hemodynamic instability 7
• Very early rebleeding is a strong independent predictor of in-hospital mortality 7
• If rebleeding occurs, repeat cyanoacrylate injection achieves hemostasis in 76.2% of cases 4

Complications to Monitor

• Pulmonary embolism: occurs in approximately 1-2% of patients 4, 6
• Splenic infarction: rare, typically recovers without specific treatment 4
• Needle impaction: can lead to fatal bleeding if needle not withdrawn immediately 5
• Treatment failure-related mortality: 1.4-2.2% 3, 4

Follow-Up Endoscopy

• Perform endoscopic surveillance with retreatment as necessary 3
• Reinjection may be required in 16.7% of patients for recurrent bleeding 3
• Eradication of gastric varices achieved in 93.1% of patients (20% in 1 session, 4% in 2 sessions, 3% in 3-6 sessions) 5

Critical Pitfalls to Avoid

Technical Errors

• Never attempt band ligation on large GOV2/IGV1 varices—this creates dangerous ulcers over vessels leading to catastrophic rebleeding 1, 8, 2
• Band ligation only appropriate if both mucosal and contralateral walls can be suctioned into ligator 1, 8
• Do not delay needle withdrawal after injection—this is the most common cause of fatal complications 5

Patient Selection Errors

• Recognize that TIPS is superior to cyanoacrylate for preventing rebleeding in GOV2, though with higher encephalopathy rates 1
• Consider early TIPS within 72 hours for high-risk patients (achieves 100% rebleeding-free survival versus 28% with standard therapy) 2
• Reserve cyanoacrylate for centers with expertise—this is not a procedure for occasional use 1

Regulatory Considerations

• Cyanoacrylate is not FDA-approved for gastric varices in the United States and should only be used in centers with established expertise 1
• N-butyl-2-cyanoacrylate is the agent used in randomized trials; 2-octyl cyanoacrylate has longer polymerization time 1

Alternative Management

• If cyanoacrylate fails or is unavailable, TIPS should be performed urgently 1
• Balloon-occluded retrograde transvenous obliteration (BRTO) achieves >90% hemostasis rates when gastrorenal or gastrocaval shunt is patent 2
• Balloon tamponade with Linton-Nachlas tube serves as bridge to definitive therapy in massive bleeding 1