Does a Peripherally Inserted Central Catheter (PICC) line require flushing with Heparin (unfractionated heparin)?

PICC Line Flushing: Heparin is NOT Required for Most Situations

For PICC lines in frequent use, sterile 0.9% normal saline alone is sufficient and should be the standard flushing solution—heparin offers no proven benefit and introduces unnecessary risks. 1

When Saline Alone is Adequate

• Daily or frequent use: PICCs accessed regularly for medication administration, parenteral nutrition, or other therapies require only normal saline flushes 1, 2
• Valved/closed-ended catheters: These devices should be flushed with saline only, following manufacturer instructions—never heparin 1, 2
• Evidence quality: Three separate meta-analyses and multiple Cochrane reviews demonstrate no convincing difference in catheter patency between heparin and saline flushing 3, 2, 4
• Clinical trial data: A prospective randomized study of 362 patients showed valved PICCs flushed with saline had significantly fewer complications (12 events) compared to clamped PICCs flushed with heparin (26 events, p=0.02) 5

When Heparin May Be Considered

For intermittently accessed PICCs that remain unused for prolonged periods, heparin flushing can be used but is not mandatory:

• Concentration: 5-10 U/mL heparinized saline 1, 2
• Frequency: 1-2 times weekly for intermittently accessed lines 1, 2
• Catheter size considerations: Small caliber devices (≤5 Fr) may be flushed weekly; larger caliber (≥6 Fr) every 3-4 weeks if manufacturer recommends heparin 1
• Evidence strength: This recommendation carries only Grade C evidence with conditional support 1

Critical Safety Concerns with Heparin

Heparin introduces multiple risks without proven benefit:

• Biofilm promotion: Heparin facilitates intraluminal biofilm formation, potentially increasing catheter-related bloodstream infection risk 3, 2
• Lipid incompatibility: Never use heparin immediately before or after lipid-containing parenteral nutrition—this causes lipid precipitation and emboli risk. Always interpose a saline flush 3, 2
• Bleeding complications: Risk of hemorrhage, heparin-induced thrombocytopenia (HIT), and thrombosis syndrome 6, 4
• Pediatric concerns: In premature newborns, heparin increases intraventricular hemorrhage risk 3

Proper Flushing Technique

The technique matters more than the solution:

• Always flush with saline FIRST before any heparin lock—this is more important than the heparin itself 3
• Syringe size: Use ≥10 mL syringes to avoid excessive pressure that damages the catheter 1, 3
• Push-pause technique: Employ turbulent flushing for optimal catheter clearance 3

Special Population: Neonates

For PICC occlusion prevention in newborns, the evidence is conflicting:

• Heparin (1 U/mL) reduces PICC occlusion frequency in neonates 1
• However, potential risks (intraventricular hemorrhage, bleeding) have not been adequately studied 1
• Current recommendation: Routine heparin use in neonatal PICCs cannot be recommended due to undefined safety profile (Grade: recommendation for research) 1

Managing Occluded PICCs

If occlusion occurs despite proper flushing:

• First-line treatment: Recombinant tissue plasminogen activator (tPA) or urokinase 1
• Evidence: Urokinase (5000 U/mL) restores patency in 54% of occluded catheters versus 30% with placebo (Level 1+ evidence) 1
• Technique: Always use ≥10 mL syringe to avoid catheter damage during clearance attempts 1

Bottom Line Algorithm

1. PICC in daily/frequent use → Normal saline flush only
2. Valved/closed-ended PICC → Normal saline only (manufacturer requirement)
3. PICC accessed <1-2 times weekly → Consider 5-10 U/mL heparin 1-2x/week OR continue saline (both acceptable)
4. Before/after lipid infusions → Saline only, never heparin
5. Neonatal PICC → Saline preferred due to safety concerns
6. Occluded PICC → tPA or urokinase, not prophylactic heparin

The evidence strongly supports abandoning routine heparin flushing for most PICC lines, reserving it only for specific intermittent-access situations where even then, saline remains a reasonable alternative. 1, 2, 4