What is the appropriate management of a catheter occluded by a thrombus?

Management of Blood Clots in Catheters

For thrombotic catheter occlusion, immediately attempt forceful saline irrigation to dislodge the clot, then instill 2 mg alteplase (tissue plasminogen activator) in 2 mL into the occluded lumen with a 30-minute dwell time as first-line pharmacologic therapy. 1

Initial Bedside Maneuvers (Before Pharmacologic Treatment)

• Perform forceful manual irrigation with normal saline as the absolute first intervention—this alone may resolve many occlusions without requiring thrombolytics 1
• Reposition the patient to Trendelenburg position to help restore patency 2
• Attempt catheter manipulation and patient repositioning to rule out mechanical causes (kinked catheter, malpositioned tip, catheter compressed between clavicle and first rib) 2, 1
• If applicable for dialysis catheters, temporarily reverse the arterial and venous lumens to complete the treatment session 2

Critical Pitfall: Do not skip these bedside maneuvers before using alteplase—forceful saline irrigation alone resolves many occlusions and avoids unnecessary medication use and cost 1

Thrombolytic Therapy: Alteplase Protocol

Dosing Algorithm

Adults and children ≥30 kg:

• Instill 2 mg alteplase in 2 mL into each occluded catheter lumen 2, 1, 3
• Initial dwell time: 30 minutes 1, 3
• Assess for restoration of function (ability to withdraw ≥3 mL blood and infuse 5 mL saline) 3

If unsuccessful at 30 minutes:

• Extend dwell time to 120 minutes before reassessing 1, 3
• If patency still not restored after maximum dwell time, administer a second identical 2 mg dose with the same dwell time protocol 2, 1, 3

Children <30 kg:

• Dose is 110% of estimated internal lumen volume, not to exceed 2 mg in 2 mL 3

Expected Success Rates

Occlusions present <14 days:

• 68% success after one dose 1, 3
• 88% success after two doses 1, 3

Occlusions present >14 days:

• 57% success after one dose 1, 3
• 72% success after two doses 1, 3

Overall efficacy: 85-88% catheter function restoration after up to two doses 3

Why Alteplase is the Preferred Agent

Alteplase (tissue plasminogen activator) is the agent of choice over urokinase or streptokinase based on multiple factors 2, 1:

• Superior in vitro clot lysis with complete thrombus resolution in 69% (vs 43% with urokinase, 53% with streptokinase) 1
• Higher fibrin specificity minimizes systemic effects 2, 1
• Low immunogenicity compared to streptokinase 1
• Extensive safety data: 0% incidence of intracranial hemorrhage in 1,064 adult patients and 310 pediatric patients 2, 1, 3
• No major bleeding or thromboembolic events in large trials 2, 1, 3

Alternative Thrombolytic Agents (If Alteplase Unavailable)

• Urokinase 5,000 IU/mL is considered equivalent to alteplase per KDOQI guidelines 1
• Urokinase should dwell within the catheter for 1 hour before aspiration 2
• Urokinase plus citrate 4% per lumen is also recommended by KDOQI 1

Important Note: Thrombolytic agents are NOT recommended as first-line therapy for catheter-related deep vein thrombosis due to greater risk of complications—anticoagulation is preferred for that indication 2

Determining the Cause of Occlusion

New Catheters (<2 weeks old)

Inadequate blood flow is usually due to 2:

• Mechanical obstruction (kinked catheter)
• Improper tip location affected by patient position
• Catheter integrity problems

If Trendelenburg position is needed to achieve adequate flow, the catheter is improperly placed and requires repositioning or exchange 2

Established Catheters (≥2 weeks old)

Progressive occlusion is typically from 2:

1. Intraluminal thrombus—within catheter lumen, partial or complete
2. Catheter tip thrombus—acts like a "ball valve" in catheters with side holes
3. Fibrin sheath (fibrin sleeve)—fibrin adheres to external catheter surface, trapping thrombus between sheath and tip
4. Fibrin tail (fibrin flap)—fibrin adheres to catheter end with ball valve effect

Diagnostic Imaging When Needed

• Obtain a "linogram" (contrast study) if bedside maneuvers and thrombolytics fail 2
• This identifies kinked catheter, aberrant tip position, or fibrin sheath with contrast reflux 2
• If clinical suspicion remains high despite negative ultrasound, venography is the diagnostic method of choice 2

Prevention of Recurrent Occlusion

• Consider prophylactic weekly alteplase locking solution to reduce future catheter dysfunction 1
• Low-concentration citrate (<5%) locking solutions may prevent both infection and thrombotic dysfunction 1
• Standard practice includes locking catheters with anticoagulant when not in use, though heparin has NOT been shown to reduce intracatheter thrombus formation in Cochrane review 2
• Adhere to standard procedures for accessing central venous catheters to reduce occlusion incidence 2

Evidence on heparin vs saline flushing: No differences in thrombosis rates were found when comparing heparin to 0.9% normal saline flushing 2

When to Refer for Advanced Intervention

Refer to interventional radiology or surgery if:

• Alteplase fails after two doses with maximum dwell times 2
• Imaging confirms mechanical obstruction (catheter malposition, pinch-off syndrome, catheter fracture) 2
• Suspected catheter or guidewire embolus requiring retrieval 2
• Fibrin sheath requires stripping or catheter exchange over guidewire 2

Critical Distinction: Urinary Catheters

Never use fibrinolytic drugs (urokinase, alteplase) for bladder clots in Foley catheters—these agents are indicated ONLY for catheter lumen thrombosis in central venous catheters and carry greater risk of thrombosis when used inappropriately in the urinary system 4, 5. For Foley catheter clots, use forceful manual irrigation with normal saline and continuous bladder irrigation 4, 5.

Risk Factors for Catheter Thrombosis

Factors associated with increased thrombotic occlusion include 6:

• Longer duration with catheter in place (OR 1.02 per day)
• Presence of diabetes mellitus (OR 1.56)
• Exit site infection (OR 1.57)

Note: Antiplatelet agents and prophylactic anticoagulation (warfarin 1 mg, aspirin) have NOT been successful in preventing catheter thrombosis and are not recommended due to bleeding risk without efficacy 2