Catheter-Related Thrombosis

What catheter-related thrombosis is

A central venous catheter is a thin tube placed in a large vein in the arm, neck or chest, with its tip near the heart. It is used for chemotherapy, long courses of antibiotics, nutrition, dialysis and frequent blood tests. The catheter can damage the vein lining, slow blood flow and act as a surface for clots to form.

There are two main types of clot:

• Fibrin sheath or tip clot: a thin layer of clot around the catheter tip that may block the line but not the vein
• Catheter-related deep vein thrombosis: a clot that partly or fully blocks the vein the catheter runs through, such as the arm, axillary, subclavian or jugular veins. This is a form of deep vein thrombosis of the upper body

Upper body DVTs are much less common than leg DVTs, but central catheters are the leading cause of them.

Risk factors

• Cancer, especially with chemotherapy, and some cancer drugs
• PICC lines (inserted in the arm) carry a higher clot risk than lines placed in the chest
• Large catheters relative to the vein, and multiple lumens
• Catheter tip not positioned low in the superior vena cava near the heart
• Left-sided and repeated or difficult insertions
• Infection of the catheter
• Inherited or acquired clotting disorders (thrombophilia)
• Previous clots, reduced mobility and the estrogen-containing pill

Symptoms

Many catheter clots cause no symptoms and are found incidentally on scans. When symptoms occur, they include:

• swelling of the arm, hand, shoulder, neck or face on the catheter side
• pain, aching or a feeling of heaviness in the arm
• redness or bluish discoloration of the arm
• prominent veins across the chest wall or shoulder
• a catheter that cannot be flushed or will not draw blood back
• in severe central blockage, swelling of the face and both arms with headache and breathlessness

Diagnosis

• Doppler ultrasound of the arm and neck veins is the first test. It shows whether the vein can be compressed and whether blood is flowing
• CT venography or MRI for veins inside the chest, which ultrasound cannot see well
• Contrast venogram occasionally, especially if a procedure is planned
• Line study: contrast injected through the catheter to look for a fibrin sheath or tip clot when the line is blocked
• Blood tests: platelet count and kidney function before starting anticoagulation; blood cultures if infection is suspected

Treatment

Anticoagulation

Blood thinners stop the clot growing and allow the body to break it down. Options include:

• low-molecular-weight heparin injections, often preferred in people with cancer
• direct oral anticoagulants such as apixaban or rivaroxaban
• warfarin

Treatment is usually given for at least 3 months, and for as long as the catheter remains in place. Your doctor will choose the medicine and duration based on your bleeding risk, kidney function and other treatments.

The catheter

• If the catheter is still needed, working, correctly positioned and not infected, it can usually stay in while you take blood thinners
• It is removed if it is no longer needed, is not working, is infected, or is badly positioned. Anticoagulation is often started a few days before removal
• A blocked line due to a tip clot may be cleared with a clot-dissolving medicine (alteplase) instilled into the catheter

Other treatments

• Raising the arm and gentle exercises can reduce swelling
• Catheter-directed thrombolysis or other procedures are reserved for severe, limb-threatening clots or superior vena cava syndrome
• Infected clots (septic thrombophlebitis) need antibiotics and catheter removal

Complications

• Pulmonary embolism: less common than with leg DVT but possible
• Catheter infection and bloodstream infection
• Loss of the line, delaying treatment
• Post-thrombotic syndrome: long-term arm swelling and aching
• Superior vena cava syndrome: blockage of the main vein returning blood from the upper body

Prevention

• choosing the smallest catheter with the fewest lumens needed
• correct tip placement confirmed by imaging
• removing catheters as soon as they are no longer needed
• regular flushing according to protocols
• careful insertion technique, often with ultrasound guidance

Routine preventive blood thinners for all people with central lines are not generally recommended, but they may be used in selected high-risk people.

Frequently asked questions

What are the signs of a blood clot from a PICC line?

The main signs are swelling, pain, aching, warmth or a bluish color in the arm, shoulder, neck or face on the side of the PICC, and new visible veins on the chest. A line that stops flushing can also be a clue. Tell your care team the same day.

Does the catheter need to be removed if there is a clot?

Not always. If the catheter is still needed, works properly, is well positioned and is not infected, it can usually stay in while you take blood thinners. It is removed if it is no longer needed, blocked, infected or badly placed.

How long are blood thinners needed for a catheter-related clot?

Usually for at least 3 months, and for as long as the catheter remains in place, whichever is longer. People with active cancer may need longer treatment. Your doctor will review your bleeding risk regularly.

Can a catheter-related clot cause a pulmonary embolism?

Yes, though less often than clots in the legs. Sudden breathlessness, chest pain, a fast heart rate or coughing up blood in someone with a central line needs emergency care.