Introduction

Did you know the first attempt to administer fluids or medications directly into the bloodstream dates back to the 16th century? The concept of administering medicines or fluids directly into the bloodstream has revolutionised how modern medicine works, making it more effective and faster. Anything directly injected into the vein is called “intravenous” and the instrument or device that is used is called a “cannula” or “catheter”. On the flip side, one known potential complication of this process is called “thrombophlebitis”. 

Thrombophlebitis is inflammation of the vein and formation of a thrombus/clot inside it. Thrombophlebitis is a known yet preventable complication of intravenous cannulation or catheter use. In this article, we will explore what is involved in intravenous cannulation and catheter use, what causes thrombophlebitis, and most importantly, how it can be prevented.

What is thrombophlebitis?

Thrombophlebitis is a condition where there is inflammation of the vein and formation of a clot (thrombus) inside the vein due to irritation. 

Thrombophlebitis= Thrombo (thrombus or a blood clot) + phlebitis (inflammation of a vein)

Types

There are primarily two types of thrombophlebitis: one that involves the superficial veins of the body and the other that involves the deep-seated veins in the body.

• Superficial thrombophlebitis
• Deep vein thrombosis (DVT)

Pathophysiology

What happens when you scrape your knee while playing? The first thing you see is blood in that area as the surface of the skin is broken. The body’s natural defence system sends its soldiers (white blood cells and platelets) to the area to stop the bleeding and fight off any foreign bodies that might have entered through the wound. The platelets form a clot in the area to stop the bleeding and close the wound to initiate healing. The body follows the same logic when there is an injury to a blood vessel inside the body. Whenever a catheter is used to administer any medication through the superficial veins, if there is an injury to the vein, there will be inflammation, and platelets will form a clot in that area to stop the bleeding. This results in clot or thrombus formation in that area.

Common signs and symptoms

Thrombophlebitis exhibits common signs and symptoms such as:

• Pain
• Redness
• Swelling
• Heat
• Bruising at the site

Diagnostic methods¹

Thrombophlebitis can be diagnosed using clinical examination, but scans can be used as an aid. Initially, a clinical assessment is the first step to diagnose thrombophlebitis. It uses detailed medical history and clinical assessment of the patient. This is routinely done for both superficial as well as deep vein-associated clots. Additionally, a Doppler ultrasound is used for patients with involvement of deeper veins that cannot be seen with the naked eye and therefore, has to be scanned to visualise the extent of the underlying inflammation.

IV cannulation and risk of thrombophlebitis

Now that we have understood what thrombophlebitis is, let us understand the role of intravenous (IV) cannulation and its association with the risk of thrombophlebitis. 

Mechanism of injury from IV catheter use

Irritation or injury can happen in the form of:

• Mechanical irritation: when the catheter rubs against the wall of the vein
• Chemical irritation: Some IV medications, like antibiotics or chemotherapy drugs, can irritate the lining of the vein
• Infection: if microorganisms get into the catheter or at the injection site, the vein becomes inflamed
• Clotting: as a protective measure, the body’s defence mechanism may form a clot around the catheter, assuming it’s a foreign body

Risk factors associated with cannulation

• Duration of cannula placement: prolonged use increases the chances of thrombophlebitis
• Site of insertion (lower limbs vs. upper limbs)²
• Type and size of catheter
• Patient-specific factors such as age and comorbidities
• Type of infused fluids or medications: chemotherapy drugs, potassium, and certain antibiotics like vancomycin can cause irritation

Who is most at risk?

Thrombophlebitis can happen to anyone, but certain factors increase your risk:

• Poor insertion technique: The risk of thrombophlebitis increases if the catheter is not properly inserted and causes an injury
• Comorbidities: underlying conditions like cancer, clotting disorders, or diabetes significantly increase the risk of complications such as thrombophlebitis
• Dehydration: Less fluid means veins are more vulnerable to damage and inflammation
• Smoking causes damage to the walls of the veins
• Obesity makes IV access more difficult, leading to improper insertion or multiple attempts
• Rushed procedures may also increase the chances of complications

What does it feel like?

If you’ve ever had an IV site that looked red, felt sore, or seemed unusually warm to the touch, it could have been a mild case of thrombophlebitis.

Common symptoms include:

• Redness along the vein
• Bruising 
• Pain or tenderness near the IV site
• Swelling
• Hardening or a “cord-like” feel under the skin
• Mild fever (if infection is present)

Complications of catheter-related thrombophlebitis

Catheter use can also lead to complications such as those mentioned below:

Local complications: 

1. An abscess is a localised, pus-filled infection caused by bacteria entering the body through the catheter site. It may be caused by prolonged catheter use, contamination by microorganisms or poor hygiene. The common symptoms are pain, swelling, redness, and fever
2. Cellulitis: a bacterial infection of the skin and underlying tissue

Systemic complications:

1. Deep vein thrombosis (DVT): clot formation in a deeper vein of the legs. DVTs can break loose and travel to the lungs, causing a pulmonary embolism, which is a medical emergency
2. Septic thrombophlebitis: If an infected clot travels in the bloodstream, it can spread infection throughout the body

Prevention strategies

Best practices

• Aseptic technique: taking adequate aseptic precautions while cannulation is important to prevent infections at the site of injection
• Appropriate catheter selection (material and size): Selecting the right size and type of catheter is a simple step to help prevent injuries and irritation
• Site rotation protocols: Regularly rotating or changing the site of injections helps in preventing injury to the walls of the blood vessels and ensures adequate absorption of the medication
• Studies show that proximal massage and palm fisting can reduce the risk of phlebitis considerably

Post-insertion care

• Regular monitoring and documentation
• Timely removal of unnecessary catheters
• Use of catheter securement devices

Training and protocols

The staff must be trained and periodically evaluated as an important step to prevent IV cannulation complications. In case any such complications arise, the staff should be retrained and re-evaluated before allowing them to perform any procedures.

Alternative approaches

• Use of midline catheters or peripherally inserted central catheter (PICC) when appropriate
• Ultrasound-guided insertion to minimise trauma^1,4

New frontiers in prevention

Medical technology is evolving. Some of the exciting developments to prevent cannulation complications are:

• Antimicrobial catheters: These catheters are coated with bacteria-fighting substances to reduce infection
• Vein visualisation devices: Many devices that use infrared to locate veins, reducing failed attempts, are available on the market 
• Hydrophilic catheters: They are specially designed, “water-loving” catheters that are coated with a hydrophilic substance that ensures smoother insertion and reduces friction

Management and treatment

Most of the thrombophlebitis is mild in nature and, if caught early, can be managed symptomatically. Management includes:

• Conservative treatment such as warm compress, elevation, and anti-inflammatory drugs such as NSAIDs
• Removal of the catheter or use of site rotation protocol 
• Antibiotics for suspected infection
• Anticoagulation if deeper involvement is suspected

FAQs

Are blood clots common with catheters?

Blood clots form as the body’s defence mechanism to close the site of injury. In the cases of cannulation or catheterisation, any break in the walls of the vein will form a small clot to close the wound. Therefore, it is not uncommon for a blood clot to form at the site of the IV catheter.

What is the best treatment for thrombophlebitis?

The good news is that superficial mild thrombophlebitis will usually resolve on its own. Symptomatic treatment includes warm compresses to the affected area, elevation of the affected limb and use of over-the-counter anti-inflammatory drugs such as NSAIDs.

Is thrombophlebitis an emergency?

Thrombophlebitis is not an emergency. But call the emergency number immediately if you experience chest pain, shortness of breath, cough blood, as it indicates a serious complication.

Summary

• Thrombophlebitis = blood clot + vein inflammation, often due to IV use
• Caused by irritation from the catheter, medication, or infection
• Most cases are mild but should be treated promptly
• Prevention includes proper insertion, site rotation, and patient awareness

For patients and caregivers

• Speak up: If your IV site starts hurting, burning, or swelling, tell a nurse right away
• Stay hydrated: Makes veins more resilient and easier to access
• Avoid touching or tugging the IV line: Prevents accidental damage or dislodgement

For healthcare providers

• Choose the right vein: Larger, straight veins are better. Avoid bending joints like the wrist or elbow if possible
• Use proper technique: Clean hands, sterilise the site, and use the smallest catheter size that will work
• Monitor and rotate sites: Replace IVs every 3-4 days, or sooner if signs of irritation develop
• Flush the line regularly: It will prevent clogs and keep the line clear
• Get retrained and reassessed in case of any errors while performing the procedure