What is Septic Thrombophlebitis?
Septic or suppurative thrombophlebitis (STP) is a condition where a clot forms in a blood vessel due to an infection caused by bacteria or fungi. This infection can start due to an intravenous catheter (a tube inserted into the vein to deliver medicine), skin damage, or an infection spreading from nearby body structures.
This condition can happen in both the surface and deeper vessels of your body, but it most commonly affects veins, including those in your arms and legs, pelvis, chest, neck, and brain. Depending on the infected vein’s location and severity, symptoms can range from a minor infection in the surface veins to a severe, body-wide infection.
When STP occurs, it can lead to further problems related to the spreading of bacteria through the bloodstream, such as inflammation of the heart, arthritis caused by infection, or even an eye condition known as septic uveitis.
It’s critical to get treatment if you have STP because if it isn’t treated, it can lead to serious health issues and potentially even death. The level of these risks largely depends on where the clot is located.
What Causes Septic Thrombophlebitis?
Phlebitis, a condition where your veins become inflamed, can happen without an infection being present. This can be caused by irritation from a medical procedure involving a catheter, a thin tube used to deliver or remove fluids to or from the body. However, sometimes the inflammation is linked to an infection.
Septic thrombophlebitis, a serious infection and inflammation of the veins, can also occur on its own but often it’s caused by a break in the skin, such as from a blood test or an injection. Medical devices like intravenous catheters (like a PICC line which is a long catheter inserted through a vein in the arm) can cause septic thrombophlebitis in both veins close to the skin or deeper veins like the superior vena cava, which is a large vein that carries deoxygenated blood from the upper half of the body to the heart.
There are also certain medical conditions that often result from an infection spreading from nearby tissues. For instance, STP of the veins in the pelvis, often results from infections that start in the lower abdomen or after childbirth or abortion procedures. Another example is Lemierre syndrome, an infection of the jugular vein in the neck, usually caused by a throat infection but can also be due to dental infections. Thrombophlebitis of a vein called the Dural sinus (in the brain), can be due to infections of the ear, nose, or throat, such as mastoiditis (infection of a bone in the skull), otitis media (middle ear infection), or even meningitis (an infection around the brain and spinal cord).
Risk Factors and Frequency for Septic Thrombophlebitis
People at the very beginning and end of life, such as babies and the elderly, are most susceptible to STP, which is a type of infection often related to blood clots. This vulnerability is because babies have not fully developed their immune system, and the elderly may have a weakened immune system or other health conditions. People with cancer who have a heightened risk for blood clots and are highly immunocompromised are also likely to develop STP. Other groups with a higher risk include burn victims, individuals on long-term steroid treatment, and intravenous drug users.
Estimates suggest that STP occurs in about 0.5 bloodstream infections per 1000 days of a peripherally inserted intravenous device being used. When a type of catheter known as a non-tunneled, non-medicated, central venous catheter is used, the rate increases to 2.7 per 1000 device days. Recent findings show that around 4.2% of burn patients experience STP.
STP is less common when it occurs deep within the body and not associated with a catheter. For instance, pelvic STP, which mainly affects women capable of childbearing who are under 20 years old, occurs at a range of 1 in 500 to 1 in 2000 cases for C-sections, and in 1 in 9000 cases for vaginal births. Being of African-American descent or having multiple pregnancies are also risk factors.
A condition known as pylephlebitis, which is STP in a major vein in the abdomen, has a mortality rate of up to 25% even with antibiotic treatment. It is reported to occur in about 2.7 individuals per 100,000 per year.
Lemierre syndrome, a rare condition often found in healthy young adults, has an incidence of 14.4 cases per million each year in patients aged 15-24. The mortality rate from a study spanning three years was 9%.
Before the discovery of antibiotics, STP used to be the main cause of a type of brain blood clot and was almost always fatal. However, it is now much rarer. Despite this, about 30% of the cases involving the cavernous sinus and 78% involving the superior sagittal sinus result in death. Less than half of the patients fully recover. This condition as well is more common in children than adults.
Signs and Symptoms of Septic Thrombophlebitis
Septic thrombophlebitis (STP) is a condition that can lead to a variety of symptoms, ranging from mild swelling and pain around a superficial vein to severe symptoms like shock due to sepsis. The type and severity of symptoms largely depend on how long the infection has been present and where it is located.
Most of the time, STP affects veins closer to the surface of the skin. In this case, the person affected may experience a high fever above 100.4 F, redness, and discomfort along the infected vein, and pus at the site where a catheter was previously inserted. An affected limb may also swell, and pus drainage from the vein could occur.
In some cases, a patient might experience shortness of breath, chest pain, and oxygen shortage due to septic clots in the lungs. While not so common, this can occur, especially when there’s an outside source of infection linked to a bloodstream infection and clots.
If STP affects the jugular vein, symptoms might include a high fever, localized pain in the throat or neck, difficulty swallowing, muscle stiffness in the jaw, swelling, tense skin around the jugular vein or neck muscles, and discomfort around the jawline. Associated symptoms may include ulcers or redness in the back of the mouth, along with conditions like post-septal cellulitis, sinusitis, or dental pain as a result of a dental infection.
- High fever
- Localized pain in the throat or neck
- Difficulty swallowing
- Muscle stiffness in the jaw
- Swelling over the jugular vein or neck muscles
- Ulcerations or redness in the back of the mouth
- Post-septal cellulitis, sinusitis, or dental pain from a dental infection
Pylephlebitis, another variant of STP, often presents with a high fever and abdominal pain. Symptoms like nausea, vomiting, and jaundice however are rare. Hypotension, rapid heart rate, and severe sepsis can also occur. Sepic emboli are additional complications that can travel to joints or bones, causing joint pain, body aches, or conditions such as septic arthritis or osteomyelitis.
Septic thrombophlebitis can also affect the pelvic veins in two ways. In case of an ovarian vein thrombophlebitis, symptoms might include fever and abdominal pain at the site of the affected vessel. The pain might also be felt in the groin area or the upper abdomen and be consistent. Conversely, deep pelvic STP is much more subtle. The person might appear healthy between fever episodes, and abdominal pain or tenderness might not be present. A consistent fever after childbirth that doesn’t respond to antibiotics can indicate this issue. This condition is often called “enigmatic fever” for this reason.
Testing for Septic Thrombophlebitis
If you have been given suitable antibiotics for an infection but still continue to have high fevers after 72 hours, your doctor might suspect a condition called septic thrombophlebitis. This is especially likely if you have a type of inserted tube called an endovascular catheter.
The best way to check for septic thrombophlebitis is by using a contrast-enhanced computed tomography (CT) scan. This kind of scan lets the doctor see if there are any blockages in your blood vessels that might be caused by a blood clot. It can also show any inflammation around your vessels. The doctor will make a diagnosis based on these scan results together with results from tests done on your blood or other samples from potentially infected areas. For example, they may test the tip of the catheter if it’s believed to be causing a clot. If they can, they’ll test tips from both peripheral (closer to the skin) and central (deeper in the body) sites to compare the results. The diagnosis is usually confirmed by combining these test results with the radiographic (scan) evidence.
If a CT scan isn’t available, a magnetic resonance imaging (MRI) test can also be used to check for most cases of septic thrombophlebitis. MRI combined with MR venography is the best way to check the brain’s vein system without needing to perform an invasive procedure.
In certain circumstances, an ultrasound might be useful, too. For instance, if there’s an abscess (a pocket of pus) close to an infected vessel, or if a clot is found during an infection, an ultrasound can reveal it. However, with some vessel systems, like those in the pelvic region or in the brain’s veins, ultrasound tests are not very helpful due to their inability to penetrate deeply enough to view these areas.
Your doctor may want to order some other laboratory tests in addition to the imaging tests. These might include tests to count the different types of cells in your blood, tests to examine substances in your blood related to organ function, tests for liver enzymes, tests for liver function, and tests to examine how fast your blood clots. If the veins in your brain are affected, the doctor might want to test your cerebrospinal fluid, which surrounds the brain and spinal cord.
Treatment Options for Septic Thrombophlebitis
The way doctors treat septic thrombophlebitis (STP), an infection-caused clot in a vein, depends on several factors. These can include where the infection came from, the bacteria involved, which body parts are affected, and the patient’s personal health condition. The main goals are to get rid of the infection source, which might be things like intravenous (IV) lines. They also use strong, broad-spectrum antibiotics given through an IV, and may consider using blood thinners, although there is some debate about when these should be used. Sometimes, a surgical team might need to look at the patient for possible surgery.
If there’s visible pus, the infected blood vessel might need to be removed. This is often possible if the disease is in the outer parts of the body, but can be more difficult if it’s in the central vessels near the heart.
Use of blood thinners in treating this condition is a topic of some debate. Some medical experts recommend using blood thinners to stop the clot from getting bigger, while others suggest using them only if the clot is growing. However, there are currently no clinical trials addressing this issue. Blood thinners are usually not used in patients with low platelet count (less than 50,000/microL) due to an increased risk of bleeding.
What else can Septic Thrombophlebitis be?
In patients with cancer, it can be tough to tell the difference between septic thrombophlebitis and the more common deep vein thrombosis. This is because cancer patients often have a higher chance of blood clot formation and can also have bacteria in their blood from other sources due to a weakened immune system. There currently isn’t a reliable method to differentiate a patient with an infection, who also has a blood clot due to a catheter, from a patient who has septic thrombophlebitis. However, a specific type of scan known as fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been found to be useful in diagnosing septic thrombophlebitis in cancer patients.
Additionally, cerebral venous thrombosis can often be mistaken for other conditions like pre septal cellulitis, orbital cellulitis, or ophthalmologic migraines. These conditions can cause symptoms such as eye movement problems, reduced vision, eye pain, and eye bulging.
What to expect with Septic Thrombophlebitis
The death rate from septic thrombophlebitis, an infection-related blood clot condition, has significantly decreased in the past century. This is largely due to the early use of antibiotics and advancements in diagnostic methods. Despite these improvements, some conditions, such as dural sinus thrombosis, a clot in a vein in the brain, can still lead to serious health issues and a high death rate.
Possible Complications When Diagnosed with Septic Thrombophlebitis
- Blood clots (Emboli)
- Whole-body infection (Sepsis)
- Blood clot in a vessel (Vessel thrombosis)
