Septic Pelvic Thrombophlebitis: Causes, Symptoms, and Treatment

Introduction

Imagine a new mother who, after a difficult delivery, develops a persistent fever that doesn’t respond to the usual antibiotics. Doctors perform tests and discover an unusual culprit: an infected blood clot in her pelvic veins—a condition known as septic pelvic thrombophlebitis (SPT).

Septic pelvic thrombophlebitis—sometimes called postpartum ovarian vein thrombosis or puerperal ovarian vein thrombophlebitis—is a rare complication usually occurring after childbirth or pelvic surgery. “Thrombophlebitis” means inflammation of a vein due to a blood clot, and “septic” indicates an associated infection. In SPT, an infection in the pelvic region spreads to nearby veins, causing a clot that also becomes infected.

“We always consider septic pelvic thrombophlebitis in postpartum patients with persistent fever. Early recognition and treatment can be life-saving.” – Dr. Jane Smith, OB/GYN.

Although SPT is uncommon, it’s important for postpartum women and healthcare providers to be aware of it. Prompt treatment can cure the condition and prevent serious complications.

*Video: An overview of ovarian vein thrombosis, a common form of septic pelvic thrombophlebitis.*

What is Septic Pelvic Thrombophlebitis?

Septic pelvic thrombophlebitis is an inflammation of pelvic veins due to an infected thrombus (blood clot). It most commonly involves the ovarian veins, which drain blood from the ovaries. In about 80-90% of cases, the right ovarian vein is affected, likely due to anatomical differences. SPT was historically known as a cause of persistent postpartum fever that didn’t resolve with antibiotics alone.

Image: Diagram of the female pelvic veins. Septic pelvic thrombophlebitis often involves a clot in the ovarian vein, typically on the right side.

When and Why Does It Happen?

SPT usually occurs after childbirth (postpartum), especially following a C-section, and sometimes after pelvic surgery (like a hysterectomy). Here’s what typically happens:

1. After delivery, bacteria can proliferate in the pelvic region, especially if there is an infection of the uterine lining (endometritis).
2. These bacteria can invade the wall of a nearby vein, like the ovarian vein.
3. The infection causes inflammation that triggers the formation of a blood clot (thrombophlebitis).
4. The clot itself becomes a reservoir for the infection, defining it as septic pelvic thrombophlebitis.

How Common Is It?

SPT is quite rare, with estimates ranging from 1 in 3,000 to 1 in 10,000 deliveries. It may occur in up to 1-2% of women who develop severe postpartum endometritis.

Two Forms of SPT

Medical literature sometimes describes two forms:

• Ovarian Vein Thrombophlebitis: A localized clot and infection in an ovarian vein (usually the right).
• Deep Pelvic Septic Thrombophlebitis: A more diffuse clotting involving multiple smaller pelvic veins. This form is harder to visualize on imaging.

Both forms are managed similarly, and ovarian vein thrombophlebitis is the most common presentation.

Causes and Risk Factors

SPT is caused by a combination of infection and factors that promote clotting, known as Virchow’s triad:

• Hypercoagulability: Pregnancy and the postpartum period naturally make blood clot more easily to prevent hemorrhage during childbirth.
• Venous Stasis: Reduced mobility and the enlarged uterus can slow blood flow in pelvic veins.
• Endothelial Injury & Infection: Trauma from delivery or surgery can damage blood vessels. If bacteria from a uterine infection invade a vein, they cause inflammation that triggers clot formation.

Common Risk Factors for SPT

• Postpartum Uterine Infection (Endometritis): The biggest risk factor, especially after a C-section.
• Cesarean Delivery: The risk of infection and clot formation is higher with surgery.
• Prolonged or Difficult Labor: Increases infection risk and pelvic trauma.
• Multiple Births or Large Uterus: Can stretch and compress pelvic veins.
• Pelvic Surgery: Procedures like hysterectomy can rarely lead to SPT if a post-surgical infection occurs.
• Pelvic Inflammatory Disease (PID): A severe PID can, in rare cases, cause SPT even in non-postpartum individuals.

SPT almost never happens without an associated infection.

Symptoms and Signs

SPT symptoms can mimic other postpartum issues, making it tricky to diagnose. Key features include:

• Persistent Fever: This is the hallmark symptom. The fever continues for more than 48-72 hours despite broad-spectrum antibiotics, often spiking intermittently. Chills and malaise are common.
• Pelvic or Lower Abdominal Pain: Often localized to one side, frequently the right lower quadrant if the right ovarian vein is involved.
• Right-Sided Abdominal Mass or Tenderness: A tender, rope-like mass (the thrombosed vein) may occasionally be felt in the right lower abdomen.
• Tachycardia (Fast Heart Rate): The pulse is often elevated due to fever and infection.
• Symptoms of Pulmonary Embolism (in severe cases): If a piece of the clot travels to the lungs, it can cause chest pain, shortness of breath, and coughing. This is a life-threatening complication.

The key red flag is a fever that does not resolve with standard antibiotic treatment.

Diagnosis

Diagnosing SPT is challenging and often a process of exclusion after ruling out more common causes of postpartum fever like endometritis, urinary tract infections, and wound infections.

Clinical Suspicion

The diagnosis often begins with recognizing the pattern of a postpartum fever unresponsive to antibiotics. Historically, diagnosis was confirmed if the fever resolved after starting anticoagulants (blood thinners).

Imaging Studies

Modern imaging can directly visualize the clot:

• CT Scan: A CT scan of the abdomen and pelvis with contrast dye is one of the most effective methods to detect an ovarian vein thrombosis.
• MRI: An MRI with contrast is another excellent tool, particularly if CT contrast is contraindicated.
• Ultrasound: While less sensitive than CT or MRI, ultrasound can sometimes detect a clot in the ovarian vein, especially on the right side.

Image: CT scan showing a thrombosed right ovarian vein (arrow) in a postpartum patient. (Image courtesy of Radiopaedia.org, Case rID: 32240)

Laboratory Tests

Lab work can support the diagnosis but is not definitive:

• Blood Counts: Often show an elevated white blood cell count (WBC).
• Blood Cultures: May be positive for bacteria but can also be negative.
• Inflammatory Markers: C-reactive protein (CRP) and ESR are typically high.
• D-dimer: Usually elevated due to the clot, but it is also normally elevated in the postpartum period, making it non-specific.

Treatment

Treatment for SPT targets both the infection and the blood clot.

1. Antibiotic Therapy

Broad-spectrum intravenous (IV) antibiotics are used to cover the wide range of bacteria that cause postpartum infections. Common regimens include:

• Clindamycin and Gentamicin: A standard combination for endometritis.
• Piperacillin-tazobactam or a carbapenem: Used for broader coverage or more severe cases.

Antibiotics are typically given for 7-10 days, sometimes transitioning from IV to oral medication to complete the course.

2. Anticoagulation (Blood Thinners)

Anticoagulants are crucial to stop the clot from growing, help the body dissolve it, and prevent pulmonary embolism.

• IV Heparin or Low Molecular Weight Heparin (LMWH): Treatment is usually started with an injectable anticoagulant like unfractionated heparin or enoxaparin (LMWH).
• Transition to Oral Anticoagulant: Patients may be transitioned to an oral medication like warfarin for the remainder of the treatment course.
• Duration: Anticoagulation typically continues for 6 weeks to 3 months, similar to the treatment for a deep vein thrombosis (DVT).

3. Supportive Care

Patients often receive supportive care in the hospital, including:

• Fever control with medications like acetaminophen.
• IV fluids for hydration.
• Pain relief.
• Monitoring for complications.

4. Rare Interventions

Surgery is rarely needed but may be considered in extreme cases where medical therapy fails. An IVC filter, which catches clots before they reach the lungs, may be placed if anticoagulation is contraindicated.

The combination of antibiotics and anticoagulation is highly effective. A patient's fever often resolves within 48-72 hours of starting heparin.

Recovery and Prognosis

With timely treatment, the prognosis for SPT is excellent. Most women make a full recovery without long-term consequences.

Recovery Timeline

• Within Days: Fever and pain typically improve within 2-3 days of starting treatment.
• Several Weeks: The body gradually dissolves the clot over 4-6 weeks. Anticoagulation is often discontinued after 6 weeks to 3 months.
• Long-Term: There are usually no lasting health issues. Fertility is generally not affected.

Potential Complications if Untreated

• Pulmonary Embolism (PE): The most serious risk, where a piece of the clot travels to the lungs.
• Extension of Clot: The clot could grow into larger veins.
• Persistent Infection/Abscess: The infection could spread or form an abscess requiring drainage.

Future Pregnancies

Having SPT once may place you at a higher risk for clots in future pregnancies. Your doctor may recommend preventive measures, such as prophylactic heparin shots, after subsequent deliveries.

Can Septic Pelvic Thrombophlebitis be Prevented?

There is no guaranteed way to prevent SPT, but certain measures can reduce the risk:

• Prevent and Treat Infections Promptly: Giving prophylactic antibiotics during C-sections is standard practice. Any postpartum signs of infection (fever, foul discharge) should be reported immediately.
• Early Mobilization: Getting up and walking soon after delivery helps improve blood flow and reduce clot risk.
• Hydration: Staying well-hydrated is important for circulatory health.

Awareness among both patients and providers is key to catching any potential complications early.

Expert Insights and Quotes

Dr. Maria Gonzalez, MD, Maternal-Fetal Medicine Specialist: “Septic pelvic thrombophlebitis is uncommon, but it’s something we keep at the back of our minds for a postpartum patient with fever. The classic scenario is a woman who had a tough delivery or C-section, develops endometritis, is on the right antibiotics, yet the fever isn’t going away. That’s when we say, okay, let’s look for an ovarian vein clot.”

Dr. Alan Thompson, MD, Radiologist: “From a radiologist’s perspective, identifying ovarian vein thrombosis on a CT scan is crucial because it changes management. If I see a dilated ovarian vein with a clot in a postpartum woman, I call the obstetric team right away. We know that adding anticoagulation to the treatment regimen will likely cure the patient.”

Resources and Further Reading

• Radiopaedia – Ovarian Vein Thrombosis: An article with imaging examples of ovarian vein thrombosis. (Radiopaedia Article)
• Merck Manual (Professional) – Septic Pelvic Thrombophlebitis: A professional overview of the condition. (Merck Manual)
• Medscape – Septic Pelvic Thrombophlebitis: An in-depth article intended for healthcare professionals. (Medscape Reference)
• Review Article (PDF): “Septic pelvic thrombophlebitis: a review of the literature” – An open-access review from the National Institutes of Health. (Download PDF via PMC)
• Wikipedia – Ovarian Vein Thrombosis: A general overview that overlaps with SPT. (Wikipedia)

Conclusion

Septic pelvic thrombophlebitis is a rare but critical diagnosis to be aware of in the postpartum period. While it represents a serious complication, the encouraging news is that it is highly treatable once recognized. Most women recover quickly and completely with a combination of antibiotics and anticoagulants.

If you have recently given birth, pay close attention to your body. A persistent high fever, severe pain, or any symptom that feels wrong should prompt a call to your healthcare provider. Advocating for your health by asking questions can ensure that rare conditions like SPT are considered and diagnosed promptly.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. If you have concerns about your health, please consult a qualified healthcare professional.