Septic Pelvic Thrombophlebitis
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Direct answer
Septic pelvic thrombophlebitis is infective thrombosis of the pelvic veins, most often the ovarian vein, following caesarean section or postpartum infection. It classically presents as spiking fever persisting beyond 48 to 72 hours despite broad-spectrum antibiotics, often with lower abdominal or flank pain. Contrast-enhanced CT or MRI shows the thrombosed vein. Treatment combines antibiotics with therapeutic anticoagulation, with drainage of any associated abscess.
What you must remember
- Site: pelvic veins, most commonly the ovarian vein, with the right side described as more frequent in many series; uterine and internal iliac branches can also be involved.
- Setting: postpartum or post-caesarean endometritis, pelvic infection and septic abortion.
- Presentation: persistent fever despite antibiotics, with lower abdominal or flank pain and an unremarkable wound.
- Diagnosis: contrast-enhanced CT or MRI shows a non-enhancing thrombosed vein and looks for coexisting abscess.
- Treatment: broad-spectrum antibiotics plus therapeutic heparin or low-molecular-weight heparin, continued as per guidance.
- Abscess: percutaneous or surgical drainage when a collection is present.
- Complication: pulmonary embolism from pelvic thrombus, so breathlessness, chest pain or hypoxia need urgent review.
Fever that will not settle after caesarean
A woman develops fever on day 5 after caesarean section and has not improved after 72 hours of broad-spectrum antibiotics. The wound and uterus may look unremarkable, so the cause must be sought deeper in the pelvis. The steps below follow a logical search for the source, moving from clinical review to imaging and then to treatment.
- Re-evaluate the source: examine the wound, uterus and pelvis, and send blood and high vaginal cultures.
- Image the pelvis: contrast CT or MRI looks for a pelvic abscess and a thrombosed ovarian vein.
- Confirm the thrombus: the vein appears as a non-enhancing filling defect or tubular structure on contrast study.
- Start anticoagulation: therapeutic heparin or low-molecular-weight heparin is added to antibiotics unless contraindicated.
- Drain any collection: percutaneous or surgical drainage of an associated abscess is undertaken.
- Plan follow-up: monitor for pulmonary embolism and agree the duration of anticoagulation with a physician.
Where the exam tries to catch you
Thrombophlebitis questions test the persistence of fever and the investigation that proves the diagnosis.
- Trap: escalating antibiotics indefinitely for persistent fever Correct: look for thrombosis or abscess on contrast imaging and add anticoagulation.
- Trap: labelling every post-caesarean fever as endometritis Correct: fever persisting despite antibiotics raises the possibility of septic pelvic thrombophlebitis.
- Trap: ruling out pelvic thrombophlebitis because leg veins look normal Correct: the thrombus lies in pelvic veins, which lower limb ultrasound does not image.
Frequently asked questions
Which vein is commonly involved in septic pelvic thrombophlebitis?
The ovarian vein is most commonly involved in septic pelvic thrombophlebitis, with the right side described as more frequent in many series. Thrombosis can extend to the uterine and pelvic veins. Contrast CT or MRI identifies the thrombosed vein.
How does septic pelvic thrombophlebitis present after delivery?
Septic pelvic thrombophlebitis presents as persistent fever beyond 48 to 72 hours despite broad-spectrum antibiotics, often with lower abdominal or flank pain. The wound and uterus may appear unremarkable. Diagnosis needs imaging, not clinical signs alone.
Which investigation diagnoses septic pelvic thrombophlebitis?
Contrast-enhanced CT or MRI is the investigation of choice for septic pelvic thrombophlebitis, showing thrombus in the ovarian or pelvic veins. Ultrasound may show findings but is less reliable for deep pelvic veins. Imaging also looks for a coexisting abscess.
What is the treatment for septic pelvic thrombophlebitis?
Septic pelvic thrombophlebitis is treated with broad-spectrum antibiotics and therapeutic anticoagulation, usually heparin or low-molecular-weight heparin. Abscesses are drained when present. Surgical ligation is reserved for failure of medical therapy.
Why must pulmonary embolism be considered in this condition?
Pulmonary embolism is a risk in septic pelvic thrombophlebitis because thrombus from pelvic veins can embolise to the lungs. Patients need monitoring for breathlessness, chest pain or hypoxia. Anticoagulation reduces this risk.