Septic Pelvic Thrombophlebitis

Septic pelvic thrombophlebitis (SPT) is infected thrombosis of the pelvic veins (ovarian, uterine, internal iliac veins and the inferior vena cava). It mostly follows delivery or pelvic surgery and pelvic infection (endometritis, septic abortion, PID).

It occurs in about 1 in 3,000 deliveries: 1 in 9,000 vaginal births, and higher after caesarean at 1 in 800 to 1 in 3,000.

Pregnancy and the puerperium produce venous stasis and hypercoagulability, and infection (polymicrobial anaerobes, E. coli, streptococci, Bacteroides) causes endothelial damage. The right ovarian vein is most often involved (about 90% in ovarian vein thrombosis), because of the longer course, retrograde flow and compression by the dextrorotated uterus.

Complications: septic pulmonary emboli (up to 30%), propagation to the IVC or renal vein, abscess, bowel ischaemia, and maternal death.

• Persistent spiking fever (above 38.5 degrees C, "picket fence" pattern) despite 48 to 72 hours of appropriate broad spectrum antibiotics for endometritis, typically starting 2 to 7 days postpartum
• Abdominal or flank pain (right lower quadrant or flank in ovarian vein thrombosis), a palpable tender cord like mass near the uterine cornu
• Tachycardia, mild leucocytosis, normal pelvic examination
• Pleuritic chest pain, cough, and haemoptysis from septic pulmonary emboli
• Ileus, nausea; urinary symptoms with ureteric obstruction (right hydronephrosis)
• Bacteraemia, septic shock

• A diagnosis of exclusion: persistent fever with no source after 48 to 72 hours, excluding wound infection, abscess, UTI, mastitis, pneumonia, drug fever, and retained products
• Contrast enhanced CT of the abdomen and pelvis (sensitivity 80 to 100%): enlarged thrombosed ovarian vein with a "target" or rim enhancing appearance, a filling defect in the pelvic veins, IVC extension; also shows abscess
• MRI or Doppler ultrasound (right ovarian vein; sensitivity limited) where radiation or contrast avoided
• Blood cultures (positive in about 10 to 20%), full blood count, coagulation profile; thrombophilia screening (antiphospholipid antibodies, factor V Leiden, protein C and S, antithrombin) later
• Chest CT or CT pulmonary angiography for septic pulmonary emboli (multiple peripheral nodular infiltrates with cavitation)

• Broad spectrum IV antibiotics covering anaerobes and Gram negative organisms. Use one of:
  • piperacillin tazobactam 4.5 g IV every 6 hours
  • ampicillin sulbactam 3 g every 6 hours
  • ceftriaxone 2 g daily with metronidazole 500 mg every 8 hours
  • clindamycin 900 mg every 8 hours with gentamicin 5 mg/kg daily
  Add vancomycin for resistant cocci.
• Continue antibiotics for at least 48 hours after clinical improvement (afebrile 24 to 48 hours), total of 7 to 14 days (up to 4 to 6 weeks with septic emboli, abscess or bacteraemia).
• Therapeutic anticoagulation, starting with antibiotics: unfractionated heparin (80 units/kg bolus then 18 units/kg/hour, adjusting to aPTT 1.5 to 2.5 times control) or enoxaparin 1 mg/kg every 12 hours (or 1.5 mg/kg daily).
• Continue anticoagulation for 6 weeks to 3 months for ovarian vein or pelvic vein thrombosis, and indefinitely if thrombophilia or extension to IVC. Oral options are warfarin INR 2 to 3, or direct oral anticoagulants in non-breastfeeding women. Warfarin and heparin are compatible with breastfeeding.
• Fever response to heparin helps confirm the diagnosis (typically within 24 to 48 hours).
• Drainage of abscess (percutaneous) or surgery: ovarian vein ligation, thrombectomy, or hysterectomy with salpingo oophorectomy in refractory disease; IVC filter in patients who cannot be anticoagulated or with recurrent emboli.
• Supportive care: fluids, oxygen, and critical care for sepsis; monitoring for bleeding.
• Follow up: repeat imaging to confirm thrombus resolution, thrombophilia workup, and counselling for future pregnancy (prophylactic LMWH in subsequent pregnancies).