Postpartum Pyelonephritis

Postpartum pyelonephritis is infection of the kidney within 6 weeks of birth, caused by bacteria (usually Escherichia coli) that ascend from the bladder. Dilatation of the ureters and kidneys in pregnancy takes 6 to 12 weeks to resolve, and catheterisation and retention add risk. It matters because it causes sepsis, kidney injury and readmission.

• Risk factors: bladder catheterisation, urinary retention, caesarean section, epidural anaesthesia, untreated bacteriuria in pregnancy, diabetes, kidney stones, sickle cell disease, HIV.
• Right side is affected more often.
• Most women recover within 72 hours of IV treatment.

Women have fever above 38 degrees Celsius, rigors, loin pain, vomiting and malaise, often after earlier burning on passing urine. The costovertebral angle is tender.

• Fever with chills and loin tenderness.
• Pulse above 100 per minute in sepsis.
• Differential diagnosis: endometritis, wound infection, mastitis, malaria, pneumonia, kidney stone, pelvic abscess, appendicitis, septic pelvic thrombophlebitis.
• Complications: bacteraemia and septic shock, perinephric abscess, acute kidney injury, obstruction, recurrent infection, chronic kidney scarring.

The approach is culture and imaging.

• Mid stream urine culture and blood cultures before antibiotics; dipstick and microscopy.
• Full blood count, C-reactive protein, urea, creatinine, electrolytes, lactate, malaria test.
• Renal and pelvic ultrasound for obstruction, stones, abscess and retained products.
• CT of the kidneys if no response in 72 hours.

The principle is admission, IV antibiotics and fluids, and drainage of any obstruction.

• Supportive: admit; Ringer's lactate 1 litre IV over 2 hours then maintenance; hourly urine output; paracetamol for fever; oral fluids when able; breastfeeding continues.
• Pharmacological: ceftriaxone 2 g IV once daily until afebrile for 24 to 48 hours, then cefalexin 500 mg oral 6-hourly or amoxicillin-clavulanate 625 mg oral 8-hourly or ciprofloxacin 500 mg oral 12-hourly to complete 10 to 14 days (guided by culture); gentamicin 5 mg/kg IV once daily for severe sepsis (avoid in kidney impairment); meropenem 1 g IV 8-hourly for extended spectrum beta lactamase organisms; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); enoxaparin 40 mg subcutaneous once daily during admission.
• Procedures: ureteric stent or percutaneous nephrostomy for obstruction with infection or no response by 72 hours; drainage of perinephric abscess.
• Special groups: renal impairment avoids gentamicin and uses ceftriaxone; severe penicillin allergy uses gentamicin 5 mg/kg IV once daily or ciprofloxacin 400 mg IV 12-hourly; diabetic women need insulin and a 14 day course.
• Red flags: systolic blood pressure below 90 mmHg, urine below 30 mL per hour, fever beyond 72 hours of treatment, severe loin pain, vomiting preventing oral intake, confusion.
• Follow-up: culture at 1 to 2 weeks after treatment; renal ultrasound at 6 weeks for first infection with recurrence or stones; review at 6 weeks.