Pyelonephritis in Pregnancy

Pyelonephritis in pregnancy is infection of the kidney, usually from Escherichia coli ascending from the bladder. It is a common non obstetric reason for antenatal admission. It matters because it causes septic shock, acute respiratory distress syndrome, preterm labour and acute kidney injury.

• Right side is more often affected.
• Risk factors: untreated bacteriuria, diabetes, previous pyelonephritis, stones, sickle cell disease, renal anomalies.
• Most settle within 48 to 72 hours of IV treatment.

Women have fever above 38 degrees Celsius, rigors, loin pain, vomiting and often earlier cystitis symptoms. Examine costovertebral angle tenderness, pulse, blood pressure, uterine contractions and fetal heart.

• Tachycardia and tachypnoea suggest sepsis.
• Respiratory distress can follow endotoxin release.
• Differential diagnosis: appendicitis, cholecystitis, pneumonia, chorioamnionitis, malaria, renal stone, abruption, labour.
• Complications: septic shock, acute respiratory distress syndrome, acute kidney injury, anaemia, preterm labour, perinephric abscess, recurrence.

The approach is culture with assessment of severity and obstruction.

• Mid stream urine and blood cultures before antibiotics; urine dipstick and microscopy.
• Full blood count, creatinine, electrolytes, C-reactive protein, lactate; malaria test.
• Renal ultrasound for obstruction, stones or abscess; chest X-ray with shielding if breathless.
• Fetal heart monitoring and cardiotocography.

The principle is admission with IV antibiotics, fluids and monitoring for sepsis, followed by prophylaxis.

• Supportive: admit; IV fluids Ringer's lactate 1 litre over 2 hours then maintenance; paracetamol 1 g oral or IV 6-hourly (maximum 4 g in 24 hours) to keep temperature below 38 degrees Celsius; oxygen if saturation is below 94 percent; hourly urine output; monitor oxygen saturation and respiratory rate.
• Pharmacological: ceftriaxone 1 to 2 g IV 24-hourly until afebrile for 24 to 48 hours, then cefalexin 500 mg oral 6-hourly or amoxicillin-clavulanate 625 mg oral 8-hourly to complete 10 to 14 days; for severe sepsis add gentamicin 5 mg/kg IV daily (avoid in renal impairment); for extended spectrum beta lactamase organisms give meropenem 1 g IV 8-hourly; betamethasone 12 mg IM twice, 24 hours apart, if preterm labour before 34 weeks; prophylaxis: cefalexin 250 mg oral at night or nitrofurantoin 50 mg oral at night until 6 weeks postpartum; avoid trimethoprim, tetracyclines and fluoroquinolones.
• Procedures: ureteric stent or percutaneous nephrostomy for obstruction or failure to improve within 72 hours; drainage of abscess.
• Special groups: renal impairment replaces gentamicin with ceftriaxone; penicillin allergy with severe reaction uses gentamicin 5 mg/kg IV daily or aztreonam 1 g IV 8-hourly; septic shock is managed in high dependency with noradrenaline 0.05 micrograms/kg/minute titrated.
• Red flags: systolic blood pressure below 90 mmHg, respiratory rate above 24 per minute, oxygen saturation below 94 percent, oliguria, persistent fever after 72 hours, contractions.
• Follow-up: culture 1 to 2 weeks after treatment and monthly; renal ultrasound after recovery; review at 6 weeks postpartum.