Pyelonephritis is bacterial infection of the renal parenchyma.
Pyelonephritis may occur postpartum if bacteria ascend from the bladder. The infection may begin as asymptomatic bacteriuria during pregnancy and is sometimes associated with bladder catheterization to relieve urinary distention during or after labor. The causative organism is usually a type of coliform bacteria (eg, Escherichia coli).
Symptoms include fever, flank pain, general malaise, and, occasionally, painful urination.
Diagnosis is based on urinalysis, urine culture, and clinical findings (see Bacterial Urinary Tract Infections (UTIs) : Diagnosis).
Initial treatment is ceftriaxone 1 to 2 g IV q 12 to 24 h alone or ampicillin 1 g IV q 6 h plus gentamicin 1.5 mg/kg IV q 8 h until women are afebrile for 48 h. Sensitivities with culture should be checked. Treatment is adjusted accordingly and continued for a total of 7 to 14 days; oral antibiotics are used after the initial IV antibiotics. Women should be encouraged to consume large amounts of liquids.
A urine culture should be repeated 6 to 8 wk after delivery to verify cure. If episodes of pyelonephritis recur, imaging should be considered to look for calculi or congenital malformations. Imaging during pregnancy is usually with ultrasonography; imaging after pregnancy is usually with contrast CT.