A retrospective cohort study of patients with pyelonephritis in pregnancy and immediately postpartum was conducted. Participants delivered between 2005 and 2009 at a single university center (Lucile Packard Children's Hospital at Stanford) were reviewed. Pyelonephritis was defined by a temperature greater than 38.0°C, flank pain or costovertebral angle tenderness, and bacteruria or pyuria on urinalysis. All patients with pyelonephritis and urine culture results were included. Univariate analyses were performed with the χ2 test. Means were compared with the Student's t test.
One hundred thirteen patients were admitted with pyelonephritis and had a urine culture performed. Of the entire cohort, 70% of patients were Hispanic, 53% were nulliparous, and most were diagnosed in the third trimester. A total of 94 patients (83%) had positive urine cultures. There were no differences in adverse outcomes (preterm birth, anemia, bacteremia, acute respiratory distress syndrome, and hospital stay) between those with positive and negative urine cultures. Among those with positive cultures, there was a statistically significant increase in preterm birth (less than 37 weeks of gestation) between those with resistant uropathogens and those with pan-sensitive pathogens (26.5% compared with 7.6%, P=.01) (Table 1).
Among women with pyelonephritis, complications did not differ between those with positive and negative urine culture results. Women with resistant bacterial uropathogens are at increased risk for preterm birth compared with those with sensitive pathogens.