Uterine contractions after antibiotic therapy for pyelonephritis in pregnancy.

OBJECTIVE

The purpose of our study was to investigate the pathogenesis of preterm labor in pyelonephritis, we determined the number of uterine contractions occurring in patients with pyelonephritis before and after antibiotic therapy.

STUDY DESIGN

We recorded the uterine contractions before and after antibiotic administration in 30 patients with acute pyelonephritis at Lyndon B. Johnson Hospital in Houston. Exclusion criteria were cervical dilatation > or = 4 cm, < 26 weeks' gestation, antibiotics within 7 days, clinical intraamniotic infection, rupture of membranes, or other maternal infection. Statistical analysis was by Kruskal-Wallis analysis of variance and Wilcoxon rank sum tests.

RESULTS

The patients averaged eight contractions per hour on admission. The contraction rate significantly increased in hours +1 to +4 after antibiotic administration. The increase in uterine contractility occurred in patients with urinary tract gram-negative isolates.

CONCLUSIONS

Pregnant women with pyelonephritis resulting from gram-negative bacteria increase their rate of uterine contractility after antibiotic treatment. This observation may be important in understanding the pathogenesis of preterm labor in pyelonephritis.