Clinical findings predictive of maternal adverse outcomes with pyelonephritis

Abstract

Background: Pyelonephritis, a leading cause of infection during pregnancy, is associated with increased maternal adverse outcomes. Therefore, early recognition and intervention of pyelonephritis are important. Early recognition of pyelonephritis has historically been dependent on fever and costovertebral angle tenderness. However, the reliability of these findings to distinguish women who will develop maternal adverse outcomes is limited.

Objective: This study aimed to identify clinical variables on presentation that are predictive of maternal adverse outcomes associated with pyelonephritis during pregnancy.

Study design: A retrospective cohort study of pregnant women admitted with pyelonephritis at a single hospital from October 1, 2015, to July 31, 2021, was conducted. The primary outcome was a composite maternal adverse outcome consisting of any of the following: maternal intensive care unit admission, surgical intervention, hypotension requiring vasopressors, acute respiratory distress syndrome, pulmonary edema, mechanical ventilation, high-flow nasal cannula, disseminated intravascular coagulation, altered mental status, dialysis, organ failure, venous thromboembolism, or maternal death. Differences in maternal characteristics and clinical signs and symptoms on admission were stratified by the presence or absence of a maternal adverse outcome. Categorical variables were analyzed using the Fisher exact test. Continuous data were analyzed with Wilcoxon rank-sum test. Sensitivity and specificity and likelihood ratios with 95% confidence intervals were calculated for the detection of maternal adverse outcomes by specified admission physical examination and laboratory findings.

Results: Of 97 women that met the inclusion criteria, 28 (28.9%) had maternal adverse outcomes. Moreover, 50 of 97 women (51.5%) had fever on presentation, with no difference between cohorts recognized. Admission vital signs were not significantly different between cohorts. Costovertebral angle tenderness was present in 78 of 97 women (80.4%) on presentation, with no difference between cohorts. Compared with women without a maternal adverse outcome, women with maternal adverse outcomes were more likely to have leukocytosis (18/28 [64.3%] vs 20/69 [29.0%]), thrombocytosis (3/28 [10.7%] vs 5/69 [7.2%]), bandemia (8/28 [28.6%] vs 7/69 [10.1%]), and an abnormal serum potassium (20/28 [71.4%] vs 32/63 [50.8%]).

Conclusion: Admission vital signs may not reliably identify women with pyelonephritis at risk of maternal adverse outcomes. Laboratory studies, particularly a complete blood count and electrolytes, may provide a means of distinguishing those at risk of maternal adverse outcomes.

Keywords: Adverse maternal outcomes; infection; pyelonephritis.