(1265) Postpartum Spontaneous Diuresis and Risk of Hospital Return in Preeclampsia with Severe Features

Objective:
To evaluate the association between postpartum urine output (UOP) and hospital return within 28 days among individuals with preeclampsia with severe features.

Study Design:
This was a retrospective cohort study of deliveries at a quaternary care center from 2018-2023. Eligible individuals were identified based on diagnosis of a hypertensive disorder of pregnancy plus receipt of postpartum magnesium sulfate. Exclusion criteria were pre-existing renal disease, acute renal failure, pulmonary edema, heart failure, and receipt of diuretics during delivery admission. The primary outcome was hospital return (emergency department, triage or readmission) within 28 days of discharge. The primary exposure was UOP in the first 24 hours postpartum, analyzed in quartiles based on the sample distribution: Q1 (≤ 135.4 mL/hr), Q2 (135.4–209.2 mL/hr), Q3 (209.2–284.2 mL/hr), and Q4 ( > 284.2 mL/hr). Bivariate analyses was used to compare fluid intake and output by hospital return status. Multivariable logistic regression was performed to estimate the association between UOP quartile and hospital return, adjusting for covariates. Sensitivity analysis used weight-adjusted UOP (mL/kg/hr), also in quartiles.

Results:
Of 1,819 eligible individuals, 175 (10.6%) returned to the hospital within 28 days. Those with a hospital return had lower total UOP in the first 24 hours postpartum (4.8 vs 5.3 L, p = 0.01). Total intravenous fluid intake did not differ significantly between groups. Hospital return rates varied significantly by UOP quartile, with lower rates observed in the highest quartile (p = 0.04; Table 1). After adjusting for covariates, patients in the highest UOP quartile had 57% lower adjusted odds of hospital return compared to those in the lowest quartile (aOR 0.43, 95% CI 0.26–0.72, p = 0.001; Table 2). Using weight-adjusted UOP (mL/kg/hr) yielded consistent findings, with an aOR of 0.43 (95% CI 0.26–0.71; p = 0.001) for the highest vs lowest quartile.

Conclusion:

Among individuals with preeclampsia with severe features, higher UOP in the first 24 hours postpartum was associated with lower odds of hospital return.