Renal failure in obstetrics: epidemiology and outcome in the intensive care unit

Introduction

Acute renal failure (ARF) is a serious complication of pregnancy. It is associated with an increased mortality.

Objective

To determine risk factors and outcome of peripartum ARF.

Design

Demographic and obstetric management (transfusion, cesarean section, hysterectomy, anesthetic complications, etc.) data were collected and analysed. ARF was defined as creatinine levels ≥ 100 μmol/l and/or oliguria <150 ml/8 hours or < 500 ml/day. Generalistic scoring systems (APACHE II, APACHE III) and organ dysfunction scoring systems were calculated at admission and on a daily basis. Data were computed on SPSS 11.5 XP-Windows compatible. Results were expressed as means ± standard deviation. Statistical analysis was based on the chi-squared test and Student t test corrected by the Fisher exact test.

Setting

A multidisciplinary ICU.

Study period

January 1996–December 2003.

Patients

Obstetric patients (n = 541) admitted in the ICU.

Measurements and results

The mean age was 31.2 ± 5.9 years, mean term was 34.7 ± 4.5 weeks. The major part of our patients were admitted after delivery. Obstetric complications accounted for 70% of admissions. Pre-eclampsia, eclampsia and peripartum haemorrage were the leading causes associated with ARF. Overall mortality was 10.4% (n = 57). ARF was noticed in 68 patients, with a mortality of 33.8% (n = 23). The relative risk (RR) of mortality when patients developed ARF was 4.7 with an odds ratio (OR) of 6.6. We distinguished two populations: ARF with (Dial+) (n = 22) or without (Dial-) dialysis (n = 46); mortality was respectively 10/22 and 13/46. Mean scores for patients with and without ARF were respectively: 41.1 ± 20.9 and 21.6 ± 13.7 for SAPS II; 16 ± 8 and 7.5 ± 6 for APACHE II and 63.3 ± 31.6 and 24.4 ± 23.8 for APACHE III (P < 0.01 for all scores). Renal failure was usually associated with at least another organ dysfunction as demonstrated by mean SOFA at day 1 (9.3 ± 4.5) whereas without ARF it was 3.7 ± 3 (P < 0.001). Dial+ and Dial- respectively showed an OR concerning mortality of 8.37 and 4.04 and a respective RR of 6.33 and 3.93 compared with patients without ARF. Persistant oliguria was the major cause of dialysis. A cut-off point of creatinine at 300 μmol/l is associated with a RR of mortality of 3.5 compared with patients that developed ARF with lower creatinine levels.

Univariate analysis found that uterine atonia, transfusion, multiple pregnancy and vaginal delivery were significantly associated with ARF, whereas cesarean section showed an OR = 0.455. Multiple regression analysis retained only transfusion prior to ICU hospitalization as significantly associated with ARF. Oliguria and the level of renal failure are predicting factors of mortality.

Conclusion

ARF is associated with high mortality (> 30%). Aggressive treatment and prevention of renal failure is necessary to improve prognosis.