Clinical value of c-reactive protein level in predicting the development of postpartum endometritis

Hypothesis/aims of study. In the Russian Federation, postpartum septic complications are third among the causes of maternal mortality, along with obstetric bleeding and preeclampsia. A wide range of methods for predicting postpartum endometritis has been proposed. However, none of these methods has sufficient clinical efficacy. The lack of information and the lack of clear criteria highlight the difficulties in the early diagnosis and prognosis of postpartum endometritis. The aim of this study was to evaluate the role of C-reactive protein (CRP) in the prediction of postpartum endometritis in puerperas with a high risk of developing septic complications.

Study design, materials and methods. The study included 135 puerperas, who were retrospectively divided into two groups. The main group consisted of women with developed postpartum endometritis (n = 72), and the comparison group comprised individuals with physiological course of the postpartum period (n = 63). Serum CRP levels were determined for all puerperas on days 1 and 3 of the postpartum period using the immunoturbodimetric method.

Results. On day 1 of the postpartum period, the diagnostic threshold value for CRP levels was 69 mg / ml. The sensitivity and specificity of the method were low: 62% (95% CI 50–74) and 65% (95% CI 51–76), respectively. The predictability at a CRP level above 69 mg / ml was 67% (95% CI 54–77). Thus, in puerperas on day 1 of the postpartum period at a CRP level above 69 mg / ml, the probability of developing postpartum endometritis was 67%, the chances of developing postpartum endometritis being extremely low, increasing by 1.76 times. There were no statistically significant differences when comparing CRP levels in the study groups of puerperas on day 1 of the postpartum period. On day 3 of the postpartum period, CRP level was significantly higher in the main group of puerperas — 148 mg / ml (95% CI 126–171), and in the comparison group — 43 mg / ml (95% CI 38–49) (p = 6 × 10^–14). On the 3rd day of the postpartum period, the diagnostic threshold value for CRP levels was 60 mg / ml. The sensitivity of the method was moderate — 79% (95% CI 68–86), the specificity of the method being high — 93% (95% CI 85–98). The predictability at a CRP level above 60 mg / ml was 93% (95% CI 84–96). Thus, in postpartum women on day 3 of the postpartum period at a CRP level above 60 mg / ml, the probability of developing postpartum endometritis was 93%, with the chances of developing postpartum endometritis increased by 10 times (95% CI 5–30). In addition, determining CRP level on day 3 of the postpartum period is clinically informative, as evidenced by the standardized effect size (SES) equal to 1.4 (p = 6 × 10^–14). This is confirmed by the ROC analysis data: the clinical significance value (AUC indicator) was 0.89 (CI 0.81–0.93), according to which CRP determination is evaluated as a method with high clinical informativity.

Conclusion. The determination of CRP on day 3 of the postpartum period is a clinically informative method. An increase in CRP level above 60 mg / ml is a predictor of postpartum endometritis with a sensitivity of 79% and a high probability (93%).