791: Influencing parameters affecting fetal pH taken from category II tracing

Abstract

FHR (Fetal Heart Rate) monitoring during labor has been used extensively as a predictor of fetal well-being despite inaccuracy and a high false positive rate. ACOG defined categories to improve interpretation. Category II FHR is common and its clinical implication is not accurate. In this study we examined predictive factors in addition to category II FHR monitoring that might imply for of fetal acidosis and its risk of Asphyxia. This retrospective cohort study compared two groups of patients with Category II FHR monitoring that was considered significant by the care givers to perform a prompt delivery. Patients were divided into two groups based on fetal cord pH≤7.1 and pH >7.1. Demographics, medical history, delivery data and early neonatal outcome were reviewed. Cohort included 428 women who met the inclusion criteria. Forty-three of them (10%) were in the study group of cord PH < 7.1 and 385 (90%) in the control group. Background characteristiscs were similar in both groups. There were no differences between the groups in the rates or indications for labor induction, rates of non-reassuring fetal heart rate (NRFHR) at admission, duration of ruptured membranes (ROM), meconium stained amniotic fluid, maternal fever during labor and the duration of labor. As expected, more patients in the low pH group delivered by a cesarean section 39.8% vs 31.3%, p=0.04, both are significantly higher than the average rate of 18% cesarean in our institution. Five-minute Apgar scores were similar in both groups. In our retrospective study we could not detect a specific parameter that can help predict the prognosis. Since we only included patients that had a category II tracing which was worrying enough to lead to prompt delivery, it's reasonable to believe that this is an outcome of the patient selection, meaning that when the category II FHR leads to a clinical decision of prompt delivery, there is no added value for more clinical characteristics. The evaluation should be expended to all patients with category II tracing for better interpretation tools of category II FHR monitors.