Effect of mild preoperative thrombocytopenia on postpartum hemorrhage after cesarean deliveries

BACKGROUND: Thrombocytopenia at the time of delivery is considered as a risk factor for postpartum hemorrhage. However, platelet count thresholds for postpartum hemorrhage are variable and not extensively studied. OBJECTIVE: This study aimed to examine whether mild thrombocytopenia is associated with an increased risk of postpartum hemorrhage among women undergoing cesarean delivery. STUDY DESIGN: This was a retrospective cohort study of all women who underwent cesarean delivery at a tertiary care hospital labor and delivery unit from September 2015 to June 2018. Women with normal platelet counts (>= 150,000/mu L) were compared with women with mild thrombocytopenia (100,000-149,000/AL). Women were excluded if they had moderate to severe thrombocytopenia (platelet count of <100,000/mu L) or had received a platelet transfusion. The primary outcome was postpartum hemorrhage (quantitative blood loss of >= 1000 mL). Secondary outcomes included frequencies of red blood cell transfusion, wound complications (surgical site infections, dehiscence, or hematoma), and postpartum emergency department visits. Adjusted odds ratios with 95% confidence intervals were calculated, controlling for maternal age, gestational age, body mass index, scheduled cesarean delivery, hypertension, and preoperative hemoglobin level. RESULTS: Of 3133 women, 2799 (89.3%) had normal platelet levels, 298 (9.5%) had mild thrombocytopenia, and 36 (1.2%) had moderate to severe thrombocytopenia. There were no differences in the risks of postpartum hemorrhage, need for a red blood cell transfusion, wound complications, or postpartum emergency department visit comparing women with normal platelet counts with those with mild thrombocytopenia (24.6% vs 25.8% [adjusted odds ratio, 1.16; 95% confidence interval, 0.88-1.54]; 6.5% vs 6.7% [adjusted odds ratio, 1.34; 95% confidence interval, 0.80-2.24]; 4.5% vs 5.4% [adjusted odds ratio, 1.53; 95% confidence interval, 0.88-2.64]; 9.0% vs 10.7% [adjusted odds ratio, 1.37; 95% confidence interval, 0.92-2.03], respectively). CONCLUSION: Preoperative mild thrombocytopenia was not associated with postpartum hemorrhage, red blood cell transfusion, wound complications, or postpartum emergency department visits in women undergoing cesarean delivery.