Risk factors for blood transfusion in Cesarean section: A systematic review and meta-analysis.

Objective: The current study has been conducted to identify the risk factors associated with blood transfusion in women undergoing cesarean section (C-section). A detailed account of the risk factors associated withblood transfusion will ultimately prevent unnecessary crossmatching in hospitals , leading to the conservation of declining blood supplies and resources without subjugating the quality of care.
Material and Methods: We performed a rigorous literature search using electronic databases, including PubMed, Cochrane CENTRAL, and Embase, for studies evaluating the risk factors for blood transfusion in C-section published until March 31, 2021. The Newcastle-Ottawa Quality Assessment Scale was deployed to assess the methodologic quality of the included studies. Mean differences (MD) and odds ratios (OR) with 95% confidence intervals were calculated using Review Manager version 5.3.
Results: The search yielded 1563 records, 22 of which were eligible for inclusion, representing 426,094 women (10,959 in the transfused group and 415,135 in the non-transfused group). Participants in the transfused group had lower mean preoperative hematocrit (MD=-3.71 [-4.46, -2.96]; p<0.00001; I ² =88%). Placenta previa (OR=9.54 [7.23, 12.59]; p<0.00001; I ² =88%), placental abruption (OR=6.77 [5.25, 8.73]; p<0.00001; I ² =72%), emergency C-section (OR=1.92 [1.42, 2.60]; p<0.0001; I ² =75%), general anesthesia (OR=8.43 [7.90, 9.00]; p<0.00001; I ² =72%), multiple gestations (OR=1.60 [1.24, 2.06]; p=0.0003; I ² =85%), preterm labor (OR=3.34 [2.75, 4.06]; p<0.00001; I ² =85%), prolonged labor (OR=1.68 [1.44, 1.96]; p<0.00001; I ² =78%), unbooked cases (OR=2.42 [1.22, 4.80]; p=0.01; I ² =80%), hypertensive disorders of pregnancy (OR=1.81 [1.72, 1.90]; p<0.00001; I ² =71%), and fibroids (OR=2.32 [1.55, 3.47]; p<0.0001; I ² =72%) were significantly higher in the transfused group compared to the non-transfused group. Chronic hypertension (OR=0.67 [0.29, 1.55]; p=0.36; I ² =90%), maternal age (MD=0.09 [-0.27, 0.45]; p=0.62; I ² =50%), maternal body mass index (MD=-0.14 [-0.81, 0.53]; p=0.67, I ² =86%), diabetes (OR=0.93 [0.75, 1.15]; p=0.51; I ² =52%), and malpresentation (OR=0.65 [0.38, 1.11]; p=0.13; I ² =64%) were not significantly associated with an increased risk of blood transfusion in C-section in the two groups.
Conclusion: Placenta previa, placental abruption, emergency C-section, booking status, multiple gestations, and preoperative hematocrit were the risk factors most significantly associated with blood transfusion, while a prior C-section did not increase the risk of transfusion.
(Copyright © 2021 Société française de transfusion sanguine (SFTS). Published by Elsevier Masson SAS. All rights reserved.)