Blood loss and transfusion in assisted vaginal birth: A retrospective, single-centre cohort study

To evaluate blood loss, blood product use and associated maternal and neonatal outcomes following attempted assisted vaginal birth (AVB).

Retrospective cohort study of women who had an attempted AVB during 18-months (01/08/2019 - 31/01/2021) at a tertiary level maternity unit (North Bristol Trust, UK).

total weighed blood loss (WBL), PPH ≥ 1,000 mLs and ≥ 1,500 mLs, blood transfusion, blood cell salvage, maternal and neonatal length of stay (LOS), NICU admission and neonatal IV antibiotics. Data analysis used SPSS.

1,061 attempted AVBs were included: 989 (93.2 %) successful and 72 (6.8 %) unsuccessful, converted to CS. Median total WBL was significantly higher in those with a successful AVB (673 mLs [IQR 406,1065]) compared to those converted to CS (501 mLs [377,712]), p = 0.002. Other significant risk factors for PPH ≥ 1,000 mLs following AVB included: longer second stage (p < 0.001), non-rotational forceps (p < 0.001), augmented labour (p = 0.012), OASI (p < 0.001), nulliparity (p = 0.002), high maternal BMI (p = 0.003) and high neonatal birthweight (p < 0.001). Rate of blood transfusion (p < 0.001), rate of neonatal IV antibiotics (p < 0.001) and maternal LOS (p = 0.006) were significantly higher after AVB-associated PPH. Of those who had an attempted AVB in theatre, the rate of PPH ≥ 1,000 mLs was significantly higher in those who had a successful AVB than in those converted to CS (p < 0.001).

This study demonstrates the importance of considering blood loss following AVB. Maternal, intrapartum and neonatal factors contributing to higher blood loss were identified together with the post-natal impact of PPH. This highlights the potential role for blood conservation strategies such as cell-salvage during AVB.