IntroductionThe incidence of severe postpartum haemorrhage (PPH) that requires blood transfusion is on the increase. Fibrinogen levels have been shown to drop early and significantly during PPH, which is associated with worse outcomes. Early fibrinogen replacement could potentially improve outcomes. No studies have investigated the clinical impact of early cryoprecipitate transfusion in PPH. Prior to performing a full-scale trial, a pilot study is needed to determine feasibility of the intervention and recruitment.MethodsACROBAT is a cluster-randomised pilot study with a qualitative evaluation. Four large London maternity units are randomised to either the intervention or control group. The intervention group will adapt their major obstetric haemorrhage procedures to administer cryoprecipitate early for primary PPH. The control group will retain their standard of care.We include women at >24 weeks gestation who are actively bleeding within 24 hours of delivery and for whom transfusion of red blood cells (RBCs) has been started. We exclude women who decline blood transfusions in advance or have inherited Factor XIII or fibrinogen deficiency. Due to the emergency nature of the intervention, informed consent for administering the intervention is waived.The primary objective is to assess the feasibility of administering cryoprecipitate within 90 min of RBC request, as compared with standard treatment where cryoprecipitate is given later or not at all. Secondary objectives include the feasibility of recruitment and data collection, reasons for and barriers to consent, preliminary maternal clinical outcomes, identification of the optimal infrastructure pathways for study delivery, and acceptability of the intervention and outcomes.Ethics and disseminationThe trial has approvals from the London—Brighton & Sussex Research Ethics Committee (ref. 18/LO/2062), the Confidentiality Advisory Group (ref. 18/CAG/0199) and Health Research Authority (IRAS number 237959). Data analysis and publication of manuscripts will start in Q3 2020.Trial registration numberISRCTN12146519.