Advancing accurate blood loss measurement to save mothers’ lives globally
A WRH Research Group operates within our department's Global Health theme led by Prof Arri Coomarasamy
E-MASTER Phase I
Diagnosis of postpartum haemorrhage at caesarean section: a multi-country diagnostic and prognostic accuracy study.
Why is this project important?
Postpartum haemorrhage (PPH), defined as a blood loss ≥500 mL after childbirth, accounts for 15% of maternal deaths worldwide.1 An estimated 9 million women having a caesarean section suffer PPH every year and this is expected to increase. 2 A third of all deaths following caesarean section are attributed to PPH.3
Currently, the assessment of blood loss during caesarean section can be inaccurate and involve subjective visual estimation which can result in underestimation of blood loss and under-diagnosis of PPH. This can result in delayed intervention and increase morbidity.
How the study can help
This study is evaluating the accuracy of an innovative technology – the colorimetric sponge and canister system (Triton System, Stryker Inc.) which uses advanced image processing and machine learning algorithms to provide real-time, quantitative estimation of blood loss by analysing surgical sponges and fluid in suction canisters during a caesarean section procedure.
This system is designed to reduce human error and improve accuracy and precision, offering the potential to standardise and enhance blood loss assessment during caesarean section. This study will assess the first-time use of this technology for objective blood loss measurement in Low- and Middle-Income Countries and provide insights on implementation feasibility of the technology in this setting.
1 Cresswell JA, Alexander M, Chong MYC, et al. Global and regional causes of maternal deaths 2009-20: a WHO systematic analysis. Lancet Glob Health. 2025 Apr;13(4):e626-e634.
2 Betran AP, Ye J, Moller AB, Souza JP, Zhang J. Trends and projections of caesarean section rates: global and regional estimates. BMJ Glob Health. 2021 Jun;6(6):e005671.
3 Sobhy S, Arroyo-Manzano D, Murugesu N, Karthikeyan G, Kumar V, Kaur I, Fernandez E, Gundabattula SR, Betran AP, Khan K, Zamora J, Thangaratinam S. Maternal and perinatal mortality and complications associated with caesarean section in low-income and middle-income countries: a systematic review and meta-analysis. Lancet. 2019 May 11;393(10184):1973-1982.
E-Master Phase 1 study design
E-MASTER Phase I is a prospective, multi-country diagnostic and prognostic test accuracy study, along with an embedded mixed-methods implementation evaluation.
- Agreement and diagnostic test accuracy studies: We will establish the level of agreement (bias), scatter and heteroscedasticity of the colorimetric sponge and canister system and the gravimetric and volumetric blood loss measurement method against the reference method of Hb mass method from surgical sponges and swabs and suction canister. We will also assess the diagnostic test accuracy of the colorimetric sponge and canister system against the reference method of gravimetric and volumetric methods.
- Prognostic test accuracy study: We will assess the prognostic accuracy of the colorimetric sponge and canister system and gravimetric and volumetric methods on the composite clinical outcome of blood transfusion, Hb <6g/dL or a decrease of 4g/dL or greater from baseline, as well as PPH-related procedures (compression sutures, major vessel ligation or hysterectomy), maternal HDU/ICU admission, or maternal mortality. Prognostic accuracy analysis will also be conducted for the individual components of the composite outcome separately, and in addition, for shock, uterine tamponade, uterine tourniquet, organ failure, re-laparotomy and other key outcomes from the PPH core outcome set. We will report prognostic sensitivity, prognostic specificity, positive likelihood ratio, negative likelihood ratio, and ROC analysis to summarise prognostic accuracy, and relative risks or odds ratios to summarise prognostic associations.
- Mixed methods implementation evaluation: We will conduct a mixed method study to evaluate the feasibility, acceptability, barriers, enablers and facilitators to implementation of the colorimetric sponge and canister system and the gravimetric and volumetric blood loss measurement method in clinical care across diverse LMIC settings.
The sample size for the agreement study is 250 women and sample size for the diagnostic and prognostic accuracy studies is 1,245 women. Women recruited to the agreement study will also contribute to the diagnostic and prognostic accuracy studies.
Aim of the Study
The primary aim of this study is to estimate the diagnostic and prognostic accuracy of a colorimetric sponge and canister system (Triton System, Stryker Inc.) and a gravimetric and volumetric method for the intraoperative measurement of blood loss at caesarean birth, as well as evaluate their implementation in low-and middle-income settings.
Objectives
- Evaluate the agreement of 1) the colorimetric sponge and canister system, and 2) the gravimetric and volumetric blood loss measurement method against the reference method of haemoglobin (Hb) mass method from surgical sponges and swabs and suction canister. We will also explore the diagnostic test accuracy of 1) the colorimetric sponge and canister system, and 2) the gravimetric and volumetric blood loss measurement method against the reference method of Hb mass method from surgical sponges and swabs and suction canister for the outcome of blood loss ≥500 mL.
- Evaluate the diagnostic test accuracy of the colorimetric sponge and canister system, against the reference method of gravimetric and volumetric blood loss measurement method for the outcome of blood loss ≥500 mL.
- Evaluate the prognostic accuracy of the colorimetric sponge and canister system and the gravimetric and volumetric blood loss measurement method on the composite clinical outcome of blood transfusion, Hb <6g/dL or a decrease of 4g/dL or greater from baseline, as well as PPH-related procedures (compression sutures, major vessel ligation or hysterectomy), maternal HDU/ICU admission, or maternal mortality. Prognostic accuracy analysis will also be conducted for the individual components of the composite outcome separately, and in addition, for shock, uterine tamponade, uterine tourniquet, organ failure, re-laparotomy and other key outcomes from the PPH core outcome set.
- Evaluate the implementation of the colorimetric sponge and canister system and the gravimetric and volumetric blood loss measurement method (mixed-methods implementation evaluation).
Setting
The study will be conducted in up to 10 secondary- and/or tertiary-level health facilities in Kenya, Nigeria, Rwanda, India and Pakistan.
Participant population
Women undergoing elective or semi-emergency caesarean section (category 2 or 3) at participating health facilities
Eligibility criteria
Women are eligible for inclusion if they are aged 18 or over, undergoing birth by caesarean section (elective or semi-emergency [category 2 or 3]) during the study period at a participating health facility, and they have provided written informed consent. Women undergoing a caesarean section with a planned hysterectomy, participating in another PPH study or with a diagnosed major bleeding disorder are ineligible
Measurement of outcomes
The primary outcome will be a composite of any of the following: blood transfusion, Hb <6g/dL or a decrease of 4g/dL or greater from baseline, as well as PPH-related procedures (compression sutures, major vessel ligation or hysterectomy), maternal HDU/ICU admission, or maternal mortality.
Secondary outcomes will include the individual components of the composite outcome separately, and in addition, for shock, uterine tamponade, uterine tourniquet, organ failure, re-laparotomy and other key outcomes from the PPH core outcome set.
Latest update
Overall recruitment to the study started on 12 Mar 2026 in Rwanda.
Recruitment started in Nigeria on 16 April 2026.
Recruitment started in Pakistan on 09 May 2026.
Recruitment is expected to start in India in June 2026 and in Kenya from June 2026.
Useful links
Gates Foundation
Global philanthropic organisation focused on improving health, reducing poverty, and expanding educational opportunities worldwide.
Triton system
Supporting your journey towards standardised safe OR solutions.
E-Motive Trial
Early detection of Postpartum Haemorrhage and treatment using the WHO MOTIVE 'first response' bundle: a cluster randomised trial with health economic analysis and mixed methods evaluation.
The research team at Oxford
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Arri Coomarasamy
Professor of Gynaecology and Reproductive Medicine
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Adam Devall
Professor of Maternal Health Clinical Trials
Other members of the team
- Prof Yemisi Takwoingi; Professor of Test Evaluation Research; University of Birmingham
- Dr Soha Sobhy; Associate Clinical Professor; University of Birmingham
- Mr Lee Middleton; Statistics Team Leader; University of Birmingham
- Samir Mehta; Senior Medical Statistician; University of Birmingham
- Yongzhong Sun; Medical Statistician; University of Birmingham
- Prof Laura Jones; Professor of Qualitative and Mixed Methods Women’s Health Research; University of Birmingham
More information
- Chief Investigator: Professor Arri Coomarasamy
- Sponsor: University of Oxford
- Sponsor Ref (OxTREC): 2453849
- PACTR No.: PACTR202602844431769
- Funder: Gates Foundation