Thirty-six studies were included that evaluated the accuracy of visual estimation; tested methods to improve
skills in measurement; examined their effect on PPH diagnosis and treatment, and / or explored additional factors
associated with blood loss evaluation. The review found that health professionals were highly inaccurate at estimating
blood loss as a volume. Training resulted in short term improvements in skills but these were not retained and did not
improve clinical outcomes. Multi-faceted interventions changed some clinical practices but did not reduce the incidence
of severe PPH or the timing of responses to excessive bleeding. Blood collection bags improved the accuracy of
estimation but did not prevent delays or progression to severe PPH. Practitioners commonly used the nature and
speed of blood flow, and the condition of the woman to indicate that the blood loss was abnormal.