Better accuracy is only the first step towards improving outcomes Delayed diagnosis and poor management of postpartum haemorrhage is associated with increased mortality and morbidity.1 2 3 4 The challenge, particularly in developing countries, is to improve management—for example, by using prophylactic administration of uterotonics in deliveries. In the linked cluster randomised controlled trial (doi:10.1136/bmj.c293), Zhang and colleagues assessed whether using a transparent plastic collector bag to measure postpartum blood loss after vaginal delivery reduced the incidence of severe postpartum haemorrhage. Clinicians continue to rely on visual assessment to determine the volume of postpartum blood loss. Studies have repeatedly shown visual estimates to be inaccurate (overestimating blood loss at low volumes and underestimating blood loss at high volumes).5 6 Several technologies have been developed to help clinicians to measure postpartum blood loss more accurately, with the intention of improving outcomes after postpartum haemorrhage. These include direct collection of blood in pans, gravimetric measurement of sponges (weighed before and after use), …