In EDs throughout the United States, emergency physicians commonly estimate blood loss as part of ongoing evaluation of patients or during procedures. In many scenarios, there may not be other useful indicators of significant blood loss. For example, hematocrit levels are often a poor indicator of acute blood loss. Furthermore, vital signs can remain normal despite large losses, and patients’ own estimates are often not trusted.

Accurate blood loss estimates are obviously important if this information is used during the clinical decision-making process. They also help physicians create a complete picture of the severity of the problems patients are experiencing. Unfortunately, previous studies have demonstrated that trauma surgeons, nurses, paramedics, obstetricians, and general surgeons often have difficulties with estimating blood loss accurately.


Examining New Data

In the Western Journal of Emergency Medicine, a study examined the accuracy of ED physicians in estimating blood loss on different surfaces. In it, 56 ED physicians—consisting of 30 attending physicians and 26 residents—were asked to estimate the amount of moulage blood that was present in four scenarios:

1)     500 mL spilled onto an ED cot.
2)     25 mL spilled onto a 10-pack of 4×4-inch gauze.
3)     100 mL on a T-shirt.
4)     150 mL in a commode filled with water.

 In the study, only 8% of blood loss estimates fell within 20% of the true value. On average, estimates were more than 100% off from the actual amounts. Estimates were most accurate for the cot scenario and least accurate for the commode scenario. Residents and attending physicians performed about the same in the scenarios assessed. Overall, the analysis adds evidence that ED physicians—like other specialists— do not appear to estimate blood loss well. Furthermore, clinical experience did not appear to improve estimation ability in the study.

Important Ramifications

Considering the potential impact on patients and decision making, these findings may be important to ED care. The types of situations assessed in the study were found to lead to both low precision and poor accuracy in estimating blood loss. Emergency physicians should be aware of the potential for inaccuracies in making and using these estimates in clinical care.

Future research should explore various interventions that may improve the ability to estimate blood loss during clinical decision making. More information on the value of adding these estimation skills to emergency medicine training is also warranted. Training programs to enhance the estimation skills of physicians should be tested, evaluated, and, if successful, incorporated into emergency medicine and advanced trauma care. Many factors can lead to poor estimation of blood loss, especially during early evaluations. The key is to interpret blood loss estimates with great caution.


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Moscati R, Billittier AJ, Marshall B, et al. Blood loss estimation by out-of hospital emergency care providers. Prehosp Emerg Care. 1999;3:239-242.

Larsson C, Saltvedt S, Wiklund I, et al. Estimation of blood loss after cesarean section and vaginal delivery has low validity with a tendency to exaggeration. Acta Obstet Gynecol Scand. 2006;85:1448-1452.