The Role of Weighing in Quantification of Blood Loss

Nurses and Doctors in Hospital

During surgery and labor, blood loss must be consistently and accurately monitored in order to keep the patient safe through all phases of the operation. However, it can be difficult to accurately measure blood loss: visual estimations, even when conducted by trained professionals, are well established to result in consistent underestimation, especially in large quantities, which can be dangerous for patients. Weighing can be an effective way to quantify blood loss.

Why it's important to measure blood loss accurately

Underestimating blood loss can delay life-saving treatments, as hemorrhages are not recognized early enough. Failure to recognize the magnitude of blood loss is a leading cause of mortality during labor. Blood loss can cause shock and death.

Because labor can be difficult and complicated by other conditions, it can be difficult for healthcare practitioners to ascertain if symptoms are cause by blood loss or by something else. The first clinical signs of blood loss don't appear until the patient has lost more than 30%, so medical practitioners cannot rely on symptoms.

Overestimation can lead to costly, invasive procedures that can put the patient at further risk. Treating blood loss early can help patients heal more quickly and lead to a full recovery.

Hospital Hallway

Why use a scale to measure blood loss?

Blood and other fluids are usually suctioned, but that option is not always available as some healthcare providers have limited resources. Furthermore, some blood ends up spilled on sheets below the patient. The blood would have to be placed in a container that has clear measuring graduation and the spilled blood would have to somehow be wrung into the container. Estimated Blood Loss (EBL), a method commonly used to visually estimate blood loss, is often very inaccurate and demands consistent training multiple times a year to be conducted properly. According to studies, visual estimations can underestimate blood loss by as much as 50%! Because blood clots, the resulting clumps can be left out of the measuring process. They can be weighed on the scale with the soaked linen or drapes. Using a scale can be a quick, easy way to quantify blood loss that offers high accuracy and needs very little training. Even blood spilled on the floor can be absorbed and weighed.

How are scales used to measure blood loss?

Blood bags, drapes or other materials soaked in blood are placed on the scale. The materials used to collect blood should all be tared or their weight must be subtracted as to not overestimate blood loss. Healthcare workers also must keep in mind that during certain operations (like labor), the lost fluids are not all blood (saline, for example), and that the placenta should not be counted for blood loss. Once the weight is obtained, cumulative volume is determined. 1 gram is roughly equal to 1 millimeter of blood loss. The formula is Wet Item Weight in Grams – Dry Weight in Grams = Milliliters of Blood Within the Item.

While this method is not exact, it's much more accurate and features a much lower error rate (about 15%, according to the Association of Women's Health, Obstetric and Neonatal Nurses).

Operation Room During Surgery

What kind of features are needed to measure blood?

A tare feature is useful and being able to preset a tare (or multiple, depending on how many containers are used) can save a lot of time since nurses won't have to manually subtract the dry weight. AWHONN suggests attaching a laminated card with dry weights on or near the scale if the scale does not include this feature.

The scale must be easy to wash. A lot of scales feature a grade 304 stainless steel pan, which are easy to wash and can handle chemicals. An IP rating of 65 or 66 can ensure the scale can be hosed down or sprayed with ease. Even if the scale is not used to measure blood loss, organs are often weighed and the scales must be cleaned frequently to help prevent contamination. Washdown scales like Adam Equipment's Gladiator can handle high capacities and demanding settings.

If the scale is used during labor, using a scale with a cradle can also allow nurses to weigh the newborn. Our MTB features a removable cradle for weighing babies. Other scales like our LBX can get an attachment to get a scoop or cradle in factory installation. If the baby is wrapped in blankets, the weight of the blanket must be tared.

Because results must be recorded in metric units, scales and balances must measure in metric units. The scales can have other units, but they must not be used for official weighings. The display must be clearly visible.

Don't hesitate to contact us if you need help finding the right scale for your healthcare practice.

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