Measurement of Blood Loss: Review of the Literature
Mavis N. Schorn, CNM, PhD
Mavis N. Schorn, CNM, PhD
Abstract
It is important to recognize excessive blood loss during childbirth, which is a significant cause of morbidity and mortality. This article reviews methods to measure blood loss that could be used during childbirth. PubMed, CINAHL, and MEDLINE databases were searched using the phrases "blood loss" and "measurement." The bibliographies of publications were scanned for applicable references. A total of 46 publications are included in this review. The methods used to measure blood loss are categorized into visual estimation, direct measurement, gravimetric, photometry, and miscellaneous. Methods are described and compared. A combination of direct measurement and gravimetric methods are the most practical. Photometry is the most precise, but also the most expensive and complex to use. A variety of miscellaneous methods are presented, but none is a practical or reliable method. Visual estimation of blood loss is so inaccurate that its continued use in practice is questionable and it should not be used in research to evaluate treatment.
It is important to recognize excessive blood loss during childbirth, which is a significant cause of morbidity and mortality. This article reviews methods to measure blood loss that could be used during childbirth. PubMed, CINAHL, and MEDLINE databases were searched using the phrases "blood loss" and "measurement." The bibliographies of publications were scanned for applicable references. A total of 46 publications are included in this review. The methods used to measure blood loss are categorized into visual estimation, direct measurement, gravimetric, photometry, and miscellaneous. Methods are described and compared. A combination of direct measurement and gravimetric methods are the most practical. Photometry is the most precise, but also the most expensive and complex to use. A variety of miscellaneous methods are presented, but none is a practical or reliable method. Visual estimation of blood loss is so inaccurate that its continued use in practice is questionable and it should not be used in research to evaluate treatment.
Introduction
Excessive blood loss during childbirth and the resultant morbidity and mortality is a problem that has occurred throughout history. Williams[1] made reference to researchers who attempted to quantify blood loss during childbirth in the late 1800s. Today, hemorrhage continues to be one of the leading causes of maternal mortality in the United States[2] and around the world. Obstetric care has changed in an attempt to decrease blood loss, yet postpartum hemorrhage (PPH) still confounds and alarms birth attendants because of the rapidity of its onset and danger it represents if uncontrolled.
Most blood loss related to childbirth occurs within the first hour after birth, and the most frequent cause of hemorrhage is early postpartum uterine atony. For a vaginal birth, hemorrhage is considered a blood loss of > 500 mL. In clinical practice, the amount of blood lost during childbirth is typically visually estimated by the birth attendant. Even with repetitive studies identifying the limitations and inaccuracies of estimation, it is the easiest and most common method of quickly gauging blood loss. Research has been focused on determining the amount of blood loss that is normal, identifying the frequency of PPH, identifying those women who require intervention for excessive blood loss, evaluating intervention strategies to ameliorate blood loss thereby preventing PPH, and evaluating treatment methods for PPH. The accurate measurement of blood loss iscritical for these research purposes.
The purpose of this article is to present a review of methods to measure blood loss that can be used during a vaginal birth. PubMed, CINAHL, and MEDLINE databases were searched without date limits. The phrases "blood loss" and "measurement" were used in combination to find articles specific to measuring blood loss. The bibliographies of publications were scanned for applicable references. Articles in languages other than English were omitted. Articles that applied the measurement to intervention effectiveness were not included. Reviews were not restricted to measurement of blood loss at childbirth or only to human blood loss because the focus was on blood measurement methods. Simulation, human, and animal research was included. Forty-six publications were included in this review (Table 1). Methods of measuring blood loss were divided into five categories: visual estimation, direct measurement, gravimetric, photometry, and miscellaneous methods. Each of these methods is described along with its strengths and weaknesses.
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Excessive blood loss during childbirth and the resultant morbidity and mortality is a problem that has occurred throughout history. Williams[1] made reference to researchers who attempted to quantify blood loss during childbirth in the late 1800s. Today, hemorrhage continues to be one of the leading causes of maternal mortality in the United States[2] and around the world. Obstetric care has changed in an attempt to decrease blood loss, yet postpartum hemorrhage (PPH) still confounds and alarms birth attendants because of the rapidity of its onset and danger it represents if uncontrolled.
Most blood loss related to childbirth occurs within the first hour after birth, and the most frequent cause of hemorrhage is early postpartum uterine atony. For a vaginal birth, hemorrhage is considered a blood loss of > 500 mL. In clinical practice, the amount of blood lost during childbirth is typically visually estimated by the birth attendant. Even with repetitive studies identifying the limitations and inaccuracies of estimation, it is the easiest and most common method of quickly gauging blood loss. Research has been focused on determining the amount of blood loss that is normal, identifying the frequency of PPH, identifying those women who require intervention for excessive blood loss, evaluating intervention strategies to ameliorate blood loss thereby preventing PPH, and evaluating treatment methods for PPH. The accurate measurement of blood loss iscritical for these research purposes.
The purpose of this article is to present a review of methods to measure blood loss that can be used during a vaginal birth. PubMed, CINAHL, and MEDLINE databases were searched without date limits. The phrases "blood loss" and "measurement" were used in combination to find articles specific to measuring blood loss. The bibliographies of publications were scanned for applicable references. Articles in languages other than English were omitted. Articles that applied the measurement to intervention effectiveness were not included. Reviews were not restricted to measurement of blood loss at childbirth or only to human blood loss because the focus was on blood measurement methods. Simulation, human, and animal research was included. Forty-six publications were included in this review (Table 1). Methods of measuring blood loss were divided into five categories: visual estimation, direct measurement, gravimetric, photometry, and miscellaneous methods. Each of these methods is described along with its strengths and weaknesses.
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yes, I agree that visual estimating would be different and vary from one to another person. So, whatever the method might be better than just visual measuring.