Relative blood loss in forensic medicine\u2014do we need a change in doctrine?

Stefan Potente,Mattias Kettner,Patrick Sauer,Peter Schmidt,Frank Ramsthaler

doi:10.1007/s00414-020-02260-w

Stefan Potente, Mattias Kettner + Show 3 more

Open Access

https://doi.org/10.1007/s00414-020-02260-w

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Abstract

In forensic medicine, blood loss is encountered frequently, either as a cause of death or as a contributing factor. Here, risk to life and lethality assessment is based on the concept of relative blood loss (absolute loss out of total volume). In emergency medicine, the Advanced Trauma Life Support (ATLSⓇ) classification also refers to relative blood loss. We tested the validity of relative blood loss benchmarks with reference to lethality. Depending on the quality of the total blood volume (TBV) estimation formula, relative blood loss rates should be reflected in the case cohort as significantly higher absolute blood loss in heavier individuals since all TBV estimation formulas positively correlate body weight with TBV. Method: 80 autopsy cases with sudden, quantifiable, exclusively internal blood loss were retrospectively analyzed and a total of 8 different formulas for TBV estimation were applied. Results: No statistical correlation between body weight and absolute blood loss was found for any of the tested TBV estimation algorithms. All cases showed a wide spread of both absolute and relative blood loss. Discussion: The principle of relative blood loss is of very limited use in casework. It opens the forensic expert opinion to unnecessary criticism and possible negative legal implications. Conclusion: We challenge the use of relative blood loss benchmarks in textbooks and practical casework and advocate for its elimination from the ATLSⓇ ’s grading system. If necessary, we recommend the use of BMI-adjusted algorithms for TBV estimation.

Highlights

Lethality and relative blood loss in forensic medicineBlood loss is a frequent finding in routine forensic pathology case work
Autopsy reports from the forensic medicine departments of the University of Saarland Medical School in Homburg/Saar and the Goethe University Frankfurt Medical School in Frankfurt/Main were retrospectively screened for ‘bleeding to death’, exsanguination, haemorrhagic shock and hypovolemic shock as cause of death
The absolute blood loss found at autopsy ranged from 660 ml up to 3800 ml (2 outliers, see ‘Discussion’)

Summary

Introduction

Lethality and relative blood loss in forensic medicine. Blood loss is a frequent finding in routine forensic pathology case work. It may constitute a genuine cause of death (in 5 to 10% of forensic autopsies, according to [1]) or a contributing factor tovadjust another primary cause of death. As referenced in different textbooks, relates lethality and risk of death to the relative blood loss (blood lost out of total blood volume). A relative blood loss of more than 33%. Other authors have described relative blood loss percentages 66%’. In addition to absolute and relative loss, internal blood loss with collection of blood in cavities and defined spaces may cause compressive mechanical effects, such as in the skull, the pericardial sac or the thoracic cavity [6]

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Conclusion