Post-mortem evaluation of drowning with whole body CT

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Highlights

Abstract

Purpose

The aim of this study is to investigate the value of whole body computed tomography (WB-CT) in bodies recovered from water by analysis of the imaging findings after drowning.

Methods

The bodies of 41 drowning victims and 9 persons who died from mechanical asphyxia by hanging underwent post-mortem whole body computed tomography.

Results and conclusions

Excessive fluid in the paranasal sinuses (98%), nasal pharynx (98%), oropharynx (95%), trachea (83%), ground glass opacities in the lung (89%), pleural fluid (71%), pericardial fluid (59%), esophageal fluid (81%), stomach fluid and distension (71%), duodenal (34%) and jejunal distension (31%) were the most frequent drowning related imaging findings which significantly differed from the group of mechanical asphyxia by hanging. In cases of fresh water drowning hemodilution was present in 79%. New and up to now unpublished findings were lower density in the spleen, indicative for hemodilution and detection of a pronounced amount of pericardial fluid, only seen in drowning victims.

Introduction

The debut of radiology in forensic medicine dates back from the late 19th century, when radiography made its first appearance in the court room [2]. In the last few decades, techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) opened up a whole new range of possibilities to determine cause of death, to provide information in the identification of bodies or the discovering of previous medical conditions. To date, some causes of death are still difficult to determine, in particular when a body is found in water. The key question remains if the individual was dead before entering the water or if “true drowning” was the cause of death [19].

Whether drowning occurs in a suicide attempt, by accident or in relation to an intentional act (such as pushing), the pathophysiology of drowning is a complicated process where different steps can take place: such as breath holding, CO2 accumulation and water aspiration [8], [19]. Depending on the drowning medium, fresh or salt water, a variety of physiological alterations appear such as bronchospasms, electrolyte changes. Another phenomenon is the surfactant deficiency where both fresh and – to a lesser degree – seawater, induces alveolar instability and permeability, resulting in pulmonary edema [8]. Aspiration of seawater leads to an increase in the volume of fluid within the air spaces of the lungs [8]. Additionally the hypertonic seawater pulls fluid from the circulation into the lungs [8]. Hypotonic fresh water causes a massive absorption of water through the alveolar membrane, with an increase in blood volume and hemodilution within minutes. This hemodilution can be visible on CT images as a reduction in blood density [1]. Seawater, on the other hand, causes a hypovolemia and hemoconcentration [8].

In addition, referring to the effects of the different types of drowning medium, even though the majority of drownings are so-called “wet drownings”, approximately 10% of drowning cases happens without fluid aspiration, the so-called “dry drownings” [3]. Furthermore, the post-mortem interval between drowning and the recovery of the body, influences the external examination and autopsy findings. During agony and in the early post-mortem period, a plume of froth can be visible around nose and mouth, but it is rather transient and can even be absent or washed away when the body was discovered [14], [17]. Other external findings such as skin maceration or cutis anserina are mere signs of immersion, than proof of a vital drowning [14]. By internal examination, rather non-specific findings can be present: frothy fluid in the airways, pleural fluid, emphysema aquosum (hyperexpansion of the lungs [8]), froth or foreign material in airways or the digestive system [12], [19], [20]. To date, the gold standard to substantiate “true drowning” remains diatom investigation, although certain critics and technical difficulties need to be taken into account [14]. Detection of chemical substances (found in water) in the blood of drowned victims, such as strontium and other markers has also been done, but is nevertheless also endowed with difficulties [15], [16].

Previous studies on post-mortem computed tomography imaging were conducted on groups ranging from 6 to 39 drowning subjects [1], [6]. In maxillary and sphenoidal sinuses, fluid was present in up to 100% of the drowning cases, in the frontal sinus in 70% to 100% and 80% to 100% had ethmoidal fluid [3], [11]. In the paranasal sinuses of eleven deaths by asphyxiation (by another manner than submersion in liquid), fluid was present in 78% [18]. Levy et al. found fluid in mastoid air cells in 100% of drowning victims [11].

Up to 93% had fluid in trachea and main bronchi and in 50% there was high-attenuation sediment in trachea or main bronchi [11]. In the lungs the most common finding was the presence of ground glass opacities (GGO), in a mosaic pattern of hypoperfused and hyperperfused lung areas [3], [9], [11], [18]. Pleural effusions were found in approximately 70% of drowning subjects [3], [11]. The position of the diaphragmatic dome of drowning subjects is at an average level of the fifth anterior rib, which is lower than in control groups, [3], [18].

When the density of cardiac chambers was measured, some studies found a lower density, others found a higher density than in their control group [1], [3], [18]. In drowning victims the average density of the stomach content was 20 Hounsfield units (HU) and up to 90% had a duodenal distension [3].

Section snippets

Study cases

We retrospectively reviewed 50 cases which had undergone post-mortem CT between January 2009 and July 2014. Forty-one of the cases, were bodies retrieved from water; 28 males and 13 females. The mean age at death was 58 years, ranging from 15 to 90 years. The majority of the bodies were usually found in fresh water (37 cases), 4 cases were found in seawater. In 11 of these 41 cases, an autopsy was performed, an additional toxicological analysis was performed in 20 external examinations and in

Sinuses

Up to 98% of the drowning subjects had fluid in the maxillary and ethmoidal sinuses, 88% in the sphenoidal and 83% in the frontal sinuses (Fig. 1). There was one case where fluid was absent in all of the paranasal sinuses. In 37% of the subjects more than 50% of the volume of the maxillary sinuses was filled with fluid, in all other cases this was less than 50%. None of the control cases presented with fluid in the paranasal sinuses, which was a significant difference (for all sinuses p < 0.001

Head – respiratory system

The results of our study using computed tomography to investigate drowning cases confirm the presence of fluid in sinuses and trachea, which is in accordance with literature findings [3], [6], [9], [11], [18]. None of the control cases had fluid in the paranasal sinuses or trachea, which can be explained by the fact that in hanging victims there is no exposure to water. Ideally true controls should be the submersed hanging controls, which of course are ethically not justified. The mean density

Ethical standards

This study was approved by the ethics board of our institution and was carried out in accordance with existing ethical laws and rules (Ref. B67020085151 and B670201420557). An informed consent was not required for this study.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Acknowledgements

We thank Brecht Houthoofd and Thomas De Groote for technical assistance to perform this study.

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