Postmortem Characteristics of Drowning Death in Freshwater: A Systematic Review

Abstract

Background: Drowning is the third leading cause of death by unintentional injury, accounting for 7% of all injury-related deaths worldwide. The latest World Health Organization Global Health Estimates estimate that 236,000 people died from drowning in 2019.

Objective: This study used a systematic review to examine the clinical, laboratory, and other postmortem characteristics associated with death from drowning in freshwater areas.

Method: A systematic search of PubMed, Epistemonikos, and Cochrane Library databases was performed with no restrictions to find relevant literature. After removal of duplicates, articles were reviewed, and information on clinical, laboratory, and other postmortem characteristics of freshwater drowning deaths was extracted.

Result: Of 493 articles found, 73 papers were considered relevant for full-text review. Of these, 22 articles met the inclusion criteria for the review. Most of the drowning deaths occurred in fresh water and only one case was described as a drowning in a freshwater area. Victims were male, with a male-to-female ratio of 8:3. External clinical characteristics that were found only in the freshwater drowning case were washerwoman's hand and pink teeth. Internal clinical findings unique to the freshwater drowning case were debris in the airways and Neil’s sign.

Conclusion: Our study suggests that washerwoman's hand, pink teeth, debris in airways, and Neil’s sign are associated with drowning death in freshwater areas.

Full Text

Introduction

Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid and is essentially a death by asphyxia.¹ Complete submersion is not necessary for drowning; submersion of only the nose and mouth for a sufficient period can result in death. The latest World Health Organization Global Health Estimates indicate that 236,000 people died from drowning in 2019. Drowning is the third leading cause of unintentional injury death, accounting for 7% of all injury-related deaths worldwide.²

 

Drowning deaths often occur during water recreational activities such as swimming, bathing, and boating, as well as in accidents with motor vehicles. Suicide is another common cause of drowning and is often related to known psychiatric illness. In addition, diseases such as epilepsy may play a role in drowning, and alcohol and drugs are often factors.³

 

Mortality rates from drowning are higher in low-income countries. While drowning often occurs in swimming pools in high-income countries, it is more common in natural bodies of water such as ponds, ditches, rivers, lakes, drains, sumps, and water behind dams in low-middle-income countries. Lack of awareness of water safety, risky behavior around water, and low perceived risk are also considered to be important factors.⁴

 

A postmortem diagnosis of drowning has been described in the literature as one of the most difficult in forensic medicine.⁵ Findings from the external examination and autopsy are non-specific in most cases, and the interpretation of laboratory findings remains under debate in the scientific community.^6,7 Investigating deaths associated with natural bodies of water such as lakes, rivers, and oceans can be particularly challenging due to their constantly changing character. It is also important to recognize that not all water-related deaths are drownings; other factors such as extreme water and weather conditions, drug or alcohol intoxication, or disease may be sufficient to cause death and thus preclude a postmortem finding of drowning.⁸ A finding of death by drowning may be reached only after reviewing all external, internal, and laboratory findings from the forensic examination.⁷

 

There are not many studies that discuss drowning in freshwater areas.⁹ Because of that in this study, we aimed to review and characterize the clinical, laboratory, and other postmortem findings typical of drowning death in freshwater areas.

Method

We performed a systematic review of the medical literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement Guidelines for the identification, screening, and inclusion of articles (Figure 1). A database search of PubMed, Epistemonikos, and the Cochrane Library was conducted on 12 July 2022 by three of the authors. The search terms were “drowning death” or “death drowning” with no database restrictions. While we did not apply any restrictions on publication type, status, language, or publication period in our search, papers in languages other than English and animal studies were excluded. Letters, editorials, reviews, and systematic reviews or meta-analyses were also excluded.

 

Three reviewers screened the identified articles based on evaluation of the titles and abstracts. If the title and abstract of the article did not meet the inclusion criteria, the article was excluded. Differences of opinion between the three reviewers regarding the inclusion of articles were discussed until agreement was reached. After the first screening, the full text of the articles was reviewed for a final assessment of eligibility for inclusion in the study.

 

During the final assessment, articles were evaluated based on the level of evidence, quality, and risk of bias. The quality of articles was evaluated using the Joanna Briggs Institute Critical Appraisal, which was used to categorize each paper as include, exclude, or need information. Only those articles categorized as include were analyzed and reported here. Following screening, feasibility, and assessment of quality and risk of bias, data were extracted from all included articles. Important findings from each article were recorded and the data was synthesized. Data extraction was carried out by three independent authors, and all extracted results were cross-checked. The extracted data included 1) clinical postmortem findings, 2) laboratory postmortem findings, and 3) other postmortem findings on death from drowning in a freshwater area.

result

The systematic database search revealed 493 papers after duplicates were removed. Following a review of the papers by title and abstract, 73 papers underwent full-text review. A total of 51 papers were excluded after full-text review, leaving 22 articles that met the inclusion criteria for the review (Figure 1).

 

Most of the drownings occurred in fresh water and only one case was a drowning in a freshwater area. Most of the victims were male, with a male-to-female ratio of 8:3. Body decomposition was the most common external clinical finding in fresh water, salt water, and freshwater drownings, while the most common internal clinical findings were froth in the airway, emphysema aquosum, paltauf spot and water and debris in the stomach. Diatoms were detected in most drowning cases. In addition, bilateral pleural effusion and emphysema aquosum were the most common findings on postmortem computed tomography (CT) scans in all cases. Pulmonary edema was the most common histological finding.

 

External clinical findings that were reported only in the freshwater drowning victim were washerwoman's hand and pink teeth, while the internal clinical findings unique to the freshwater drowning were debris in the airways and Neil’s sign.

 

In drowning in salt water, no studies report the characteristics of external findings. However, regarding the characteristics of internal findings, a study reports the presence of deposited seawater component elements on enamel and increased adhesion of phytoplankton to the enamel surface. Besides that, bilateral pleural effusion and lung edema were also found in some studies. If we look at the size of the bilateral pleural effusion, drowning in salt water has a more significant bilateral pleural effusion than drowning in fresh water. Moreover, saltwater drowning has more significant lung and intrathoracic weight than freshwater drowning.

 

In drowning in fresh water, the most common external characteristic reported was froth exuding from the nostril. However, other findings, such as skin abrasion and cyanosis of the lips and bilateral fingernails, are also found in cases of drowning in fresh water. Meanwhile, internal characteristics such as the Svechnikov sign, respiratory muscle hemorrhage, froth in the airway, Wydler sign, pericardial effusion, and heart dilatation were often found in drowning in fresh water.

discussion

Recently, the role of the forensic pathologist has expanded beyond criminal justice to include public health and safety. Forensic pathologists are in a unique position to clarify the cause and manner of sudden unexpected death.¹⁸ Drowning is a significant and neglected public health problem worldwide.¹ The mechanism of death by drowning is complicated by the involvement of asphyxia and filling of the airways with fluid, with associated hydrostatic and osmotic effects. As a result, although autopsy findings among drowning cases are usually characteristic, they are often not diagnostic.⁴

 

This study described rates of drowning death that were higher in men than women. The higher incidence in males is likely due to increased exposure to risky situations, increased risk-taking behavior, and greater involvement in activities outside the home.⁴

 

Decomposition involves two processes, autolysis (destruction of cells and organs by intracellular enzymes) and putrefaction caused by bacteria and fermentation. Decomposition begins approximately 24 hours after death, showing as a greenish color in the lower right abdomen. It gradually becomes more visible, spreads across the abdomen and chest, and causes a foul smell. According to Casper’s law of decomposition, the environment where the body is left affects the decay process such that the proportional rate of decomposition in air, water, and soil is 1:2:8.⁷

 

Froth in the airways was a commonly reported finding in external and internal examinations of drowning victims. In the forensic literature, the frequency of frothy liquid and foam in the airways is 13.5–40%. It is caused by the mechanical action of terminal respiratory efforts on the mixture of residual intrapulmonary air, intrapulmonary drowning, and edema. Extravasated blood from alveolar capillary rupture is the likely source of the pink or red-tinged froth noted on examination.⁸

 

Emphysema aquosum has frequently been highlighted in forensic literature as an important sign of drowning, and the correct interpretation of the accompanying lung changes is important. Under certain circumstances, lung changes have been misinterpreted as emphysema aquosum. Hyperinflated lungs often contain additional edematous fluid, which can also be observed in cases of left heart failure, intoxication, or following prolonged resuscitation. Furthermore, many elderly deceased people have evidence of emphysematous lung changes, which must be distinguished from emphysema aquosum.¹⁵

 

Paltauf’s spot was the spots of bleeding that occurs due to increased pressure, leading to rupture of the alveolar walls, mostly found on the anterior surface and border of the lung, but can also be found in the subpleural if there has been further leakage or rupture.⁷

 

Diatoms are unicellular algae belonging to the class of bacillariophycae which includes more than 15,000 species living in fresh, brackish, or sea water. Diatoms are inhaled during drowning and once in the bloodstream, they can reach the organs. If extracted and identified using strict protocols, these organisms are good markers of death by drowning.

 

Recent advances in forensic radiology include postmortem imaging using CT and magnetic resonance imaging (MRI), which provide non-invasive methods to detect bone and visceral lesions (virtual autopsy) as well as ways to analyze the status of viscera before autopsy. Postmortem CT is especially useful for investigating air/gas distribution and content in body cavities and viscera, providing quantitative data to reinforce autopsy findings.²¹ Moreover, histological examination must be performed on all non-putrefied organs to differentiate between drowning and other causes of death.⁶

Washerwoman’s hand is a condition involving pallor with wrinkling of the palms, soles, fingers, and toes. These changes result from dermal absorption of water apparent at the fingertips. Although washerwoman’s hand can appear as little as 20–30 minutes after immersion/submersion, it can slowly disappear upon exposure to the open air and may not be apparent at autopsy. In a forensic pathology context, pink teeth have often been observed in drowning victims. The reddish discoloration of the teeth involves the diffusion of blood into the pulp in the dentinal tubules. Environmental conditions, particularly humidity, play an essential role in the development of pink teeth.⁷

 

Neil’s sign is a black field that forms due to bleeding into the middle ear cavity and blood adherence to the mastoid process; it is likely caused by pressure changes during drowning. Bleeding points found on the mucous membranes of the mastoid bone and middle ear are strong indications of drowning.⁷ In a body recovered from natural water environment, aquatic debris such as silt, mud, sand, gravel, vegetation, or algae may adhere to the airways and stomach.

Conclusion

In conclusion, our study suggests that characteristics associated with drowning death were washerwoman's hand, pink teeth, debris in the airways, and Neil’s sign. Other common findings in drowning deaths were froth in the airway, emphysema aquosum, paltauf spot, water and debris in the stomach, and the presence of diatoms. Identifying key clinical, laboratory, and other postmortem characteristics should help forensic pathologists to recognize and diagnose drowning death.

Additional information

Funding. This study is supported by Universitas Lambung Mangkurat DIPA Funding Allocation No SP- DIPA – 023.17.2.677518/2023 through the “Program Dosen Wajib Meneliti” program on 2023 with the ID number 615/UN8/PG/2023

Conflict of interest. The authors declare that they have no competing interests.

Contribution of authors. "All of the authors read and approved the final version of the manuscript before publication, agreed to be responsible for all aspects of the work, implying proper examination and resolution of issues relating to the accuracy or integrity of any part of the work".

Acknowledgment. Thank those whose contributions to the writing of the manuscript were insufficient to be recognized as authors (e.g., they met only three of the four criteria for authorship), but are still considered significant by authors. Specify what was this person’ impact (advises, technical assistance, translation, etc.)