Electrolyte analysis of pleural effusion as an indicator of drowning in seawater
Yosuke Usumoto MD (Postgraduate Student)
, Naomi Sameshima ABc (Research Technician)
Wakako Hikiji MD (Postgraduate Student)
, Akiko Tsuji PhD (Assistant Professor)
Keiko Kudo PhD (Assistant Professor)
, Hiromasa Inoue MD, PhD (Associate Professor)
Noriaki Ikeda MD, PhD (Professor)
Department of Forensic Pathology and Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
Department of Forensic Medicine and Sciences, Institute of Social and Environmental Medicine, Mie University Graduate School of Medicine, Edobashi 2-174, Tsu, Mie 514-8507,
Received 10 June 2008
Received in revised form 2 October 2008
Accepted 23 December 2008
Available online 31 January 2009
It is important for forensic pathologists to determine the diagnosis of drowning as well as the site of
drowning. In a previous study, we propose that analysis of electrolytes in pleural effusion from rats
may be useful for determining whether drowning has occurred in seawater or freshwater. To test this
proposal, we measured the concentration of sodium, potassium and chloride ions and total protein in
pleural effusion from 40 autopsy cases: 24 involving seawater drowning, 9 freshwater drowning and 7
no drowning. The concentrations of sodium and chloride ions in pleural effusion showed a signiﬁcant dif-
ference between seawater drowning and freshwater drowning. The concentration of potassium ions and
total protein showed no difference between each group, although they increased in proportion to the
postmortem interval in cases of both seawater and freshwater drowning. These results are almost same
as our previous study and, thus, the quantitative analysis of electrolytes in pleural effusion may be useful
for determining whether drowning has occurred in seawater or freshwater.
Ó 2008 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
Drowning is one of the most frequent causes of accidental death
in the world, especially in children.
It is important for forensic
pathologists to determine the cause of death when victims are
recovered from water.
If the cause of death is determined as
drowning, it is also important to specify where the body had
drowned. To obtain clues about the site of drowning, many exam-
inations have been carried out, such as diatom analysis, blood ﬂuo-
ride concentration and the use of immunohistochemical and
molecular biological techniques.
The methodologies used in
these studies are useful, however, these require special techniques
It is well known that pleural effusion is often present within the
thoracic cavities of a drowned body.
According to some investiga-
tors, pleural effusion more likely occurs if the individual has
drowned in seawater rather than in freshwater
and, thus, a
comparison of the amount of pleural ﬂuid might be used to deter-
mine the site of drowning.
Instead of the volume of pleural effusion, we focused on the dif-
ference in the character of the pleural effusion between seawater
drowning and freshwater drowning, and found that the concentra-
tion of electrolytes in pleural effusion correlated with that in the
drowning medium in rat experiments. Also, we proposed the use-
fulness of analyzing electrolytes in pleural effusion to determine
the site of drowning.
The purpose of this prospective study is to examine the useful-
ness of our simple approach by analyzing concentrations of elec-
trolytes in pleural effusion in our autopsy cases.
2. Subjects and methods
Cases of cadavers with over 20 ml pleural effusion in the tho-
racic cavity were selected together with information on the age,
sex, cause of death, postmortem interval and autopsy ﬁndings from
the forensic autopsies performed at Kyushu University between
2003 and 2007. Of the 44 forensic autopsy cases with over 20 ml
pleural effusion, 37 cases were diagnosed as drowning after careful
consideration involving several ﬁndings, such as detection of dia-
toms, pulmonary emphysema and edema, Paltauf’s spots and froth
1752-928X/$ - see front matter Ó 2008 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
* Corresponding author. Tel.: +81 92 642 6124; fax: +81 92 642 6126.
E-mail address: firstname.lastname@example.org (N. Ikeda).
Journal of Forensic and Legal Medicine 16 (2009) 321–324
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