Histopathological differentiation of drowning in freshwater and saltwater in rats: forensic point of view / Diferenciación histopatológica de ahogamiento en agua dulce y agua salada en ratas: punto de vista forense

SUMMARY: The postmortem diagnosis of death by drowning is one of the most difficult issues in forensic pathology. We investigated possible evidence differentiating saltwater drowning from freshwater drowning by histopathological changes in brain, heart, lungs, liver, and kidneys tissues. A cross section descriptive study was carried out on eighteen 12-week-old male Wistar rats; they were divided equally into 3 groups. Group 1: control group; Group 2: death by drowning in freshwater; Group 3: death by drowning in saltwater. Immediately after death, all tested organs were removed and fixed for histopathological examination. The brain of freshwater group depicted degenerated neurocytes with dystrophic changes in the form of shrunken cell, pyknotic nuclei and deeply eosinophilic cytoplasm. The heart showed clear evidence of myocyte injuries in saltwater drowning compared to the control and freshwater groups. The kidneys of rats drown in saltwater revealed more glomerular destruction with no differences in tubulo-interstitial changes in comparison with those drown in freshwater. In the lungs, the changes in freshwater were restricted to the alveoli, and the bronchial changes were more distinctive in saltwater. No disturbed liver architecture was seen in both test groups, however hydropic degeneration, congested vessels, and sinusoids were more distinct in saltwater group. In conclusion, diagnostic differentiation between fresh and saltwater drowning was reliable in rats' lungs and heart with minimal differentiation in liver, kidneys, and brain. Further studies of drowning with different staining techniques will help to clarify the potential role of histopathological changes in body organs as indicator of drowning.

RESUMEN: El diagnóstico post mortem de muerte por ahogamiento es uno de los temas más difíciles de la patología forense. Investigamos la posible evidencia que diferencia el ahogamiento en agua salada del ahogamiento en agua dulce por cambios histopatológicos en los tejidos del cerebro, el corazón, los pulmones, el hígado y los riñones. Se realizó un estudio descriptivo de corte transversal en dieciocho ratas Wistar macho de 12 semanas de edad; se dividieron por igual en 3 grupos. Grupo 1: grupo control; Grupo 2: muerte por ahogamiento en agua dulce; Grupo 3: muerte por ahogamiento en agua salada. Inmediatamente después de la muerte, se extirparon todos los órganos analizados y se fijaron para el examen histopatológico. El cerebro del grupo de agua dulce mostró neurocitos degenerados con cambios distróficos en forma de células encogidas, núcleos picnóticos y citoplasma profundamente eosinofílico. El corazón mostró una clara evidencia de lesiones de miocitos en los ahogamientos en agua salada en comparación con los grupos de control y de agua dulce. Los riñones de ratas ahogadas en agua salada revelaron una mayor destrucción glomerular sin diferencias en los cambios túbulo-intersticiales en comparación con las ahogadas en agua dulce. En los pulmones, los cambios en agua dulce se restringieron a los alvéolos y los cambios bronquiales fueron más distintivos en agua salada. No se observó una arquitectura hepática alterada en ambos grupos de prueba, sin embargo, la degeneración hidrópica, los vasos congestionados y los sinusoides fueron más distintos en el grupo de agua salada. En conclusión, la diferenciación diagnóstica entre ahogamiento en agua dulce y salada fue confiable en los pulmones y el corazón de las ratas con una diferenciación mínima en el hígado, los riñones y el cerebro. Estudios adicionales de ahogamiento con diferentes técnicas de tinción ayudarán a aclarar el papel potencial de los cambios histopatológicos en los órganos del cuerpo como indicador de ahogamiento.

Postmortem findings in Magellanic penguins (Spheniscus magellanicus) caught in a drift gillnet.

BACKGROUND: Penguin interaction with gillnets has been extensively reported in the Atlantic and Pacific Oceans, and is considered a major conservation threat. Among penguin species, Magellanic penguins (Spheniscus magellanicus) are currently considered of great concern, particularly in Brazil, where they are highly susceptible to gillnet bycatch. Nevertheless, information about drowning-associated microscopic findings in penguins is limited. RESULTS: We describe the anatomopathological findings of 20 Magellanic penguins that drowned after getting entangled in a drift gillnet while wintering along the Brazilian shelf and washed ashore still enmeshed in Santa Catarina, Brazil. All 20 birds (19 juveniles and 1 adult; 18 females and 2 males) were in good body condition. Major gross findings were abrasion, bruising, and local erythema and edema of the wings, multiorgan congestion, jugular vein engorgement, pulmonary edema and hemorrhage, splenomegaly and hepatomegaly, fluid in the trachea, serous bloody fluid in the lungs, gastrointestinal parasites (nematodes, cestodes and trematodes), and debris in the stomach. The most common histopathological findings were cerebral and pulmonary congestion, pulmonary edema, splenic histiocytosis, lymphoid splenic hyperplasia, acute splenitis, extramedullary hepatic hematopoiesis, and parasitic enteritis. Although unspecific, the observed multiorgan congestion and pulmonary edema are consistent with previous reports of drowning in birds and may be indicative of this process. CONCLUSIONS: Drowning may be a challenging diagnosis (e.g., carcass decomposition, predation), but must be considered as a differential in all beach-cast seabird postmortem examinations. To the authors' knowledge this is the largest anatomopathological study based on microscopic examination in drowned penguins.

Lesions associated with drowning in bycaught penguins.

Fisheries bycatch, the incidental mortality that occurs as a result of entanglement in fishing gear, is an important conservation threat to penguins and other seabirds. Identification of entanglement and drowning in beach-cast carcasses of seabirds remains a challenge, as it is still unclear what lesions are to be expected in a bycaught seabird. We necropsied 2 Magellanic penguins Spheniscus magellanicus that were entangled and drowned in gillnets. Marked distension of the lungs with foamy red fluid and marked oedema of the dorsal visceral pleura were prominent lesions consistent with those described in cases of 'wet drowning' in humans. On the other hand, the air sacs contained very small quantities of liquid, suggesting that absence of water in the air sacs might not be a reliable sign to exclude drowning. Other relevant findings included cutaneous lacerations and bruising in one bird and cervical and pectoral rhabdomyolysis in both birds. While cutaneous or subcutaneous hematomas may be an indication of bycatch, especially if linear or cross-linear patterns consistent with fishing nets are present, these lesions might not always be discernible and their absence does not suffice to exclude the possibility of entanglement in fishing nets. Additionally, our findings suggest that the histological examination of skeletal muscles, particularly of the neck, may provide additional clues to corroborate the diagnosis of drowning in penguins.

Use of the histopathology in the differential diagnosis of drowning in fresh and salty water: an experimental model establishment in rats.

PURPOSE: To develop a method of differential diagnosis to drowning, due to analysis of the alveolar macrophages quantitative, in rats submitted to induced drowning in fresh water and salty water. METHODS: Were used 15 male adult rats Wistar EPM-1, weight 360g (SD=21,3), randomized in three groups: G1--Control; G2--Fresh water; G3--Salty water, each one with n=5. The animals have been anesthetized and tracheostomized to insert a cannula inside the trachea, for drowning induction. The lungs have been removed, weighed, prepared for histology and colored by immunohistochemistry. The macrophages have been counted in both lungs (right and left) of each animal. The statistical test used was ANOVA (SPSS.10) with p<0,05. RESULTS: The amount of macrophages was G3>G2>G1 with p=0,0001 in each comparison. The weight of lungs of G3 and G2 was higher than G1, with p>0,0001, however G3 and G2 do not possess difference statistics in the weight of lungs. CONCLUSION: The developed diagnostic method was efficient in rats. The results, if expanded, will be able to assist the Forensic Pathology for technique of low cost and high trustworthiness.

Morphologic determinants of asphyxia in lungs: a semiquantitative study in forensic autopsies.

Asphyxia is a name given to different kinds of lesions that can produce similar histologic findings. Thus, because of the varied nature of the different kinds of lesions, as well as the incidence of similar qualitative histologic findings with different causes, the aim of this work was to study special kinds of injuries with particular subsequent impairment. These include some diagnostic problems of sudden death of natural causes, including aspiration, suffocation, drowning, and strangulation. Ranking was made of 167 victims based on the diagnosis as having: aspiration (n = 35), suffocation (n = 88), drowning (n = 27), and strangulation (n = 17). Stepwise discriminant analysis of the resulting data showed that lung necropsies from victims of these four events could be distinguished from one another. Statistical differences among the four groups were observed for eight morphologic parameters. A robust discriminant function permitted an adequate classification of the four groups of disease in 85.03% of the cases. Lung autopsies with congestion, septal hemorrhage, and foreign body showed a specificity of 100% for victims of aspiration, whereas ductal overinsufflation, interstitial edema, and bronchiolar constriction showed a specificity of 81.8% in victims of suffocation. Intraalveolar edema and dilatation of the alveolar spaces with secondary compression of the septal capillaries characterized drowning. Victims of strangulation showed a strong alveolar hemorrhage, with alveolar collapse and overinsufflation, associated with bronchiolar dilatation. It is concluded that semiquantitative analysis of lung autopsies might be a useful supplementary histologic criterion to support the diagnosis of asphyxia.