Acute poisoning is a significant public health concern worldwide, contributing to substantial morbidity and mortality. The epidemiology of acute poisoning is diverse and influenced by socioeconomic factors, cultural practices, and regional variations in the availability of toxic agents.

Poisons have fascinated humanity since ancient times, and their systematic study dates back to the 16th century. Traditionally, arsenic has been a common choice for homicide, while opium has often been associated with suicide. However, there has been a troubling increase in the use of organophosphorus insecticides for suicidal purposes. In India, the relative ease of access to poisons, whether naturally occurring or commercially available, results in a higher incidence of poisoning cases compared to Western countries [1]. For instance, the reported mortality from snake bites in India exceeds 15,000 annually [2], and the World Health Organization (WHO) has noted rising rates of snakebite deaths in India and Sri Lanka, particularly in areas where large forests have been cleared for hydroelectric projects or highways [3]. In forensic medicine and toxicology, it is essential to understand the patterns, mechanisms, and outcomes of poisoning for accurate cause-of-death determinations and prevention strategies. Autopsy examinations play a crucial role in cases of suspected poisoning by providing vital insights into the pathological effects of toxic substances on the human body. A detailed evaluation of autopsy findings paired with toxicological analyses helps identify the poison, the mode of exposure, and underlying contributing factors. This information aids not only in medicolegal investigations but also in understanding poisoning trends and developing effective public health interventions.

Various external and internal post-mortem findings can be key indicators for identifying acute poisoning cases and ruling out other causes of death. Therefore, it is critical to firmly establish these factors. This study aims to examine the characteristic external and internal post-mortem examination findings in cases of acute poisoning, which is essential for recognizing poisoning as a cause of death. The identification of poisoning is particularly important for medical jurists, whose responsibility is to help uncover the perpetrator. The results of this study will assist medical officers in recognizing common external and internal post-mortem findings in acute poisoning cases, which, in turn, will support the judiciary in delivering appropriate justice. This study will focus on the autopsy findings in cases of acute poisoning, aiming to identify common toxic agents, patterns of organ involvement, and their correlation with clinical history and circumstantial evidence. The findings will enhance the knowledge base in forensic toxicology and contribute to improved diagnostic accuracy and preventive measures

This hospital-based prospective cross-sectional study was carried out over a period of one-year duration from date 01/01/2023 to 31/12/2023 in the Department of Forensic Medicine and Toxicology, Sri Krishna Medical College and Hospital, Muzaffarpur, Bihar, India, which is a tertiary care teaching hospital chiefly catering to the demands of rural area of Muzaffarpur, and adjacent districts of Bihar.  

Inclusion Criteria:

1. Cases of Acute Poisoning: The study included all cases where acute poisoning was suspected or confirmed based on clinical history, circumstantial evidence, or toxicological findings.
2. Cases Referred for Postmortem Examination: Only cases referred to the forensic department for a detailed postmortem evaluation were considered.
3. Brought in Deceased or Died During Treatment: Cases where individuals were either declared dead upon arrival or succumbed to the effects of poisoning while undergoing medical treatment were included.
4. History of Acute Poisoning: Individuals with documented or strongly suspected ingestion, inhalation, injection, or dermal exposure to toxic substances were included.
5. Bites and Stings: Cases involving acute poisoning resulting from known or unknown bites and stings, such as those caused by venomous animals or insects, were part of the study.

Exclusion Criteria:

1. Chronic Poisoning: Cases with a history of prolonged exposure to toxic agents, leading to chronic poisoning, were excluded to maintain focus on acute presentations.
2. Brought in Dead without History of Poisoning: Cases where individuals were brought in deceased, and no clinical, circumstantial, or toxicological evidence suggested acute poisoning, were excluded.
3. Non-Poisoning-Related Bites and Stings: Cases involving bites and stings where the death was due to non-toxic effects, such as anaphylaxis or secondary infections, without direct toxicological involvement, were excluded.
4. Unconfirmed Cases: Cases lacking definitive evidence or clinical history suggestive of acute poisoning, despite being referred for postmortem, were not considered for the study.

A comprehensive proforma for the study was created, which documented both the external and internal findings from the postmortem examination. The external findings comprised the presence of odor from the mouth, froth or secretions around the mouth and nostrils, stains around the lips and nostrils, cyanosis, soiling of clothing with vomitus, subconjunctival hemorrhage, bite or sting marks, signs of inflammation at the bite or sting site, and corrosions around the oral cavity. The internal examination involved a thorough assessment of the gastrointestinal tract and other organs. Relevant information regarding each poisoning case was collected from the medico-legal cases register in the casualty department, case papers from the relevant department, inquest reports, postmortem reports, and chemical analysis reports, all obtained after securing informed consent from patients or their relatives.

The collected data was recorded in a master chart and analyzed using statistical software, SPSS Statistics 18, and Microsoft Office Excel 2021. The analysis was performed to calculate percentages and proportions. The observations were systematically organized and presented in tabular format

During the study period, 1,410 autopsies were conducted. Acute poisoning cases constituted 7.8% (n=110) of the total autopsies performed (Figure 1). Incidence was more common among males [67 (60.9%)] compared to females [43 (39.1%)].

Figure 1: Showing the distribution of the total number of autopsies during the study period

Table 1: Showing the distribution of external postmortem findings in fatal cases of acute poisoning (n=110, Multiple responses)

The analysis of external postmortem findings in fatal cases of acute poisoning highlights several characteristic features (Table 1). The most prevalent observation was the presence of frothy secretions at the mouth and nostrils, documented in 60.91% of cases, underscoring its prominence as a hallmark feature of acute poisoning. This was followed by the detection of a distinctive odor emanating from the oral cavity (45.45%) and the occurrence of perioral and perinasal staining (35.45%), which are suggestive of specific toxic agents or the mode of ingestion. Other significant findings included cyanosis, observed in 31.82% of cases, indicative of hypoxia as a systemic consequence of poisoning, and vomitus staining on clothing (21.82%), reflecting the expulsion of gastric contents. Less frequently encountered findings, such as bite or sting marks and their associated inflammatory signs (both at 10.91%), point to envenomation as a contributory factor in a subset of cases. Rare manifestations, including subconjunctival hemorrhages and oral cavity corrosion (2.73% each), likely correlate with specific toxicological profiles or caustic agents.

Table 2: Showing the distribution of internal postmortem findings in fatal cases of acute poisoning (n=110, Multiple responses)

Internal autopsy findings in fatal cases of acute poisoning revealed that the most common pathological changes were inflammation and congestion of the mucosa, particularly affecting the stomach (97.27%), followed by the oesophagus (92.73%), small intestine (70%), and large intestine (12.72%). These results suggest that the gastrointestinal tract is particularly vulnerable to toxic insults, especially in the upper segments. In contrast, the least common findings included mucosal corrosion in the oesophagus, stomach, and small intestine, as well as softening of the mucosa in the oesophagus and stomach, ulceration in the oesophagus and small intestine, and perforation in the oesophagus, stomach, and small intestine. Each of these findings was observed in only 1.82% of cases, indicating their association with severe or specific toxic exposures. Petechial hemorrhages were most frequently noted on the mucosa of the stomach (42.73%), followed by the small intestine (12.72%), oesophagus (7.27%), and large intestine (5.45%). Softening of the mucosa was limited to the oesophagus and stomach, with each being affected in 1.82% of cases. Ulceration predominantly involved the stomach (5.45%), with isolated instances in the oesophagus and small intestine (1.82% each). Similarly, perforation was a rare finding, evenly distributed across the oesophagus, stomach, and small intestine (1.82% each).

Table 3: Showing the distribution of congestion of organs in the fatal cases of acute poisoning (n=110, Multiple responses)

The analysis of organ congestion in fatal cases of acute poisoning reveals a high prevalence of pathological changes, reflecting the systemic effects of toxic exposure. Congestion of the brain and meninges was the most frequently observed finding, documented in 98.18% of cases, highlighting its critical vulnerability to toxic insults. This was closely followed by congestion in the spleen and kidneys, each present in 97.27% of cases, and the liver, observed in 96.36% of cases. These findings underscore the significant impact of poisoning on vital metabolic and filtration organs. Additionally, pulmonary congestion was noted in 63.64% of cases, indicating the involvement of the respiratory system, although it was less frequent than congestion in other organs. Overall, these results suggest that acute poisoning has widespread systemic effects, with congestion serving as a consistent indicator of toxic injury.

Table 4: Showing the distribution of edema and  petechial hemorrhage in lungs and brain in the fatal cases of acute poisoning (n=110, Multiple responses)

The distribution of edema and petechial hemorrhages in the lungs and brain in fatal cases of acute poisoning highlights significant pathological changes in these critical organs. Edema was the most common finding, particularly in the brain, where it was observed in 98.18% of cases, indicating its consistent involvement in toxicological pathology. Pulmonary edema was also prevalent, affecting 75.45% of cases, which reflects the frequent compromise of the respiratory system in poisoning incidents. Although petechial hemorrhages were less common than edema, they were more frequently observed in the brain (20.91%) compared to the lungs (12.73%). This suggests microvascular damage and hypoxic effects in both organs. These findings underscore the profound impact of acute poisoning on the central nervous and respiratory systems.

Table 5: Showing the distribution of the odor from the mouth and stomach with its contents in fatal cases of acute poisoning (n=98)

[# Out of 110 fatal cases; 12 cases of snake bites were excluded from this table.]

The distribution of odors from the mouth and stomach contents in fatal cases of acute poisoning reveals distinct patterns associated with different toxic agents. A garlicky odor was the most prevalent, found in 38.78% of mouth samples and 81.64% of stomach contents. This odor is commonly linked to the ingestion of substances such as zinc phosphide or aluminum phosphide, which release phosphine gas when they react with stomach acids, resulting in this characteristic smell. A kerosene-like odor was observed in 7.14% of mouth samples and 8.16% of stomach contents, suggesting poisoning by hydrocarbon-based substances that are often used in rodenticides and other industrial toxins. An acetone-like odor was present in 4.08% of cases in both the mouth and stomach contents, which may indicate exposure to substances such as acetone or isopropanol, known for being volatile organic solvents. Notably, the absence of any odor was recorded in 50% of mouth samples and 6.12% of stomach contents. This absence could point to poisoning by odorless substances or advanced decomposition, where volatile compounds may have dissipated or been masked by other factors.

Table 6: Showing the distribution of different types of poisoning in the fatal cases of acute poisoning (n=110)

The distribution of various types of poisoning in fatal cases of acute poisoning reveals significant patterns related to the agents involved. Rat poison was identified as the most common cause, accounting for 37.27% of cases, which highlights its widespread use and the potential for both accidental and intentional ingestion. Organophosphorus compounds were the second most frequent type of poisoning, observed in 13.64% of cases. This reflects their availability as agricultural pesticides and their high toxicity. Additionally, drug-related poisonings (8.18%) and snake bites (10.91%) also significantly contributed to fatalities, emphasizing the diverse origins of poisoning incidents. Corrosive agents, which cause severe tissue damage when ingested, accounted for 6.36% of cases. Organocarbamates (2.73%) and organochlorines (1.82%), both of which are commonly used pesticides, were less frequent but still noteworthy.  A considerable proportion of cases (19.09%) fell into the miscellaneous or unknown category, indicating instances where the agents involved were unidentified or where determining the exact cause of poisoning was challenging.

Figure 2: Showing the distribution of different types of poisoning in the fatal cases of acute poisoning during the study period.

During the study period, a total of 110 cases of acute poisoning were recorded, and comprehensive examination findings were noted and statistically analyzed. The results of this study were then compared with available literature from similar studies conducted both in India and internationally, providing valuable insights into the trends and commonalities of acute poisoning cases.

One significant finding of the present study was the presence of froth or secretions at the mouth and nostrils, observed in 60.91% of the cases (Table 1). This finding is consistent with previous research by Job C [4] and Zariwala RC [5], who reported froth from the mouth in 63.28% and 35.94% of cases, respectively. Additionally, Pillay VV [6] noted that characteristic odor from the mouth and cyanosis were common external autopsy findings in cases of acute poisoning, which aligns with the results of the current study. The study further found that inflammation and congestion of the mucosa of the stomach were present in 97.27% of cases, with corrosions found in 1.82% of cases (Table 2). These findings are in agreement with Job C's study [4], which identified gastric mucosal congestion as the most common autopsy finding, present in 76.33% of cases, while gastric corrosion was observed in 5.59% of cases. Regarding organ congestion, the study revealed a significant prevalence, but due to the lack of organ-specific congestion data in other studies, comparisons could not be drawn (Table 3). Nevertheless, Pillay VV [6] observed that congestion of organs is a common finding in cases of acute poisoning, which aligns with the results in our study, reinforcing the systemic impact of poisoning on major organs.

The study also documented the presence of pulmonary edema in 75.45% of cases (Table 4), which was comparable to Job C's study [4], where pulmonary edema was present in 90.16% of poisoning cases. Additionally, Pillay VV [6] noted that cerebral and pulmonary edema are common autopsy findings in poisoning cases, and these findings were present in 98.18% and 75.45% of cases, respectively, in the current study.

An interesting observation in this study was the detection of a kerosene-like odor from the stomach and its contents in 8.16% of poisoning cases (Table 5). This finding contrasts with Zariwala RC's study [5], which reported a kerosene-like odor in only 1.80% of cases. The discrepancy may be due to Zariwala's classification of a different category of odor labeled as "insecticide," which included 46.40% of cases, and many insecticides contain petroleum derivatives such as aromax, which also produce a kerosene-like odor. Furthermore, our study's finding of an acetone-like odor in 4.08% of cases was comparable to Job C's study [4], where it was observed in 6.38% of cases.

In this study, rat poison was the most prevalent form of poisoning, followed by organophosphorus poisoning. A study conducted in Pondicherry noted a significant increase in the incidence of organophosphorus compound (OPC) poisoning over a three-year period [7]. Other research has identified organophosphorus poisoning as one of the most commonly encountered poisoning substances [8-12]. However, contrasting findings have been reported in studies where pharmaceutical agents were found to be the primary cause of poisoning admissions [13, 14]. For instance, a study at the All India Institute of Medical Sciences, New Delhi, revealed that drugs (18%) and insecticides (12.80%) were the most frequent poisoning agents among a total of 726 cases. Within the insecticide group, carbamate poisoning (47 cases) was the most common, followed by organophosphorus compounds (43 cases) and organochlorine compounds [13]. These variations in poisoning types across different regions of the country could be attributed to differences in the patterns of pesticide usage and their availability.

Limitations of the study: The limitations of our study include its retrospective record-based nature and relatively small sample size.

The external autopsy findings in fatal acute poisoning cases predominantly included froth or secretion at the mouth and nostrils, followed by a characteristic odor from the mouth. Additional common findings were stains around the lips and nostrils, cyanosis, soiling of clothes with vomitus, bite or sting marks, and signs of inflammation at the site of bites or stings. Internally, the most prevalent findings were inflammation and congestion, alongside petechial hemorrhages of the mucosa, particularly in the stomach. Other notable internal findings included corrosion, softening, ulceration, and perforation of the mucosa in the esophagus, stomach, and small intestine. Congestion of organs, along with cerebral and pulmonary edema, were also commonly observed. Regarding the contents of the stomach, a garlicky odor was identified in the majority of cases, followed by kerosene-like and acetone-like odors. Rat poison emerged as the leading cause of fatal acute poisoning, followed by organophosphorus compounds and drug-related poisonings. Other significant causes included snake bites, corrosive agents, and pesticides, with a substantial portion of cases categorized as miscellaneous or unknown due to unidentified or ambiguous agents.

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