Relationship between the period of Survival and Chemical Analysis Positivity in Poisoning Cases

Poisoning remains not only a global health challenge but one that has a specific significance in the Indian setting. Unfortunately, the postmortem chemical diagnosis of poisoning cases is no more straightforward and is laid with difficulties and technical issues. Hence, it is imperative that antemortem diagnosis of poisoning cases be made based on well-established guidelines; discrepancies with postmortem toxicological analysis reports be addressed and explained scientifically. This study was done with an intention to primarily find out the relationship between time of alleged poison consumption, period of survival and its effects on the positivity rates of chemical analysis reports.

Present study was done on suspected poisoning cases brought for medicolegal autopsy at Kasturba Medical College, Mangalore, from January 2014 to December 2017.

The time-interval for the period of survival post poison consumption was divided into four groups, i.e., < 24 hours, 1-5 days, 6-10 days, and > 10 days. In 55 (30.21%) cases, the deceased succumbed within 24 hours of the poison consumption. In 53 cases (29.12%), the post-poison consumption period was 1-5 days. For 29 cases (15.93%), the patients succumbed between 6-10 days. In 16 (8.79%), the post-poison consumption period was greater than 10 days. The post-poison consumption period was unknown in another 29 cases (15.93%). Out of the 55 cases in which the survival period post-poison consumption was less than 24 hours, 48 cases (87.27%) showed a positive chemical analysis report. This timeframe showed the highest percentage of positive chemical analysis reports. For the cases wherein the survival period was 1-5 days, the positivity rate was 77.35 % (41 out of 53 cases). Between 6-10 days, only 9 cases out of 29 (31.03%) showed a positive chemical analysis report. Only 1 case out of the 19, where the survival period was more than 10 days, showed a positive result (6.25%).

Our study shows that beyond 10 days, the likelihood of a positive result is negligible. We, therefore, suggest that stomach wash may be considered an alternative source of evidence to analytically prove a case of poisoning, and in cases where stomach wash has not been done, the diagnosis of death by poisoning should take into consideration history as well as clinical symptoms. Also, investigating authorities and medical caregivers must be encouraged to preserve/obtain the alleged container/source of poison as this may be the only source to accurately find out the poison consumed.