Assessment of the drowning index in diagnosing freshwater drowning: A comparative study

Drowning is a diagnosis of exclusion, as no finding is pathognomonic to drowning, making it a challenging task during autopsy. The drowning index (DI) is the ratio of the combined weights of both lungs and pleural effusion to the weight of the spleen. This prospective cross-sectional study was conducted at a tertiary healthcare center in Northern India, including 75 cases of freshwater drowning, 64 cases of sudden cardiac death, and 40 cases of hanging deaths. We measured DI parameters such as the weights of both lungs, pleural effusion, and spleen, and the DI was calculated and compared among the groups. We also calculated the cut-off DI value using receiver operating characteristic (ROC) curve analysis. We observed that in drowning cases, the value of DI, combined weight of both lungs, and pleural effusion is significantly higher, whereas the weight of the spleen is lower when compared with cardiac and hanging deaths. However, lung weight alone is not suggestive of drowning. A DI value of more than 9.7 is highly suggestive of freshwater drowning death, with a sensitivity of 86.7% and specificity of 70.2% within a postmortem interval (PMI) of up to 2 weeks. The DI value is higher in males compared with females, but the difference is not statistically significant among the drowning group.