To calculate the net autopsy rate, you must subtract:

The net autopsy rate is a crucial metric in assessing the effectiveness and thoroughness of post-mortem examinations within a healthcare system. To accurately calculate this rate, it is essential to account for cases that should not be included in the total number of autopsies performed.

Subtracting unautopsied coroner's or medical examiner's cases is necessary because these cases typically involve deaths that are outside the control of the healthcare system, such as those that occur suddenly or under suspicious circumstances. These cases may have been investigated without the need for an autopsy or have already been resolved through other means. By excluding these unautopsied cases, the calculation focuses solely on the deaths that fell under regular circumstances, thereby providing a more accurate net autopsy rate reflective of the medical facility's performance in conducting autopsies where they are applicable.

In contrast, other factors, such as deaths occurring under or over specific time frames or categories like postoperative deaths, do not directly address the issue of unautopsied cases in the calculation of the net autopsy rate. Including these could lead to distortions in the understanding of how effectively autopsies are being performed in the context of patient deaths that are relevant to the facility's operations.