Parameters for estimating the time of death at perinatal autopsy of stillborn fetuses: a systematic review.

Background: Stillbirth is defined by the WHO as birth of a fetus with no vital signs, at or over 28 weeks of pregnancy age. The estimation of time of death in stillbirth appears crucial in forensic pathology. However, there are no validated methods for this purpose.

Objective: To perform a systematic review of the available literature regarding the estimation of the time of death in stillborn fetuses, in terms of hours or days.

Methods: Electronic databases were searched from their inception to August 2018 for relevant articles. Macroscopic, histologic, and radiologic parameters were evaluated.

Results: Nine studies with 664 stillborns were included. The evaluation of extent and location of fetal maceration signs showed good accuracy in estimating the time of death; by contrast, a dichotomous assessment of maceration (present vs absent) was found to be unreliable in a subsequent study. Histologic assessment of the loss of nuclear basophilia in fetal and placental tissues showed excellent accuracy; an "autolysis equation" was proposed to achieve an even higher accuracy in fetuses who had been dead for < 24 h. Magnetic resonance imaging of the lung parenchyma, pleural fluids, and brain parenchyma could estimate the death-to-autopsy time, but the results appeared weak and conflicting.

Conclusion: Pathologic examination, based on the assessment of maceration, and even more of the loss of nuclear basophilia, may be a reliable method to estimate the time of death in stillborn fetuses. Further studies should be encouraged to validate these results. Imaging techniques have not yet found application in this field.