Clinical experience of a fetal postmortem imaging service using microfocus computed tomography

Postmortem imaging is becoming a more acceptable part of perinatal autopsy, particularly for early gestation or small fetuses in which conventional autopsies may be challenging and rejected by parents.

This study aimed to establish the relative diagnostic yield of microfocus computed tomography as part of a less invasive autopsy in fetuses at <24 weeks of gestation.

This was a single-center, retrospective study of 7 years of 1007 consecutive unselected perinatal autopsies (2016-2023) of fetuses with a body weight of <300 g. Microfocus computed tomography was offered as an option to all referred fetuses with a body weight of <300 g. All parents gave fully informed written consent.

Of note, 1007 fetuses with a mean 17.9 weeks of gestation and a body weight of 92.4 g were imaged and categorized according to the mode of death. A diagnosis was made due to a range of examinations, including microfocus computed tomography, conventional autopsy, and external and placental examination in 515 of 1007 fetuses (51.1%), with a fetal cause in 212 of 1007 cases (21.1%; eg, cardiac septal abnormalities or neural tube defects), placental cause in 264 of 1007 cases (26.2%; eg, placental abruption or chorioamnionitis), or elements of both in 39 of 1007 cases (3.9%). The single most important diagnostic contributor was placental examination (353 cases [35.1%]). Microfocus computed tomography image quality enabled a diagnosis in 598 of 1007 cases (59.4%), higher in miscarriage (80.3%) and termination of pregnancy (74.9%) than in utero deaths (41.4%), in which maceration did not reduce the overall tissue state to nondiagnostic. The overall microfocus computed tomography abnormality detection rate, in which an abnormality was identified, was 31.0% (312/1007), the highest in the termination of pregnancy (80.7%) vs spontaneous miscarriage (17.9%). Only 43 fetuses required additional invasive autopsy (an autopsy "avoidance rate" of 95.7% [964/1007]). The median turnaround time was 18 days (interquartile range, 13-23).

The combination of routine external examination, placental assessment, and microfocus computed tomography postmortem imaging reached a diagnosis in >50% of early gestation fetuses, similar to historical cohorts. This was achieved within 3 weeks, with an autopsy avoidance rate of 96%, in line with parental consent.