Clinical experience of a fetal post-mortem imaging service using microfocus computed tomography.

BACKGROUND Post-mortem imaging is becoming a more acceptable part of perinatal autopsy, particularly for early gestation or small fetuses where conventional autopsies may be challenging and rejected by parents. OBJECTIVE(S) The purpose of this study was to establish the relative diagnostic yield of microfocus computed tomography (Micro-CT) as part of less invasive autopsy in fetuses below 24 weeks gestation. STUDY DESIGN We completed a single center, retrospective study of 7 years of 1007 consecutive unselected perinatal autopsies (2016 - 2023) for fetuses below 300g. Micro-CT was offered as an option to all referred fetuses below 300 g body weight; all parents gave fully informed written consent. RESULTS We imaged 1007 fetuses with mean 17.9 weeks gestation and 92.4g body weight, categorized according to mode of death. A diagnosis was made due to a range of examinations including Micro-CT, conventional autopsy, external and placental examination in 51.1% (515 / 1007), with a fetal cause in 212 / 1007 (21.1%); for example cardiac septal abnormalities or neural tube defects, placental cause in 264 / 1007 (26.2%); for example placental abruption or chorioamnionitis, or elements of both in 39 / 1007 (3.9%). The single most important diagnostic contributor was the placental examination (353 cases; 35.1%). Micro-CT image quality enabled a diagnosis in 598 / 1007 cases (59.4%), higher in miscarriage (80.3%) and termination of pregnancy (74.9%) than in utero deaths (41.4%), where maceration did not reduce the overall tissue state to non-diagnostic. The overall micro-CT abnormality detection rate, where an abnormality was identified, was 312 / 1007 (31%), highest in 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). Median turnaround time was 18 days (range 13 - 23 days). CONCLUSION(S) The combination of a routine external examination, placental assessment and micro-CT post-mortem imaging reached a diagnosis in early gestation fetuses in over 50%, similar to historical cohorts. This was achieved within 3 weeks, with an autopsy avoidance rate of 96%, in line with parental consent.