Post-mortem perinatal imaging: what is the evidence?

Abstract

Post-mortem imaging for the investigation of perinatal deaths is an acceptable tool amongst parents and religious groups, enabling a less invasive autopsy examination. Nevertheless, availability is scarce nationwide, and there is some debate amongst radiologists regarding the best practice and optimal protocols for performing such studies. Much of the published literature to date focusses on single centre experiences or interesting case reports. Diagnostic accuracy studies are available for a variety of individual imaging modalities (e.g. post-mortem CT, MRI, ultrasound and micro-CT), however, assimilating this information is important when attempting to start a local service.In this article, we present a comprehensive review summarising the latest research, recently published international guidelines, and describe which imaging modalities are best suited for specific indications. When the antenatal clinical findings are not supported by the post-mortem imaging, we also suggest how and when an invasive autopsy may be considered. In general, a collaborative working relationship within a multidisciplinary team (consisting of radiologists, radiographers, the local pathology department, mortuary staff, foetal medicine specialists, obstetricians and bereavement midwives) is vital for a successful service.

Figure 1.

Comparison of post-mortem MRI and CT imaging in the same stillborn foetus of 36 weeks gestational age. Coronal post-mortem MRI (a) and CT (b) of the thorax and abdomen, with axial T ₂ weighted post-mortem MRI (c) and axial CT (d) of the brain are demonstrated. There were no congenital abnormalities seen on antenatal or post-mortem imaging, however, it is clear that the non-contrast MRI allows for better internal soft tissue differentiation compared with the CT imaging. For this reason, post-mortem CT is not recommended as a routine tool for non-forensic perinatal post-mortem imaging.

Figure 2.

Typical estimated gestational ages and the approximate post-mortem weights (g) at which various post-mortem imaging modalities would provide diagnostic quality examinations. ** Technically, radiographs and CT can be performed at any age after 8 weeks gestation (when the foetal skeleton beings to ossify), but in practice they are best reserved for specific clinical situations, such as for suspected skeletal abnormalities or trauma. Reproduced from Shelmerdine SC et al, Insights into Imaging 2021.

Figure 3.

Recommended post-mortem imaging flowchart for non-invasive investigation of perinatal loss. Small foetuses present a challenge for post-mortem imaging, and care should be taken when interpreting imaging results in this cohort. A foetus weighing over 500 g provides the greatest likelihood for a diagnostic quality 1.5 T MRI study, and those weighing <300 g are best suited for micro-CT or high-field MRI. Where neither MRI nor micro-CT are available, ultrasound may be attempted but there is a higher likelihood of a false or non-diagnostic result. Foetuses weighing between 300 and 500 g have been reported to take >7 days to iodinate, and therefore delay micro-CT imaging. If available, 3 T MRI could be attempted for this foetal cohort. Reproduced from Shelmerdine et al, Insights into Imaging 2021.