A pragmatic evidence-based approach to post-mortem perinatal imaging

Body weight-based iodinated contrast immersion timing for human fetal postmortem microfocus computed tomography

Objectives

The aim of this study was to evaluate the length of time required to achieve full iodination using potassium tri-iodide as a contrast agent, prior to human fetal postmortem microfocus computed tomography (micro-CT) imaging.

Methods

Prospective assessment of optimal contrast iodination was conducted across 157 human fetuses (postmortem weight range 2-298 g; gestational age range 12-37 weeks), following micro-CT imaging. Simple linear regression was conducted to analyse which fetal demographic factors could produce the most accurate estimate for optimal iodination time.

Results

Postmortem body weight (r2 = 0.6435) was better correlated with iodination time than gestational age (r2 = 0.1384), producing a line of best fit, y = [0.0304 × body weight (g)] - 2.2103. This can be simplified for clinical use whereby immersion time (days) = [0.03 × body weight (g)] - 2.2. Using this formula, for example, a 100-g fetus would take 5.2 days to reach optimal contrast enhancement.

Conclusions

The simplified equation can now be used to provide estimation times for fetal contrast preparation time prior to micro-CT imaging and can be used to manage service throughput and parental expectation for return of their fetus.

Advances in knowledge

A simple equation from empirical data can now be used to estimate preparation time for human fetal postmortem micro-CT imaging.

Stillbirth Investigations: An Iconographic and Concise Diagnostic Workup in Perinatal Pathology

Introduction  Stillbirth is a dramatic event for the parents, health care team, and anyone close to the expectant parents. Multidisciplinary team (MDT) meetings are essential to improve communication in health care. We review the most frequent findings discussed at MDT meetings. Methods  A PubMed search was conducted through December 2021 since the inception (1965) using clinical queries with the key terms "stillbirth" AND "investigation" AND "pathology" AND "human." The search strategy included reviews, meta-analyses, randomized controlled trials, clinical trials, and observational studies. This systematic review is based on, but not limited to, the search results. It is the experience of more than 30 years of pediatrics, obstetrics, and pathology staff. Results  Two hundred and six articles were screened and complemented through the perusal of congressional activities and personal communications. Pathological findings following perinatal death can be divided into macroscopic, histologic, and placental findings. The placenta is crucial in fetal medicine and is key in determining the cause of stillbirth in a substantial number of events. Perinatal lung disease is essential to evaluate the response of newborns to extrauterine life and address newborns' outcomes appropriately. Conclusions  Stillbirth remains one of the less explored areas of medicine, and we can determine the cause in a limited number of cases. Nevertheless, placental pathology is critical in the etiology discovery pathway. Accurate investigations and discussion of photography-supported findings are vital in promoting communication at MDT meetings.

Stillbirth: prevention and supportive bereavement care

Around half of the two million stillbirths occurring worldwide each year are preventable. This review compiles the most up-to-date evidence to inform stillbirth prevention. Many general maternal health interventions also reduce the risk of stillbirth, for example, antenatal care attendance. This review focuses on specific aspects of care: glucose metabolism, targeted aspirin prophylaxis, clotting and immune disorders, sleep positions, fetal movement monitoring, and preconception and interconception health. In the past few years, covid-19 infection during pregnancy has emerged as a risk factor for stillbirth, particularly among women who were not vaccinated. Alongside prevention, efforts to address stillbirth must include provision of high quality, supportive, and compassionate bereavement care to improve parents' wellbeing. A growing body of evidence suggests beneficial effects for parents who received supportive care and were offered choices such as mode of birth and the option to see and hold their baby. Staff need support to be able to care for parents effectively, yet, studies consistently highlight the scarcity of specific bereavement care training for healthcare providers. Action is urgently needed and is possible. Action must be taken with the evidence available now, in healthcare settings with high or low resources, to reduce stillbirths and improve training and care.

Fetal brain maceration score on postmortem magnetic resonance imaging vs. conventional autopsy

BACKGROUND

Postmortem fetal magnetic resonance imaging (MRI) has been on the rise since it was proven to be a good alternative to conventional autopsy. Since the fetal brain is sensitive to postmortem changes, extensive tissue fixation is required for macroscopic and microscopic assessment. Estimation of brain maceration on MRI, before autopsy, may optimize histopathological resources.

OBJECTIVE

The aim of the study is to develop an MRI-based postmortem fetal brain maceration score and to correlate it with brain maceration as assessed by autopsy.

MATERIALS AND METHODS

This retrospective single-center study includes 79 fetuses who had postmortem MRI followed by autopsy. Maceration was scored on MRI on a numerical severity scale, based on our brain-specific maceration score and the whole-body score of Montaldo. Additionally, maceration was scored on histopathology with a semiquantitative severity scale. Both the brain-specific and the whole-body maceration imaging scores were correlated with the histopathological maceration score. Intra- and interobserver agreements were tested for the brain-specific maceration score.

RESULTS

The proposed brain-specific maceration score correlates well with fetal brain maceration assessed by autopsy (τ = 0.690), compared to a poorer correlation of the whole-body method (τ = 0.452). The intra- and interobserver agreement was excellent (correlation coefficients of 0.943 and 0.864, respectively).

CONCLUSION

We present a brain-specific postmortem MRI maceration score that correlates well with the degree of fetal brain maceration seen at histopathological exam. The score is reliably reproduced by different observers with different experience.

Comparison of postmortem whole-body contrast-enhanced microfocus computed tomography and high-field magnetic resonance imaging of human fetuses

OBJECTIVE

Although fetal autopsy is generally recommended to confirm or refute the antemortem diagnosis, parental acceptance of the procedure has fallen over time, mainly due to its invasiveness. Contrast-enhanced microfocus CT (micro-CT) and high-field magnetic resonance imaging (HF-MRI, ≥ 3 Tesla) have both been suggested as non-invasive alternatives to conventional fetal autopsy for fetuses < 20 weeks of gestation. The aim of this study was to compare these two modalities in postmortem whole-body fetal imaging.

METHODS

In this study, the imaging process and quality of micro-CT and HF-MRI were compared using both qualitative and quantitative assessments. For the qualitative evaluation, fetal anatomy experts scored 56 HF-MRI and 56 micro-CT images of four human fetuses aged 13-18 gestational weeks on two components: overall image quality and the ability to recognize and assess 21 anatomical structures. For the quantitative evaluation, participants segmented manually three organs with increasing complexity to assess interobserver variability. In addition, the signal-to-noise and contrast-to-noise ratios of five major organs were determined.

RESULTS

Both imaging techniques were able to reach submillimeter voxel size. The highest resolution of micro-CT was 22 µm (isotropic), while the highest resolution of HF-MRI was 137 µm (isotropic). The qualitative image assessment form was sent to 45 fetal anatomy experts, of whom 36 (80%) responded. It was observed that micro-CT scored higher on all components of the qualitative assessment compared with HF-MRI. In addition, the quantitative assessment showed that micro-CT had lower interobserver variability and higher signal-to-noise and contrast-to-noise ratios.

CONCLUSIONS

Our findings show that micro-CT outperforms HF-MRI in postmortem whole-body fetal imaging in terms of both quantitative and qualitative outcomes. Combined, these findings suggest that the ability to extract diagnostic information is greater when assessing micro-CT compared with HF-MRI images. We, therefore, believe that micro-CT is the preferred imaging modality as an alternative to conventional fetal autopsy for early gestation and is an indispensable tool in postmortem imaging services. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Post-mortem perinatal imaging: what is the evidence?

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.