A validation of placental pathology reports by ethnicity in New Zealand, through systematic analysis of histological slides.

INTRODUCTION: Reliability studies of placental examination have shown differing interobserver agreement for certain pathological features, a lack of uniform reporting criteria and variable experience among pathologists. In previous analyses we have shown that placental pathology differs by ethnicity. This validation study was performed to investigate whether bias related to ethnicity is a feature of placental pathology reporting in New Zealand (NZ). METHODS: 199 of 1726 eligible perinatal death cases between 2008 and 2017 were selected at random for this audit-type study, including 51 cases from South Asian, Maori and NZ European ethnicity and 46 cases from Pacific mothers. Stored histology slides were blinded and re-examined by an experienced perinatal pathologist, and linked to the corresponding original pathology report. Interobserver agreement (overall, by ethnicity and by gestational age) was described by proportional differences and kappa coefficients. RESULTS: Total interobserver agreement between original placental reporting and the validation review was 89.7 %, which differed by pathological feature. There was generally more underreporting than overreporting (3.6 % and 6.7 %, respectively). There was little disagreement by ethnicity (decidual vasculopathy [p = 0.03]), although there were more differences by gestational age (villous morphology [p < 0.01], chorioamnionitis [p = 0.03], high-grade villitis of unknown etiology [p < 0.01], and placental haemorrhage [p = 0.03]). DISCUSSION: No systematic bias in placental pathology reporting in NZ was identified by ethnicity or gestational age, as observed differences could be related to the underlying prevalence of pathology. We identified more underreporting than overreporting of pathology in the original reports, emphasizing the importance of placental investigation by specialised perinatal pathologists.

Placental pathology findings in perinatal deaths from 28 weeks gestation in Aotearoa New Zealand.

INTRODUCTION: Women of South Asian ethnicity are overrepresented in adverse pregnancy outcome across high-income countries, including those related to placental dysfunction. It has been hypothesised that placental aging occurs at earlier gestation in South Asian pregnancies. We aimed to identify differences in placental pathology among perinatal deaths ≥28 weeks gestation, between South Asian, Maori and New Zealand (NZ) European women in Aotearoa NZ, with a focus on women of South Asian ethnicity. METHODS: Placental pathology reports and clinical data from perinatal deaths between 2008 and 2017 were provided by the NZ Perinatal and Maternal Mortality Review Committee, blinded, and analysed by an experienced perinatal pathologist using the Amsterdam Placental Workshop Group Consensus Statement criteria. RESULTS: 790 of 1161 placental pathology reports, 346 preterm (28+0 to 36+6 weeks) and 444 term (≥37+0 weeks) deaths, met the inclusion criteria. Among preterm deaths, South Asian women had higher rates of maternal vascular malperfusion compared with Maori (aOR 4.16, 95%CI 1.55-11.15) and NZ European (aOR 2.60, 95%CI 1.10-6.16). Among term deaths, South Asian women had higher rates of abnormal villous morphology compared with Maori (aOR 2.19, 95%CI 1.04-4.62) and NZ European (aOR 2.12, 95%CI 1.14-3.94), mostly due to increased rates of chorangiosis (36.7%, compared to 23.3% and 21.7%, respectively). DISCUSSION: Differences in placental pathology by ethnicity were observed among preterm and term perinatal deaths. While we suspect differing underlying causal pathways, these deaths may be associated with maternal diabetic and red blood cell disorders among South Asian women, leading to a hypoxic state in-utero.

Placental pathology findings amongst extremely preterm perinatal deaths in Aotearoa New Zealand.

INTRODUCTION: Women of South Asian ethnicity are overrepresented in adverse pregnancy outcomes across high-income countries, including placental dysfunction and antepartum haemorrhage. As the burden of mortality is highest for extremely preterm infants, we aimed to identify any differences in placental pathology among perinatal deaths from 20+0 to 27+6 weeks gestation between South Asian, Maori and New Zealand (NZ) European women in Aotearoa NZ, with a focus on women of South Asian ethnicity. METHODS: Placental pathology reports and clinical data from perinatal deaths between 2008 and 2017 were provided by the NZ Perinatal and Maternal Mortality Review Committee, blinded and analysed by an experienced perinatal pathologist using the Amsterdam Placental Workshop Group Consensus Statement criteria. South Asian ethnicity was classified as Indian, Fijian Indian, South African Indian, Sri Lankan, Pakistani and Bangladeshi. RESULTS: 886 of 1571 placental pathology reports met the inclusion criteria. Women of South Asian ethnicity were significantly more likely to show features of histologic chorioamnionitis (aOR 1.87, 95%CI 1.19-2.94) and chorionic vasculitis (aOR 1.92, 95%CI 1.13-3.29), than NZ European and Maori women respectively. 13 of 15 (87%) of South Asian mothers with a diabetic disorder were identified with chorioamnionitis, compared to 1 in 5 (20%) of Maori and 5 in 12 (41%) of NZ European women. Cord hyper-coiling was also more common among South Asian pregnancies, compared to NZ European (aOR 1.98, 95%CI 1.10-3.56). DISCUSSION: Differences in placental pathology by ethnicity were observed among extremely preterm perinatal deaths. Underlying metabolic disorders and an associated pro-inflammatory environment may play an important role in the causal pathway leading to these deaths in women of South Asian ethnicity.

Rethinking placental pathology in the PSANZ classification of unexplained stillbirth at term.

BACKGROUND: Approximately 30 per cent of stillbirths are currently classified 'unexplained' using the Perinatal Society of Australia and New Zealand (PSANZ) classification system in New Zealand. This unexplained category includes deaths with placental pathology even though the importance of placental pathology and its causal relationship to stillbirth is well described. AIMS: To determine whether unexplained stillbirths in New Zealand classified using PSANZ criteria can be more usefully classified based on placental pathology. METHODS: Audit of the classification of cause of death among 'unexplained antepartum death' at term by perinatal pathologist review of postmortem and/or placental pathology reports using the current PSANZ Perinatal Death Classification (PDC)10 classification and a proposed 'significant placental pathology' subclassification. The main outcome measure was a change in cause of death from unexplained term stillbirth to an alternative PSANZ classification or to significant placental pathology subcategory. RESULTS: In total, 177 unexplained stillbirths with a postmortem and/or placental pathology report in New Zealand between 2007 and 2013 inclusive were reviewed. Twenty-three cases (13%) had significant placental pathology that could have been a direct cause of the stillbirth. A further seven cases (4%) were misclassified and could be better classified within another PDC category. CONCLUSIONS: A classification system incorporating placental pathologies which are recognised by the current literature to be causative of stillbirth would better describe stillbirths at term in New Zealand. This would benefit parental counselling and follow-up in subsequent pregnancies. A standard approach to reporting placental pathology would benefit clinicians. Education on placental pathology for clinicians working with parents experiencing stillbirth and multidisciplinary approach to classification is also recommended.

Polarographic Electrode Measures of Cerebral Tissue Oxygenation: Implications for Functional Brain Imaging.

The changes in blood flow, blood volume and oxygenation that accompany focal increases in neural activity are collectively referred to as the hemodynamic response and form the basis of non-invasive neuroimaging techniques such as blood oxygen level dependent (BOLD) functional magnetic resonance imaging. A principle factor influencing blood oxygenation, the cerebral metabolic rate of oxygen consumption is poorly understood and as such, data from imaging techniques are difficult to interpret in terms of the underlying neural activity. In particular how neurometabolic changes vary temporally, spatially and in magnitude remains uncertain. Furthermore knowledge of which aspects of neural activity are closely reflected by metabolic changes is essential for the correct interpretation of cognitive neuroscience studies in terms of information processing. Polarographic electrode measurements of cerebral tissue oxygenation in animal models following presentation of sensory stimuli have started to address these issues. Early studies demonstrated both increases and decreases in tissue oxygenation following neural activation. However a recent series of elegant studies in the cat visual system demonstrated a tight spatial and temporal coupling between evoked peri-synaptic activity and oxygen consumption following presentation of visual stimuli.