An Update on COVID-19-Associated Placental Pathologies

COVID-19 pregnancies are associated with increased rates of premature delivery and stillbirths. It is still a matter of debate whether there is a COVID-19-associated pattern of placenta pathology. We updated our previously published results on a systematic literature review and meta-analysis of COVID-19 pregnancies. In total, 38 reports on 3677 placentas were evaluated regarding histopathological changes. Maternal vascular malperfusion (32%), fetal vascular malperfusion (19%), acute and chronic inflammation (20% and 22%) were frequent pathologies. In non-COVID-19 pregnancies, placentas show similar histologic patterns and mainly similar frequencies of manifestation. It has to be taken into account that there might be an observation bias, because some findings are diagnosed as a "pathology" that might have been classified as minor or unspecific findings in non-COVID-19 placentas. COVID-19 placentitis occurs in 1-2% of cases at the most. In conclusion, this updated meta-analysis indicates that COVID-19 infection during pregnancy does not result in an increased rate of a specific placenta pathology and COVID-19 placentitis is rare.

Comparison of Prenatal and Postmortem Diagnoses from 251 Fetal Autopsies: High Rate of Placenta Pathologies, Low Rate of Discrepancies

Background: In cases of intrauterine fetal death (IUFD), autopsy and placenta pathology can provide additional information to sonographic findings. We assessed the frequency of prenatally missed relevant diagnoses. Materials and methods: A retrospective evaluation of fetal autopsies from 2006 to 2021 was performed and were classified as: i) agreement, ii) cases where autopsy revealed additional findings, or iii) postmortem findings which changed the diagnosis. Results: A total of 199/251 spontaneous IUFD and 52/251 induced abortions were included. In spontaneous IUFD, placenta pathologies were the leading cause of death (89%). Full agreement was found in most cases (91% and 87% in spontaneous IUFD and induced abortion, respectively), while additional findings (7% and 12%) and major discrepancies (each 2%) were detected less frequently. Conclusion: In some cases where major findings were missed, autopsy could establish a diagnosis.

Meta-analysis on COVID-19-pregnancy-related placental pathologies shows no specific pattern

Coronavirus disease 2019 (COVID-19) pneumonia rarely occurs in pregnant women. Case reports indicate that fibrin and lymphohistiocytic lesions in placentas may be typical. However, a meta-analysis to clarify whether there is a COVID-19-associated pattern of placental lesions has not yet been conducted. Systematic literature search with meta-analysis of publications on 10 or more cases of pregnancy with SARS-CoV-2 infection and placenta examination (30 publications from 2019 to 2021; 1452 placenta cases) was performed. The meta-analysis did not reveal any COVID-19-specific placenta changes. The incidence of both vascular and inflammatory lesions was mainly comparable to that of non-COVID-19 pregnancies. Transplacental viral transmission is very rare and there are no typical placental changes. The most important prognostic factor seems to be maternal-fetal hypoxia in the context of pneumonia.