Fetal and Neonatal Autopsy in the Molecular Age: Exploring Tissue Selection for Testing Success.

While conventional autopsy is the gold-standard for determining cause of demise in the fetal and neonatal population, molecular analysis is increasingly used as an ancillary tool. Testing methods and tissue selection should be optimized to provide informative genetic results. This institutional review compares testing modalities and postmortem tissue type in 53 demises occurring between 20 weeks of gestation and 28 days of life. Testing success, defined as completion of analysis, varies by technique and may require viable cells for culture or extractable nucleic acid. Success was achieved by microarray in 29/30 tests (96.7%), karyotype in 40/54 tests (74.1%), fluorescent in situ hybridization in 5/9 tests (55.6%), and focused gene panels in 2/2 tests (100%). With respect to tissue type, postmortem prepartum amniotic fluid was analyzed to completion in 100% of tests performed; compared to 84.0%, 54.5%, and 80.8% of tests using placenta, fetal only, and mixed fetal-placental tissue collection, respectively. Sampling skin (83.3%, in cases with minimal maceration) and kidney (75.0%) were often successful, compared to lower efficacy of umbilical cord (57.1%) and liver (25.0%). Addition of genetic testing into cases with anomalous clinical and gross findings can increase the utility of the final report for family counseling and future pregnancy planning.