OBJECTIVES: To determine factors in non-diagnostic fetal and neonatal post-mortem ultrasound (PMUS) examinations. METHODS: All fetal and neonatal PMUS examinations were included over a 5 year study period (2014 - 2019). Non-diagnostic image quality by body parts (brain, spine, thorax, cardiac, abdomen) were recorded, and correlated with patient variables. Descriptive statistics and logistic regression analyses were performed to identify significant factors for non-diagnostic studies. RESULTS: 265 PMUS examinations were included, with median gestational age of 22 weeks (12 - 42 weeks), post-mortem weight 363g (16 - 4033g) and post-mortem interval of 8 days (0 - 39 days). Diagnostic imaging quality was achieved for 178/265 (67.2%) studies. It was high for abdominal (263/265, 99.2%); thoracic (264/265, 99.6%) and spine (265/265, 100%), but lower for brain (210/265, 79.2%) and cardiac imaging (213/265, 80.4%). Maceration was the best overall predictor for non-diagnostic imaging quality (p<0.0001). Post-mortem fetal weight was positively associated with cardiac (p =0.0133), and negatively associated with brain imaging quality (p =0.0002). Post-mortem interval was not a significant predictor. CONCLUSIONS: Fetal maceration was the best predictor for non-diagnostic PMUS, particularly for brain and heart. Fetuses with marked maceration and suspected cardiac or brain anomalies should be prioritised for post-mortem MRI
