Placental pathology of neonates diagnosed with encephalopathy soon after birth: A retrospective analytical study

Abstract

Background. Placental pathology has been linked to neonatal encephalopathy (NE). Despite the high prevalence of NE in low- and middle- income countries (LMICs), there are limited published studies exploring this association from LMICs. Objective. To describe and analyse the histopathology of placentas from neonates diagnosed with encephalopathy shortly after birth. Methods. A retrospective analytical study was conducted on neonates diagnosed with encephalopathy at Klerksdorp/Tshepong hospital complex, South Africa. Placentas from term and near-term neonates (birthweight ≥2 000 g) diagnosed with encephalopathy within the first 24 hours of life were sent for histopathological examination. Neonates were grouped into those with encephalopathy with or without intrapartum hypoxia (IH) (base deficit ≥12 mmol/L). The severity of NE was assessed as mild, moderate or severe, according to Sarnat staging. The types and extent of placental lesions were compared between those with mild and moderate-to-severe NE, and between cases with or without IH. Results. Of 16 336 live births, 271 neonates were diagnosed with NE, and of these, 193 (71.2%) had NE with IH. Placental histopathology results were available for 239 neonates (88.2%). The median placental weight was 428 g, with 46.6% of placentas weighing below the 10th percentile. Cord abnormalities were observed in 27.2% of placentas. Nearly all placentas (98.2%) exhibited at least one histopathological lesion. The most common microscopic placental lesions identified were maternal vascular malperfusion (MVM) (55.6%), fetal vascular malperfusion (55.1%), acute chorioamnionitis (41.2%) and villitis of unknown aetiology (28.9%). There was a significant association between NE with IH and the presence of MVM, with an adjusted odds ratio of 3.24 (95% confidence interval 1.19 - 8.79). No significant association was found between the presence or number of different placental lesions and the severity of NE. Factors associated with severity of any NE (with and without IH) included an Apgar score <7 at 10 minutes (p<0.001) and pH <7.00 (p<0.001). Conclusion. A high proportion of neonates with encephalopathy showed evidence of IH. Approximately half of the placentas were below the 10th percentile in weight, and about a quarter had macroscopic cord abnormalities. Almost all neonates with encephalopathy displayed ≥1 microscopic placental lesion. A strong association was found between the presence of MVM and NE with IH.