Assessment of fetal lung maturity using analysis of amniotic fluid from ewes that gave birth prematurely and at term

Abstract

The aim of this study was to evaluate the lung maturity of premature and full-term lambs by analyzing amniotic fluid using the following methods: Clements test, Nile blue cytology test, hematoxylin-Shorr stain, lamellar body count, and radiographic tests. The use of these methods is intended to identify high-risk newborns and provide immediate clinical intervention after birth. Altogether, 56 animals (24 ewes and 32 lambs) were included in the study and divided into 3 groups. Group I consisted of 8 ewes that were at approximately 145 days of gestation; this group delivered 10 lambs naturally. Group II consisted of 8 ewes that were at 138 days’ gestation; this group delivered 11 lambs by cesarean section. Group III consisted of 8 ewes at 138 days’ gestation; this group was administered intramuscular dexamethasone (16mg/animal) 36 hours prior to a cesarean section. Group III delivered11 lambs. Cytological tests were performed using a microscope with a maximum magnification of 1000x, while the Clements test was visually observed by one of the researchers. Amnioticfluid lamellar body counts were measured using transmission electron microscopy. Among the staining methods, hematoxylin-Shorr was reliable, and Group III had a greater number of orangeophilic cells when compared to Group II, probably due to corticoid administration. The Clements test showed pulmonary maturity in approximately 20% of Group I lambs and Group II showed 9.1% of bubbles; however, Group III had the highest pulmonary maturity percentage (36.4%). The lamellar bodies were measured, and all groups had sizes between 0.019 and 0.590μm. Radiographic evaluation revealed that the majority of lambs presented some level of pulmonary radiodensity, indicating an acinar pattern at birth. These results are in line with the expectations of each group. We found that the normal group showed greater pulmonary maturity, whereas Group II presented pulmonary immaturity, which is expected because this group comprised lambs born prematurely and Group III showed pulmonary maturity almost comparable to the normal delivery group (Group I). This is due to the fact that although these animals are premature, the use of dexamethasone helped in pulmonary maturation. Therefore, these pulmonary maturity tests are considered effective when more than one technique is used and can be used routinely in the care of a pregnant ewe in labor, where a simple collection of amniotic fluid can predict a high-risk pregnancy and alert the veterinarian if the newborn needs intensive supportive treatment.

Monitoring periodontal lesions and their effects during pregnancy: microbiological aspects of the oral cavity and amniotic fluid in pregnant ewes

“…In some cases, these pathogens can reach the placental membranes and induce abortion through acute chorioamnionitis (Bohrer et al 2012). Considering that sheep born before 138 days of gestation are classified as premature (Radostits et al 2002, Souza et al 2020, signs of prematurity were not observed in any of the groups in this study. Furthermore, although the neonates in the OGP group had lower birth weights than those of the OGCH group (Table 4), they were all within the normal range (>2kg).…”

“…All animals were evaluated for the entire period until delivery. Amniotic fluid was collected according to the methodology described by Souza et al (2020). Sample collection was performed using a 40 × 12 gauge needle attached to a 20-mL syringe during the expulsion phase of the product.…”