Lamellar Bodies Count (LBC) in Amniotic Fluid from Vaginal Pool as a Predictor for Fetal Lung Maturity in Preterm Premature Rupture of Membranes

Abstract

Summary P retermpremature rupture of membranes (PPROM) defines spontaneous rupture of the fetal membranes before completed 37 weeksgestation and before labor onset. PPROM is a complication of approximately 1/3 of all preterm births. Birth within 1 week is the most likely outcome for any patient with PPROM in the absence of adjunctive treatments. The earlier in gestation PPROM occurs, the longer the latency period (time between PROM and delivery). Outcomes of survivors of preterm PROM depend on GA, presence of infection, length of latency, and other maternal and fetal complications. The most significant risks to the fetus after preterm PROM are complications of prematurity. Respiratory distress has been reported to be the most common complication of preterm birth. Sepsis, intraventricular haemorrhage, and necrotizing enterocolitis also are associated with prematurity, but these are less common near to term. Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality, affecting approximately 1% of all live births and 10% of all preterm infants. It is caused by insufficient production of surfactant by type II pneumocytes, along with structural immaturity of the lung. The risk and severity rise with increasing prematurity, and infants born before 29 weeks of gestation have a 60% chance of developing RDS. In management strategies to limit the risk of RDS, the assessment of fetal lung maturity (FLM) in amniotic fluid can assist in determining the timing of delivery, particularly in pregnancies with maternal and/or fetal complications for which a temporizing strategy in favour of fetal lung maturation is still considered safe, but which may eventually require preterm delivery. Lamellar bodies represent a storage form of pulmonary surfactant within type II pneumocytes, secretion of which increases with advancing gestational age, thus enabling prediction of the degree of FLM. The size of lamellar bodies is similar to platelets, which permits the use of widely available cell counters to quantify the lamellar bodies in amniotic fluid, as described by Dubin. This makes the LBC an easy-to perform, rapid, inexpensive FLM test which is available to all hospitals 24 h per day. Lamellar bodies are packages of surfactant secreted into alveolar spaces between 28 and 32 weeks’ gestation. The concentration of lamellar bodies (reflecting surfactant production and release) in the amniotic fluid has gained popularity as a cheap and easily accessible test of preterm fetal lung maturity, as prior tests involving phospholipid analysis are expensive and labour intensive, making them unavailable in many clinical settings, including our own.