Lamellar body count versus the shake test in the assessment of fetal lung maturity in diabetics - Revista Brasileira de Ginecologia e Obstetrícia

Lamellar body count versus the shake test in the assessment of fetal lung maturity in diabetics |

PURPOSE: to assess the performance of lamellar body count compared to the shake (Clements) test in the prediction of fetal lung maturity in diabetics. METHODS: prospective study of 62 patients who underwent amniocentesis between the 26th and 39th week of pregnancy. Immediately after collection, the amniotic fluid sample was submitted to the shake test and lamellar body count. Deliveries occurred within three days of amniocentesis. Immature test results (absence of a complete bubble ring in the third tube for the shake test and less than 50,000 lamellar bodies) were confronted with the occurrence of pulmonary immaturity in the neonate (respiratory distress syndrome). The performance of both tests was compared using the chi2 test and p<0.05 was considered to be significant. RESULTS: seven infants had respiratory distress syndrome (11.3%). The lamellar body count and shake test were similar regarding sensitivity (100 vs 71.4%, respectively) and negative predictive value (100 vs 93.5%). Lamellar body count was superior as regards specificity (87.3 vs 52.7%, p=0.0001), positive predictive value (50 vs 16.1%, p=0.017), and accuracy (88.7 vs 54.8%, p<0.001). CONCLUSIONS: lamellar body count is a simple and accurate method of assessing fetal lung maturity. It performs slightly better than the shake test in terms of specificity, positive predictive value and accuracy, with the advantage of not requiring manipulation or reagents. Similar to the shake test, lamellar body count has a high-negative predictive value: mature results (50,000 or more) indicate thar the infant will not have hyaline membrane.