The tap test—a rapid bedside indicator of fetal lung maturity

Abstract

Summary. The reliability of two rapid bedside tests of fetal lung maturity was investigated in 80 amniotic fluid samples. The results of the ‘tap’ test and those of the shake test were compared with the results of laboratory measurements of phospholipid profiles for fetal lung maturity. The tap test was found to be more reliable with a positive predictive value of 91% and a negative predictive value of 63%, whereas the shake test had a positive predictive value of 79% and a negative predictive value of 31%. The tap test was also more reliable in identifying fetuses with borderline lecithin/sphingomyelin ratios in the range 3.2–3.7:1.

Comparison of Reliability of Tap Test and Shake Test for Determination of Fetal Lung Maturity

“…Similar to other studies done by Guidozzi et al, 1991;Rodriguez-Macias KA, 1995 andKucuk M, 1997, this study also reveals that the tap test has better specificity and predictive value for fetal lung immaturity than the shake test. However, unlike in other studies done by Guidozzi F et al, 1991;Rodriguez-Macias KA, 1995 andKucuk M, 1998 where the tap test had better sensitivity and predictive value for fetal lung maturity compared to the shake test, this study had better sensitivity for shake test than for the tap test and comparable predictive value for fetal lung maturity between the two tests. 3,6,10 The tap test is semi quantitative with arbitrary cut off for maturity and the shake test is also qualitative.…”

“…However, unlike in other studies done by Guidozzi F et al, 1991;Rodriguez-Macias KA, 1995 andKucuk M, 1998 where the tap test had better sensitivity and predictive value for fetal lung maturity compared to the shake test, this study had better sensitivity for shake test than for the tap test and comparable predictive value for fetal lung maturity between the two tests. 3,6,10 The tap test is semi quantitative with arbitrary cut off for maturity and the shake test is also qualitative. The borderline results like 6 to 20 bubbles in the ether layer in tap test and incomplete ring of bubbles at the meniscus in the shake test were considered immature in this study.…”

“…No single test of amniotic fluid has yet been found to be exclusively secure, easily performed and completely relevant in the prediction of fetal lung maturity. 3,5,6 The phospholipids profile, which includes the determination of phosphatidylglycerol and the lecithin/ spingomyelin ratio, is the most accepted test of fetal lung maturity worldwide. It has a high sensitivity and predictive value for assessing fetal lung maturity but only a modest specificity and a low predictive value for assessing fetal lung immaturity.…”

“…However, this test is costly, takes time and is not readily available outside normal working hours. 3,5,6 So alternatively quick, simpler and inexpensive bedside tap test and shake test have been used in which pulmonary surfactant development correlates with the stability of the bubbles in amniotic fluid mixed with the respective diluents in a solution.…”

Gastric Aspirate Shake Test for Prediction of Hyaline Membrane Disease in Preterm Babies

“…[11][12][13][14][15] The ideal test for fetal lung maturity should be rapid, inexpensive, and capable of being done at the patient's bedside, with high predictive value for both positive and negative results. 16,17 Fetal lung maturity can be determined as soon as the baby is born from gastric aspirate at the bedside and can be decided accordingly with the referral of the patients to the higher center where all neonatal facilities are available. Studies about the feasibility of a single-step shake test on gastric aspirates in the rapid evaluation of pulmonary surfactant maturity at birth in Nepali neonates have so far been not done.…”