The tap test- an accurate First-line test for fetal lung maturity testing

  • W K H Kuchenbecker
  • L R Pistorius
  • R C Pattinson


Objective. To determine the accuracy of near-patient and laboratory- based fetal lung maturity tests in predicting the need for neonatal ventilation.

Design. A prospective descriptive study.

Subjects. One hundred high-risk obstetric patients where confirmation of fetal lung maturity would initiate delivery.

Methods. Fetal weight estimation, placental maturity grading, and amniocentesis were performed. The investigators examined the amniotic fluid visually, and performed the tap test and shake test. Laboratory technicians estimated the lecithin-sphingomyelin (L/S) ratio, determined the presence of a phosphatidyl glycerol (PG) band on gel electrophoresis, and the optical density at 650 nm. Neonates delivered within 1 week of amniocentesis were included in the analysis. The primary end-point was the ability of the lung maturity tests to predict the need for neonatal ventilation.

Results. Twelve of 100 neonates required ventilation. The tap test and optical density (OD) shift at 650 nm predicted the need for neonatal ventilation with the greatest accuracy.

Conclusion. The tap test is a rapid, easy and accurate predictor of the need for neonatal ventilation. The OD shift at 650 nm is the laboratory-based test with the greatest accuracy in our setting.


Journal Identifiers

eISSN: 0256-95749
print ISSN: 2078-5135