Nonstress test

Nonstress test
Diagnostics
ICD-9-CM	75.34

A nonstress test (NST) is a screening test used in pregnancy. A cardiotocograph is used to monitor the fetal heart rate.^[1]

Premise

The premise of the NST is that a well-oxygenated, non-acidemic fetus will spontaneously have temporary increases in the fetal heart rate (FHR). ^[2]

Interpretation

• Reactive (normal)- presence of two or more fetal heart rate accelerations within a 20-minute period, with or without fetal movement discernible by the woman. ^[3]
• Nonreactive- presence of less than two fetal heart rate accelerations within a 20-minute period over a 40-minute testing period.^[3]

Vibroacoustic stimulation can wake the fetus, and is sometimes used to speed up the test or to facilitate further evaluation of a nonreactive nonstress test. ^[4]

References

1. ^ London, Marcia; Patrica Ladewig, Jane Ball, & Ruth Bindler (2007). Maternal & Child Nursing Care. Upper Saddle River, NJ: Prentice Hall. 
2. ^ Smith, C. V., Nguyen, H. N., Phelan, J. P., & Paul, R. H. (1986). "Intrapartum assessment of fetal well-being: a comparison of fetal acoustic stimulation with acid-base determinations". Am J Obstet Gynecol 155: 726–728. 
3. ^ ^{a b} Association of Women’s Health, Obstetric, and Neonatal Nurses (2005). Audrey Lyndon, Linda Usher Ali. ed. Fetal Heart Monitoring: Principles and Practices (3rd ed.). Dubuque, IA: Kendall/Hunt Publishing Co. ISBN 9780757562341. 
4. ^ Chervenak, Frank A.; Kurjak, Asim (2006). Textbook of Perinatal Medicine, Second Edition (Two Volumes). Informa Healthcare. pp. 963. ISBN 1-84214-333-6. 

See also: Cardiotocography, Biophysical profile, Contraction stress test