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Contraction stress test

Medical test on pregnant women

Summary

Medical test on pregnant women

Field	Value
name	Contraction stress test
purpose	fetal test (heart rate)
DiseasesDB
ICD10
MedlinePlus
eMedicine
OPS301
LOINC

A contraction stress test (CST) is performed near the end of pregnancy (34 weeks' gestation) to determine how well the fetus will cope with the contractions of childbirth. The aim is to induce contractions and monitor the fetus to check for heart rate abnormalities using a cardiotocograph. A CST is one type of antenatal fetal surveillance technique.

During uterine contractions, fetal oxygenation is worsened. Late decelerations in fetal heart rate occurring during uterine contractions are associated with increased fetal death rate, growth retardation and neonatal depression. This test assesses fetal heart rate in response to uterine contractions via electronic fetal monitoring. Uterine activity is monitored by tocodynamometer.

Medical uses

The CST is used for its high negative predictive value. A negative result is highly predictive of fetal wellbeing and tolerance of labor. The test has a poor positive predictive value with false-positive results in as many as 30% of cases. A positive CST indicates high risk of fetal death due to hypoxia

Contraindications

This "stress test" is usually not performed if there are any signs of premature birth, placenta praevia, vasa praevia, cervical incompetence, multiple gestation, previous classic caesarian section. Other contraindications include but are not limited to previous uterine incision with scarring, previous myomectomy entering the uterine cavity, and PROM. Any contraindication to labor is contraindication to CST.

Procedure

CST is performed weekly, This test is done in hospital or clinic setting. External fetal monitors are put in place and then either nipple stimulation or IV pitocin (oxytocin) is used to stimulate uterine contractions.

Nipple stimulation

This is a procedure that relies on endogenous release of oxytocin following nipple stimulation, and is conducted by the patient. The nurse instructs the patient on the procedure, as follows. One nipple is massaged gently through clothing until a contraction begins, or for a maximum of 2 minutes. If at least 3 contractions in 10 minutes is not achieved, then the patient rests for 5 minutes and the other nipple is stimulated.

Oxytocin challenge test (OCT)

If adequate contractions (at least 3 in 10 minutes) cannot be achieved with nipple stimulation, an oxytocin challenge test may be performed. It involves the intravenous administration of exogenous oxytocin to the pregnant woman. The target is to achieve around three contractions every ten minutes.

Interpretation

Result	Interpretation
Positive	last=Evans	editor=Arthur T.	title=Manual of obstetrics	year=2007	publisher=Wolters Kluwer / Lippincott Williams & Wilkins	location=Philadelphia	isbn=9780781796965	pages=587	edition=7th}}
Negative	last=Anderson	editor=Jean R.	title=A guide to the clinical care of women with HIV	year=2005	publisher=U.S. Dept. of Health & Human Services, Health Resources & Services Administration, HIV/AIDS Bureau	location=Rockville, MD	isbn=9780160726118	pages=270	edition=2005}}
Equivocal—Suspicious	Presence of late decelerations with fewer than 50% of contractions or significant variable decelerations. Requires repeat testing on following day.
Equivocal—Tachysystole	Presence of contractions that occur more frequently than every 2 minutes or last longer than 90 seconds in the presence of late decelerations. Requires repeat testing on following day.
Equivocal—Unsatisfactory	Fewer than three contractions occur within 10 minutes, or a tracing quality that cannot be interpreted. Requires repeat testing on following day.

History

The CST was the first antenatal surveillance test that was developed after the development of the cardiotocograph. The oxytocin challenge test was first described in 1972 and was standardised in 1975 when the parameters of contraction number and frequency were given.

Historically, a CST was done after a non reactive NST. Today, a biophysical profile (BPP) is usually performed.

References

(2008). "Danforth's obstetrics and gynecology". Lippincott Williams & Wilkins.
(2007). "Current diagnosis & treatment : Obstetrics & gynecology". McGraw-Hill.
III, Frances Talaska Fischbach, Marshall Barnett Dunning. (2009). "A manual of laboratory and diagnostic tests". Wolters Kluwer Health/Lippincott Williams & Wilkins.
((Lagrew DC Jr)). (March 1995). "The contraction stress test.". Clinical Obstetrics and Gynecology.
Tao Le. (2008). "First aid for the family medicine boards". McGraw-Hill Medical.
Munden, Julie. (2005). "Professional guide to diagnostic tests". Lippincott Williams & Wilkins.
American College of Obstetricians and Gynecologists (ACOG). (1999). Antepartum fetal surveillance (Practice Bulletin No. 9). Washington, DC: Author.
((Association of Women's Health, Obstetric, and Neonatal Nurses)). (2005). "Fetal Heart Monitoring: Principles and Practices". Kendall/Hunt Publishing Co..
Evans. (2007). "Manual of obstetrics". Wolters Kluwer / Lippincott Williams & Wilkins.
Anderson. (2005). "A guide to the clinical care of women with HIV". U.S. Dept. of Health & Human Services, Health Resources & Services Administration, HIV/AIDS Bureau.
(September 1972). "Clinical experience with the oxytocin challenge test". Am. J. Obstet. Gynecol..

Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

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