# Contraction stress test

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Contraction_stress_test
> Markdown URL: https://mediated.wiki/source/Contraction_stress_test.md
> Source: https://en.wikipedia.org/wiki/Contraction_stress_test
> Source revision: 1271892912
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{short description|Medical test on pregnant women}}
{{Infobox diagnostic
| name            = Contraction stress test
| image           = 
| alt             = 
| caption         = 
| pronounce       =  
| purpose         =fetal test (heart rate)
| test of         =
| based on        =
| synonyms        = 
| reference_range =
| calculator      = 
| DiseasesDB      = <!--{{DiseasesDB2|numeric_id}}-->
| ICD10           = <!--{{ICD10|Group|Major|minor|LinkGroup|LinkMajor}} or {{ICD10PCS|code|char1/char2/char3/char4}}-->
| ICD9            = 
| ICDO            =
| MedlinePlus     = <!--article_number-->
| eMedicine       = <!--article_number-->
| MeshID          = 
| OPS301          = <!--{{OPS301|code}}-->
| LOINC           = <!--{{LOINC|code}}-->
}}
A '''contraction stress test''' (CST) is performed near the end of [pregnancy](/source/pregnancy) (34 weeks' gestation) to determine how well the [fetus](/source/fetus) will cope with the [contractions](/source/contraction_(childbirth)) of [childbirth](/source/childbirth). The aim is to induce contractions and monitor the [fetus](/source/fetus) to check for [heart rate](/source/heart_rate) abnormalities using a [cardiotocograph](/source/cardiotocography). A CST is one type of antenatal fetal surveillance technique.

During uterine contractions, fetal oxygenation is worsened. Late decelerations in [fetal heart rate](/source/fetal_heart_rate) occurring during uterine contractions are associated with increased fetal death rate, [growth retardation](/source/IUGR) and neonatal depression.<ref name=danforth>{{cite book|editor=Ronald S. Gibbs|display-editors=etal|title=Danforth's obstetrics and gynecology|year=2008|publisher=Lippincott Williams & Wilkins|location=Philadelphia|isbn=9780781769372|pages=161|edition=10th}}</ref><ref name=curr>{{cite book|editor=Alan H. DeCherney|editor2=T. Murphy Goodwin|display-editors=etal|title=Current diagnosis & treatment : Obstetrics & gynecology|year=2007|publisher=McGraw-Hill|location=New York|isbn=978-0-07-143900-8|pages=[https://archive.org/details/currentdiagnosis0000dech/page/255 255]|edition=10th|url-access=registration|url=https://archive.org/details/currentdiagnosis0000dech/page/255}}</ref>  This test assesses fetal heart rate in response to uterine contractions via [electronic fetal monitoring](/source/electronic_fetal_monitoring). Uterine activity is monitored by [tocodynamometer](/source/Cardiotocography).<ref name=fischbach>{{cite book|last=III|first=Frances Talaska Fischbach, Marshall Barnett Dunning|title=A manual of laboratory and diagnostic tests|year=2009|publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins|location=Philadelphia|isbn=9780781771948|pages=1030–31|edition=8th}}</ref>

==Medical uses==
The CST is used for its high [negative predictive value](/source/negative_predictive_value). A negative result is highly predictive of fetal wellbeing and tolerance of labor. The test has a poor [positive predictive value](/source/positive_predictive_value) with false-positive results in as many as 30% of cases.<ref name="FHM" /><ref>{{cite journal|author=((Lagrew DC Jr))|title=The contraction stress test.|journal=Clinical Obstetrics and Gynecology|date=March 1995|volume=38|issue=1|pages=11–25|pmid=7796539|doi=10.1097/00003081-199503000-00005|s2cid=45260930 }}<!--|accessdate=11 January 2013--></ref> A positive CST indicates high risk of fetal death due to hypoxia<ref name=fischbach/> and is a contraindication to [labor](/source/childbirth). Patient's obstetricians usually consider operative delivery in such situations.<ref name=firstaid>{{cite book|author=Tao Le|display-authors=etal|title=First aid for the family medicine boards|url=https://archive.org/details/firstaidforfamil00leta|url-access=limited|year=2008|publisher=McGraw-Hill Medical|location=New York|isbn=978-0-07-159382-3|pages=[https://archive.org/details/firstaidforfamil00leta/page/n573 556]}}</ref>

==Contraindications==
This "stress test" is usually not performed if there are any signs of [premature birth](/source/premature_birth), [placenta praevia](/source/placenta_praevia), [vasa praevia](/source/vasa_praevia), [cervical incompetence](/source/cervical_incompetence), [multiple gestation](/source/multiple_gestation), previous classic [caesarian section](/source/caesarian_section).<ref name=danforth/>
Other contraindications include but are not limited to previous uterine incision with scarring, previous [myomectomy](/source/myomectomy) entering the uterine cavity, and [PROM](/source/premature_rupture_of_membranes). Any contraindication to labor is contraindication to CST.

==Procedure==
CST is performed weekly,<ref name=danforth/> as the fetus is assumed to be healthy after a negative test and should remain so for another week.<ref>{{cite book|last=Munden|first=Julie|title=Professional guide to diagnostic tests|year=2005|publisher=Lippincott Williams & Wilkins|location=Philadelphia|isbn=9781582553047|pages=[https://archive.org/details/professionalguid0000unse_y2e2/page/682 682]|url=https://archive.org/details/professionalguid0000unse_y2e2/page/682}}</ref>  This test is done in hospital or clinic setting.<ref name=fischbach/> External fetal monitors are put in place and then either [nipple stimulation](/source/nipple_stimulation) or IV [pitocin](/source/pitocin) (oxytocin) is used to stimulate uterine contractions.

===Nipple stimulation===
This is a procedure that relies on [endogenous](/source/endogenous) release of [oxytocin](/source/oxytocin) following [nipple](/source/nipple) stimulation, and is conducted by the patient.  The [nurse](/source/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.<ref name="ACOG">American College of Obstetricians and Gynecologists (ACOG). (1999). Antepartum fetal surveillance (Practice Bulletin No. 9). Washington, DC: Author.</ref><ref name="FHM">{{cite book |title= Fetal Heart Monitoring: Principles and Practices|author= ((Association of Women's Health, Obstetric, and Neonatal Nurses)) |author-link= AWHONN|editor= Audrey Lyndon|editor2= Linda Usher Ali|edition= 3rd|year= 2005|publisher= Kendall/Hunt Publishing Co.|location=Dubuque, IA |isbn= 978-0-7575-6234-1}}</ref>

===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](/source/intravenous_drip) administration of [exogenous](/source/exogenous) [oxytocin](/source/oxytocin) to the pregnant woman. The target is to achieve around three contractions every ten minutes.<ref name="ACOG" /><ref name= "FHM" />

===Interpretation===

{| class="wikitable"
|-
! Result !! Interpretation
|-
| Positive|| Presence of late decelerations with at least 50% of the contractions<ref name=manual>{{cite book|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}}</ref>
|-
| Negative|| No late or significant variable decelerations,<ref name=manual/> with at least 3 uterine contractions (lasting 40 seconds) in 10 minute period.<ref>{{cite book|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}}</ref>
|-
| Equivocal—Suspicious|| Presence of late decelerations with fewer than 50% of contractions or significant variable decelerations. Requires repeat testing on following day.<ref name=danforth/>
|-
| 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.<ref name=danforth/>
|-
| Equivocal—Unsatisfactory|| Fewer than three contractions occur within 10 minutes, or a tracing quality that cannot be interpreted. Requires repeat testing on following day.<ref name=danforth/>
|}

==History==
The CST was the first antenatal surveillance test that was developed after the development of the [cardiotocograph](/source/cardiotocograph).<ref name="FHM" />  The oxytocin challenge test was first described in 1972<ref name="pmid4637035">{{cite journal |vauthors=Ray M, Freeman R, Pine S, Hesselgesser R |title=Clinical experience with the oxytocin challenge test |journal=Am. J. Obstet. Gynecol. |volume=114 |issue=1 |pages=1–9 |date=September 1972 |pmid=4637035 |doi= 10.1016/0002-9378(72)90279-7}}</ref> 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](/source/nonstress_test).  Today, a [biophysical profile (BPP)](/source/Biophysical_profile) is usually performed.

==See also==
* [Nonstress test](/source/Nonstress_test)
* [Cardiotocography](/source/Cardiotocography)

==References==
{{reflist|2}}

==External links==
*[https://web.archive.org/web/20070501155147/http://www.webmd.com/baby/Contraction-Stress-Test Contraction Stress Test] at webmd.com

{{Obstetrical procedures}}
{{Pregnancy}}

Category:Tests during pregnancy

---
Adapted from the Wikipedia article [Contraction stress test](https://en.wikipedia.org/wiki/Contraction_stress_test) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Contraction_stress_test?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.