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Short-term Variability vs Long-term Variability


Specializes in Gerontological, cardiac, med-surg, peds. Has 16 years experience.

Help! Anyone able to explain in a simple way the difference between STV and LTV on a fetal monitoring strip to make it easier to communicate the differences to students? I know STV is related to the parasympathetic nervous system (according to the book--why is this?) and is beat-to-beat differences. I am still a bit confused as to what "beat-to-beat" differences are. LTV is related to the sympathetic nervous system (seems like it should be the other way around:confused:)and is the cyclical changes or rhythmic changes seen over a minute on the strip. Are the facilities using the two criteria or is it just "variability" that is being assessed and charted at your facility? If you are only assessing variability, what are the different categories of variability you are documenting? Thank you so much for your help!:kiss BTW, I have worked as a L& D nurse in the past, but the concepts are still difficult to understand.


Has 20 years experience.

Hi there! Since this is the 2nd question you asked regarding FHM I went ahead and got an article I found very informative for you....

maybe itwill answer some other questions floating in your head too!!!

By the way if you are teaching the OB component in nursing school, I would advise against getting TOO steeped in the ins and outs of FHM....it's more complicated than that and likely won't make a whole lot of sense to nursing students.....JMO...

anyhow here is the article:


good luck! I do hope this helps you.

Short term is the change from beat to beat, so it shows up as jagged marks on the strip...where long term is the long wavy hills of changes in heart rate over minutes. We document short term only if an inernal device is used...external monitoring is used for measuring long term variability.


Has 20 years experience.

Like mishl, we only document and assess STV when a fetal spiral electrode is in place. EVERY AWHONN class I have been to advises we cannot accurately assess beat to beat variability unless using internal monitors to do so, although youwill find nurses all over who do it anyway. I say, stick to the standard held by AWHONN when documenting/assessing fetal heart monitoring.


Specializes in Gerontological, cardiac, med-surg, peds. Has 16 years experience.

Thanks! This is a big help. Will try also to keep it simple; teach the basics--that is all.

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