Hearing Variability with a Stethoscope

Association of Radical Midwives

From MIDWIFERY MATTERS, Spring 2000, Issue No. 84

Hearing Variability

What can midwives learn from intermittent monitoring? How do Sonicaids and Pinard stethoscopes compare to continuous electronic fetal monitoring?

Note: ARM sells beautiful varnished beechwood Pinard stethoscopes… for photos and prices, see our Items for Sale page.

This column is compiled from the UK Midwifery mailing list. Open to midwives, students, mothers, and anyone interested in improving maternity services in UK.

Can you hear variability with your ears?

“Today in class we looked at CTGs. I asked if variability could not be heard with our ears, because I remember having a conversation with Ishbel Kargar at the Royal College of Midwives conference about intermittent monitoring. Ishbel said that many things could be heard with our ears. Up till that time, when I had done intermittent monitoring I didn’t feel comfortable because I felt as though I was only ensuring that the fetus was alive each time I listened in. “

“So back to class – when I asked the tutor if it was possible to hear variability she said – no, it can only be recorded electronically. What do you all think?”

Student Midwife

Variability CAN be heard

Without going into the growing body of evidence to support intermittent auscultation as the standard of routine care, here is my two crowns’ (Norwegian) worth.

I think it depends some on your sense of rhythm. When I hear variability, I can only say subjectively that I have heard it, I can’t count and multiply over short intervals in rapid enough succession to give a numerical value to the variability I hear.

What is recorded on a CTG trace is a series of single points which are so close together that they appear to be a continuous curve. The microprocessor in the machine calculates FHR per minute by counting how many beats it `hears’ in a short interval (3-4 seconds or so, can’t remember) and then multiplying that number by 20 or 15 to get the rate per minute. Since the FHR changes often, or at least it ought to, the point for each reading will be at a slightly different height on the graph.

(With a scalp electrode, variability is even more accurately recorded because no beats are missed and there is much less artifact – interference from maternal pulse, primarily.)

Lean in close to the monitor sometime and listen to the marker— it makes a sound as it moves in its jerky little excursions between each point it draws. When it draws an erratic zigzaggy line at certain heights, we are all much happier than when it either refuses to draw any line or draws a line which is not zigzaggy enough, or is too zigzaggy, or is at the wrong height. Degree of zigzagginess and height which make us happy will depend less on an objective normal standard and more on what kinds of local attitudes reign in our ward. (In my view, this is the heart of the problem with the CTG.)

The tutor is right in that this representation of variability is dependent on sophisticated electronic instruments for recording it. But she is wrong in saying that you can’t hear it, because you most certainly CAN, at least if you listen for a full 60 seconds. If I hear an absolutely even rhythm for a whole minute, I want to know whether that baby is sleeping. Checking again within 20-30 minutes satisfies my need to know in the vast majority of cases.

FHR is just one of many parameters we pick up on when spending time with a labouring woman. I wonder if it gets a lot of undeserved PR because it is the easiest parameter to quantify?

Rachel Myr

Hear! Hear!

How I rejoiced to read this – many thanks, Rachel! I love your wonderful explanation of how the external CTG actually counts the FHR – most people believe it’s a true reading of every beat. I tried to explain this to some colleagues once, but I was ignored.

I am also a `Pinard devotee of the rabid persuasion’ though my skills are very rusty, I retired in 1992 and haven’t put Pinard to belly since that time. I sometimes despair of midwifery as a profession when I hear of the almost total reliance on electronic fetal monitoring – it’s a wonderful tool for problem cases, but when it’s used for every woman there’s a loss of personal contact and listening skills.

I hold an ARM stand at many midwifery conferences and study days, and some months ago a student midwife just into her second year pointed to the beechwood Pinards on our table, and asked, “What’s that?”

I thought she must be joking, perhaps because they weren’t the usual plastic or metal, but she really hadn’t had a chance to use a Pinard – even the community midwife used a portable Sonicaid.

I remember learning so much about the skills of auscultation with a Pinard, almost made me think of the Chinese diagnostic pulse-taking. Of course, the actual beats per minute is important, but so is the variability and the strength. Those skills will never be acquired unless the Pinard is used on every possible occasion.

I acknowledge the argument that ‘the mother likes to hear her baby’s heartbeat’. But for generations, mothers have known that the baby is alive and kicking – literally! It’s all part and parcel of the so-called need of the parents to ‘bond’ with the growing baby – witness the numerous scans in early pregnancy, with photographs of the fetus being proudly displayed afterwards. Are the parents given the down-side to all this? Do they know that the sonic beams have not yet been proved harmless? I know there’s no actual evidence of harm – yet.

The good things about using a Pinard with skill is that it is a really close, personal thing to do with a pregnant woman, it’s a non-intervention procedure, and even better – you don’t need to worry about being without batteries!

Okay, I’ll get down off the soap-box now, and wish you all goodnight!

Ishbel

Here’s How

It’s easy to count and consider variability. Count for six seconds and multiply by 10. Very easy and fast.

Sharon

 

It Takes Experience

As a tutor, I have to say that although I agree that it’s not possible to pick up variability by using a Pinard, I think she [your tutor] is missing out one vital component here. The art of midwifery. With sufficient experience – and my students are not getting enough – the midwife can hear the different intervals between beats, and accelerations, although could not possible define them in statistical terms. Which is all the CTG gives you. Bring back routine use of the Pinard!

Coyote

Objective Evidence for the Hearing ….?

It sounds like the main benefit of electronic monitoring is that you have some written record – some evidence to show in court 🙁 .. of what was observed, whereas with intermittent ausculation you have ‘only’ the word of the midwife.

I would personally rather rely on the interpretation of an experienced midwife, but in a practice/ward where several midwives or doctors are involved in a woman’s care, I could see why they might want one consistent record, taken by the same machine, throughout labour, to avoid problems with people interpreting things differently. Primarily, though, it would be an exercise in covering the practice against litigation, presumably – how sad.

As a midwife using intermittent ausculation, would you have the evidence you might need to show that you had acted correctly, if there was a problem? I know healthcare shouldn’t be driven by ‘what if we get sued?’, but since the loveliest person can turn into a vexatious litigant, if I was a midwife it would worry me. How do you all manage?

Angela

… or is it?

Ha! But there’s the rub! What about the studies that showed the identical trace to a number of ‘highly experienced’ clinicians and got widely (and wildly) different interpretations….? There is no ‘right’ way of interpreting a trace, or an auscultation, come to that.

In court, practitioners have to demonstrate they used their clinical judgement and were not negligent. They don’t have to prove they made the ‘right’ decision.

All a print-out does is show what the machine recorded at the time. It does not tell a clinician (midwife or doctor) what to do about it.

Does anyone know of any court case where a print out has been used in evidence or where the clinician was put at a disadvantage because there was no print out available?

(And that’s not to even mention machines that break down or record unreliably. Or the effect of having a machine on the mother and her carers, which we ‘know’ can alter the course of her labour)

Heather

Interpreting Traces

Thank you, Heather, for being your usual incisive self. I, too, have seen CTG traces which were technically so bad that the ward is making itself more vulnerable by filing them in the record than it would if the midwife simply pretended it had never been used.

The Danish study of over 10 years ago showed indeed that there was unacceptable inter-observer reliability in interpreting traces. My favourite part of the study was where they showed the SAME traces to the SAME experts two months after the first go-round, and discovered that the intra-observer reliability was no better than inter. What was the point of CTG again? Someone, help me here!

We had a summer fill-in midwife from Denmark who claimed that in her unit, the CTG was only kept in the notes if the baby had a problem needing special care at birth. If the baby cried spontaneously and had Apgars over 7 or 8 (can’t recall), the midwife simply tossed the CTG trace in the same bin as all the other waste after the birth, because they felt it had no value beyond that moment. I was utterly charmed.

Rachel Myr

Trust Your Ears …

When I was training I recall a case that the CTG was used and thought to be picking up a low base line of 110 with reduced variability. The midwife then listened in with a Pinard to confirm the reading and unfortunately she could not hear a fetal heart. I think this is a horribly frightening example of how technology can make you think that all is OK when it is not..

Also the RCOG (1993) recommend that if the woman has had no complications during her pregnancy the best way to monitor FH is via a hand held instrument once every 15 mins.

… not Machines

I do so agree with you – I know of a similar case, but the midwife had great difficulty in convincing ‘the boss’ that there was no fetal heart. Electronics can be very temperamental, and not everyone knows how to interpret anomalies. There’s a tendency to think its the machine that is faulty, and waste time finding a different machine, instead of just listening in with a Pinard and making a decision on what you hear.

Ishbel

Practicalities

I’m a second year student midwife. I’d like to ask you more experienced midwives something. When I care for a woman in labour although I’d like to use the Pinard, I often find myself using the Sonicaid, this is only because I find it much more ‘flexible’. When the woman is coping well with labour by standing up and walking around and finds it extremely uncomfortable to sit down or lie down for a minute or two while I listen with my Pinard, I feel like I am being horrible to them by asking them to assume an uncomfortable position which will give them more pain and ‘disturb’ labour (and because in established labour we listen to the FH quite often I would have to ‘disturb’ her many times).

I don’t know if it’s me (because I am still learning and need more experience) but I find it rather difficult, almost impossible to listen to with a Pinard unless the woman stays still and preferably lies down. Is it possible to use the Pinard and hear a good heartbeat if the woman is standing up? (probably yes, only I tried once, failed and gave up, that’s maybe why I have gone wrong).

Jo

Learning from the CTG

I do think you can hear variability. After some experience of being in the room listening to the heartbeat on the CTG you do pick up rhythms and beats….. you can tell when the rate is ‘flat’ or the variability ‘good’…… you can almost begin to sense when the heart rate will fall…. i.e. early decels or even late……. sometimes I know when the contraction is coming before seeing the woman because I can hear the baby reacting to it….

It’s not a thing I can prove with research….. but I know it to be true after eight years of doing it day in and day out…..

Kelly

Graphing Variability

Variability can be heard with a Pinard. You just have to listen for a while and write your times down. I do non-stress tests on women who are overdue and listen for 10 minutes. I count every other 5 seconds and get them to write down the numbers I call out. Then I graph it. But even without that, I can hear variability, even over just a couple of minutes, and often without counting it, although I usually do count.

Melody

Hearing Bad News

I know of another independent midwife, Katy, who picked up a congenital heart defect by listening. It took a lot of convincing on her part to get the mother to go in and once detected, she had the baby in hospital and the baby had immediate heart surgery. Katy probably saved that baby’s life with her good ears.

Melody

Power of the Pinard

Hurray! Another witness to the power of the Pinard! I had begun to wonder whether I was talking through my hat when I described the variety of information to be gained from using a Pinard.

How can we make sure these skills are not lost? So many student midwives hardly get a chance to use a Pinard these days, even the community midwives they are placed with use the Sonicaids, “the women like to hear the heart-beat!”

Ishbel

Learning Model

I heard today of a model which is available which enables the learner to detect the fetal heart in an artificial abdomen, and it can be with done with a Pinard! Anyone aware of a supplier?

Lorna

Reassuring Ishbel

All is not lost… I confess to using the Sonicaid “so mums can hear the baby”, but now I have a student midwife placed with me (for the first time… very scary!), I make a point of using my Pinard… (a very nice beechwood model… bought at a certain stall at conference!)… I think the student feels a sense of achievement at being able to identify the fetal heart.

Janet

P.S. Surely the best way to learn is to listen to a real baby in a real abdomen… with the mum’s consent of course.

Hard of Hearing?

Me, too – Janet – I just love using my Pinard! (although my new cheapo plastic Pinard much clearer than my ancient, well-used wood one – or maybe my ears are just older…)

Why Listen at All?

Something I read just yesterday has made me pause for thought. GP Gavin Young, writing in the book Community-based Maternity Care says he has ‘given up listening to the fetal heart in antenatal checks once the woman begins to feel fetal movements from 20 weeks unless she wishes me to listen’.

He feel that listening to the fetal heart: ‘sends an implicit message that a woman needs a check-up to tell if her baby is alive… listening to the heartbeat in pregnancy implies to the woman that we can tell something she cannot’. The woman is, after all, the ‘primary care-giver to her baby’.

Hannah

A Fine OB

I experienced shared GP/midwife antenatal care in the US in 1981. My GP was still in training, and was required to see me together with the obstetric consultant for one visit. He was of the good old school, and I do mean good. He recoiled on learning that I had worried throughout my pregnancy about my clinically judged ‘borderline’ pelvis, and said, without more than a glance at me, that there was nothing borderline about it. He went on to say this was no guarantee of a normal labour, but he had seen lots of women he wouldn’t have given ‘a snowball’s chance’ of a normal birth, and their labours went fine. Then he said there were equally many women whose pelves could ‘pass a watermelon’ and who still experienced such delays in labour that c-s was necessary. “All of which just goes to show that we really don’t understand what makes labour progress, or not progress.”

When my GP tried to conclude the appointment by auscultating the fetal heart, the consultant looked at him incredulously and said, “What are you doing that for? We just saw the baby kicking!”

Too bad they are a dying breed— there was nothing disempowering about seeing this man. On the contrary, I feel it was very opportune that this appointment was at 38 weeks, so his comments were still fresh in my mind when labour started. Over 18 years later, they are still firmly imprinted there.

Rachel Myr (5′ short (152 cm) and proud of it)

The ‘Done Thing’

What’s the research behind listening to fetal heart anyway? Do we ‘know’ it’s beneficial or is just one more thing that’s done because, um, well, er, um…..it’s always been done? I mean, it sounds as if it should be a good idea, but maybe it isn’t.

Fetal movement may be no better a sign of well-being…anyone else remember women keeping ‘kick charts’ before they were found to be misleading, anxiety-making and, well, useless as a routine check? I think there could be drawbacks in asking the woman to keep a sort of 24-hour check on her baby in this way (even the kick charts only asked her to record the first 10 movements each day).

What’s the evidence either way?

Heather

What about the baby?

This is really interesting – during my last pregnancy I did not want my baby exposed to more ultrasound than was really necessary.. I didn’t like the idea of having a Sonicaid used so many times during the pregnancy, but I bottled out of asking the midwives to use a Pinard – felt I was being awkward enough on other matters.

Throughout the pregnancy the baby’s heart rate was on the high side of average, but once, just out of interest, I asked a midwife to listen with a stethoscope before she used the Sonicaid. The heart rate was steady with the stethoscope, but increased noticeably when the Sonicaid was used. You could hear it accelerating when the Sonicaid was first put on. He clearly didn’t like it.

These posts have made me realise that routine fetal heart rate checks are not necessary anyway – I can see how they would perhaps help in late pregnancy to get a baseline for comparison in case the baby was distressed, but not earlier on. This time I will be more confident about asking them to use a Pinard or stethoscope, or if not, not to bother.

Angela

What’s the Difference?

This raises a perhaps naive question from a layperson — what’s the difference in what you hear between using a Pinard and using a [conventional] stethoscope?

With a stethoscope, you can hand the ear part over to the mum and she can hear the heartbeat, too, if that’s really an issue for her. Seems a reasonable compromise to me. And I can add my anecdotal affirmation of ultrasound raising the fetal heart rate — and it was clear to me from the way the baby squirmed that mine didn’t like it at all!

Melanie

Pinard More Direct

I too always found it difficult to hear the baby’s heart with an ordinary stethoscope. Probably, as you suggest, because the Pinard earpiece is much wider, and the sound is coming straight up, rather than being converted from vibrations of the membrane in the ordinary stethoscope.

Ishbel

Pinard Easier

Not a naive question at all – and, yes, it would seem a good compromise. However, I’ve always found the fetal heart much harder to hear through a conventional stethoscope (the open end of a Pinard is generally far wider than a conventional stethoscope – and, of course, the midwife’s ear is a lot closer to the baby than when listening through a stethoscope).

Do other midwives find listening to the fetal heart through a stethoscope a bit tricky (or is it me and my ears again!)?

One further point – and call me an old-fashioned softie – but I rather like the story behind the Pinard. Did you see the doctor on BBC’s Wives and Daughters using a Pinard to listen to Lady Whatsit’s chest? Apparently, that’s how it was always done until (male) doctors felt that using a Pinard in this way was far too intimate – hence the invention of the conventional medical stethoscope to place suitable distance between doctor and patient.

Meanwhile, midwives have stuck with the intimacy of the Pinard…

Pinards are (furthermore) easy to make/improvise and very cheap (my plastic one was £3.50). They hang around (albeit often dusty and unused) on wards far longer than smart medical stethoscopes. Even the most remote and basic of clinics in Ghana had a Pinard when I worked there – but very few had a stethoscope.

Hannah

Last Word – Ultra Low-Tech

Apparently you can use an empty loo roll tube as a fetal stethoscope!!! I’ll stick with my cheap plastic Pinard for now though, it’s very efficient.

Kaz

Hear Variability using a Sonicaid …

With reference to hearing variability without the use of a CTG – I as a first (nearly 2nd) year student have been taught at a midwifery led unit to listen for a full minute (with a hand held doppler). Within this minute you can divide it up into 4 sections of 15 seconds. You count the heart beats for each 15 minutes separately and by multiplying each 15 second by 4 you can get an average for the minute. By comparing these four averages you can produce a variant amount. A variant of + or – 5 beats is an ideal and a good indicator that the baby is happy.

Obviously if intervention such as a VE has been performed then you would expect the heart beat to have more variance.

I hope my understanding and explanation of this is correct.

Helen

… And Progress to a Pinard!

Although this is helpful as far as it goes, it is still using ultrasound. I know the hand held Doppler is not so continuous or invasive as continuous CTG, but the principle remains, that Pinard skills are not being learnt. I suppose it could be used as a sort of stepping down from hi-tech – learn to assess variability using the hand-held sonicaid, then start doing the same with a Pinard!

Ishbel

LW updated February 4, 2005


Articles and Information

Radical Midwives’ Homepage – www.midwifery.org.uk

2 Responses

  1. Hi
    Just read you page on using pinards. Im a first year midwifery student and just getting to grips with pinard use. Can you distinguish a materanl heart and fetal heart using a pinard, or just a fetal heart. With a sonicad both can be picked up. Could you enlighten me please.

    Thanks

    1. Hi Rachel

      What you can pick up with either pinard or sonicaid sometimes is the maternal heart as a swooshing noise as it passes into the placenta. Best practice in either case is to ensure you are listening to the one pulse you think is the fetal heart, and check by palpating the radial pulse at the same time so you can determine the difference.

      Linda

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