From MIDWIFERY MATTERS, Issue No.94, Autumn 2002
Mary Cronk
THIS ARTICLE has been in my head for some time. I actually didn't believe that there were midwives qualifying who had never heard a fetal heart, didn't know what it sounded like, and didn't know the provenence of the Pinard's stethoscope. Then I met several students who asked me to teach them how to use it and then I realised that an article like this might be useful.
'Pinard's' has a capital P as it is named after a Dr.Pinard, a Frenchman who produced it sometime in the mid 19th century. It was widely used for auscultation in medical practice until the binaural stethescope was invented. Before I became a midwife I trained as a nurse at Glasgow Royal Infirmary. In those days medical practitioners had little or no technology other than Xrays to assist them in diagnosis and they relied almost totally upon clinical observation. A venerable Honorary Cardiac Physician, when he did his Ward Round insisted on a tray being carried by the senior staff nurse who followed Sister who followed Sir. On this tray were laid out Sir's equipment: various hammers, head mirror, etc. and three different designs of Pinard's stethoscopes. He used these if he wished to confirm what he was hearing with that new-fangled piece of equipment - the binaural stethoscope. He also insisted that the students listen with it, they did this with varying degrees of hidden sniggering, scepticism and sneering.
A careful palpation saves lots of time. The aim is to hear the fetal heart through the fetal back. Thus, the bell end of the instrument is positioned over the place on the maternal abdomen under which it is felt that the baby's back lies, remember the lungs are not inflated and the fetal heart can be heard clearly through the back. If the position seems to be LOA, position the wide end of the Pinard's about half way between the umbilicus and the symphysis pubis and about two inches to the left. If the head is engaged move it down a bit. Apply your ear to the flat end; you will need to apply gentle pressure and indent the abdomen nearly a centimetre, depending on the thickness of the abdominal wall. Take your hand away from the Pinard's, listen - and keep listening. You are listening for a sound that is in the distance and sounds like a watch ticking under a pillow, but of course faster than a ticking watch. If you have an old fashioned watch that ticks, try it (borrow one from your grandpa). Often, at first, it feels more like a vibration than a sound. If you hear a slow 'shooching' noise you are probably hearing the maternal vessels supplying the uterus. Feel the maternal pulse at the same time and if it coincides with the 'shooching' you are hearing the uterine vessels. The technical name for that is a 'uterine souffle' - don't ask me why.
If after careful listening you really can't hear a thing, repeat the palpation and try on the right. If you still can't hear anything that could conceivably be the fetal heart, consider whether the fetus could be in an OP position. If so, you may be able to hear nearer the midline, in which case, you will be hearing the fetal heart through the anterior fetal chest wall. Alternatively, try placing the Pinard's on the maternal flank, i.e. at the side where the mother's waist would have been if she still had one! You may have to practise and practise, but once you can hear it you have acquired an invaluable skill. If the baby is presenting by the breech, you may be able to hear it better above the umbilicus. Those of us who worked before ultrasound, often used the place where the fetal heart could be heard most clearly to help us to assess the position and presentation of the fetus. I can rarely hear a fetal heart much before 26 weeks, and if I don't hear it until 30 weeks so what?
Having managed to find the fetal heart, don't try and count it until your ear is 'tuned' and you have listened to several fetal hearts and feel confident. Use a watch with a decent second hand. I use a digital watch, but many of my colleagues prefer a sweep second hand. Wait until the second hand is at one of the quarters and start counting. Count for 15 seconds and multiply by four i.e. 35 beats in 15 seconds = 140 bpm. Listen for four quarters of a minute, not necessarily consecutively. Once you have mastered this, try counting each 5 second interval separately - it should not always be the same. In one 5 second interval you may hear 10 beats (l2O bpm) then you may hear 14 (168 bpm) or 12 (144 bpm). You may even hear an occasional 15 (180 bpm). This is how one assesses the beat-to-beat variations. If you find you are consistently hearing exactly the same number of beats every 5 seconds then there is not much beat-to-beat variation and the little darling's probably asleep! Listen again 15 minutes later.
You are hearing this baby's heart beating with your own ears. You are not hearing the ultrasound Doppler effect converted by technology back into sound. What you are hearing is direct; it is not computed or averaged by a hand-held Doppler or a CTG. I am confident that I can nearly always hear a problem before it is picked up on a CTG. Several of my clients do not wish any ultrasound to be used, unless there is a clear indication, and I am glad that I have retained the skill of using a Pinard's. Having said that, we are encouraged to auscultate much more often these days, and a hand-held Doppler does make life much easier if the woman is on all-fours.
If one is attending a woman who is labouring in a pooi and does not wish ultrasound to be used, the long Pinard's (13") enables the fetal heart to be auscultated when the woman is submerged. She does need to raise her abdomen out of the water while you apply the end of the long Pinard's, then she can submerge again keeping a seal between the end of the Pinard's and the abdomen. Put your ear to the flat end and if you are in the right place you will hear the fetal heart.
I have recently bought a new toy. It is an American fetoscope and I am learning to use it. I think that, when I am a bit more experienced in its use, I will find that I can hear the fetal heart as clearly as with my Pinard's and, of course, the woman can be in any position she wants.
LW updated February 4, 2005