Listen to the foetal heartbeat with the foetal doppler or with the monaural stethoscope. From the 10th week onwards the heartbeat can be heard with a foetal doppler in the majority of cases. With the monaural stethoscope this is possible after 18 to 20 weeks. The heartbeat only becomes clearly audible in the third trimester because there is a relative decrease in the volume of amniotic fluid compared to the volume of the foetus, and so the beat is less muffled.
Auscultation: Model With Abdominal Cover
Procedure
- Place the stethoscope on the auscultation point using one hand, while placing the other hand contralaterally against the uterus. The best auscultation point for the child in head presentation is usually the back of the foetus beneath the mother’s navel. In the case of a breech presentation, this position is often above the navel.
- Press the ear against the flat end of the stethoscope.
- Press firmly with the contralateral supporting hand so that the foetus does not become displaced under the pressure of the stethoscope and so that as little amniotic fluid as possible is located between the stethoscope and the foetus.
- Let go of the stethoscope as soon as it has been pressed onto the abdomen with the ear. This prevents interference sound.
- While listening feel the pulse rate of the mother so as to prevent confusion with the maternal heartbeat or vascular sounds.
- Note the findings with respect to the frequency and regularity of the foetal heartbeat. The physiological heart rate lies between 120 and 160 beats per minute.
Auscultation: Model Without Abdominal Cover