Leeds Fetal Medicine Unit Website

Third Trimester Scanning

Third trimester scanning in the fetal medicine unit usually takes place following diagnosis of a problem earlier in pregnancy or after problems in a previous pregnancy during the third trimester. In Leeds (as in most pregnancy units) we have the facilities to measure the growth of the fetus (using head, abdomen and femur measurements) and assess its well being using other ultrasound parameters. The measurements we obtain are plotted along a centile chart (see below) and can be used assess whehter growth is symmetrical or asymmetrical; fetal weight can also be estimated (accurate to ~10%). Normal growth along an individual centile is usually a good indicator of fetal well-being, but in isolation growth measurements cannot assess whether fetal growth is normal. For this reason we also measure liquor volume measurements and doppler measurements which are explained in further detail below. Lastly in certain circumstance it is useful to know whether a fetus is at immediate risk by remaining in the womb, on these occasions we use Biophysical profile measurements (also explained further below).

Picture of fetal head and abdomen here

Femur (thigh bone) length

Assessment of Liquor Volume

Estimated Fetal Weights

Doppler measurements

Need description of of why we measure what we do and what doppler are

As well as these standard measures we also have the facilities to measure more specialised fetal dopplers. Middle cerebral artery dopplers are particularly useful when assessing the presence of fetal anaemia in Rhesus disease and can also be useful in cases of fetal growth restriction

DV and umbilical vein description

Biophysical Profile

The fetal biophysical profile was designed in the 1980s to enable immediate fetal well being to be determined using ultrasound. The most established fetal biophysical profile included four ultrasound parameters with the addition of

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