Which part of Umbilical cord is assesed by Doppler ? What are the indices that are commonly used and clinicians mast be aware of such indices. measured

, 9:-Doppler ultrasound:-Where to place the probe?? –Principle is the impedance highest at the fetal end.    Preferably at fetal end, and Doppler studies are assessed at   the free loop

·         Q. 9: Which kind of wave tio use in the machine?? Ans; By  the spectral Doppler indices and one has to asses pulsatility index (PI) (Gosling index): (PSV - EDV) / TAV

·         resistive index (RI) (Pourcelot index): (PSV - EDV) / PSV etc. and documented and a printed curve should be handed over to the elatives as per formalities.

 

Why Foetal end is chosen?? Ans:-PI/RI measured at the fetal end, the free loop and the placental end of the umbilical cord are different with the impedance highest at the fetal end. The changes in the indices are likely to be seen at the fetal end first. Ideally the measurements should be made in the free cord, however, for consistency of recording in cases being followed up, a fixed site would be more appropriate, i.e. fetal end, placental end or intra-abdominal portion.

Q.10. When foetal end of cord is assessed??  Sometimes , foetal end is difficult to located due to oligohydramnios in such cases  due to difficulty with measuring the cord at the fetal end in many growth-restricted fetuses, measurement in a free loop is acceptable,

Q. 12: What is the normal waveform look like ?? Ans:-The umbilical arterial waveform usually has a "saw tooth" pattern with flow always in the forward direction that is towards the placenta.

Q. 13:-An abnormal waveform shows absent or reversed diastolic flow. Before the 15^th week, absent diastolic flow may be a normal finding . Both PI & RI decreases slowly decreases for both the resistive index (RI) and pulsatility index (PI) through the course of gestation due to progressive maturation of the placenta and increase in the number of tertiary stem villi.

 Q. 14: What parameters are used???

The commonly used parameters are:

·         umbilical arterial S/D ratio (SDR): systolic velocity / diastolic velocity

·         pulsatility index (PI) (Gosling index): (PSV - EDV) / TAV

·         resistive index (RI) (Pourcelot index): (PSV - EDV) / PSV

·         PSV: peak systolic velocity 

·         EDV: end-diastolic velocity 

TAV: time-averaged velocity