Role of colour Doppler USG in IUI practice ??

 

Those who are carrying out IUI procedure better have facility of Colour Doppler to optimize the timing of Inj hCG and timing of IUI!!  

A)           What are the expected images in Midfollicular (Preovulatory) scan?

     It is known that not all antral follicles grow to become dominant and mature follicle. A follicle that grows to 12 mm is a dominant follicle, Then speed of growth is at a rate of 2-3mm/day and ovulation occurs at 18-24 mm size usually. Follicular flow can be first detected when follicular size is 10 mm  and its resistance starts falling two days to ovulation due to low vascular impedance induced by rising oestrgen , .

A)           What are the sonological Features of a mature follicle? :

     A rounded 16-18 mm sized follicle with thin walls and no internal echogenecity is expected to be mature. A sonolucent halo appears surrounding the follicle, 24 hours prior to ovulation. Cumulus oophorus a very small small projection from wall in the follicular lumen may be seen.

B)            How much vascular flow around the mature Follicle?  This offers an indirect evidence of functional competency of Oocyte which is going to be released. On colour Doppler vascularity is seen surrounding 3/4^th of the follicular circumference. On pulse Doppler these vessels show RI 0.4-0.48,  PSV >10 cms/sec(Peak Systolic Velocity) .

This flow indices are of perifollicular vessels vessels are the ones that overlap the follicular wall. If the follicular vascular indices are not in the defined range, it means that the follicle is not yet physiologically mature and therefore stimulation still needs to be continued. 24 mm is the follicle size till which one can wait for the optimum flows to be achieved.

     This means that if the follicle is said to be functionally mature when PSV is 10 cms/sec, that is the time when the LH surge starts and under the effect of that LH, the perifollicular PSV keeps on rising constantly.

Follicular blood flow velocity starts increasing approximately 26-29 hours before rupture and continues till 72 hours after rupture. The perifollicular PSV rises as high as 45 cms/sec before an hour of ovulation.