Ultrasound imaging in gynaecology Flashcards
How does an ultrasounds transducer work?
Piezoelectric crystal in the transducer.
Electrodes apply an alternating potential difference across the crystal.
The crystal grows and shrinks depending on the voltage run through it.
Running alternating current through it causes vibration at a high speed and production of an US wave.
This sound is the reflected back to the PE crystal converting sound to electrical energy and then to photo energy.
What is the Doppler effect?
The shift between emitted and observed frequency of sound.
What colour is emitted by objects moving away?
Red.
What colour is emitted by object moving towards?
Blue.
What do different numbers of follicles in the ovary relate to?
2-3 = perimenopausal 3-5 = low follicle production 5-11 = normal 11+ = PCO
What does the endometrium look like shortly after menses?
A thin white line.
What does the endometrium look like during the mid-late proliferative phase?
Thick and manifests as a triple layer appearance.
What does the endometrium look like a day before ovulation?
Still has thick triple layer appearance but also has thick white line surrounding it which is likely to reflect more progesterone production from the dominant follicle.
What does the endometrium look like in the luteal phase of the cycle?
thick and homogenously hyperechoic (brighter than normal).
What is the size of a follicle during the early follicular phase?
less than 8mm in size. multiple present.
What is the size of a mid follicular follicle?
Dominant follicle present ahead of other follicles.
Periovulatory follicle
17-23mm
What is the appearance of a CL?
cystic or solid collapsed OR full appearance with irregular edge and shadows within the cyst. Irregularity of edges due to the presence of progesterone.
What is classical as 21 days?
Raised Doppler.
What is the Resistance Index?
A-B/Mean Difference of the highest and lowest value divided by the mean in one cardiac cycle.
