US gynae & obstetrics Flashcards
what is included in the gynae US
- uterus
- ovaries
- fallopian tube
- bladder
- adnexa
- pouch of douglas
anatomy of uterus
- pear-shaped organ
function of uterus
- provides mechanical protection, nutritional support and waste removal for pregnancy
- contractions of muscular walls during labour is responsible for pushing out fetus
variations in uterine positions
- anteverted
- midposition/ axial
- retroverted
- anteflexed
- retroflexed
location of ovaries
- varies due to laxity of ligamentous attachments
- ovaries usually seen lateral to the uterus
- internal iliac vessels are found at the posterolateral border of the ovaries
what is menstrual and ovarian cycle
- repeating series of changes in the endometrium
- avg of 28 days
3 phases of menstrual cycle
- menstrual phase
- proliferative phase
- secretory phase
2 phases of ovarian cycle
- follicular phase
- luteal phase
describe what happens during the menstrual phase
- functional layer of endometrial lining of the uterus is shed and exits through vagina
- slowly rising levels of FSH and LH secreted by pituitary gland –> cause development of ~20 primary follicles
- pri follicles grow and develop into secondary follicles –> release estrogen and low level of progesterone
describe what happens during the proliferative phase
- after ~5 days, estrogen levels rise and enters proliferative phase
- endometrium begins to regenerate, blood vessels and glands begin to regrow
- ~ day 9, only one healthy secondary follicle becomes dominant while other follicles become antretic
- dominant follicle continues to grow in size and is responsible for producing large amounts of estrogen during late follicular phase
describe what happens during ovulation
~ day 14, high levels of estrogen causes FSH and LH to rise rapidly
- spike in LH cause ovulation –> mature dominant follicle ruptures and release egg
- follicles that did not rupture degenerate and their eggs are lost
- level of estrogen decreases when extra follicles degenerate
describe what happens during secretory phase
- after ovulation, menstrual cycle enters the secretory phase
- ovarian cycle enters the luteal phase
- cells in the follicle that ruptured during ovulation undergoes changes and form the corpus luteum –> produces significant amount of progesterone and smaller amount of estrogren
- progesterone facilitates the regrowth of the uterine lining to prepare for implantation
- progesterone also inhibits release of further FSH and LH –> prevents any further egg and follicles from developing
what happens if no egg is fertilised
- corpus luteum degenerates and levels of estrogen and progesterone decreases, initiating the next menstrual cycle
- decrease in progesterone also allows hypothalamus to send GnRH to anterior pituitary, releasing FSH and LH and starting cycle again
possible causes for abnormal PV bleed
- irregular menstrual cycle
- menorrhagia
- dysmenorrhea
- postmenopausal bleeding
possible causes of pelvic pain
- torsion
- pelvic inflammatory disease
- ruptured cyst
common clinical indications that warrants a gynae scan
- abnormal vaginal discharge
- amenorrhea
- pelvic mass
- infertility
- follicle monitoring
- locate intrauterine contraceptive device (IUCD)
- developmental abnormality
- postpartum complications (RPC)
- abnormal PV
- pelvic pain
2 types of sonographic methods performed in gyane
transabdominal (TA)
- transducer placed on lower abdomen to acquire images of the female pelvis
transvaginal (TV)
- transducer placed within the vaginal cavity
advantages of TA approach
- non-invasive (for female who has never had sexual intercourse before, whose hymen remains unbroken: virgo intacta)
- visualises the entire pelvis
- gives a global overview
limitations of TA apporach
- patients unable to fill the bladder will result in poor quality image
- patient unable to hold bladder for duration of scan - feel uncomfortable
- obese patients (fats attenuate signals)
- retroverted uterus
advantages of a TV approach
- examinations of patients who are unable to fill up bladder
- examinations of obese patients
- examinations of retroverted uterus
- allows use of higher-frequency transducers –> better resolution, better image quality & better anatomic detail
- better detail and characterisation of the internal characteristics of the internal characteristics of a pelvic mass
- better detail of the endometrium
limitations of TV approach
- because of higher frequencies, FOV is limited
- orientation difficult for larger masses (extend if out FOV)
- limited depth (superiorly or laterally placed ovaries or masses may not be visualised)
contraindications of TV
patient:
- is a virgin
- is an elderly
- refuses
what transducer is used for TA scan
- low frequency (1-5MHz) curvilinear probe
- provides adequate penetration and large footprint to image the reproductive organs and surroundings
why is full bladder required for a TA scan
- bladder located anterior to the uterus
- full bladder provides an acoustic window for the US waves to pass through
- also displaces small bowels from FOV - bowel gas obscures visualisation of uterus and ovaries and any pelvic mass