Normal Anatomy (Female Pelvis) Flashcards
Echogenicity of Muscle
- moderate echogenicity
- echogenic striations within
How many planes do we image muscles in?
2
What can muscles be mistaken for?
- ovaries or masses in pelvis
- ex. iliopsoas can look like a bullseye in TRV
Is the uterus retroperitoneal or intraperitoneal?
-retroperitoneal
What happens to the uterus between birth and puberty?
-descends from lower abd into true pelvis
3 Major Portions of Uterus
- fundus
- body
- cervix
Cornua
-area of body where tubes enter
Body of Uterus
-area between cervix and cornua
Fundus of Uterus
-at/superior to cornua
What does the cervix open into?
-upper vagina
What is the cervix made of internally?
-canal made up of internal and external os
What is at the distal end of the cervix?
- 2 lateral fornix
- anterior fornix
- posterior fornix
Where is the fibromuscular canal, and where does it run from?
- midline of vagina
- runs from cervix to eternal genitalia
Uterus
-hollow, thick walled organ
3 Layers of Uterus
- perimetrium
- myometrium
- endometrium
Myometrium
- big muscle
- majority of uterus
- 3 layers: inner (subendometrial halo), intermediate, outer
Superficial Functional Layer of the Endometrium
-parts that sloughs off each menses
Deep Basal Layer of Endometrium
-stays attached to uterus
Uterine Ligaments
- broad (paired)
- cardinal (paired)
- uterosacral (paired)
- posterior (single)
- anterior (single)
- round (paired)
Broad Ligaments
- double folds of peritoneum
- uterus in suspended between these folds
- extend from the lateral aspects of uterus to the lateral pelvic walls
Cardinal Ligaments
-lower extensions of broad
Round Ligaments
-fibromuscular cord extends from upper outer angles of uterus through the inguinal canal and connect to labia majora
Uterosacral Ligaments
-fold like extensions of peritoneum
Anterior Ligament
- fold in peritoneum
- from anterior surface of uterus to posterior surface of bladder
- forms anterior cul de sac (vesicouterine pouch)
- fluid collects in this area
Posterior Ligament
- extends from posterior side of uterus to rectum
- forms deep pouch (aka pouch of douglas, posterior cul de sac or rectouterine recess)
- fluid collects in this area
Where does fertilization implant?
-endometrial lining
Where does fertilization develop?
-uterus
What contracts during labour?
-myometrium
What happens if fertilization doesn’t occur?
- menstruation
- myometrial contractions aid sloughing off endometrium
Blood Supply
- uterine arteries arise from internal iliac arteries
- travel within broad ligament, at cornua anastomose with ovarian artery
- enters myometrium
- uterine plexus of veins runs along with arteries
Which parts of the uterus are mobile?
- body and fundus
- cervix is fixed midline
Flexion
-axis of uterine body relative to the cervix
Version
-axis of the cervix relative to the vagina
What can affect/change the position of the uterus?
- distension of bladder
- rectal fullness
Which way does the uterus normally lie?
-anteverted and anteflexed
Retroverted Uterus
-entire uterus is tilted backward
Retroflexed
-body is tilted posteriorly
Uterus Size and Shape
-vary throughout life (age, hormonal status, etc.)
Infantile Uterus
- 8cm long
- cervix is 2/3 total length
- pear shaped
Neonate Uterus
- slightly larger than infantile due to maternal hormone stimulation
- 3.4cm long
- pear shaped
Uterus (age 8-puberty)
-gradually increases in size
Uterus at Puberty
- increase in size (especially body)
- diameter and length of body are double cervical size
- becomes adult size and shape
Adult Size Uterus
- 8 cm long
- 5 cm wide
- 4 cm AP
- pear shaped
Parity
-pregnancy
What does pregnancy do to the size of the uterus?
-increased normal size by 1cm in each dimension
Menopausal Uterus
- atrophies 3.5 to 6.5 cm (L) by 1.2 to 1.8 cm (AP)
- pear shaped
- small
What is the echotexture of the myometrium in an adult uterus?
-homogenous
What is the contour of the adult uterus?
-smooth
What is the echogenicity of the inner layer of the myometrium (subendometrial halo)?
-hypoechoic
Sonographic Appearance of the Intermediate Layer of the Myometrium
- thickest
- homogenous
- low to moderate echogenicity
Sonographic Appearance of the Outer Layer of the Myometrium
- thin
- slightly less echogenic than intermediate layer
What separates the intermediate and outer layers of the myometrium?
-arcuate arteries
Sonographic Appearance of Postmenopausal Uterus
-small
-can half calcification in arcuate arteries (linear calcific foci)
-small echogenic foci within inner myometrium
(single or multiple, non shadowing)
Endometrium Sonographic Appearance in Reproductive Years
- varies depends on stage of cycle
- size varies
Where is the Ap measurement of the endometrium done?
-thickest part
LMP
-day 1 of the first day of menses
How long is the average menstrual cycle?
28 days
4 Phases of Menstrual Cycle
1) early proliferate
2) late proliferate
3) secretory
4) menses
Early Proliferate
- 1st stage of menstrual cycle
- days 5 to 13
- 5mm
Late Proliferate
- 2nd phase of menstrual cycle
- days 14 to 16
- 11mm
Secretory
- 3rd phase of menstrual cycle
- days 16 to 28
- 16mm
Menses
- 4th stage of menstrual cycle
- day 1 to 5
What are some clinical indications for scanning the female pelvis?
- pregnancy (dating)
- pelvic pain (RLQ, LLQ, generalized, chronic, acute, etc.)
Transabdominal US of Pelvis
- global view
- limited to patients ability to fill and hold bladder
- difficult on obese patients
- retroverted uterus is beyond the focal zone of transducer
Patient Prep. for Pelvic Exam
- fills bladder (24 to 32 oz)
- approx. 4 glasses of water (finish 1 hour before exam)
Why do we get patients to fill their bladder?
- displaces uterus from pelvis
- displaces gas filled bowel
- use as an acoustic window
Technical Difficulties with Transabdominal US
- obese patients
- surgical scars (artifacts)
- barium or gas filled bowel
- abdominal dressings
Transvaginal Prep.
- discuss what is involved
- verbal consent
- empty bladder
- 5 to 8MHz transducer
- cover transducer with probe cover
- follow proper cleaning procedures after exam
Advantages of TVP
- better resolution (higher frequency transducer)
- obese patients
- patients who cannot fill bladder
- retroverted uterus
- better distinction between masses and bowel
- better detail of pelvic lesion
- better detail of endometrium
Disadvantage of Transvaginal US
- smaller FOV
- cannot do on elderly or young patients or people with complicated pregnancies
Where are the fallopian tubes?
-run lateral from uterus in the upper free margin of broad ligament
How long are the fallopian tubes?
-7 to 12 cm long
4 Portions of Fallopian Tubes
- intramural
- isthmus
- ampulla
- infundibulum
Intramural Portion of Fallopian Tubes
- 1cm long
- narrowest portion
- in muscular wall of uterus
Isthmus Portion of Fallopian Tubes
- medial third of tube
- wider and cordlike
Ampulla Portion of Fallopian Tubes
- tortuous
- approx. 1/2 of tube
Infundibulum Portion of Fallopian Tube
- most distal portion
- funnel shaped end
- opens into the peritoneal cavity
Shape of Ovaries
-elliptical shaped
What is the surface of the ovaries covered with?
- single layer called germinal epithelium
- continuous with peritoneum at hilum of ovary
Are the ovaries intraperitoneal or retroperitoneal?
-intraperitoneal
Ovary Parts
Germinal Epithelium
-single layer
Tunica Albuginea
-fibrous capsule
Cortex
-where follicles develop and mature
Medulla
- smaller in volume than cortex
- composed of fibrous tissue and blood vessels
Ovarian Ligaments
- mesovarian
- ovarian
- suspensory
Mesovarian Ligament
-attaches anterior surface of ovary to posterior surface of broad ligament
Ovarian Ligament
-attaches lower pole of ovary to uterus
Suspensory Ligament
- attaches upper pole to lateral wall of pelvis
- lateral extension of broad ligament
- ovarian vessels and nerves run within
- not rigid
Can ovaries be mobile?
Yes.
Ovarian Arteries
- from AO, just inferior to renal arteries
- run within suspensory ligament
- gives off branches to ovaries
- anastomose with branches of uterine artery
Ovarian Veins
- Rt ovarian vein drains into IVC
- Lt ovarian vein drains into Lt renal vein
Normal Sonographic Appearance of Ovaries
- uterine position affects ovarian position
- usually lateral or posterolateral to anteflexed midline uterus
- variable positions (laxity of ligaments)
Can ovaries be seen transvaginally?
-may be out of FOV
Size of Ovaries
- volume is best method
- L x W x AP x 0.523
Volume in 1st Year of Ovary
1cc
Volume in 2nd Year of Ovary
0.7cc
What is the volume of ovaries from 0-5 years?
-stable
What is the volume of ovaries from 5 years to menarche?
- gradually increase
- 4cc
What is the volume of ovaries in a menstruating adult?
- 6.8cc
- upper limit is 18cc
What is the postmenopausal volume of ovaries?
- 1.2 to 5.8cc
- over 8cc is abnormal
Echotexture of Ovaries
-homogenous
Echogenicity of Ovaries
- central, echogenic medulla
- small, well defined, anechoic/cystic follicles may be seen in periphery of cortex
- echogenic ovarian foci is commonly seen (non shadowing)
Echogenic Foci
- usually in periphery (can diffuse)
- specular reflectors of tint, unresolved cysts
Focal Calcification
- occasionally seen
- stromal reaction, previous hemorage or infection
Normal Changes in the Early Proliferate Phase
- follicles stimulated by FSH and LH
- increase in size until day 8 or 9
- one follicle becomes dominant
- dominant reaches size 2 to 2.5 cm at ovulation
- follicle cyst develops if fluid in one of the non dominant follicles is not resorbed
Corpus Luteum
- develops after ovulation (empty house)
- small, hypoechoic/isoechoic structure in periphery of ovary
- involutes before menstruation
Sonographic Appearance of Ovaries
- small
- lack follicles
- less likely seen after hysterectomy due to loss of normal anatomic landmarks
Postmenopausal Ovary Sonographic Appearance
- small
- lack of follicles or completely absent
- hard to find on US
Adnexa
-appendages or accessory structures of an organ
What are the adnexa of the uterus?
- uterine tubes
- uterine ligaments
- ovaries
-we image the Lt and Rt adnexa adjacent to uterus
