Download Gynecology. Lecture ONE. Normal Anatomy of the Female Pelvis

Lecture One
Normal Anatomy of the Female Pelvis and Transvaginal Sonography
Holdorf
ULTRASOUND OF THE FEMALE
PELVIS
Outline
 Skeletal
 Ligaments
 Musculature
 True Pelvic Muscles
 Pelvic Organs
 Urinary Bladder
 Vagina
 Uterus
 Cervix
 Layers of the Uterus
 Uterine Size
 Uterine Positional Variations
 Ovaries
 Ovarian Size
 Fallopian Tubes
 Other Stuff
 Peritoneal Recesses
 Vascular Anatomy
 Doppler Flow Characteristics
Transvaginal Sonography
Skeletal
 The word pelvis is derived from the Latin and
Greek, meaning “dish” or “bowl”. The bony
Pelvic girdle is the central section of the axial
skeleton.
 It is positioned between the lower end of the
spine, which it supports, and the lower
extremities, upon which it rests.
Four bones compose the bony pelvis:
 Sacrum
 Coccyx
 Two innominate bones-fusion of the ilium,
ischium, and the pubis.
 False pelvis sits above this plane and is
bounded by the iliac wings. It is a broad
shallow cavity that supports the abdominal
viscera.
 True pelvis sits below this plane and is further
divided into the pelvic inlet and the pelvic
outlet.
 In the absence of masses in the non-gravid
patient, the uterus, ovaries, and adnexa are
situated in the true pelvis.
Of interest:
The Sacrum, Coccyx, and two innominate
bones.
True Pelvis and False pelvis.
Sacrum, Coccyx, and two
innominate bones…
True pelvis/False Pelvis
Ligaments
 Pelvic ligaments can be classified as those
which bind the pelvic bones together
(Osseous) and those which support the uterus
and ovaries (suspensory).
Osseous ligaments
 Sacroiliac binds the sacrum and iliac bones
 Sacrosiatic binds the sacrum, iliac and coccyx
 Sacrococcygeal binds the sacrum and coccyx
 Pubic binds the two pubic rami
Suspensory Ligaments
 Cardinal: arise superiorly and laterally from
the uterus and inferiorly from the vagina to
provide primary support for the uterus
 Broad: extend from the lateral aspects of the
uterus, and attach to the lateral pelvic side
walls.
 Sacro-uterine extends posterolaterally from
the supravaginal cervix, encircle the rectum,
and insert onto the fascia over the sacrum.
Suspensory Ligaments
 Round: situated anterior and inferior to the
broad ligaments and fallopian tubes, they attach
the uterine cornu, to the anterior pelvic wall.
 Ovarian: Attach the inferior ovary to the uterine
cornu, posterior to the fallopian tube on each
side.
 Mesovarium: Attach the ovary to the posterior
layer of the broad ligament on each side.
 Infundibulopelvic are actually the superior
margin of the broad ligament on each side,
lateral to the fimbrial of the fallopian tubes,
through which course the ovarian vessels and
nerves.
Musculature
 Most pelvic muscles are paired structures that
form the limits of the pelvic space. They can
be divided into the following groups:
False Pelvis Muscles (Abdomino-pelvic)
 Since the false pelvis sits well above the
pelvic floor, few muscles are required to
support the organs found within.
 Rectus Abdominis forms the anterior margin
of the abdominal and pelvic spaces. It
extends from the symphysis pubis to the
costal margin.
 Psoas Major: originates at the lower thoracic
vertebrae and extends lateral and anterior as
it courses through the lower abdomen, along
the pelvic side wall to eventually insert on the
lesser trochanter. Just inferior to the iliac
Crest, it merges with the iliacus muscle
creating the Iliopsoas muscle. It forms part of
the lateral margins of the pelvic basin.
 Iliacus: arises at the iliac crest and extends
inferiorly until it merges with the psoas
major. It forms the iliac fossa on both of the
pelvic side walls.
Broad Ligament (Ascites must
be present)
Transverse Iliopsoas muscle
True Pelvic Muscles
 The floor of the true pelvis consists of two
layers of muscle: Those of the perineum and
those deep in the pelvis.
 The primary purpose of these muscles is to
hold the pelvic organs in place. Muscular
fibers from these muscles insert onto the
walls of the rectum, vagina and urethra
preventing them from being displaced during
episodes of increased intraabdominal
pressure.
Levator Ani and Coccygeus:
Constitute the pelvic diaphragm muscles.
 The levator ani attaches to fuse with the
opposite side, and thus form the floor of
the pelvic cavity.
 The coccygeous arise from the Ischial spine
and the sacro-sciatic ligament on either
side, insert onto the coccyx and close the
posterior part of the pelvic diaphragm and
outlet.
Levator Ani
 Obturator Internus is a triangular muscle
arising from the anterio-lateral wall of the
pelvis. It extends from the brim of the true
pelvis and exits through the lesser sciatic
foramen to insert on the greater trochanter
of the femur.
 Piriformis arises from the sacrum, pass
laterally through the grater sciatic notch, and
insert on the greater trochanter of the femur.
They are identified posteriorly in the pelvis.
PELVIC ORGANS
Urinary Bladder
 A musculomembranous, highly distensible
sac located between the symphysis pubis and
the vagina.
 The ureters insert in the inferior third of the
posterior wall on either side.
 The superior concavity of the balder is called
the dome.
 The walls are composed of three layers of
tissue: Outer epithelial, middle Muscularis,
and inner mucosal.
 When empty, the mucosal layer is quite thick
and can be seen sonographically.
 When the bladder is distended, the mucosa is
stretched and can no longer be seen.
 The urethra, which allows for the excretion of
urine, arises along the inferior middle portion
of the bladder. At its point of exit, it is
surrounded by a thickened region of the
bladder wall referred to as the internal
urethral sphincter.
Full urinary bladder
Trans abdominal imaging
Vagina
 The vagina is a muscular tube, approximately
7-10 cm in length, extending from the cervix
to the external vaginal introitus.
 A ring-like bind pouch surrounds the cervix,
known as the vaginal fornix, and is
categorized as follows:
 Posterior fornix: surrounds the posterior
aspect of the external cervix. It is a frequent
site of vaginal fluid collections due to gravity
dependence.
 Lateral fornix: surround the lateral aspect of
the external cervix on either side.
 Anterior fornix: Surrounds the anterior aspect
of the external cervix. It is much smaller than
the posterior fornix.
Vaginal fornices
Uterus
 The uterus is a muscular structure suspended by
ligaments, and is normally located in a mid
Sagittal plane in the true pelvis. It is bordered
anteriorly by the urinary bladder, and posteriorly
by the recto sigmoid colon.
 The uterus is divided into two major portions:
 The body: Is the largest part, and contains the
uterine cavity. It is muscular, and widens
superiorly at the fundus, above the insertion of
the fallopian tubes. The cone-shaped cornua are
lateral, where the tubes enter the uterus.
 The lower uterine segment, sometimes called
the isthmus, transitions into the cervix at the
location of the internal os.
Longitudinal Uterus
Transverse Uterus with IUCD
The Cervix
 Located posterior to the angle of the urinary
bladder, is comprised of elastic tissue.
 It is narrower than the uterine body and
measures 3-4 cm in length in the nulliparous
female. The lower portion of the cervix
projects into the vagina.
Image of the Cervix
Layers of the Uterus
 Mucosa (Endometrium) is the innermost
lining. It consists of a superficial layer (Zona
Functionalis) and a deeper basal layer. It
varies in thickness in the premenopausal
woman during the different stages of the
menstrual cycle. Thickness varies from 1mm
immediately following menstruation to up to
8mm just prior to the beginning of
menstruation. The measurements are
obtained sonographically in the anteroposterior (AP) Dimension.
 Muscularis (Myometrium) is an extremely
thick, smooth muscle layer that is continuous
with that of the fallopian tubes and vagina.
 Serosa (Perimetrium) is the peritoneal
covering of the uterus. It adheres to the
fundus and most of the body and is not visible
sonographically
Uterine Size
Age in years
Length in mm
AP in mm
2-8
33
7.5
9-menarche
43
13
Nulliparous
80
30
Multiparous
90
40
Postmenopausal
Varied based on parity
Varied based on parity
Uterine Positional Variations
 Uterine position is highly variable, and
changes with varying degrees of bladder and
rectal distention.
Anteversion
 Refers to the cervix, which is anchored at the
angle of the bladder and freely movable than
the corpus and fundus, forming a 90-degree
angle with the vagina.
Retroversion
 refers to the cervix oriented more linearly in
relation to the vagina.
 In the case of a flexion (or bending) between
the uterine body and the cervix, the terms
ANTEFLEXION and RETROFLEXTION are
used to describe the orientation of the
endometrial cavity
 ANTEFLEXTION describes the corpus and
fundus bending forward and resting over the
lower uterine segment.
 RETROFLEXION refers to the corpus and
fundus bending to lie posterior to the cervix.
A.
B.
C.
D.
Anteversion-Anteflexion
Anteversion-Retroflexion
Retroversion-Anteflexion
Retroversion-Retroflexion
Uterine Position
Anteverted/Anteflexed
 Anteverted/anteflexe
d is the normal
uterine position
when the urinary
bladder is empty.
 In anteflexed the
fundus is bent
forward and rests
over the lower
uterine segment
Retroverted
 A retroverted uterus
is one that is tilted
backwards inside of
the pelvis
Retroflexed
 A retroflexed uterus
has the fundus tilted
down toward the
rectum, while the
cervix remains in the
normal position
Endometrial Thickness & Sonographic
Appearance
 The endometrium varies in thickness and sonographic
appearance according to the menstrual cycle
 During the menstrual phase, the endometrium is thin and




echogenic
During the proliferative phase the endometrium is a thin
echogenic line that increases in thickness and measures 4-8
mm
During the periovulatory period the endometrium measures 610 mm
During the secretory phase the endometrium measures 7-14
mm
For postmenopausal women the endometrium measures less
than 8 mm
Side-to-Side deviation
 The long axis of the uterus may also deviate
to either side of midline.
 Unless there is pelvic pathology displacing
the uterus, any of the above configurations
are considered normal variants in position.
Ovaries
 The ovaries are ovoid-shaped structures
suspended within the pelvic peritoneal sac,
posterior to the broad ligament.
 Ovarian location is variable, especially in
women who have been pregnant.
 The parenchyma is divided into an outer
functional layer (cortex) which contains a
large number or primordial follicles, the
source of eggs at ovulation, and the inner
ovary (medulla) which is essentially blood
vessels and connective tissue.
 The hilum, through which channel the
ovarian vessels and nerves, is situated on the
anterior surface of each ovary.
 Both the suspensory ligament of the ovary
and fimbriae of the fallopian tube attach to
the superior surface of each ovary.
Normal Ovary with
Functioning Cysts
Ovarian Size
Size
Volume
Premenopausal
Varies with Ovulatory stage
3.5 cm x 2.0 cm x 1.5 cm
5.1cm3 -3.2cm3
Postmenopausal
Varies with number of years since
menopause
2.0 cm x 1.0 cm x .05 cm
1.3cm3
Ovarian Volume
length x width x AP (in cm) x 0.523
Fallopian Tubes
 The fallopian tubes are musculomembranous
tubes, approximately 7-12 cm in length, that
widen as they extend from the uterine cornu
laterally to the ovaries.
 Intramural or interstitial region is the narrowest
portion where the tube is contained within the
cornu of the uterus.
 Isthmus is the narrow segment of the tube
adjacent to the uterine wall.
 Ampulla is the longest portion. The lumen
increases in diameter to terminate as the
trumpet-shaped infundibulum, opening into
the peritoneal cavity. Small finger-like
projections called fimbria extend to capture
the released ovum from the ovary.
Intramural, isthmic, ampullary and fimbria portions of the
fallopian tube
A Dilated Fallopian Tube:
Pyosalpinx
Other Stuff
Peritoneal Recesses
 Several potential spaces exist in the pelvic
cavity, created by the locations of the organs
and suspensory structures
 SPACE OF RETZIOUS aka prevesical or retropubic
space is situated between the pubic bone and
anterior urinary bladder wall. Rarely, fluid is seen in
this space. Masses in this space will displace the
bladder posteriorly.

 VESICOUTERINE POUCH aka anterior cul-de-sac is
located anterior to the lower uterus and posterior to
the urinary bladder. This space is usually empty, but
may contain loops of small bowel.

 RECTOUTERINE SPACE aka the posterior cul-de-sac,
or pouch of Douglas is located posterior to the cervix
and anterior to the rectum. It is the most common
location where free fluid is located.
Space of Retzius
Vesicouterine Pouch
Vascular anatomy
Arterial
 The internal iliac arteries dive deep into the
pelvis and divide into anterior and posterior
trunks. The anterior branches give rise to
several arteries: obturator, umbilical, superior
vesicle, inferior vesicle, uterine, vaginal, and
inferior gluteal arteries.
Diagram of the uterine
arteries
Doppler flow characteristics
Uterine arteries
 Moderate to high velocity/high resistance
flow
 Higher resistance flow in the proliferative
phase than the luteal phase
 Higher resistance flow in postmenopausal
women than in women of reproductive age
 Ovarian Arteries
 In the follicular phase, flow is often low
velocity and high resistance.
 In the periovulatory period and luteal phase,
impedance drops dramatically on the side
with the dominant follicle.
 In post-menopausal women, the resistive
index approaches 1.0 with increasing age.
 Hint: Everything is high resistance except for
the ovary that has the dominant follicle,
where the resistance is low.
Doppler flow of the Dominant
ovary (low resistance)
Doppler Flow of a non-dominant ovary
(high resistance)
Transvaginal Sonography
 Depicts anatomy within a 2 to 7cm focal
range.
 Cannot be inserted past the area of vaginal
fornices.
 Limited to visualizing the uterus and
adnexa in the non-gravid patient and the
lower uterine segment in a gravid patient.
 Provides a more extensive view of the pelvic
anatomy.
 There are many applications for a transvaginal
sonogram including but not limited to:
•
•
•
•
•
Evaluation of ectopic pregnancy
Uterine, ovarian and pelvic inflammatory disease
Placenta previa
Fetal anatomy and cardiovascular systems
Monitoring ovulation
 TVS may also be used for guided procedures
such as:
•
•
•
•
Ova aspiration
Embryo transfer
Drainage or aspiration of pelvic fluid
Treatment of ectopic pregnancy
 Transvaginal ultrasound is performed very
much like a gynecologic exam and involves
the insertion of the transducer into the vagina
after the patient empties her bladder.
 The tip of the transducer is smaller than the
standard speculum used when performing a
Pap test.
 A protective cover is placed over the
transducer, lubricated with a small amount of
gel and then inserted into the vagina.
 Only two to three inches of the transducer
end are inserted into the vagina. The images
are obtained from different orientations to
get the best views of the uterus and ovaries.
 Transvaginal ultrasound is usually performed
with the patient lying on her back, possibly
with her feet in stirrups similar to a
gynecologic exam.
 How do you scan?
 Transversely and sagittal. This is not
something you answer on paper. You have to
get your hands on a probe and just do it.
 Why can’t you perform a TVU after 14
weeks gestation, but you can have
intercourse?
 You CAN use the TV probe after 14 weeks: to
assess placenta previa, the internal cranial
structures in a cephalic presentation, and the
L/S spine in breech presentations.
What are the benefits of TV over
transabdominal?
 Higher resolution means clearer image.
 Higher frequency means better resolution.
 Well tolerated by most patients.
What are the risks of the TV procedure?
 Patient may accurse the sonographer of
assault or worse.
 Latex allergy
 Chemical sensitivity-irritation to the vaginal
area.
 Decrease sperm mobility due to the applied
gel.
A miscarriage or abortion following the
procedure may initiate a lawsuit against the
hospital/doctor/sonographer
When was the first TVU performed?
 Do not know. Was used infrequently in the late
70s. Took off in the mid-late 80s.
What are the contraindications for a TV?
 Patient too young
 Patient too old
 Patient bleeding profusely.
 Virginal patient
 Non-compliant patient.
How do you know if you are in Transverse of
Sag?
 By rotating the transducer, keeping the
bladder in sight as a landmark.
Can you rupture a cyst upon probe insertion?
 There is always the possibility-especially if a
cyst is very large (Ovarian cyst), and the probe
is jabbed or pushed up against the lower
cervical area. More than likely, the answer to
this is no.
Can you perform Doppler with a Transvaginal
probe?
 Yes…it is done all the time.
Can you harm a fetus with a TV probe?
 No. The probe cannot be inserted far enough
to harm the fetus, if inserted in properly and
with care.
At what age can you first perform this?
(Minimum age)
 In the case of precious puberty, it may be
indicated quite young… But what is too
young? The probe is big relatively speaking so
you will not want to tear any structures. 10, 11,
12 usually is the cut off age.
