DMSM 117 Obstetrical Sonography II

DMSM 117 Obstetrical Sonography II

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

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 anteriolateral 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 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 antero-posterior (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/ anteflexed 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 6-10 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 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 cant 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? Yesit 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.

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