The Female Pelvis Embryonic Development Fetal Biometry Workshop Day 1

The Female PelvisEmbryonic Development

Fetal Biometry Workshop

Day 1

Expected Learning Outcomes

Describe embryology, anatomy, function of the female pelvis.

Describe sonographic techniques applied in the assessment of the female pelvis.

Describe congenital abnormalities of the female pelvis.

Detection of Genital Anomalies

Fetal period Urinary tract abnormalities – 50% of all congenital

anomalies Hydrometrocolpos of vagina & uterus most common Hydronephrosis or hydroureter

Neonatal period Renal in origin Hydrometrocolpos secondary to an atretic vagina

Premenarche to Adulthood Duplicated uterus with one septated vagina

Expression of Gender in Embryo

Primordial Germ Cells

Inducer Germ Cells

Embryonic Development

Genital Ducts Formation of Fallopian Tubes

Embryonic Development

Formation of the Broad Ligament

Formation of the Vagina

Mullerian Ducts

Embryological ducts fuse together during organogenesis

Form Uterus Upper portion of Vagina Fallopian tubes

Ovaries and lower vagina form from primitive YS Anomalies can lead to infertility Delayed onset of menarche Increased Risk of

IUGR Preterm labor Retained placenta

Wolffian Ducts

Embryologically sits along side with the Mullerian ducts

Male becomes the vas deferens Develops into the trigone of the urinary

bladder and ureters In absence of testosterone these regress Known remnant is Gartner’s duct cyst

Embryonic Development

Formation of the Vagina

Review – embryonic developmentUrinary System Gonads Ducts Mesenteries

3rd Week Pronephros differentiates Primordial cells in allantois

4th Week Pronephros disappears and mesoephros differentiates

Formation of genital ridges

5th Week Metanephros starts to differentiate

Migration of primordial germ cells

6th Week Primitive germ cells invade gonadal ridges

2 sets of ducts exist: wolffian and mullerian

Formation of primitive sex cords: “indifferent stage”

7th Week Primitive sex cords disappear; Cortical cords arise

8th Week Mesonephros disappears, only its duct remains

Mullerian ducts fuse to form uterovaginal canal and fallopian tubes

12th Week Ovary descends Median septum disappears

12th Week to 5th month

Metanephros [3rd stage kidney]

Cortical cords split up and surround primitive germ cells – oogonia

Formation mesosalpinix, mesovarium, broad, proper ovarian & suspensory ligaments

Pelvic Skeleton

Ring of 4 bones Sacrum Coccyx 2 large innominate or hip

bones Principle functions:

1. Weight-bearing bridge between spinal column and bones of lower limbs

2. Directs the pathway of fetal head during childbirth [parturition]

3. Protects the reproductive organs

Pelvic Skeleton

Pelvic Spaces

True Pelvis False Pelvis

Pelvic Muscles

Region Muscle Location

Abdominopelvic Rectus abdominisPsoas major

Anterior wallPosterior wall

False pelvis Iliacus Iliac fossa

True pelvis Obturator internusPiriformisCoccygeusLevator ani

Lateral wallPosterior wallPosterior floorMiddle, anterior floor

Pelvis Muscles

True Pelvis Muscles

Pelvic Organs

Urinary Bladder & urethra Uterus Fallopian tubes Vagina Ovaries Pelvic colon Rectum

Urinary Bladder & urethra

Urinary Bladder Thick-walled Highly distensible

muscular sac Lies between

symphysis pubis & vagina

The Vagina

Uterine Ligaments

Cardinal Round Broad

The Uterus

Uterus Size & Shape Newborns

“adult” contour due to maternal estrogen Infant

Small, high in pelvis, cylindrical, lies along same axis as vagina

Young girls Nearly cylindrical, body more globular

Puberty Characteristic inverted pear shape

Pregnancy Corpus and fundus grow thicker, increasing globularity

Menopause Corpus and fundus shrink and regress to prepubertal state Elderly women – little more than a cap above the cervix

Variants of Uterine Position

Anteflexed forward

Retroflexion backward

Anteverted anterior incline

Retroverted posterior incline

Retroflexed Uterus

Anteflexed Uterus

Retroverted Uterus

Anteverted Uterus

Uterine Malformation

Mullerian agenesis Bicornuate Unicornuate Didelphys Septated Arcuate DES exposure High incidence of uterine malformations and

renal abnormalities Abnormalities are always on the same side

Mullerian agenesis

No uterus What would be a symptom Where else should we look

Unicornuate

Only one side of the mullerian duct forms Takes on a penis shape Difficult to tell by US

Bicornuate

Didelphys

Both mullerian ducts fail to fuse Double uterus, cervix, and vagina Endometrial cavities are widely separated Partial

Uterus Bicornis Bicollis One vagina 2 cervices 2 uterine horns 1 side has not outlet for menstrual flow

Causes hematometrocolpos Uterus Bicornis Unicollis

One vagina Once cervix 2 uterine horns

Septated Uterus

Arcuate Uterus

DES Exposure

Diethylstilbestrol Synthetic estrogen Used in 40’s-70’s Small, irregular T shaped uterus is the most

common malformation related to drug

The Fallopian Tubes

The Ovaries

Follicular Development

Ovary Location

Bladder empty – ovarian fossa Posterolateral pelvic wall beneath the brim of

pelvis Filling bladder – ovarian fossa at the sides of

uterine fundus Distended bladder – increasing pressure

forces downward in the adnexal space

The Pelvic BowelEcho pattern Shadows

Small Bowel

Variably echogenic content with thin, anechoic ring representing the muscular wall

Shifts with movement of bowel and content

Cecum Same as small bowel Constant except when peristalsis occurs

Sigmoid Echogenic content with thin, anechoic ring representing the muscular wall

Constant except when peristalsis occurs

Rectum Same as Sigmoid Constant and nearly complete; only top surface of fecal boluses can be seen

Pelvic Spaces

Adnexa

Area that is adjacent to uterus

Includes ovaries and fallopian tubes

Arterial System of Pelvis Aorta

Common iliac arteries External and internal or

hypogastric artery Internal courses down into pelvic

cavity Superior gluteal artery is

branch Oburator artery Umbilical artery Uterine-vaginal artery Superior vesical artery Internal pudendal and

inferior gluteal arteries

Venous System of the Pelvis

Inferior vena cava Common iliac veins

External iliac veins – legs

Internal iliac veins – pelvic organs and muscles

Ureter

Courses lateral pelvic wall posterior to the ovary

Enter pelvis at point just caudad to bifurcation of common iliac vessels.

Most anterior and lateral of the 3 tubular structures seen deep to the ovary

Review