The Female Pelvis Embryonic 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 development Urinary SystemGonadsDuctsMesenteries 3 rd WeekPronephros differentiatesPrimordial cells in allantois 4 th WeekPronephros disappears and mesoephros differentiates Formation of genital ridges 5 th WeekMetanephros starts to differentiate Migration of primordial germ cells 6 th WeekPrimitive germ cells invade gonadal ridges 2 sets of ducts exist: wolffian and mullerian Formation of primitive sex cords: “indifferent stage” 7 th WeekPrimitive sex cords disappear; Cortical cords arise 8 th WeekMesonephros disappears, only its duct remains Mullerian ducts fuse to form uterovaginal canal and fallopian tubes 12 th WeekOvary descendsMedian septum disappears 12 th Week to 5 th month Metanephros [3 rd 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 RegionMuscleLocation AbdominopelvicRectus abdominis Psoas major Anterior wall Posterior wall False pelvisIliacusIliac fossa True pelvisObturator internus Piriformis Coccygeus Levator ani Lateral wall Posterior wall Posterior floor Middle, 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 Bowel Echo patternShadows Small Bowel Variably echogenic content with thin, anechoic ring representing the muscular wall Shifts with movement of bowel and content CecumSame as small bowelConstant except when peristalsis occurs SigmoidEchogenic content with thin, anechoic ring representing the muscular wall Constant except when peristalsis occurs RectumSame as SigmoidConstant 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