12A pelvis and female genitalia

Lecture 12A: Pelvis & Female Genitalia

Learning Objectives

1. Pelvic Bones and Landmarks

   • Identify the bones of the true and false pelvis.

   • Discuss markings and surface landmarks.

   • Examine anatomic boundaries and sex differences.

2. Pelvic Organ Changes

   • Describe components and positional changes of:

     • Bladder

     • Rectum

     • Ovaries

     • Fallopian tubes

     • Uterus

   • Modifications during pregnancy and urinary retention.

3. Vascular and Nervous Supply

   • Describe and trace the courses of:

     • Vessels supplying pelvic organs.

     • Lymphatics and nerves.

4. Pelvic Ligaments

   • Describe various ligaments:

     • Composition and function.

     • Role in organ fixation.

5. Anatomic Pathology and Procedures

   • Discuss pathologies like:

     • Stress incontinence

     • Bladder injury

     • Salpingitis

     • Ectopic pregnancy

     • Endometriosis

     • Prolapse conditions (uterine, vaginal, cystocele, rectocele).

   • Procedures:

     • Suprapubic catheterization

     • Tubal ligation.

6. Imaging Techniques

   • Identify structures visible on:

     • Standard radiographs of the pelvis

     • Ultrasound

     • Hysterosalpingography.

7. Nerves and Anesthesia

   • Describe the courses of vessels and nerves that supply pelvic structures.

   • Understand the basis for caudal anesthesia and pudendal nerve blocks.

8. Reproductive Pathways

   • Trace the pathways of:

     • Ovum through female reproductive tract.

     • Spermatozoon through male reproductive tract.

9. Common Procedures

   • Describe procedures:

     • Vasectomy

     • Tubal ligation

     • Pap smear

     • Colposcopy

     • LEEP (Loop Electrosurgical Excision Procedure).

Anatomy of the Uterus

• Uterus Structure

  • Thick-walled muscular organ.

  • Layers:

    • Endometrium: innermost, mucosal layer;.

    • Highly vascularized; responds to hormonal changes.

    • Myometrium: middle layer of smooth muscle; responsible for uterine contractions.

    • Perimetrium: outermost serous layer, a continuation of the peritoneum.

  • Location: Positioned between the bladder and rectum, joining the vagina.

  • Uterine/fallopian tubes project laterally, opening into the peritoneal cavity.

• Regions of the Uterus

  • Fundus: rounded superior portion above opens of fallopian tubes.

  • Body: central, largest portion that expands during pregnancy.

  • Cervix: cylindrical, inferior portion projecting into vagina; includes:

    • Short, broad cylinder with a narrow central canal.

    • Central canal opens into the vagina (external os) and into the uterus (internal os).

• Positioning and Support

  • Uterus positioned in true pelvis.

  • Supported by ligaments:

    • Broad Ligament: double layers of peritoneum from lateral borders of the uterus to pelvic walls.

    • Round Ligament: connects lateral aspect of the uterus near fallopian tube to labia majora (gubernaculum remnant).

    • Uterosacral Ligaments: attach posterior cervix and upper vagina to sacrum; supports anteflexed position.

    • Transverse Cervical (“cardinal”) Ligaments: attach lateral walls of cervix to lateral pelvic wall; contain uterine artery and vein.

    • Pubocervical Ligaments: support cervix and bladder by attaching anterior aspect of cervix to the posterior pubic symphysis.

Pelvic Spaces

• Rectouterine Pouch of Douglas: space between uterus and rectum, the most inferior point for the collection of pus/blood in females.

• Vesicouterine Pouch: anterior space between bladder and uterus.

• Rectovesical Pouch: space between bladder and rectum in males.

Uterine Pathology

• Retroflexed Uterus: fundus sagging posteriorly; difficult to judge uterine size on bimanual exam, but usually harmless.

• Uterine Prolapse: uterus descends from vaginal apex instead of anterior/posterior vaginal wall; treatment includes pessaries or surgery.

  • Prolapse: "to slip" forward or down.

    • Vaginal Vault Prolapse: protrusion of superior vagina cuff post-hysterectomy.

    • Rectal Prolapse: protrusion of rectal wall through the anus.

    • Urethral Prolapse: protrusion of distal urethra through external meatus.

• Cystocele: protrusion of bladder into vaginal wall.

• Urethrocele: protrusion of urethra through vaginal opening.

• Rectocele: herniation of rectum into posterior vaginal wall.

• Didelphic Uterus: improper fusion of Mullerian tubes during development, resulting in two uteri with two cervices.

Endometrial Pathologies

• Endometrial Polyp: benign growth in lining; focal hyperplasia often related to estrogen.

  • Symptoms: irregular/heavy menstrual bleeding and dull, aching abdomen; may cause infertility.

  • Treatment: observation or polypectomy for symptomatic lesions.

• Leiomyoma: uterine fibroid, benign smooth muscle tumor of myometrium; hormone-dependent (estrogen & progesterone).

  • Symptoms: irregular/heavy bleeding, pain, urinary frequency, constipation.

  • Treatment: observation if asymptomatic, medical therapy to shrink fibroids, or surgical removal.

Changes Due to Pregnancy

• Uterine Growth: measured by fundal height, which rises approximately 1 cm/week.

  • 1st suprapubic mass at 12 weeks gestation, reaches umbilicus at 20 weeks.

  • Variations due to conditions like oligohydramnios and polyhydramnios affecting fluid levels and fetal growth.

  • Causes of decreased bladder capacity, urinary frequency, and increased gastric pressure due to organ movements and compressions.

Placenta Formation and Conditions

• Placenta: organ developing within the uterus to provide oxygen, nutrients, and waste removal for the fetus; formed from maternal and embryonic tissues.

  • Layers:

    • Chorion: outer fetal membrane.

    • Decidua: modified endometrial lining responding to embryo.

  • Developmentally complete by 10-12 weeks gestation.

• Placenta Conditions:

  • Placenta Previa: partial/complete coverage of cervix; risks include preterm birth and hemorrhage.

  • Abruptio Placentae: rare complication of separation from the uterine wall before birth.

  • Placenta Accreta: grows into uterine wall and fails to separate postpartum.

Birth Process Stages

1. First Stage: Dilation

   • Regular contractions cause effacement and dilation of the cervix.

2. Second Stage: Expulsion

   • Fetal head descends through birth canal, requiring muscle and perineum stretching.

3. Third Stage: Placental

   • Separation of the placenta from uterine wall.

4. Fourth Stage: Recovery

   • Uterus contracts to minimize bleeding; tissue repair begins.

Cardinal Movements of Labor

• Engagement: fetal head enters pelvic inlet.

• Descent: progression through pelvic cavity.

• Flexion: fetal chin moves toward chest.

• Internal Rotation: head aligns with pelvic outlet.

• Extension: head passes under pubic symphysis.

• External Rotation: realignment of head with shoulders after delivery.

Cesarean Section Indications

• Maternal: Cephalopelvic disproportion, previous C-section, placenta previa, severe preeclampsia.

• Fetal: distress, malpresentation, multiple gestations.

• Types of Incisions:

  • Classical: vertical incision; prone to rupture.

  • Low Transverse: most common, horizontal; less rupture risk, but potential for vascular injury.

Pelvic Exam Techniques

• Standard Pelvic Exam:

  • Bimanual exam: evaluation of cervix and uterus.

  • Speculum Examination: assess vagina and cervix characteristics.

  • Pap Smear: screening for cervical carcinoma.

• HPV: sexually transmitted virus that can lead to cervical cancer and genital warts.

Pathology of Fallopian Tubes & Ovaries

• Ectopic Pregnancy: implantation within fallopian tube.

  • Treatment: Methotrexate for un-ruptured, salpingostomy or salpingectomy for ruptured.

• Ovarian Cysts: typically benign, could lead to complications requiring surgical intervention upon rupture or torsion.