LG 5

Dr. Rose Meerany: Anatomy of Episiotomy and Anesthesia

Episiotomy Overview

  • Defining episiotomy: An incision made in the perineum during childbirth to widen the vaginal opening and facilitate delivery.

Female Pelvis Anatomy

A. Female Pelvis Organs
  • Ovaries
  • Uterus
  • Fallopian tubes
  • Cervix
  • Vagina
  • Rectum
  • Bladder
  • Urethra
  • Vulva
B. Female Pelvis Bones
  1. Ischium
    • Supports body weight while sitting, known as "sit bones."
  2. Pubis
    • Each pubis bone joins at the pubic symphysis.
  3. Ilium
    • Broadest and fan-shaped section of the hip bone.
  4. Sacrum
    • Comprised of five fused vertebrae; aids body weight support.
  5. Coccyx
    • Known as the tailbone; consists of four fused vertebrae, triangular shape, supported by ligaments, attached to sacrum.
C. Female Pelvis Muscles
  • Levator ani muscles: Largest pelvic muscle group, supporting pelvic organs.
    1. Pubococcygeus
    • Extends from pubic bone to coccyx; major component of the levator ani.
    1. Puborectalis
    • Responsible for urine and feces retention; relaxes during urination or bowel movements.
    1. Iliococcygeus
    • Thinner fibers that elevate pelvic floor and anal canal.
  • Coccygeus
    • Originates from ischium; connects to sacrum and coccyx.
D. Female Pelvis Ligaments
  • The ligaments support the pelvic organs and maintain pelvic floor integrity.

Perineum

Definition and Location
  • Area of skin and tissue between vaginal opening and anus.
  • Diamond-shaped area below pelvic floor between thighs.
  • Vital for urination, defecation, sexual activity, and childbirth.
  • Contains external genitalia; common site for tears during childbirth.
Perineum Boundaries
  • Pubic arch: Antero-laterally
  • Ischial tuberosities: Laterally
  • Sacrotuberous ligament: Postero-laterally
  • Coccyx: Posteriorly
Anatomy of the Perineum
  1. Divided into two triangles:
    • Urogenital triangle
    • Anal triangle
  2. Perineal body: Central point of the perineum.
  3. Components within triangles: Includes the vagina, urethra, anal sphincter, and associated musculature.

Urogenital Triangle

  1. Deep pouch: Contains deeper structures above the perineal membrane.
  2. Superficial pouch: Located below the perineal membrane; contains external genital structures.
Superficial Pouch Structure (Female)
  • Mons pubis
  • Labia majora and minora
  • Clitoris
  • Bartholin's glands
  • Frenulum of clitoris

Female Urethra

Structure and Function
  • Length: 3 to 4 cm long.
  • Support and Anatomy:
    • Muscular layer continuous with the bladder; contains spongy erectile tissue and venous plexus.
    • Pierces perineal membrane; opens into vestibule.
  • Sphincter control:
    • Internal sphincter: Smooth muscle, involuntary control.
    • External sphincter: Skeletal muscle, voluntary control.
  • Nerve Supply:
    • Supplied by the pelvic fascia, pubo-vesical, and pubocervical ligaments.
    • Insufficient support can lead to stress urinary incontinence (SUI).

Control of Micturition

  • Detrusor Muscle (Smooth Muscle):
    • Controlled by sympathetic and parasympathetic nerve plexus.
    • Parasympathetic induces contraction, then relaxes the internal sphincter.
  • Sphincter and Nerve Supply:
    • External sphincter supplied by the perineal branch of the pudendal nerve (S2,3,4).

Perineal Body

  • Fibrous tissue between lower vagina and anal canal.
  • Supports posterior vaginal wall; lacerations during childbirth can cause weakness in pelvic floor.

Episiotomy in Childbirth

  • Surgical incision made to prevent perineal tearing.
  • Direction: Posterolateral to avoid anal sphincter.

Nerve Supply of the Perineum

Urogenital Triangle Supply
  • Anteriorly: Supplied by ilioinguinal nerve and genital branch of genitofemoral nerve.
  • Posteriorly: Supplied by perineal branch of pudendal nerve.
Pudendal Nerve Characteristics
  • Branch of sacral plexus; enters perineum through lesser sciatic foramen.
  • Branches include:
    1. Inferior rectal nerve: Provides supply to external anal sphincter, lower half of anal canal, and perineal skin.
    2. Dorsal nerve of clitoris: Supplies the clitoris.
    3. Perineal nerve: Supplies urogenital triangle muscles, posterior labia majora skin.

Anesthesia for Episiotomy

  1. Pudendal nerve block: Anesthetic technique for pain management during childbirth.
  2. Perineal infiltration: Technique involving local anesthetic injection in the perineum during second stage of labor.
Pudendal Block Techniques
  • Transvaginal method:
    • Needle inserted after palpating the ischial spine; anesthetic administered around the pudendal nerve.
  • Perineal method:
    • Palpate ischial tuberosity; needle inserted to anesthetize the pudendal nerve.
  • Perineal infiltration:
    • Local anesthetic injected directly into perineal tissues during labor.

Summary and Importance of Knowledge

  • Understanding perineal anatomy and nerve supply is crucial for effective analgesia and anesthesia during childbirth to prevent maternal and fetal morbidity.

Conclusion

  • Integrity of urinary sphincters is vital for normal voiding habits; knowledge of anatomy helps address urinary issues post-delivery.