Part 1 obgyn notes Sri Lanka
    NOTES for part 1
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    Anatomy
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    Pelvic spaces

    Pelvic spaces

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    AVASCULAR_PELVIC_SPACES.pdf3.8 MiB

    okabyashi,latzko-https://www.youtube.com/watch?v=WMeKLGtsHHM

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    Feature
    Medial Paravesical Space (MPS)
    Lateral Paravesical Space (LPS)
    Divided by
    → Medial to obliterated umbilical artery
    → Lateral to obliterated umbilical artery
    Also called
    Medial compartment
    Obturator space
    Medial relation
    Bladder
    Obliterated umbilical artery
    Lateral relation
    Obliterated umbilical artery
    External iliac vessels
    Main contents
    Loose areolar tissue
    Obturator nerve, artery, vein + lymphatics
    Floor
    Iliococcygeus + pubocervical fascia
    Same
    Surgical use
    • Bladder mobilization • Ureteric surgery • Anterior exenteration
    • Pelvic lymphadenectomy • Burch colposuspension • Paravaginal repair
    Oncologic relevance
    Access to bladder / ureter
    Node dissection zone
    Key risk
    Bladder / ureter injury
    Obturator nerve + Corona mortis bleeding
    Opened until
    Levator ani
    Obturator nerve
    Feature
    Latzko’s Space (Lateral PRS)
    Okabayashi’s Space (Medial PRS)
    Position
    Lateral to ureter / mesoureter
    Medial to ureter / mesoureter
    Also called
    Lateral pararectal space
    Medial pararectal space
    Medial boundary
    Ureter + mesoureter
    Rectum+rectal pillers
    Lateral boundary
    Internal iliac artery
    Ureter + mesoureter
    Ventral boundary
    Cardinal ligament
    Cardinal ligament
    Dorsal boundary
    Presacral fascia / sacrum
    Presacral fascia / sacrum
    Dividing structure (practical)
    Ureter / hypogastric nerve
    Ureter / hypogastric nerve
    Main contents
    Loose areolar tissue
    Lateral ligament of rectum + middle rectal vessels
    Key exposure
    Uterine artery origin
    Hypogastric nerve + pelvic plexus
    Primary surgical use
    • Pelvic lymphadenectomy • Internal iliac ligation • Radical hysterectomy
    • Nerve-sparing radical hysterectomy • Deep endometriosis • Ureter mobilization
    Main purpose
    Vascular access
    Nerve preservation
    Important risk
    Internal iliac vein / ureter
    Pelvic plexus / middle rectal artery
    Feature
    Yabuki Space
    Described by
    Yoshihiko Yabuki (2000)
    Also called
    Fourth space / Okabayashi paravaginal space
    Location
    Between ureter and cranial vesico-uterine ligament
    Alternative description
    Between lateral vagina & caudal vesico-cervical ligament
    Opened after
    Dissection of cranial vesico-uterine ligament
    Medial relation
    Bladder / vagina
    Lateral relation
    Ureter
    Key contents
    Pelvic splanchnic nerves (bladder innervation)
    Dissection direction
    Toward vesicoureteric junction
    Main surgical role
    Nerve-sparing radical hysterectomy
    Functional importance
    Preserves bladder autonomic function
    High-risk injury
    Pelvic splanchnic nerves → postoperative urinary dysfunction
    Feature
    Retzius Space (Cavum Retzii)
    Named after
    Anders Retzius
    Type of space
    Extraperitoneal potential space
    Ventral boundary
    Pubic symphysis
    Dorsal boundary
    Bladder + parietal peritoneum
    Cranial boundary
    Transversalis fascia
    Caudal boundary
    Urethra, bladder neck, pubocervical fascia
    Lateral boundary
    Arcus tendineus fascia pelvis (over obturator internus)
    Medial contents
    Bladder / urethra
    Important structures
    Pubourethral ligament, urachus (median umbilical ligament)
    Major venous structure
    Veins of Santorini (retropubic venous plexus)
    Relationship to paravesical space
    Paravesical spaces lie laterally
    Nature
    Not a single cavity → multiple fascial planes
    Surgical access landmark
    Median + medial umbilical ligaments
    Main urogynecologic uses
    • Burch colposuspension • Retropubic TVT • Anterior compartment repair
    Gynecologic uses
    • Bladder endometriosis
    Oncologic uses
    • Anterior exenteration • Anterior peritonectomy
    Major risks
    Bladder injury + Santorini plexus bleeding
    Space (All 9)
    Class
    Key “Finder” Landmark
    Core Boundaries (must-know)
    Direct Connections (how you “move” between spaces)
    Main Uses (ObGyn / Urogyn / Obstetrics)
    Main Danger / “Exam Trap”
    7) Vesicocervical Space
    Median
    “Anterior cul-de-sac axis” between bladder & cervix
    Anterior: bladderPosterior: pubocervical fascia + cervix (upper)Lateral: cranial vesicouterine ligamentCranial: peritoneal reflection between bladder dome & low uterine segment
    ↔ Vesicovaginal space (its inferior extension; same longitudinal axis)↔ Links medially with MPS during bladder mobilisation and with vesicouterine ligament planes
    All hysterectomies (abdominal/laparoscopic/robotic/vaginal), radical hysterectomy (deeper dissection), nerve-sparing work in DIE/cancer
    Must stay above pubovesical fascia: “fat belongs to bladder”; lateral dissection risks ureter/vessels in vesicouterine ligament
    8) Vesicovaginal Space
    Median
    Inferior continuation of vesicocervical; near trigone
    Anterior: trigone of bladderPosterior: pubocervical fascia + vagina (inferior)Lateral: cranial vesicouterine ligamentCranial: same peritoneal reflection as aboveCaudal: junction of proximal & middle thirds of urethra; below this vagina and urethra fuse
    ↔ Vesicocervical space (continuous)↔ Links to MPS/Yabuki planes laterally/at ligament–ureter interface in nerve-sparing dissections
    Urogyn: vesicovaginal/ureterovaginal fistula repair, cystocele surgery, sacrocolpopexy/hysterocolpopexyGyn/Oncogyn: hysterectomy, radical hysterectomy (remove upper vagina), nerve-sparing DIE/cancer, vaginal cuff resectionObs: CS, cesarean hysterectomy, cerclage, CS scar ectopic excision
    Cranial vesicouterine ligament contains uterine artery + superficial uterine vein + ureteric branch + superior vesical vein + cervicovesical vessels; lateral dissection → ureter/vessel injury
    9) Rectovaginal Space
    Median
    Posterior cul-de-sac plane; between rectum & vagina
    Anterior: posterior vaginal wallPosterior: anterior rectal wallLateral: uterosacral ligaments (cranial) + rectovaginal ligament (caudal)Cranial: pouch of Douglas reflectionCaudal: levator ani
    ↔ Links with Okabayashi/Latzko planes in deep endometriosis approaches (lateral-to-medial technique after opening both pararectal spaces described)↔ Continues posteriorly toward presacral planes depending on approach
    Gyn/Oncogyn: radical hysterectomy, pelvic adhesions, deep endometriosis, rectovaginal fistula repairUrogyn: sacrocolpopexy, uterosacral suspensionVaginal route: rectocele repair
    Rule: “fat belongs to rectum”; bleeding from middle rectal vessels/vaginal veins/presacral veins; rectal injury if wrong plane
    10) Presacral / Retrorectal Space
    Median
    Promontory + common iliac vessels + ureters; “holy plane” concept (inter-fascial)
    Anterior: mesorectal fascia/rectumPosterior: anterior longitudinal ligament + sacral promontory + sacrumLateral: right common iliac artery/ureter; left common iliac vein/ureter; hypogastric fascia (medial fibers of USL)Cranial: rectosigmoid peritoneal reflectionCaudal: pelvic floorAlso divided by Waldeyer’s fascia into superior/inferior retrorectal space
    ↔ Posterior continuation from pararectal spaces (Latzko/Okabayashi) toward sacral planes↔ Links superiorly to para-aortic lymphadenectomy initiation planes↔ Links to sacrocolpopexy “prelumbar/presacral” access
    Oncogyn: TME for ovarian cancer infiltrating rectum; start para-aortic lymphadenectomyGyn: bowel endometriosis surgery (approach choice: inter-fascial vs trans-mesorectal described)Urogyn: sacrocolpopexyGyn: presacral neurectomy
    High risk early: common iliac vessels, IMA, ureters; hard-to-control bleeding from middle sacral vessels; protect superior hypogastric plexus + hypogastric nerves

    1️⃣ Big picture: what are pelvic spaces?

    • Pelvic spaces = potential spaces
    • Created by pelvic fascia splitting
    • Usually avascular or relatively bloodless
    • Used to:
      • Mobilize organs
      • Control hemorrhage
      • Avoid nerves & ureters
      • Perform radical pelvic surgery safely

    2️⃣ Classification (exam-friendly)

    ▶️ Anterior pelvic spaces

    • Retropubic space (Space of Retzius)
    • Vesicouterine space

    ▶️ Posterior pelvic spaces

    • Rectouterine space (Pouch of Douglas)
    • Presacral (retrorectal) space

    ▶️ Lateral pelvic spaces (MOST IMPORTANT surgically)

    • Paravesical space
    • Pararectal space
      • Medial pararectal space (Okabayashi)
      • Lateral pararectal space (Latzko)

    3️⃣ Individual spaces — boundaries, relations, surgical value

    🟦 Retropubic space (Space of Retzius)

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    Location

    Between pubic symphysis and urinary bladder

    Boundaries

    • Anterior → Pubic symphysis
    • Posterior → Bladder
    • Superior → Peritoneal reflection
    • Inferior → Endopelvic fascia

    Contents

    • Loose areolar tissue
    • Dorsal venous complex (important in males)

    Surgical importance

    • Entry point for:
      • Burch colposuspension
      • Retropubic sling (TVT)
    • Bladder mobilization
    • Avoids peritoneal breach

    ⚠️ Injury risk: bladder perforation, venous bleeding

    🟦 Vesicouterine space

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    Location

    Between bladder and uterus/cervix

    Boundaries

    • Anterior → Bladder
    • Posterior → Cervix & lower uterine segment
    • Superior → Peritoneal fold
    • Inferior → Vaginal vault

    Surgical importance

    • Opened in:
      • Abdominal hysterectomy
      • Caesarean section
    • Allows safe bladder reflection

    ⚠️ In repeat CS: adhesions obliterate this space → bladder injury risk

    🟦 Rectouterine space (Pouch of Douglas)

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    Location

    Between posterior vaginal wall / uterus and rectum

    Boundaries

    • Anterior → Posterior fornix, cervix
    • Posterior → Rectum
    • Lateral → Uterosacral ligaments

    Clinical importance

    • Lowest peritoneal point → fluid collection
    • Accessed via posterior colpotomy

    Surgical relevance

    • Drainage of pelvic abscess
    • Endometriosis surgery
    • Posterior vaginal wall procedures

    🟦 Presacral (retrorectal) space

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    Location

    Between rectum and sacrum

    Boundaries

    • Anterior → Rectum
    • Posterior → Presacral fascia & sacrum
    • Lateral → Iliac vessels
    • Inferior → Pelvic floor

    Contents

    • Presacral venous plexus (⚠️ dangerous!)

    Surgical importance

    • Total mesorectal excision (TME)
    • Rectal cancer surgery

    ⚠️ Presacral bleeding is:

    • Profuse
    • Difficult to control
    • Potentially fatal

    4️⃣ Lateral pelvic spaces (CORE EXAM + SURGERY)

    🟩 Paravesical space

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    Location

    Lateral to bladder, medial to pelvic sidewall

    Boundaries

    • Medial → Bladder
    • Lateral → Obturator internus & pelvic sidewall
    • Anterior → Pubic bone
    • Posterior → Cardinal ligament

    Contents (on lateral wall)

    • External iliac vessels
    • Obturator nerve & vessels

    Surgical use

    • Pelvic lymph node dissection
    • Radical hysterectomy
    • Access to obturator fossa

    🟩 Pararectal space (MOST TESTED)

    Divided by ureter

    • Ureter = key landmark

    ▶️ Medial pararectal space (Okabayashi space)

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    Boundaries

    • Medial → Rectum
    • Lateral → Ureter
    • Anterior → Cardinal ligament
    • Posterior → Uterosacral ligament

    Surgical value

    • Nerve-sparing radical hysterectomy
    • Hypogastric nerve identification

    ▶️ Lateral pararectal space (Latzko space)

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    Boundaries

    • Medial → Ureter
    • Lateral → Internal iliac vessels
    • Posterior → Sacrum

    Surgical value

    • Internal iliac artery ligation
    • Uterine artery ligation at origin
    • Control of pelvic hemorrhage

    5️⃣ Why pelvic spaces matter in surgery (EXAM GOLD)

    🔑 Key principles

    • Bleeding occurs when you leave the space
    • Safe surgery = stay inside correct space
    • Nerves & ureters lie in walls, not inside spaces

    Applications

    • Radical hysterectomy
    • Pelvic lymphadenectomy
    • Endometriosis excision
    • Pelvic hemorrhage control
    • Ureteric injury prevention

    6️⃣ One-glance memory map (exam lock 🔒)

    • Anterior → bladder related (Retzius, vesicouterine)
    • Posterior → rectum related (Douglas, presacral)
    • Lateral → vessels & nerves (paravesical, pararectal)
    • Ureter divides pararectal space
    • Presacral = dangerous bleeding
    • Paravesical = lymph nodes
    • Latzko = vessels
    • Okabayashi = nerves