--- module: 079-02 language: en chapter: 79 title: "Pelvic, Perineal, Reproductive, and Urinary Anatomy" module_title: "Pelvic viscera, ureters, bladder, rectum, continence, and pelvic relations" source_sha256: c79d03080977f9391d713b7708e4fc0908e1ff823422dbb723fc8c136d5e1609 --- # Pelvic viscera, continence, and relations ## Ureters in the pelvis ### Cross brim near iliac bifurcation ### Run on lateral wall, then anteromedially ### Below uterine artery near cervix ### Below ductus deferens before bladder #### Crossings create surgical risk ### Oblique intramural course #### Flap valve limits reflux ### Narrowings where stones impact #### Pelviureteric, iliac crossing, ureterovesical ### Segmental arterial supply #### Medial in abdomen, lateral in pelvis #### Wide mobilisation devascularises ## Bladder and urethra ### Empty behind symphysis, rises on filling ### Apex to umbilicus via urachal remnant ### Trigone between ureteric and urethral openings ### Detrusor contracts for voiding ### Posterior relations differ by anatomy ### Short female urethra #### Ascending infection risk ### Male urethra in four portions #### Membranous part vulnerable in pelvic trauma ## Innervation and voiding ### Parasympathetic: detrusor contraction ### Sympathetic supports storage #### Beta relaxes detrusor #### Alpha tightens bladder neck ### Pudendal controls external sphincter ### Stretch afferents to sacral and pontine centres ### Pons coordinates micturition ### Suprasacral lesion: overactivity, dyssynergia #### High bladder pressures ### Sacral or peripheral lesion: weak sensation, contraction ### Urodynamics measures actual function ## Urinary continence ### Many components must work together #### Bladder, sensation, outlet, support, cognition, access ### Female: urethral support closes during cough ### Male: prostate, bladder neck, membranous sphincter ### Stress: outlet fails under abdominal pressure ### Urgency: often detrusor overactivity ### Overflow: incomplete emptying ### Continuous: fistula or ectopic ureter ## Rectum and mesorectum ### Begins near S3, follows sacral curve ### Peritoneum: upper front and sides, middle front ### Mesorectum: vessels, lymphatics, nodes #### Mesorectal fascia: cancer excision plane #### Protect autonomic nerves ### Anterior relations differ by organs ### Superior, middle, inferior rectal supply ## Defecation and faecal continence ### Internal sphincter: much of resting pressure ### External sphincter, puborectalis augment ### Rectoanal inhibitory reflex samples contents ### Defecation straightens anorectal angle ### Dyssynergia: outlet fails to relax #### Assess anatomy and physiology ### Incontinence: sphincter, nerve, stool, capacity #### Childbirth injures sphincter and pudendal paths ## Prolapse, compartments, and imaging ### Anterior, apical, posterior descent #### Continuous supports, defects not independent ### Rectal prolapse is full thickness ### Mass in one compartment alters another ### Read imaging from wall inward #### Fat planes lost by inflammation or tumour #### MRI fascia, CT trauma, ultrasound dynamic #### Re-establish orientation every study ### Describe collections by boundaries ## Lymphatics and spread ### Superior bladder: external iliac nodes ### Bladder neck: internal iliac, sacral ### Prostate: internal iliac, sacral, obturator ### Rectum: inferior mesenteric and internal iliac routes #### Anal drainage changes at pectinate line ### Tumour also follows fascia, veins, nerves ### Localise failure: reservoir, outlet, support, control