Pelvic Anatomy - Johns Hopkins Medicine [PDF]

Pelvic Anatomy Robert E. Gutman, MD

Objectives ƒ Understand pelvic anatomy ƒ Organs and structures of the female pelvis ƒ Vascular Supply ƒ Neurologic supply ƒ Pelvic and retroperitoneal contents and spaces ƒ Bony structures ƒ Connective tissue (fascia, ligaments) ƒ Pelvic floor and abdominal musculature

ƒ Describe functional anatomy and relevant pathophysiology ƒ ƒ ƒ

Pelvic support Urinary continence Fecal continence

Abdominal Wall

Rectus Fascia Layers ƒ What are the layers of the rectus fascia ƒ Above the arcuate line? ƒ Below the arcuate line?

Median umbilical fold Medial umbilical ligaments & folds Lateral umbilical folds

Bony Anatomy and Ligaments

Bony Pelvis ƒ The bony pelvis is comprised of 2 innominate bones, the sacrum, and the coccyx. What 3 pieces fuse to make the Innominate bone? ƒ Pubis ƒ Ischium ƒ Ilium

Clinical Pelvimetry Which measurements that can be made on exam? ƒ Inlet ƒ Midplane ƒ Outlet

ƒ Diagonal Conjugate ƒ Interspinous diameter ƒ Transverse diameter (intertuberous) and AP diameter (symphysis to coccyx)

Retrospective Case Control Study MRI Pelvimetry ƒ Pelvic MRI 1998 – 2002 ƒ Medical record review ƒ Pelvic examination ƒ Pelvic floor dysfunction symptoms

ƒ 98 total women ƒ 59 with pelvic floor disorders ƒ 39 without pelvic floor disorders Handa VL, et al. Architectural Differences in the Bony Pelvis of Women With and Without Pelvic Floor Disorders. Obstet Gynecol 2003;102:1283-90.

Retrospective Case Control Study MRI Pelvimetry ƒ Women with pelvic floor disorders: ƒ ƒ ƒ ƒ ƒ ƒ

Wider transverse inlet Wider intertuberous diameter Wider interspinous diameter Greater sacrococcygeal length Deeper sacral curvature Narrower AP outlet

ƒ After controlling for age, race and parity ƒ Wider transverse inlet (OR 3.4, p = .006) ƒ Shorter obstetrical conjugate (OR 0.2, p = .026) ƒ Wider interspinous diameter (OR 2.8, p = .069)

Pelvic Vasculature ƒ Ovarian arteries originate from: ƒ Aorta

ƒ Ovarian veins return to: ƒ IVC and Left renal vein

ƒ Ureter ƒ ƒ ƒ ƒ ƒ ƒ

Below kidney, lateral/medial to ovarian A? Lateral Near pelvic brim, lateral/medial to ovarian A? Medial Over or under the uterine vessels? Under

Branches of the Internal Iliac Artery ƒ Anterior Division ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Obturator Obliterated umbilical Sup & Inf vesical Uterine Vaginal Middle rectal Pudendal Inferior gluteal

ƒ Posterior Division ƒ ƒ ƒ

Iliolumbar Lateral sacral Superior gluteal

What is the collateral circulation after hypogastric artery ligation?

Pudendal Artery

Blood Supply to the Ureter

Blood Supply to Colon/Rectum

Nerves of the Pelvis

Innervation to Levator Ani ƒ 12 fresh-frozen female cadavers ƒ Each innervated S3-5 ƒ ƒ ƒ

S4 alone S3-4 S4-5

30% 40% 30%

ƒ No pudendal nerve supply identified ƒ Similar findings in rat studies Barber MD, et al. Innervation of the female levator ani muscles. Am J Obstet Gynecol 2002;187:64-71. Bremer RE, Barber MD, et al. Innervation of the Levator Ani and Coccygeus Muscles of the Female Rat. Anat Rec Part A 2003;275A:1031-41.

Nerve Injury What nerve can be injured with: ƒ Placement of deep lateral wall retractors on Psoas at laparotomy? ƒ Hyperflexion of the hips in lithotomy position or tight underwear? ƒ Leaning on the back of the legs during vaginal surgery or sacrospinous ligament fixation? ƒ Making a pfannensteil incision? ƒ Pelvic lymph node dissection?

Ilioinguinal and Iliohypogastric Nerve Injuries ƒ Mapping in 11 fresh frozen cadavers ƒ Ilioinguinal nerve

ƒ Entered 3.1 ± 1.5 cm medial, 3.7 ± 1.5 cm inferior to ASIS ƒ Terminated 2.7 ± 0.9 cm lateral to midline, 1.7 ± 0.9 cm superior to pubic symphysis

ƒ Iliohypogastric nerve

ƒ Entered 2.1 ± 1.8 cm medial and 0.9 ± 2.8 cm lateral to ASIS ƒ Terminated 3.7 ± 2.7 cm lateral to midline and 5.2 ± 2.6 cm superior to pubic symphysis

Whiteside JL, et al. Anatomy of ilioinguinal and iliohypogastric nerves in relation to trocar placement and low transverse incisions. Am J Obstet Gynecol. 2003;189:1574-8.

Nerve Injury During Uterosacral Ligament Suspension

Siddique SA, et al. Relationship of the uterosacral ligament to the sacral plexus and to the pudendal nerve. Int Urogynecol J Pelvic Floor Dysfunct 2006;17:642-5.

Name the 7 Surgical and Anatomic Spaces ƒ Prevesical (space of Retzius) ƒ Vesicovaginal and vesicocervical ƒ Paravesical ƒ Rectovaginal ƒ Pararectal ƒ Retrorectal ƒ Presacral

Components of Pelvic Support ƒ Bony pelvis ƒ Endopelvic Fascia (fibromuscular layer)

ƒ Pelvic diaphragm

Urethral Closure Pressure 3 components Rhabdosphincter • Circular smooth muscle • Nonneuromuscular – Vascular cushions – Mucosa – Connective tissue •

Pelvic Diaphragm Components ƒ Levator ani Muscles ƒ ƒ ƒ

Puborectalis Pubococcygeus Iliococcygeus

ƒ Coccygeus muscles

Anal Continence Mechanism

“Endopelvic Fascia” ƒ Fibromuscular layer ƒ Functionally single sheet of connective tissue ƒ Ligamentous condensations ƒ Vasculature ƒ Nerves

Levels of Support ƒ Level I ƒ Uterosacral and cardinal ligaments ƒ Support uterus and vaginal apex

ƒ Level II ƒ Lateral attachments of endopelvic fascia and vagina to arcus tendineus fascia pelvis ƒ Support bladder, vagina, and rectum

ƒ Level III ƒ Perineal membrane and perineal body ƒ Support UVJ and perineum DeLancey JOL. Anatomic aspects of vaginal eversion after hysterectomy. Am J Obstet Gynecol.1992;166:1717-24.

Uterosacral Ligament ƒ ƒ ƒ ƒ

15 female cadavers USL attaches to S1-3 and variably to S4 Less vital structures below intermediate portion Mean distances from USL to ureter ƒ ƒ ƒ

Cervical Intermediate Sacral

0.9 ± 0.4 cm 2.3 ± 0.9 cm 4.1 ± 0.6 cm

ƒ Ischial spine to ureter 4.9 ± 2.0 cm ƒ Ischial spine consistently beneath intermediate portion ƒ USL tension transmitted to ureter most near cervix ƒ Cervix and intermediate portions strongest

Buller JL et al. Uterosacral Ligament: Description of Anatomic Relationships to Optimize Surgical Safety. Obstet Gynecol 2001;97:873-9.

MRI Vaginal Apex Distances

Sup/Inf

Ant/Post

Right/Left

Cervical Vaginal Junction to Ischial Spine

1.6 ± 0.5 superior

1.1 ± 0.5 anterior

4.7 ± 0.4 medial

Posterior Fornix to S2

5.3 ± 0.8 inferior

1.0 ± 1.0 anterior

Gutman RE et al. Anatomic Relationship Between the Vaginal Apex and the Bony Architecture of the Pelvis: a MRI Evaluation. Am J Obstet Gynecol 2005;

Leffler KS et al. Attachment of the rectovaginal septum to the pelvic sidewall. Am J Obstet Gynecol 2001;185:41-3.

Pelvic Diaphragm Functions ƒ Close genital hiatus ƒ Creates levator plate

Levators Toned

Interrelationship of Ligamentous and Muscular Support Muscular Support ƒ Long-term support ƒ Closure of genital hiatus ƒ Levator plate

Ligamentous support ƒ Short-term support ƒ Tether viscera during relaxation of pelvic diaphragm.

Analogy to Ship in Dry Dock

Pelvic Floor Dysfunction URINARY DYSFUNCTION •Lower urinary tract symptoms •Incontinence •Voiding difficulties

VAGINAL DYSFUNCTION •Protrusion symptoms •Sexual dysfunction

DEFECATORY DYSFUNCTION •Incontinence •Defecatory disorders

Risk Factors for Pelvic Organ Prolapse Predispose

Incite

Promote

Decompensate

Congenital

Vaginal delivery

Obesity

Aging

Racial

Surgery

Smoking

Menopause

Gender

Neuropathy

Lung disease

Neuropathy

Myopathy

Constipation

Myopathy

Recreation

Debilitation

Occupation

Medication

Mechanisms of Prolapse Neuromuscular Failure

ƒ Myopathic injury ƒ Direct muscular compromise ƒ Denervation

ƒ Neuropathic injury ƒ ƒ ƒ

Stretching – Chronic injury Compression – Acute injury Combinations

Consequences of Neuromuscular Compromise

Normal tone

Loss of tone

Fecal Continence Mechanism

Mechanisms of Prolapse ƒ Ligamentous Failure ƒ Connective tissue compromise ƒ Stretching – Chronic injury ƒ Tears – Acute injury ƒ Combinations

Lower Urinary Tract and Continence Mechanism

Perineal Descent

Pathophysiology of Prolapse Detachment

Attenuation

Inciting Promoting Factors

Neuropathy

Myopathy

Summary ƒ Pelvic floor dysfunction is common and can be debilitating. ƒ Important to understand normal anatomy and pathophysiology to properly care for women with these conditions and to avoid surgical complications.