BASIC SCIENCES GYNECOLOGY URINARY CONTINENCE MECHANISMSobstetric-ultrasound.com/lectures/gynecology/sui.pdf · BASIC SCIENCES –GYNECOLOGY URINARY CONTINENCE MECHANISMS-CONTINENCE

BASIC SCIENCES – GYNECOLOGYURINARY CONTINENCE

MECHANISMS- CONTINENCE AT REST

- CONTINENCE AT EVENT OF

INCREASED VESICAL PRESSURE

- PHYSIOLOGY OF VOIDING

Pressure Balance:

Intravesical pressure depends on the following: (1) the volume of fluid in the bladder,

(2) the part of the intra-abdominal pressure transmitted to the bladder

(3) the tension in the bladder wall related to muscular and nervous system activity and elastic properties.

The resting pressure in the bladder is between 20 and 30 cm H2O due to surrounding intraabdominal pressure with little or no pressure added from tension in the bladder wall in normal bladders (i.e., the detrusor pressure) is 0 cm H2O.

The intraurethral pressure depends on the following:

(1) striated muscle fibers of the urethral wall.(2) smooth muscle fibers of the urethral wall (a circular and longitudinal layer).(3) vascular content of the urethral submucosal cavernous plexus. (4) passive elasticity of the urethral wall.(5) the part of the intra-abdominal pressure transmitted to the urethra.

Functional Anatomy of the urethra:

zero location as that point at which the urethra leaves the bladder lumen and the 100th

percentile as that point at which the urethra terminates on the perineum.

1- The intramural urethra represents approximately 20% of the length of the urethra.

2- The portion of the urethra associated with the pubourethral ligament and vaginal levatorattachment concerns the midurethra—that is, that portion from the 20th to 60th percentile along the total length.

3- The 60th to 80th percentile of the urethral length passes through the urogenital diaphragm and is under the influence of the urethrovaginalsphincter muscles.

4- Finally, the last 20%, or distal urethra, traverses the bulbocavernosus muscles.

Urethral Closing Pressure CurveAnatomically, the exact border between the bladder and urethra is difficult to determine.

• The functional length of the urethra, however, is that part in which the urethral pressure exceeds the bladder pressure.

• Maximal urethral closure pressure(MUCP) The highest pressure in the urethra - approximately at the midpoint of the functional urethral length.

• The urethral closure pressure (UCP) is defined as the maximum urethral pressure minus the bladder pressure.

• Abdominal leak point pressure (ALPP) as the lowest of the intentional or actively increased intra-vesical pressure that provokes urinary leakage in the absence of a detrusor contraction.

• The first loop (loop I) Cortex-brain stem loop: involves a circuit from the cerebral cortex to the brain stem inhibit loop II if unfavorable conditions or facilitate loop III in favorable conditions.

• Loop II Brain Stem – sacral loop: which originates in the sacral micturition center (S2 through S4) and the detrusor muscle wall itself, represents sensory fibers to the brain stem, where modulation of the stimuli by loop I takes place.

• Loop III Vesico-Sacral loop: involves sensory flow from the bladder wall to the sacral micturition center with returning motor fibers to the urethral sphincter striated muscle, which allows the voluntary relaxation of the urethral sphincter as the detrusor contracts

• Loop IV Cerebro-Sacral loop: originates in the frontal lobe of the cerebral cortex and runs to the sacral micturition center and then to the urethral striated muscle = External urethral Sphincter. Allowing urethral voluntary muscles to contract or relax.

VoidingUnder the control of four basic autonomic and somatic nervous system feedback loops.

Parasympathetic System (Voiding):

• Bladder contracts: acetylcholine, directly stimulating muscarinic receptors in the bladder wall => signal is transmitted via the pelvic nerve and causes the detrusor to contract. Muscarinic receptors mainly M3 (continence drugs that are specific M3 receptor antagonists maximize drug

efficacy and minimize activation of other muscarinic receptors and drug side effects)

• Urethral relaxes: acetylcholine stimulates receptors in the urethra => outlet relaxation.

Sympathetic system (Prevent Micturition)

• Norepinephrine is secreted via this system, stimulating both α- and β-adrenergic receptors.

• The bladder (detrussor) Relaxes: β receptors.

• The urethra contracts: α receptors.

URINARY INCONTINENCE"a condition in which involuntary loss of

urine is a social or hygienic problem and is objectively demonstrable ".

CHAPTER 1

STRESS – URGE INCONTINENCE

Involuntary urine leakage on exertion or with sneezing or coughing

Main types of Urinary Incontinence:1. Stress incontinence, Involuntary urine leak from the bladder with cough, laugh, sneeze or any other activity that places stress on the abdomen in absence of detrusor muscle activity = Urodynamic Stress Incontinence [Urethral problem]

a) Hypermobility of the urethra => Funneling of proximal urethra (decreased functional length) – descent below Intra-Abdominal pressure zone.

b) Intrinsic sphincteric defect (ISD) stress incontinence in women with a fixed and poorly functioning urethra (radiation, neurologic conditions, scarring of the urethral sphincter)

2. Urge incontinence - Overactive Bladder (OAB) [Bladder = detrusor problem]

Urgency is the complaint of a sudden compelling desire to pass urine, which is difficult to defer.

Urge incontinence is the complaint of involuntary leakage of urine accompanied by or immediately preceded by urgency.

• Mixed SUI when both elements are present [Urethra problem + detrusor problem]

3. Overflow incontinence (Chronic retention of urine) difficulty passing urine, which causes the bladder to be permanently full and the excess spills out through the urethra (Pves > UCP).

4. Total incontinence is the continuous leakage of all the urine. It’s most often caused by an abnormal communication between the bladder and the vagina.

PREVALENCE 25 – 50%

RISK FACTORS

- AGE

- WHITE > BLACK

- COLLAGEN DISEASE

CT AND SUPPORTS OF URETHRA AND UCP – IN ADDITION, DECREASED PATIENT MOBILITY => OVERFILLING OF UB

OBESITY

SMOKING

SPORTS

COAD – CHRONIC CONSTIP.

CHRONIC INCREASE IN IAP MAY EVEN DISRUPT PELVIC MS AND

INNERVATION

CHILDBIRTH

POP

HYSTERECTOMY

PELVIC SURGERY

TRAUMA

AFFECTS PELVIC MS SUPPORT POWER AND INNERVATION

URETHRAL HYPERMOBILITY

UCP

VASCULAR DZ

NEUROLOGICAL DZ

CT DISEASE

DM

MEDICATIONS-

AFFECT MAINLY ON UCP

MEDICATIONS- COGNITIVE DISORDERS – DEPRESSION -

– UB OVERFILLING

• Diagnosis:

• History: • Risk Factors – Complication• BLADDER DIARY• Analysis of complaint:

• General Examination: Risk factors

• Abdominal Examination: Abdominal mass - Ascitis

• Local Examination: Pelvic organ prolapse (Prolapse reduction stress test)

• Special tests:• Residual Volume [Catheter after voiding N < 150 ml- increases in cases of iadequate

bladder emptying = urine retension]• Office cystometry [Instillation of saline through catheter by gravity, first sensation

200 ml – urge 400 ml – maximum capacity 600 ml] • Q-tip test [Normal angle < 30 degrees – increases in urethral hypermobility]• Cough test [Cough 10 times recumbent and standing to objectively demonstrate

incontinence or Pad test where pad is weighed before and after 1 hour of activity increase in weight by 2-3 gms = leak]

Examination:

Office Cystometry:

• First Sensation: normally occur after 150 to 200 mL of saline.

• Strong controllable urge to void at 400 to 500 mL

• Retention confirmed if large volumes reached without incontinence.

• Overactivity confirmed If < 200ml (during filling) cause urgency + the column of fluid in the syringe rises, and leakage may occur

Cough stress test: 250 to 300 mL of saline instilled in the UB, catheter is then removed:

• the woman is asked to cough 10 times while in the recumbent position. If urine spurts a positive cough stress test (CST) is noted. If no leakage is seen it should be repeated with the woman standing.

PAD STRESS TEST: Alternatively, with a 250-mL bladder volume, a pad is given to the woman and she is asked to complete a series of activities over the hour, including walking, climbing stairs, coughing, and other events.

• If the pad weighs more than 2 to 3 g more , the test is considered positive.

Q- TIP TEST:• “Q-tip test” estimated urethral hypermobility.

• Q-tip test: • Placing a cotton swab into the urethra to the bladder neck• Observing the angle that the urethra makes with the horizontal

during a strain maneuver

• Excursion angle greater than 30 degrees suggests hypermobility and is associated with higher success rates after mid-urethral sling surgery.

• Women with stress incontinence without urethral hypermobility have a risk of failure after mid-urethral sling and may be better served by a urethral bulking agent.

• Urethral mobility can also be evaluated using the prolapse quantification system, visualization, palpation, or ultrasonography.

Investigations:1- Urine analysis and culture may suggest a UTI, nephrolithiasis, kidney disease, or even urinary tract malignancy in rare cases. UTI may be associated with urgency, frequency, dysuria, and even incontinence.

2- DM screening

3- Investigations for etiological factor as needed

4- Urodynamic testing

5- CYSTOURETHROSCOPY

• The bladder may be visualized and the presence of inflammation, foreign bodies, urinary tract stones, anatomic abnormalities such as a duplicated ureter, or benign or malignant lesions noted.

• Urethroscopy, using the same cystoscopy equipment, is excellent for visualizing the urethra for inflammatory processes within the urethra, urethral diverticula, and other anatomic defects such as a urethral stricture or foreign body, and it permits some estimate of urethral tone.

URODYNAMIC STUDIESIndications:

1- If the diagnosis is unclear,

2- Failed conservative therapy, or previous failed incontinence surgery,

3- Associated Voiding complaints, Pelvic organ prolapse beyond the hymen, neurologic disease.

How it is done:

The ideal is to use a multichannel recorder for pressure determinations at:

- Two points within the urethra (proximal and midpoint to distal),

- One within the bladder, and

- One intra-abdominally as recorded by an intr-arectal sensor or by a sensor within the vagina if the vagina is in a relatively normal position

For greatest accuracy, these should be measured with the woman:

• In the sitting position as well as

• Standing, at rest, and

• Without straining

• With Straining

• UB Pressure:• First urge to void, Normal desire to void, Bladder

capacity. • Valsalva or cough (VLPP) abdominal leak point pressure

(ALPP)• The ALPP : cutoff of less than 60 cm H2O is used to define

intrinsic sphincter deficiency

• Detrusor overactivity may be noted with the symptom of urgency, with or without leakage, in association with a detrusor pressure rise.

- Poor compliance from a nonelastic bladder is noted with a gradual pressure rise of more than 15 cm H2O from baseline rather than phasic contractions of detrusor overactivity.

• Urethral Pressure:• Functional Length• MUCP• UCP

• Intrinsic sphincter dysfunction also defined as maximum urethral closure of 20 cm H2O or less

- Voiding: Pressure flow studies measure voiding in terms of detrusor and urethral function.

Conservative Management: 1- Weight Loss – Treatment of etiologic factor

Conservative Management: 2- Pelvic Floor Muscle Strengthening• Conservative measure should be discussed and offered to all women with stress incontinence.

• The first-line treatment is pelvic floor muscle training directed toward the strengthening of the levator ani and pubococcygeal muscles, which affect the urethral closure mechanism.

• This can be affected by:

1. Isometric exercises, as described by Kegel. The woman can be instructed:• How to contract these muscles by being told to attempt to stop the urinary stream while she is voiding. • After she learns which muscles to contract, she should perform the exercises at other times without any

relationship to voiding because contracting her pelvic floor muscles during voiding could lead to voiding dysfunction.

• Patient requested to contract these muscles slowly, 8 to 12 times, for a count of 6 to 8 seconds each, and to repeat this series for three sets daily.

2. Use of weighted vaginal cones. This involves a set of cones of increasing weight that require pelvic muscle contraction to hold them within the vagina.

3. Pelvic floor electrical stimulation has also been studied for improving pelvic floor muscle strength and decreasing symptoms of stress incontinence. A small, removable vaginal probe is placed in the vagina or anus and the electrical stimulation activates a pelvic muscle contraction.

Conservative Management: 3- Behavioral therapy• Behavioral management

• Fluid management,

• Avoidance of bladder irritants,

• Bladder training:• This involves a programmed progressive lengthening of the period between voiding, with

or without the addition of biofeedback techniques.

• Women need to be taught urge suppression using distraction, relaxation techniques, or pelvic floor muscle contractions.

• The goal is to increase the voiding interval to 2 to 3 hours with normal fluid intake.

Conservative Management: 4- Pessaries• Incontinence pessary:

• Silicone ring device with a knob placed in the vagina,

• The goal is stabilizing the urethra to eliminate hypermobility and increase urethral pressure during increases in intra-abdominal pressure.

• FemSoft urethral insert device Urethral plug. • Although women with stress

incontinence may have greatly reduced leakage when wearing the insert, it is not popular because a new device needs to be placed after each void.

Conservative therapy:5- Medications1. Anticholinergic (antimuscarinic) :

• - Oxybutinin 5mg (bid, tid, qid),

• - Tolterodine 2mg (bid)

• - Darifenacin 7.5 mg (bid)

• - Trospium 20mg (bid)

• - Fesoterodine 4mg (bid)

2. Beta-3 adrenergic receptor agonist mirabegron (Myrbetriq) 25mg (bid)

3. Intravesical instillation of anticholinergic medication can provide an alternative delivery mechanism for women who fail or cannot tolerate oral therapy.

Conservative therapy:5- Medications• Estrogen therapy In postmenopausal women,

• Thought to increase the vasculature and mucosal seal of the urethra, thereby increasing urethral closing pressure.

• Randomized studies have called into question these effects and, in fact, the opposite effect has been shown.

• Other non–FDA-approved drugs :• Imipramine, a tricyclic antidepressant, has α-adrenergic enhancement characteristics. Its

action on the α receptors in the bladder neck and urethra may cause muscle contraction. (there is weak evidence to suggest that any adrenergic drugs are better than placebo treatment).

• Duloxetine is a serotonin and norepinephrine reuptake inhibitor that stimulates pudendalmotor neuron activity in Onuf’s nucleus in the spinal cord and causes contraction in the urethra.

Surgical Procedures:1. Bladder Neck Urethropexy: The goal is to provide solidity to posterior UV angle increasing UCP.

1. Kellys suture 2 to 3 sutures near UB neck –2. Kennedy (sutures placed all through till lower urethra)

2. Bladder Neck Retropubic Colposuspension: The goal of these procedures was to fix the bladder neck into a high retropubic position, while returning the urethra to an abdominal position, thus allowing equal transmission of pressures to the bladder and bladder neck/proximal urethral regions.

1. Transabdominal Colposuspension procedures: MMK – Burch2. Transvaginal needle Suspension: Pyrera - Stamey

3. Bladder Neck Sling procedures [Pubo-vaginal sling]: Same as 1 & 2 + increase UCP

1. Tissue: Gracilis ms (1917 by Giordano – Pyramidalis ms 1917 by In 1917, surgeons Goebell, Frankenheim, and Stoeckel – Rectus Fascia by Aldridge 1942)

2. Synthetic materials: Mersilene Tape (Moir op.) suture bridges and patch slings.

4. Mid-urethral sling procedures: same as 3 + less invasive + Sling is placed in midurethra (less mobile part) so with increased IAP the tape interacts with muscles and fascia to place tension on the tape an allow continence while at rest the tape is tension free and does not obstruct voiding.

1. Retropubic TVT2. Obturator TVT3. Mini sling TVT

Complications of surgery:

• Injury: UB – Urethra – Vessels – Bowel

• Infection: UT – postoperative sepsis

• Failure

• Mesh related complications: erosion – exposure – infection

• Pain: retropubic (TVT) – groin & leg (TOT) – dyspareunia – dysuria

• Voiding dysfunction: Retention – obstruction – urgency –

• Pregnancy related complications

Management for ISD• Retropubic urethropexy procedures may fail as the uresthra is not

hypermobile.

• At present, treatment for urinary stress incontinence caused by ISD consists of one of the following:

1. Periurethral bulking substance injections: Blood – Fat – Teflon – Collagen - Silicone

2. Urethral bladder neck sling procedures in select woman.

3. Midurethral synthetic sling.

4. Use of an artificial sphincter device: Artificial urinary sphincters are generally placed by abdominal and vaginal surgical approaches. The artificial sphincter consists of a cuff surrounding the urethra. The device is controlled by a pressure balloon placed in the space of Retzius. The woman controls the device by releasing pressure via a pump in the labia when she wishes to void and reestablishing pressure when she wishes to be continent.

Their use has been limited by side effects including erosion and mechanical problems.

Management: OAB• Women with intractable detrusor overactivity who have failed conservative and medical treatment have

procedural and surgical options.

1. Pelvic floor electrical stimulation has been studied for improving a woman’s ability to inhibit involuntary detrusor contractions and decreasing symptoms of urge incontinence but has mixed results.

2. Neuromodulation is increasingly recognized as beneficial for women with refractory symptoms (failed behavioral treatments and medications over roughly 3 months). It includes direct sacral neuromodulationof S3 and peripheral neuromodulation through peripheral tibial nerve stimulation (PTNS) to the sacral nerve plexus. In practice, PTNS is done weekly for 30 minutes for 12 weeks and then every 3 to 4 weeks for maintenance therapy. The FDA approved InterStim (Medtronic,Minneapolis, MN) for sacral neuromodulation (SNS) in 1997

3. Intradetrusor onabotulinumtoxin A cystoscopic injection: blocks presynaptic acetylcholine from parasympathetic nerves, causing paralysis of the detrusor smooth muscle, although it may also affect bladder afferent or urothelial cell neurotransmitters. Onabotulinumtoxin A is injected into the bladder wall via cystoscopy either in the office or in an outpatient surgery setting. It is FDA approved, and published studies show 60% to 70% cure or improvement rates.