Functional Urology

Continence during raised abdominal pressure depends on passive pressure transmission to the proximal urethra (compressing it against its posterior support) and the active guarding reflex. Incontinence is classified by type, and evaluation screens for transient and treatable causes before targeting the underlying mechanism.

Sphincteric Mechanisms

• Male: the internal sphincter (bladder neck to verumontanum) contributes to continence; loss of the external sphincter may not cause incontinence if the bladder neck is intact.
• Female: continence comes mainly from striated muscle bulk along the proximal/mid-urethra under tonic pudendal tone, plus pubourethral-ligament fixation and posterior musculofascial (hammock) support; the relatively weak female bladder neck makes any sphincter deficiency more likely to cause leakage.

Types of Incontinence

1. Stress (SUI) — abdominal pressure exceeds urethral pressure (mostly women; men usually post-prostatectomy).
2. Urgency (UUI) — leakage with/just before urgency.
3. Mixed (MUI) — both SUI and urgency leakage ("OAB wet"); SUI with "OAB dry" is not MUI; treat the most bothersome symptom.
4. Continuous.
5. Nocturnal enuresis — leakage during sleep (vs nocturia, which is intentionally rising); in men may signal high-pressure chronic retention with renal risk.
6. Postmicturition dribble.
7. Insensible — urethral diverticula (postvoid), ectopic ureter (continuous), overflow (small-volume frequent loss).
8. Other — coital, giggle.

Epidemiology

• Women: prevalence 25–40% (SUI 10–25% > MUI 5–20% > UUI 3–10%).
• Men: prevalence 11–34% (SUI uncommon except after radical pelvic surgery/TURP/neurologic disease; UUI/MUI more common, often from BOO/OAB); higher remission than women.

Pathophysiology of Female SUI

Loss of posterior musculofascial (hammock) urethral support causes leakage; restoring posterior support — not necessarily repositioning the urethra — restores continence. ISD (severe SUI without hypermobility, the classic "pipe-stem" urethra) is identified by ALPP <60 cm H₂O; most SUI involves some ISD. Treatments correcting hypermobility (Burch, needle suspension) are less helpful with severe ISD and limited mobility.

Risk Factors

• Both sexes: age (the strongest risk factor in men), pelvic-floor disorders, neurologic disease.
• Women: Caucasian ethnicity (African-American women have higher urethral closure pressures); pregnancy (SUI ~40% in pregnancy; Cesarean confers advantage over vaginal delivery; increasing parity raises risk); obesity (BMI >30 doubles UI risk); smoking; diabetes; oral estrogen ± progestogen (raises UI risk — topical estrogen does not and treats atrophy); caffeine (urgency/MUI); and depression.

Transient Causes — DIAPPERS

Delirium, Infection (UTI), Atrophic vaginitis/urethritis, Psychological, Pharmacologic, Excess urine production, Restricted mobility, Stool impaction.

Diagnosis and Evaluation

• History — characterize the incontinence (severity, quantity, triggers, impact) and voiding pattern; in women add obstetric/gynecologic and menopausal/HRT history.
• Exam — BMI; in women, external genitalia and estrogen status (signs of deficiency: urethral caruncle, urethral prolapse, labial adhesions), urethral mobility (Q-tip hypermobility = >30° from horizontal), and prolapse (lithotomy and standing); anal sphincter tone (S2–4).
• Labs: urinalysis (± PSA, electrolytes). Imaging not routine (VCUG for recurrent UTI/diverticulum/VUR; MRI for anatomy/prolapse).
• Supplemental evaluation when the diagnosis is unclear, with concomitant OAB, prior LUT/anti-incontinence surgery, suspected neurogenic bladder, negative stress test, abnormal urinalysis, elevated PVR, high-grade (≥stage 3) prolapse, or dysfunctional voiding.
• Tools: a 3-day voiding diary (as informative as 7-day), questionnaires (ICIQ-SF), PVR, and selective cystoscopy (urgency, hematuria, prior anti-incontinence/radiation/prolapse surgery).
• Urodynamics only when it will change management (planned invasive surgery, prior failed reconstruction, mixed/obstructive symptoms, elevated PVR, neurologic disease). Watch for cough-induced DO incontinence (mimics SUI). Occult SUI is unmasked by prolapse reduction — 11–50% of clinically continent patients develop de novo SUI after high-grade prolapse repair. The CARE trial showed concomitant Burch at sacrocolpopexy significantly reduced postop SUI (24% vs 44%).
• Pad test: a positive 24-hour test is urine loss >1.3 g (normal vaginal secretions up to ~0.3 g).
• Dye testing distinguishes urine from discharge and localizes fistulae: oral phenazopyridine colors urine orange; intravesical methylene blue stains a tampon blue with a vesico-/urethrovaginal fistula; with intravesical blue + oral phenazopyridine, orange staining = ureterovaginal, blue = bladder communication.

Self-Test

1. List the types of urinary incontinence. Stress, urgency, mixed, continuous, nocturnal enuresis, postmicturition dribble, insensible (diverticula/ectopic ureter/overflow), and other (coital, giggle).

2. What does DIAPPERS stand for (transient incontinence)? Delirium, Infection, Atrophic vaginitis, Psychological, Pharmacologic, Excess urine output, Restricted mobility, Stool impaction.

3. What ALPP value defines ISD, and how is urethral hypermobility defined on Q-tip testing? ALPP <60 cm H₂O suggests ISD; Q-tip hypermobility is a deflection >30° from horizontal.