Pocket ObGyn – Anal Incontinence
See Abbreviations
Definition and Epidemiology
- Involuntary passage of flatus or stool
- Fecal incontinence – inability to prevent passage of stool until socially acceptable
- Prevalence 2–17% general pop, up to 50% of nursing home residents (NEJM 2007;356:1648)
- Risk factors: Female sex, pelvic radiation, obstetric trauma, neurologic d/o, prev anorectal Surg, chronic diarrhea (IBD, IBS, celiac sprue), fecal impaction, urinary incontinence, nursing home placement, smoking, obesity
Etiology
- Chronic constip is very common in women & can lead to overflow incontinence & pelvic floor dysfxn if untreated
- Etiology is commonly multifactorial
- Most common cause in otherwise healthy women is damage to anal sphincter at time of vaginal deliv
- Pseudoincontinence – fecal soiling only (rectovaginal fistula, external hemorrhoids, incomplete rectal emptying)
Clinical Manifestations
- Direct questioning or written questionnaires are important
- Detailed hx including onset, frequency, severity, consistency of stool, presence of bld, pus, or mucus, pad use, effect on QOL, bloating, fecal urgency, straining, insensible loss of stool, fecal soiling
- Thorough medication hx important (laxatives, meds causing constip [anticholinergics, iron, narcotics, ] can lead to overflow incontinence)
Physical Exam
- Inspection of perineum & anus – external hemorrhoids, dermatitis, nml perineal skin creases, rectal prolapse, scars from prev lacerations or episiotomies, patulous anus (indicative of denervation), fissures
- Dovetail sign – loss of anter perineal creases (disruption of EAS)
- Inspection w/ squeeze to evaluate symmetry of folds & mvmt of perineum
- Inspection w/ bearing down to evaluate excessive perineal descent (>3 cm)
- Perineal sensation – dull & pinprick sensation should be tested in S2–4 dermatomes
- Bulbocavernosus reflex – cotton swab touched over bulbocavernosus muscles should elicit contraction of EAS
- Digital rectal exam – evaluates resting tone, contraction of EAS & PR, areas of tenderness, fecal impaction, masses
Diagnostic Workup/Studies
- Daily stool diary, validated questionnaires
- Rule out systemic & metabolic causes (infectious, autoimmune, malig, endocrine)
- Colonoscopy: Indicated for any pt >50 yo or w/ concerning sx (weight loss, melena/ hematochezia, chronic diarrhea), family h/o colon cancer, HNPCC or Lynch syn, evaluate for IBD, celiac sprue
- Endoanal US: Useful when there is clinical suspicion for anal sphincter injury, evaluates structure only (best 1st-line test for poor anal squeeze)
- Anal manometry: Useful study in pts w/ nml anal tone who reports abn sensation to defecate, evaluates rectal sensation, compliance, & RAIR, evaluates fxn only
- Other studies: Electromyography (mapping EAS defects), pudendal nerve conduction studies, defecography (evaluates perineal descent, anorectal angle, rectocele, ), dynamic pelvic MRI, colonic transit studies
Treatment (NEJM 2007;356:1648)
- Management directed at primary cause
- Behavioral modifications
Pelvic floor exercises (Kegel)
Biofeedback: Improves perception of rectal sensation & sphincter contraction
- Medical management
| Common medications for treatment of constipation | ||||
| type | Name | Mech | Maximal dose | Side effects |
| Bulk laxative | Psyllium
(Metamucil) |
Increases colonic residue, stimulates peristalsis | Titrate up to 20 g | Bloating, flatus |
| osmotic
laxative |
Magnesium hydroxide (MOM) | Draws water into intestines | 15–30 mL up to BID | Hypermagnesemia |
| Magnesium citrate | 150–300 mL
prn |
|||
| Sodium
phosphate (Fleet) |
10–25 mL w/
12 oz water prn |
Hyperphos | ||
| Poorly
absorbed sugars |
Lactulose | Poorly absorbed, draw water into intestines | 15–30 mL 1–2
times a day |
Bloating, flatus |
| Sorbitol | ||||
| Polyethylene glycol (Miralax, GoLytely – electrolytes) | 17–36 g 1–2
times a day |
Less bloating & discomfort | ||
| stimulant laxative | Senna | Stimulates intesti- nal motility or secretion | 187 mg daily | Melanosis coli |
| Bisacodyl (Dulcolax) | 5–10 mg QHS | Cramping | ||
| Docusate sodium (Colace) | Ionic detergents allow incorpo- ration of water into stool | 100 mg BID | Diarrhea | |
| enema/
suppository |
Tap-water enema | Distends rectum to initiate evacuation, lubrication | 500 mL daily | Electrolyte abnormalities can occur if retained |
| Soapsuds enema | 1500 mL daily | |||
| Mineral oil enema | 100 mL daily | |||
| Bisacodyl suppository | Topical stimula- tion of colonic muscle | 10 mg daily | Cramping | |
| Prokinetic | Tegaserod (Zelnorm) | 5-HT4 agonist | 6 mg BID | Diarrhea |
| From NEJM 2003;349:1360–1368. | ||||
- Modification of stool consistency & deliv
Increased fiber intake increases solid stool bulk & may facilitate emptying (may worsen diarrhea in some pts) (Gastroenterology 1980;79:1272)
| Common medications for treatment of diarrhea | |||
| Name | Mech | Dosage | Side effects |
| Loperamide (Imodium) | Inhibits peristalsis | 2 mg PO TID
Max 8 mg/d |
Constip, nausea |
| Diphenoxylate– atropine (Lomotil) | Inhibits circular smooth muscle | 5 mg PO QID | CNS effects, nausea |
| Hyoscyamine sulfate | Antichol | 0.325 mg BID | Constip, dry mouth |
| From Lentz GM. Anal incontinence: Diagnosis and management. In: Lentz GM, ed. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Mosby; 2012:503–518. | |||
• Surgical management:
Generally surgical rx is the last resort & usually not effective Overlapping anal sphincteroplasty – 85% short-term improv, 50% at 5 y
Note: Studies have not shown a difference in outcomes btw end-to-end vs. overlapping sphincteroplasty for perineal laceration repair after vaginal delive
Rectal prolapse repair – transrectal, transabdominal, or laparoscopic rectopexy Sacral nerve stimulation – see OAB section, above, 37–74% continence rate at 24 mo
(NEJM 1993;329:1905)