HY lecture notes:
Stress incontinence
Answer = “laxity of pelvic floor muscles” or “downward mobility of vesicourethral junction.” USMLE will have “urethral prolapse” as a distractor answer choice re the latter descriptor.
Weakened pelvic floor muscles resulting in loss of urine with increased abdominal pressure (coughing, sneezing, laughing) –> Hx of multiple pregnancies classic, but often too easy of a descriptor and they won’t say that –> they’ll say there’s “downward movement of the vesicourethral junction with coughing”; next best step in Mx? –> pelvic floor (Kegel) exercises –> if ineffective, do mid-urethral sling; do not give medications for stress incontinence (HY!).
USMLE might ask you which muscle is not strengthened by Kegel exercises –> student then proceeds to have two thoughts: 1) “wtf, I’m supposed to know Kegel exercises at that high level of detail?” and 2) couldn’t any muscle not be strengthened by Kegel exercises; I mean, the deltoid wouldn’t be for instance.” –> answer to this Q = internal anal sphincter –> even if you have zero clue about Kegel exercises, bear in mind internal sphincters (urethral + anal) are under sympathetic control – i.e., you can’t voluntarily strengthen a muscle not under somatic (voluntary) control; in case you’re curious though, Kegels strengthen levator ani (which comprises pubococcygeus, puborectalis, and iliococcygeus).
Urge incontinence
Answer = “hyperactive detrusor,” or “detrusor instability” –> needs to run to the bathroom when sticking a key in the front door; needs to run to bathroom when opening car door; answer in multiple sclerosis + perimenopausal state (part of vasomotor Sx); can be idiopathic; answer = give oxybutynin (anti-muscarinic) or mirabegron (beta-3 agonist); once again, do not give these drugs in stress incontinence.
Overflow incontinence (neurogenic bladder)
Answer = “hypoactive detrusor” in both diabetes and BPH; sometimes for BPH the answer will be “bladder outlet obstruction.” In diabetes, neurogenic bladder is caused by myelin damage from sorbitol (glucose enters myelin, causing osmotic damage), leading to detrusor denervation; in BPH, merely due to outlet obstruction –> leads to detrusor burnout; in overflow incontinence, postvoid volume is high (i.e., 300-400 mL in USMLE Qs); normal should be <50-75 mL; for diabetic bladder, answer = bethanecol (muscarinic agonist); for BPH, insert catheter first always.
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Summary tidbits:
82M + dribbling, hesitancy, interruption of urinary stream + suprapubic mass (bladder) + bacteria in the urine –> answer = insert catheter first, not antibiotics.
Hx of many pregnancies + downward movement of vesicourethral junction –> stress incontinence.
Tx of stress incontinence –> pelvic floor exercises (Kegel); if ineffective –> mid-urethral sling.
“Hyperactive detrusor” or “detrusor instability” –> urge incontinence.
Needs to run to bathroom when sticking key in the door –> urge incontinence.
Incontinence in multiple sclerosis patient or perimenopausal –> urge incontinence.
Tx of urge incontinence –> oxybutynin (muscarinic cholinergic receptor antagonist) or mirabegron (beta-3 receptor agonist).
Incontinence + high post-void volume (usually 3-400 in question; normal is <50 mL) –> overflow incontinence.
Incontinence in diabetes –> overflow incontinence due to neurogenic bladder.
Tx for overflow incontinence in diabetes –> bethanacol (muscarinic cholinergic receptor agonist).
Incontinence in BPH –> overflow incontinence due to outlet obstruction –> eventual neurogenic bladder.
Tx for overflow incontinence in BPH –> insert catheter first; if bacteriuria, give Abx after the catheter is inserted –> manage BPH with alpha-1 blocker (e.g., tamsulosin) or 5-alpha-reductase inhibitor (finasteride, then TURP if necessary.
