Urinary incontinence

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Urinary incontinence

Renal system


Urinary incontinence


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USMLE® Step 1 questions

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High Yield Notes

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Urinary incontinence

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USMLE® Step 1 style questions USMLE

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A 55 year-old female comes to her outpatient physician because of urinary incontinence. The patient reports a sense of fullness in the bladder and continuous dribbling of urine over the past two months. Past medical history is notable for type 2 diabetes mellitus and hypertension. However, the patient reports being inconsistent in taking her medications. Her temperature is 37.1°C (98.8°F), blood pressure is 158/91 mmHg, and pulse is 75/min. Physical exam reveals decreased sensation to soft touch and pinprick in the distal arms and legs. Laboratory results are as follows:  
 Laboratory value  Result 
 Glucose  167 mg/dL 
 HbA1c  8.1% 
 Postvoid residual volume   170 ml 

Which of the following best describes the pathophysiology of this patient’s symptoms?   

External References

First Aid








Antimuscarinic drugs

urgency incontinence p. 624

Benign prostatic hyperplasia (BPH) p. 678, 731

incontinence with p. 624

Diabetes mellitus p. 352-360

urinary incontinence with p. 624

Incontinence (fecal/urinary) p. 469

Mixed incontinence (urinary) p. 624

Urinary incontinence p. 624

drug therapy for p. 242

ephedrine for p. 243

hydrocephalus p. 540

multiple sclerosis p. 541


Content Reviewers

Urinary incontinence is a problem where the process of urination, also called micturition, happens involuntarily, meaning that a person might urinate without intending to.

Urinary incontinence is particularly problematic because it affects a person’s personal hygiene as well as their social life in a way that can be very limiting.

Normally, urine is held in the bladder, which receives urine from two ureters coming down from the kidneys and then that urine leaves the bladder through the urethra. As urine flows from the kidney, through the ureters and into the bladder, the bladder starts to expand into the abdomen.

The bladder is able to expand and contract because it’s wrapped in a muscular layer, called the detrusor muscle, and within that, lining the bladder itself is a layer of transitional epithelium containing “umbrella cells”. These umbrella cells get their name because they physically stretch out as the bladder fills, just like an umbrella opening up in slow-motion. In a grown adult, the bladder can expand to hold about 750ml, slightly less in women than men because the uterus takes up space which crowds out the bladder a little bit.

Alright, so when the urine is collecting in the bladder, there are basically two “doors” that are shut, holding that urine in. The first door is the internal sphincter muscle, which is made of smooth muscle and is under involuntary control, meaning that it opens and closes automatically. Typically, that internal sphincter muscle opens up when the bladder is about half full.


Urinary incontinence is a common condition that occurs when urine involuntarily leaks from the bladder, often through the internal and external sphincter muscles. There are several types of urinary incontinence, including urge incontinence, stress incontinence, and overflow incontinence.

Urge incontinence is typically caused by an overactive bladder, which can lead to sudden and strong urges to urinate that are difficult to control. Stress incontinence, on the other hand, is often due to increased pressure on the bladder, which can happen during physical activity, sneezing, or coughing. Overflow incontinence is caused by incomplete emptying of the bladder, leading to urine leakage due to bladder overfilling.

The treatment for urinary incontinence depends on the underlying cause and severity of the condition. Some common interventions include strengthening the external sphincter muscle by doing things like Kegel exercises, and catheterization or medications like alpha-blockers, which relax the smooth muscle to assist with urination.


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