Voiding disorders are common among patients with traumatic brain injury (TBI). Such voiding disorders are referred to as neurogenic bladder dysfunction . Urological disorders in TBI can range from 32% to 70% depending on the location of the injury within the brain.
Neuroanatomy
The neuroanatomy of normal voiding can be divided into the central and peripheral nervous systems. The relevant central nervous system structures include:
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Frontal lobe of the brain
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Pontine micturition center (PMC)
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Spinal cord
The frontal lobe maintains bladder continence by preventing bladder contraction. This is accomplished by inhibitory signals sent from the frontal lobe to the detrusor muscle, preventing bladder contraction and deactivating signals to the PMC, which diminishes the urge to urinate. The PMC is a major relay center between the brain and the bladder. PMC stimulation is an excitatory response that results in efficient voiding by coordinating simultaneous bladder contraction and sphincter relaxation. Involuntary voiding is suppressed by a cascade of inhibitory signaling initiated by the brain.
Neurogenic bladder
The most common bladder abnormality after brain injury is incontinence. The incidence of urinary incontinence is 62%, and that of urinary retention is 8% to 9%. , Urinary incontinence is associated with poorer admission and discharge functional status and longer rehabilitation length of stay.
Urinary dysfunction in TBI patients varies based on the area of brain or brainstem involved. Initial voiding dysfunction may be caused by a cerebral shock with an initial period of detrusor areflexia. With lesions above the PMC, the most common chronic urinary dysfunction is involuntary bladder contractions (detrusor hyperactivity). Patients will have detrusor hyperreflexia (spastic bladder) because of an uninhibited and intact reflex pathway. Voiding is characterized by urgency with or without incontinence because of the loss of cortical tonic inhibition to the bladder. In patients with more isolated brainstem injuries involving areas at or below the PMC, detrusor sphincter dyssynergia (DSD) may also occur. DSD is characterized by intermittent or sustained failure of relaxation of the urinary sphincter during a bladder contraction. Patients with lesions in only the basal ganglia or thalamus have normal sphincter function and may gain urinary control. True urgency incontinence with reduced bladder sensation is associated with global underperfusion of the cerebral cortex, especially the right frontal areas.
Clinical features
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When caused by unawareness with poor volitional control, there will most commonly be bladder accidents when the bladder is filled (approximately 250 cc).
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Increased control of urinary continence is typically seen as cognition, communication, and behavior improve.
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A spastic bladder will often result in significant urinary retention caused by a spastic external sphincter. Without intervention, the bladder will only empty at large volumes (>500 cc) related to overflow incontinence, and there will be an elevated risk of hydronephrosis.
Assessment
Postvoid residual (PVR) measurements
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PVR urine can be determined by catheterization or by using a bedside ultrasound machine.
Anorectal examination:
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Should include an assessment of trauma, perirectal sensation, and the presence or absence of volitional rectal sphincter contraction, as well as an evaluation of sacral reflexes (anal wink and bulbocavernosus reflex)
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Is useful in predicting the potential for regaining bladder control and classifying upper or lower motor neuron patterns ,
Medication review:
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Retention can often be related to medications
Blood urea nitrogen and serum creatinine:
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Measure kidney function
Diagnostic testing:
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Urinalysis with culture and sensitivity
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Renal and bladder sonography to evaluate for the presence of vesicoureteral reflux or stones.
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Urodynamic testing measures pressure within the bladder during both storage and voiding
Management of neurogenic bladder
Bladder management
Clean intermittent catheterization
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Clean intermittent catheterization (CIC) is generally accepted as the best and safest long-term bladder management method short of controlled urination.
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CIC is typically performed four to six times daily with a goal to obtain 500 cc or less per catheterization by adjusting the frequency.
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Patients with adequate cognition and hand function should be educated on how to perform self-CIC. Others may need to rely on the assistance of caregivers.
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The patient should be monitored for return of voiding.
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If spontaneous voiding does return, PVRs should be measured to verify adequate bladder emptying. PVR volumes should be less than 100 cc.
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The most common problems associated with CIC are urinary tract infection (UTI), urethral trauma, and incontinence between catheterizations, but studies have shown no significant increase in urinary complications when proper cleaning techniques are practiced.
Timed voiding
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Schedule for regular bladder emptying, typically every 3 to 4 hours.
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Timed voiding may assist with behavioral training in cognitively impaired patients.
Reflex voiding
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Reflex voiding requires intact sacral reflexes, and voiding occurs at inappropriately low bladder volumes and may occur without voluntary control.
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In persons with lesions above the PMC, coordinated relaxation of the sphincter mechanism is present and voiding is generally efficient, even if uncontrolled.
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A condom catheter may be indicated for male patients who are incontinent between scheduled voids but must be monitored closely for penile skin breakdown.
Indwelling catheters
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There is a limited role for indwelling Foley catheterization in the TBI population.
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Indwelling catheters may be indicated for acute management or short-term management of urinary retention or if fluid output must be closely monitored.
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Complications from Foley catheters have been well documented, including UTI, epididymitis and prostatitis, urethral strictures, traumatic hypospadias, urethral incompetence in women, urethritis, bladder calculi, and development of a small, poorly compliant bladder.
Medications to manage neurogenic bladder
Pharmacotherapy is rarely indicated for voiding dysfunction in TBI. Medications, however, have been used occasionally to treat the effects of neurogenic bladder in the TBI population. These include anticholinergic agents, alpha blockers, antispasmodics, tricyclic antidepressants, and rarely cholinergic agents.
Anticholinergic agents
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Hyoscyamine, oxybutynin, tolterodine, darifenacin, solifenacin, trospium
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Used in the treatment of hyperreflexic bladder or urge incontinence by inhibiting involuntary bladder contractions
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Muscarinic cholinergic receptor antagonists that prevent uninhibited bladder contractions
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Potential adverse effects:
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Dry mouth
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Blurred vision
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Palpitations
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Drowsiness
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Constipation
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Dry Eyes
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Dizziness
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Cognitive Changes (confusion)
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Urinary retention
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Caution in TBI patients given potential negative effect on cognition
Alpha-1 blockers
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Tamsulosin, terazosin, doxazosin, prazosin
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Used for smooth muscle inhibition at the bladder neck and in the prostate
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Help open the bladder neck, especially with the reflex voiding management method
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Potential adverse effects:
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Orthostatic hypotension
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Dizziness, rhinitis
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Retrograde ejaculation
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Tricyclic antidepressants
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Amitriptyline, imipramine
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Inhibit reuptake of norepinephrine and serotonin at presynaptic neurons; have both peripheral alpha-adrenergic and central anticholinergic properties, enabling urine storage by reducing bladder contractility and increasing outlet resistance
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In some cases have been used in the treatment of hyperreflexic bladder with incontinence and may have multiple benefits when used in patients with depression or chronic neuropathic pain
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Potential adverse effects:
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Dry mouth
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Excessive drowsiness
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Constipation
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Blurred vision
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Tachycardia
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Urinary retention
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Antispasmodic agents
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Baclofen, diazepam, botulinum toxin
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Used for bladder spasticity with DSD
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Potentially relax both the urinary bladder, by exerting a direct spasmolytic action on the smooth muscle of the bladder, and the striated external sphincter
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Reported to increase bladder capacity and decrease urge incontinence
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Potential adverse effects:
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Sedation
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Muscle weakness
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Confusion
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Caution in TBI patients given sedation and potential negative effect on cognition
Cholinergic agents
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Bethanechol
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Used in the treatment of areflexic or underactive bladder
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Typically, limited role in TBI patient given that the most common voiding dysfunction in this population is bladder hyperactivity
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Muscarinic cholinergic receptor agonists that stimulate the bladder to empty
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Potential adverse effects:
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Dizziness/lightheadedness
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Diarrhea
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Bradycardia
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Increased salivation
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Sweating
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Watery eyes
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They should not be used in patients with bladder outlet obstruction, including enlarged prostate or DSD, as it may lead to elevated intravesical pressure.
Medical complications of neurogenic bladder
The treatment and prevention of medical complications are essential in the management of neurogenic bladder. Urological complications include skin irritation and breakdown, UTI, urinary stone disease, vesicoureteral reflux, renal failure, bladder cancer, and urethral strictures and trauma.
Skin irritation and breakdown
There is an elevated risk with incontinence and/or with use of condom catheter:
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Must monitor skin integrity closely and frequently
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Meticulous perineal care
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Protective skin agents and interventions should be used.
Urinary tract infections
A neurogenic bladder with incomplete bladder emptying can lead to increased frequency of UTIs and hydronephrosis.
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A UTI can lead to confusion, agitation, and increased neurological symptoms.
Symptoms
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Urinary retention
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Urinary incontinence
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Urinary frequency/urgency
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Burning with urination
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Suprapubic tenderness
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Cloudy or foul-smelling urine
Testing
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Urinalysis with culture and sensitivities
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Complete blood count, basic metabolic panel, hepatic profile
Treatment
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Antibiotics (intravenous or oral)
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Supportive measures
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Hydration
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Analgesia for pain (phenazopyridine)
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Measure postvoid residuals to ensure adequate emptying
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Catheterization for urinary retention
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Vesicoureteral reflux and renal failure
Vesicoureteral reflux may result from high detrusor pressures, which are typically related to severe DSD.
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Vesicoureteral reflux can lead to pyelonephritis and renal failure, particularly in the presence of recurrent infections.
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The occurrence of renal failure in patients with neurogenic bladder has substantially decreased because of improvements in bladder management.
Urinary stone disease
Patients with longstanding neurogenic bladder are predisposed to the development of urinary stone disease, especially in the presence of vesicoureteral reflux and recurrent infections.
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Additional risk factors:
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Hypercalcemia
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Associated complete spinal injury
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History of prior stones
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Sepsis
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Advanced age
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Use of indwelling catheter(s)
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Struvite stones and calcium oxalate stones account for 90% of calculi in patients with neurogenic bladder.
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The incidence of kidney stone formation is highest in patients with indwelling catheters.
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Bladder stones are significantly associated with indwelling catheters: 2.3% of intermittent catheter users had bladder stones in the first month, whereas 8.8% of indwelling catheter users developed bladder stones in their first month.
Cancer
Bladder cancer is associated with chronic indwelling catheters. The risk of bladder cancer has been related to the duration of chronic indwelling catheter use and attributed to chronic irritation of the bladder wall and infection of the bladder leading to dysplastic change and squamous metaplasia. ,
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Squamous cell carcinoma is the most common type of bladder cancer seen in this population. It is aggressive and is often metastatic at diagnosis with an associated poor prognosis.
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Screening
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Cystoscopy is recommended after 5 to 10 years of indwelling catheter use, then every other year.
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Review questions
- 1.
Which of these statements is true regarding neurogenic bladder in a patient with traumatic brain injury (TBI)?
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It most commonly presents as urinary retention in the brain-injured patient.
- b.
It will often involve detrusor hyporeflexia because of an uninhibited and intact reflex pathway.
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Voiding dysfunction is characterized by varying degrees of urge incontinence.
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It is often best treated with an indwelling Foley catheter.
- a.
- 2.
A 46-year-old man with TBI recently had his Foley catheter removed before transferring to the inpatient rehabilitation unit. He has started to void spontaneously but also has intermittent episodes of recorded urinary incontinence throughout the day. What is the most appropriate initial assessment of his urinary incontinence?
- a.
Perform urodynamic testing to assess bladder pressures.
- b.
Order blood urea nitrogen and serum creatinine to assess kidney function.
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Order urinalysis and urine culture to assess for infection.
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Measure postvoid residuals to verify adequate bladder emptying.
- a.
- 3.
A 25-year-old woman with severe TBI has been having frequent episodes of urinary incontinence throughout the day. Her recorded postvoid residuals have been less than 100 cc. These episodes, however, have caused disruptions in her inpatient rehabilitation therapy sessions. What is the best initial bladder management program for this patient?
- a.
Start a clean intermittent catherization program every 6 hours.
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Start a timed voiding schedule with nursing every 3 to 4 hours.
- c.
Place an indwelling Foley catheter.
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Start patient on an antispasmodic medication
- a.
Answers on page 391.
Access the full list of questions and answers online.
Available on ExpertConsult.com
- 4.
A 35-year-old man with history of TBI presents to your outpatient clinic. He was recently discharged from an outside hospital 10 days ago. At the time of discharge, he was voiding spontaneously with normal postvoid residuals. He reports that since returning home, he has had increased difficulty urinating, and his wife has started catheterizing him four times a day because of urinary retention. In reviewing his discharge medication list, which medication is likely to be the cause of his recent development of urinary retention?
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Tamsulosin
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Bethanechol
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Amitriptyline
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Melatonin
- a.
- 5.
A 56-year-old woman with TBI and spinal cord injury has been hospitalized for the past 10 weeks in the acute care hospital. The primary team removed her indwelling catheter 5 weeks ago. She has urinary retention and demonstrates overflow incontinence. She has had multiple urinary tract infections over the past several weeks and has recently developed pyelonephritis and acute renal failure. What underlying urological complication is likely the cause of her medical problems?
- a.
Vesicoureteral reflux
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Bladder cancer
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Urethral trauma
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Kidney stone
- a.
References
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