Urodynamic Testing Case File

Urodynamic Testing Case File

Eugene C. Toy, MD, Konrad P. Harms, MD, Keith O. Reeves, MD, Cristo Papasakelariou, MD, FACOG

Case 37

A 56-year-old G3P3 postmenopausal woman presents to your office with complaints of urinary incontinence for the last 6 months. She reports leakage of large amounts of urine (saturating sanitary pads) after coughing, laughing, or sneezing. She denies dysuria, frequency, or hesitancy. At times, she does have urge symptoms and nocturia. She has no known medical history and is not taking any medications. She denies loss of stool. Her previous primary care physician instructed her on Kegel exercises which she performs daily.

Her physical examination is within normal limits. Specifically, her pelvic examination revealed a parous cervical os and a mobile 7-week-size uterus with no adnexal masses. No cystocele or rectocele is appreciated. Upon Valsalva maneuver, there was no evidence of loss of urine or evidence of urethral hypermobility. Urine culture performed was negative for organisms. Her fasting blood sugar is 97 mg/dL.

➤ What is the most likely diagnosis?

➤ What would be your next management step?

ANSWERS TO CASE 37:

Urodynamic Testing

Summary: This is a 56-year-old G3P3 woman with urinary incontinence of large volumes of urine with Valsalva, nocturia, and some urgency. Her physical examination demonstrates no evidence of urinary incontinence or pelvic floor relaxation.

➤ Most likely diagnosis: This patient’s presentation is most consistent with

mixed stress and urge incontinence.

➤ Next management step: Postvoid residual (PVR), voiding diary, and urodynamic testing.

ANALYSIS

Objectives

1. List the indications for urodynamic testing.
2. Be able to interpret some basic urodynamic studies.
3. Describe the steps of basic office urodynamics.
4. Understand how to use urodynamic results to guide management of the patient.

Considerations

The patient presented in this case has an initial complaint that appears to be most consistent with stress incontinence (loss of urine with Valsalva). However, upon further questioning, other factors are evident. The patient reports losing large amounts of urine with each episode, nocturia, and urge symptoms all found with urge incontinence. In addition, her physical examination did not support the diagnosis of stress incontinence. This patient would benefit from a voiding diary to adequately assess fluid intake/output and determine precise timing of incontinence. After the diary is obtained, urodynamic studies should be performed due to her urge symptoms and normal physical examination. Other indications for urodynamic studies include failed previous treatment (either with medication or surgery), suspected neurogenic component, or suspected voiding disorders. After urodynamic studies are performed, the appropriate management plan can then be made.

APPROACH TO

Urodynamics

DEFINITIONS

URODYNAMIC STUDIES: Study of the bladder and its pressure-volume relationship.

URODYNAMIC STRESS INCONTINENCE: Involuntary stress incontinence when intravesical pressure exceeds the maximum urethral pressure in absence of detrusor activity.

STRESS URINARY INCONTINENCE: The symptom of involuntary urinary leakage on exertion or effort.

URETHRAL PRESSURE PROFILE: Intraluminal pressure within the urethra while bladder is not active.

URGE URINARY INCONTINENCE: The involuntary loss of urine associated with urgency.

CLINICAL APPROACH

Urodynamics is essentially the study of the bladder and its pressure-volume relationship. Urodynamic studies allow for a better understanding of lower urinary tract disorders and help to guide management plans. Quite often, simple office urodynamic studies can be performed and provide useful information. Sometimes, complex multichannel devices are required. Prior to any urodynamic study, a urine culture should be obtained.

Office Urodynamics

Office urodynamic studies are sometimes referred to as eye cystometry (Figure 37–1). Below is an outline of the steps used in office urodynamics:

1. The patient is instructed to void completely, and then the bladder is catheterized, and a postvoid residual (PVR) is then calculated. The PVR is considered normal if less than 50 cc and abnormal if greater than 200 cc. Measurements between 50 and 200 cc require clinical correlation.

2. Approximately 400 to 500 cc of sterile saline (room or body temperature) is slowly infused into the bladder using a 60-cc Foley tip syringe. The patient is either in standing or semierect position for the examination.

Figure 37–1. Simple cystometry using a water manometer.

3. The syringe is held 10 to 15 cm above the pubic symphysis and closely observed as the bladder is being filled in 60-cc increments. This is continued until the patient is uncomfortable and no longer able to tolerate and the number recorded as the bladder capacity. The normal bladder capacity is at least 350 to 400 cc.

4. If the meniscus in the syringe rises while filling, a detrusor contraction is suspected.

Multichannel Urodynamic Studies

Complex multichannel urodynamic studies measure the pressure within the bladder and intra-abdominal cavity during filling. Because a rise in bladder pressure can be the result of either a bladder contraction or abdominal pressure, complex urodynamic studies allow for the abdominal pressure to be substracted from the bladder pressure, resulting in an indirect determination of the true detrusor pressure. As with office urodynamics, the patient is asked to void and a PVR is obtained. The patient is placed in semierect position and room/body temperature fluid (saline or sterile water) is then instilled at a constant rate. While the bladder is filling, pressure catheters located in the bladder and rectum/ or vagina (for abdominal pressure) record the pressure in centimeter H2O. As the bladder is filling, the patient is asked to perform Valsalva maneuvers to possibly evoke incontinence. The presence of incontinence with the Valsalva confirms either stress continence or intrinsic sphincter deficiency and a leak point pressure can be determined. As the patient coughs or strains, the pressure is transmitted to both the abdominal and bladder pressure catheters, resulting in a net zero detrusor pressure change. However, if the patient has a rise in bladder pressure without an increase in abdominal pressure, the net effect would be an increase in detrusor pressure consistent with a detrusor contraction. During the filling stage, bladder sensation can be assessed along with determination of bladder capacity.

After the bladder has reached its capacity, urethra function can be assessed with a passive urethral pressure profile. The urethral catheter is withdrawn from the bladder at a fixed rate. As the catheter passes through the urethra and its sphincter, an increase in pressure is transmitted to the catheter. Urethral pressure rises to a maximum urethral closure pressure and then returns to zero after catheter leaves the urethra (Figure 37–2).

Office or multichannel urodynamic studies allow the clinician to have a better understanding of bladder function and to develop the optimal management plan. Patients who have a large PVR or decreased bladder sensation often have a neurogenic problem, resulting in their incontinence. Patients with neurogenic bladder problems are best treated with intermittent selfcatheterization and referred to urologic specialist. Increased detrusor activity during filling is consistent with urge incontinence and can be managed with numerous medication or even behavioral/biofeedback techniques. Patients who have a loss of urine with Valsalva or cough may have either simple stress incontinence or possibly intrinsic sphincter dysfunction. The finding of an abnormal urethral pressure profile or low leak point pressure implies an intrinsic sphincter problem best managed by a suburethral sling, periurethral bulking agent, or artificial sphincter. When stress incontinence is confirmed, surgery (suburethral sling or urethropexy) is often needed.

Figure 37–2. Urethral pressure profile.

Comprehension Questions

37.1 Which of the following conditions is most likely to be associated with a low leak point pressure?

A. Bladder hyperreflexia

B. Detrusor instability

C. Intrinsic urethral sphincter dysfunction

D. Stress incontinence

37.2 A 35-year-old woman is noted to have possible urinary retention. Which of the following is a normal postvoid residual?

A. < 25 cc.

B. < 50 cc.

C. < 100 cc.

D. Absolute normal values for PVR have not been established.

37.3 A 39-year-old woman is noted to have bladder hypersensitivity and reduced bladder capacity. Which of the following is the most likely diagnosis?

A. Interstitial cystitis

B. Stress urinary incontinence

C. Neurogenic bladder

D. Diabetes mellitus

ANSWERS

37.1 C. The leak point pressure is defined as the pressure that is required to overcome urethral resistance and result in incontinence. Patients with urethral sphincter deficiency have low leak point pressure measurement due to the lack of resistance that the sphincter provides against the bladder pressure. Stress incontinence may occur at low leak point pressures but not routinely as low as intrinsic urethral sphincter deficiency.

37.2 D. No absolute value has been established for a normal PVR. However, values greater than 200 mL can be considered abnormal.

37.3 A. Incontinent patients who have a history of spinal cord injury often suffer from overflow incontinence. Interstitial cystitis, cystitis, and detrusor instability all have bladder hyperactivity with reduced bladder capacity.

Clinical Pearls

See Table 1-2 for definition of level of evidence and strength of recommendation

➤ Indications for urodynamic studies include (Level C).

➤ Mixed symptomatology

➤ Suspected voiding disorder

➤ Previous unsuccessful incontinence surgery

➤ Neurogenic bladder disorders

➤ Clinical examination not consistent with history

➤ Patients in whom conservative measures have failed

➤ Patients with abnormal urethral pressure profiles or low leak point pressures should be referred to a urologist and treated with either a suburethral sling, periurethral bulking agent, or artificial sphincter (Level C).

➤ No absolute value has been established for a normal postvoid residual (Level C).

➤ Urodynamic studies are generally reliable among different observers (especially in presence of stress urinary incontinence) (Level A).

REFERENCES

1. Abrams P. Urodynamic techniques. In: Abrams P. ed. Urodynamics 3rd ed. Bristol, UK: Springer; 2006:39-46, 99-109. 

2. Cardozo L, Staskin D. Cystometry. In: Cardozo L and Staskin D. eds. Textbook of Female Urology and Urogynaecology. London, UK: Isis Medical Media Ltd; 2001: 198-204. 

3. Cardozo L, Staskin D. Urethral pressure measurements. In: Textbook of Female Urology and Urogynaecology. 2001:216-224. 

4. Diokno AC, Wells TJ, Brink CA. Urinary incontinence in elderly women: urodynamic evaluation. J Am Geriatr Soc. 1987;35:940-946. 

5. Fritel X, Fauconnier A, Pigné A. Circumstances of leakage related to low urethral closure pressure. J Urol. 2008;180:223-236. 

6. Haylen BT, Lee J, Logan V, Husselbee S, Zhou J, Law M. Immediate postvoid residual volumes in women with symptoms of pelvic floor dysfunction. Obstet Gynecol. 2008;111:1305-1312. 

7. Katz VL, Lentz GM, Lobo RA, Gershenson DM. Urogynecology. In: Comprehensive Gynecology. 5th ed. Philadelphia, PA: Mosby; 2007:537-565. 

8. Swift SE, Ostegard DR. Evaluation of current urodynamic testing methods in the diagnosis of genuine stress incontinence. Obstet Gynecol. 1995;86:85-91. 

9. Theofrastous JP, Swift SE. Urodynamic Testing. In: Ostergard’s Urogynecology and Pelvic Floor Dysfunction. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:115-139. 

10. Wall LL, Wiskind AK, Taylor PA. Simple bladder filling with a cough stress test compared with subtracted cystometry for the diagnosis of urinary incontinence. Am J Obstet Gynecol. 1994;171:1472-1477. 

11. Weber AM. Is urethral pressure profilometry a useful diagnostic test for stress urinary incontinence? Obstet Gynecol Surv. 2001;56:720-735. 

12. Weber AM. Leak point pressure measurement and stress urinary incontinence. Curr Womens Health Rep. 2001;1:45-52. 

13. Weir J, Jacques PF. Large-capacity bladder. A urodynamic survey. Urology. 1974;4:544-548. 14. Whiteside JL, Hijaz A, Imrey PB, et al. Reliability and agreement of urodynamics interpretations in a female pelvic medicine center. Obstet Gynecol. 2006;108:315-323.

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