A Case Study in Video Urodynamics: A Unique Lesson Learned

Lynn Ng Yun Shu; Wang Fenfen; Ng Lay Guat, MBBS, FRCS, MMED, FAMS


Urol Nurs. 2018;38(1):36-41. 

In This Article

Clinical Interaction

During the VUDS, the 8 Fr feed tube (for filling) and transducer catheters (for measurement of intravesical pressure, called Pves) were inserted into the bladder. A rectal balloon catheter was inserted into the patient's rectum (for measurement of abdominal pressure, called Pabd). After insertion of the catheters, the lines were calibrated. We noted that Pves showed unusual intermittent sharp spikes of raised detrusor pressure.

VUDS started with filling rate of 30 mL per minute. At this point, immediate left-sided grade 2 vesicoureteral reflux was seen (see Figure 1), and an image of reflux into the left kidney was noted (see Figure 2). Figure 3 shows the VUDS screen. Intermittent spikes of raised pressure were noted but were not associated with sensation of urge (see Figure 4). Bladder sensation was within normal range.

Figure 1.

X-Ray Showing Left Reflux During Filling

Figure 2.

X-Ray Showing Reflux into Left Kidney

Figure 3.

VUDS Screen

Figure 4.

Spikes of Raised Pressure

When the patient had sensation of full bladder capacity, filling was stopped and the regular raised spikes stopped (see Figure 5). When filling was restarted, the spikes returned (see Figure 6).

Figure 5.

Spikes Noted during the Filling Phase and the Spike Stopped When Filling Is Stopped

Figure 6.

Comparison of Spikes during the Filling Phase and the Spike Stopped Filling Phase

We suspected the left ureteral orifice (UO) had been inadvertently cannulated. The filling tube and the transducer line were withdrawn intermittently. At that point, normal detrusor tracings appeared (see Figure 7).

Figure 7.

Normal Detrusor Contractions

The patient was unable to void spontaneously while sitting on the fluoroscopy table, but she finally voided on the bedside commode with pelvic floor relaxation. No reflux or PVRU were noted after voiding (see Figure 8). The patient was instructed to stop CISC.

Figure 8.

No Reflux after Voiding

Due to the grade 2 cystocele, the transducer line was inadvertently inserted into the left UO. Regular peristalsis was noted which is common in the ureter, but it is rare to see intermittent spikes of raised pressure in detrusor muscle contractions. Upon closer observation of the fluoroscopic pictures on the Carm monitor, the transducer line was coiled and entered the left UO (see Figure 9). In our setting, the fluoroscopic pictures are superimposed on the UDS tracings and are not as clear as directly from the C-arm monitor, which caused us to miss the line initially.

Figure 9.

Colling of Transducer Line (Taken from the C-Arm Monitor)

Clinical Implications

The opening of the ureter is located at each posterior-lateral angle of the bladder trigone. These openings are generally slit-like in appearance and are approximately 2.5 cm apart in the contracted bladder. These are located about the same distance away from the internal urethral orifice (Lumen Learning, 2016).

However, the location of the UO may change in patients with cystocele, also known as bladder prolapse. In a prolapse, the organ is being "pulled down," causing distortion to the usual anatomy. Thus, in this case, the UO became easily accessible by the very fine transducer line and increased the risk of inadvertent ureteral catheterization.

During the UDS filling phase, a stable bladder will not have detrusor instability contractions. For suspected cases of overactive bladder, detrusor hyperactivity is noted during filling phase, but the contractions are smooth and gradually rise with pressure (see Figure 10). However, in this case, a sharp spike in pressure was seen instead. These phasic spikes in pressure looks like peristalsis instead of detrusor contractions.

Figure 10.

Typical Urodynamic Study with Contractions for Detrusor Overactivity

Smooth muscles in the walls of the ureters send the urine in small spurts into the bladder, in a process called peristalsis. After the urine enters the bladder from the ureters, small folds in the bladder mucosa act like valves to prevent the backward flow of urine (Lumen Learning, 2016).

The urinary bladder has two important functions: storage of urine and emptying. The detrusor smooth muscle is the main muscle component of the urinary bladder wall. Its ability to contract over a large length interval and then relax determines the bladder function during filling and micturition. Storage of urine occurs at low pressure, which implies that the bladder relaxes during the filling phase (Andersson & Amer, 2004). The bladder is, therefore, known as a highly compliant structure (com pliance = change in volume/change in pressure) (Nitti, 2005).

It is important to differentiate detrusor instability contractions from unusual contractions to recognize potential transducer line displacement and avoid inaccurate diagnosis for the patient.