Is instillation of anesthetic gel necessary in flexible cystoscopic examination? A prospective randomized study

Material and methods 

Male patients undergoing flexible cystoscopy were eligible for entry in the study. Patients were excluded if they had had an episode of hypersensitivity to amide-linked anesthetic agents or a sensory disorder such as spinal cord injury or were using regular analgesics or sedatives. A total of 133 consecutive men were recruited and randomized to receive 11 mL of 0.2% oxybuprocaine hydrochloride gel (group 1), 11 mL of plain lubrication gel (group 2), or no gel (group 3). The gel temperature was maintained at 4°C using a standard drug refrigerator. In groups 1 and 2, a urologist who was unaware of the content of the gel instilled the gel gently, and a penile clamp was placed for 15 minutes. In all groups, patients were placed in the dorsal-lithotomy position, the penis was prepared with povidone-iodine solution, and 2.0% lidocaine gel was applied to the fiberscope before insertion. Three urologic surgeons (T.K., K.N., and K.O.) performed the cystoscopies. During cystoscopic examination, the surgeon informed the patient of what step of the procedure was currently being performed, including gel instillation, scope insertion, and intravesical examination. Immediately after cystoscopic examination, the patients recorded their discomfort during gel instillation, scope insertion, and intravesical examination using a 100-mm (0, no pain; 100, worst possible pain) visual analog scale. All patients were informed about the procedure, and the Helsinki Declaration was followed throughout the study. The groups were compared statistically using the unpaired t test, chi-square test, and analysis of variance. All tests were two-tailed, with statistical significance assumed at P <0.05.

Results 

All patients enrolled in the study completed the visual analog scale sheet. The indications for cystoscopy included bladder cancer surveillance in 86 patients, hematuria in 13, upper tract urothelial cancer surveillance in 12, ureteral stent removal in 10, evaluation of urethral stricture in 8, and other in 4. All groups were well-matched for age, number of previous flexible cystoscopic examinations, and surgeons who performed the cystoscopic procedure (TABLE I, TABLE II). Figure 1 shows the pain score reported by the visual analog scale for each surgeon, indicating no significant differences in the patients’ estimation of pain in each step among the surgeons as determined by analysis of variance. However, the pain for scope insertion by a seasoned urologist (K.O.) was significantly lower than that by the less-experienced urologists (P = 0.02 in both, unpaired t test). The correlation in the degree of discomfort or tolerance between individuals who had undergone larger numbers of prior examinations and those who had undergone fewer was not high (Fig. 2).

TABLE I. Patient characteristics

	Characteristic	Group 1 (Anesthetic Gel)	Group 2 (Plain Gel)	Group 3 (No Gel)	P Value
	Mean age (yr)	66.8 ± 11.5	67.8 ± 11.1	67.4 ± 12.1	0.100
	Previous flexible cystoscopy (times)	4.17 ± 4.9	3.82 ± 5.1	3.12 ± 3.5	0.697

No statistically significant difference was found in age and previous experience of cystoscopy between each group (analysis of variance).

TABLE II. Patient distribution to surgeons and groups

	Surgeon	Group 1 (Anesthetic Gel)	Group 2 (Plain Gel)	Group 3 (No Gel)
	1 (T.K.)	23	21	16
	2 (K.N.)	2	2	6
	3 (K.O.)	21	21	21

No statistically significant association was found between each group and the urologist who performed cystoscopy (P = 0.348, chi-square test).

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FIGURE 1. Pain scores on visual analog scale (VAS) for each step with patients stratified by surgeons who performed cystoscopy. Bars and numbers represent standard deviations and mean values, respectively. No significant difference was found among the surgeons in pain score for any step of cystoscopy (analysis of variance).

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FIGURE 2. Correlation between pain score for each step of cystoscopy and number of previous cystoscopies. No highly significant correlation was found. VAS = visual analog scale; r2 = correlation coefficient.

The mean ± standard deviation pain score for gel instillation was 22.0 ± 22.0 mm and 27.0 ± 21.5 mm in groups 1 and 2, respectively (P = 0.33, Fig. 3). The pain score for scope insertion was 31.6 ± 26.8, 38.1 ± 26.1, and 30.3 ± 26.8 mm in groups 1, 2, and 3, respectively (Fig. 3). No significant difference was found in the patient estimation of pain during scope insertion among the groups. The pain score for intravesical observation was 22.7 ± 25.9, 33.7 ± 25.4, and 20.3 ± 22.4 mm in groups 1, 2, and 3, respectively (Fig. 3). The patient estimation of pain during intravesical observation among the groups was not significantly different.

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FIGURE 3. Mean pain score (number at top of each column) for each step of cystoscopy. Anesthetic gel, plain lubricating gel, or no gel was instilled before cystoscopy in groups 1, 2 and 3, respectively. Asterisk indicates unpaired t-test; dagger, analysis of variance. VAS = visual analog scale.

No patients needed additional anesthetic agents or sedatives for insufficient pain relief. No adverse reactions occurred in any of the patients.

Comment 

The use of the fiberscope for male patients is generally superior to that of conventional rigid cystoscopy regarding invasiveness. Various studies on the necessity of local anesthesia in men undergoing cystoscopy have been performed, and the amount, exposure time, and temperature of the anesthetic gel have been well discussed in previous reports. The amount of gel that should be instilled is controversial. In this regard, the present study may be open to the criticism that the amount of instilled gel was not sufficient.2, 11 However, one study reported no difference in pain reduction between the use of 20 and 10 mL of anesthetic gel.10 In the present study, we thought that a larger amount of instilled gel might result in greater pain being felt during gel instillation. Therefore, the amount of gel in the present study was set at 11 mL. How long the gel is retained in the urethra also appears to affect the degree of pain relief. To our knowledge, no study has reported that a 15-minute application was insufficient.7, 9 Thompson et al.12 demonstrated that cooling (to 4°C) the anesthetic gel significantly reduced the discomfort associated with its instillation compared with gel at 22°C and 40°C. On the basis of these reports, we set the application time and temperature of the intraurethral gel at 15 minutes and 4°C, respectively.

The surgeons’ experience also appeared to affect the degree of pain felt during cystoscopy, as did the patient’s previous experience with cystoscopy. Pain during scope insertion by a seasoned urologist might be significantly lower than that with less-experienced urologists. Although it might be a result of a shorter time of cystoscopy by a seasoned urologist, the time of each procedure was not measured in the present study. Some reports have demonstrated significant negative correlations between the degree of pain and the patients’ previous experiences with cystoscopy, as well as with patient age,3, 9 although a high correlation was not found in the present study. There may exist a skill required for pain reduction, particularly in scope insertion, and patients may be desensitized by repeated experience or aging. We believe that these factors did not affect the results of this study, because all groups were well matched for the surgeons who performed cystoscopy, history of cystoscopy, and age.

No prospective randomized study has been done to determine whether intraurethral gel instillation is necessary for pain relief in flexible cystoscopy. In the present study, there was no difference in the pain felt during either scope insertion or intravesical observation between group 1 (anesthetic gel) and group 3 (no gel). A lack of gel-instillation pain and clear vision during scope insertion in the no-gel group might counterbalance the absence of anesthetic effect. In comparison between the two groups, however, neither the patients nor the surgeons were unaware of whether any kind of gel was instilled (group 3 or others), and it is not clear how this affected the results of our study. In the patient groups in which the content of instilled gel was double-blinded (group 1 versus group 2), the pain scores for scope insertion and intravesical observation did not differ. Although anesthetic gel instillation may reduce pain after cystoscopy, pain or dysuria after cystoscopy was not evaluated in this study. At the least, the results of the present study suggest that anesthesia with gel instillation has no advantage for pain relief during cystoscopic procedures. In our opinion, it appears that the impact of intraurethral anesthetic gel on pain relief has become less significant in the era of fine flexible cystoscopy with clear vision, although it actually has some degree of pain-reducing effect.

It has never been determined how intolerable each step of the cystoscopic procedure is for male patients undergoing flexible cystoscopy. In our study, the pain of gel instillation was significant compared with that of scope insertion and intravesical observation, even though the volume and temperature of the instilled gel were designed to be low. In the group undergoing urethral instillation of anesthetic gel (group 1), the mean pain score for gel instillation, scope insertion, and intravesical observation was 22.9, 31.6, and 22.8, respectively. Given that anesthetic gel instillation yields no benefit in pain relief, instillation results in unnecessary pain that is approximately two thirds the intensity of that felt during scope insertion. In considering the necessity of intraurethral instillation, that the gel instillation itself is painful may be as important as its potential toxicity.

The pain threshold may differ individually, and a crossover study will be needed in the future to compare some procedures correctly. These results suggest that gel application to the fiberscope can replace intraurethral gel instillation for outpatient flexible cystoscopy for male patients, just as anesthetic gel is not usually instilled before placement of an indwelling Foley catheter in men.

Conclusions 

Because anesthetic gel instillation itself results in significant pain and has no advantage regarding pain relief compared with no gel injection, it is no longer necessary for outpatient flexible cystoscopy in men when gel is applied to the fiberscope.