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Adult Urology

omparative Analysis of Effectiveness ofwo Local Anesthetic Techniques in Menndergoing No-Scalpel Vasectomy

ichael A. White and Thomas J. Maatman

BJECTIVES To compare the effectiveness of two local anesthetic techniques in men undergoing no-scalpelvasectomy.

ETHODS Before undergoing no-scalpel vasectomy, 50 men underwent separate forms of anesthesia to eachside of their scrotum. One vas deferens was anesthetized with a high-pressure spray of 0.3 mL 2%lidocaine using the MadaJet Medical Injector, and the other vas deferens was anesthetized usingthe traditional vasal block performed with three 1.7-mL ampules of mepivacaine using a 27-gaugeneedle. The pain of the initial delivery of anesthesia and the pain with the subsequent vasectomywere recorded.

ESULTS Fifty men underwent no-scalpel vasectomy with a different anesthetic delivery system to each vasdeferens separately. A statistically significant reduction was noted in the visual analog pain scoresin favor of no-needle administration of anesthesia, 1.56 of 10 versus 2.12 of 10 (P �0.029). Areduction was noted in the visual analog pain score for the subsequent vasectomy after admin-istration of anesthesia using the no-needle method, but this was not statistically significant (1.68of 10 versus 1.86 of 10; P �0.66).

ONCLUSIONS No-needle anesthesia with jet injection reduced the pain associated with traditional delivery ofanesthesia to the skin and vas deferens before no-scalpel vasectomy. Additional studies areneeded with more subjects to evaluate whether the decrease in procedural pain is statisticallysignificant when comparing the two types of anesthetics. UROLOGY 70: 1187–1189, 2007. © 2007

Elsevier Inc.

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asectomy is the most common urologic proce-dure and is performed on more than 500,000men annually in the United States. Nearly 7% of

ll married couples use vasectomy as their sole form ofontraception, because it is cost-effective, safe, and theost reliable form of contraception in men.1 Since the

ntroduction of the no-scalpel vasectomy technique in974, and the popularization of the procedure in thenited States in 1991, millions of men have undergoneo-scalpel vasectomy, and it has become the technique ofhoice for surgeons in North America.2,3

Compared with conventional scalpel vasectomy, theo-scalpel technique reduces the incision size, procedureime, pain, bleeding, and postoperative complications.3

raditionally, men present to the office, and after pro-iding informed consent, the scrotum is prepared andraped, the scrotal skin and vas deferens are anesthetizedsing needle injection of an anesthetic of choice, and

. J Maatman is a speaker for Sanofi-Aventis U.S., Glaxo Smith Kline, Astellasharma, Incorporated.From the Michigan State University College of Osteopathic Medicine Urologic

onsortium; and Michigan Urologic Clinic, Grand Rapids, MichiganReprint requests: Thomas J. Maatman, D.O., Michigan Urological Clinic, 4047

ialadin Drive, Southeast, Grand Rapids, MI 49546. E-mail: maatmant@aol.comSubmitted: March 24, 2007; accepted (with revisions): July 18, 2007

2007 Elsevier Inc.ll Rights Reserved

ilateral vasectomy is performed. Recently, the introduc-ion of the no-needle no-scalpel vasectomy has furtherncreased the appeal of this minimally invasive contra-eption method.4 The technique uses a device that in-ects an aerosolized local anesthetic into the skin, subcu-aneous tissue, and vas deferens without the need for aypodermic needle. By eliminating the use of a needle,nxiety regarding the procedure might be reduced.

To date, no studies have compared jet injection anes-hesia with needle delivery for no-scalpel vasectomy. Wentroduced a method that allowed us to compare theraditional vasal block needle anesthesia versus the no-eedle jet injection using the Madajet system as annesthetic technique for no-scalpel vasectomy in theame patient. We hypothesized that the no-needle tech-ique would result in reduced pain scores for the initial

njection and the subsequent vasectomy compared withhe traditional vasal block as practiced by a single expe-ienced urologist.

ATERIAL AND METHODS

n accordance with the principles of practice, approval by the

nstitutional review board was obtained. Fifty consecutive men

0090-4295/07/$32.00 1187doi:10.1016/j.urology.2007.07.054

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age range 26 to 45 years) scheduled to undergo no-scalpelasectomy voluntarily entered the study protocol after grantingnformed consent and agreed to answer a postvasectomy painuestionnaire (Fig. 1). The inclusion criterion was the desire forlective sterilization after mutual agreement by the patient andis partner. The exclusion criterion was previous scrotal sur-ery. The patients were prepared and draped in the usual sterileashion. One vas deferens was anesthetized with the MadajetXLodified jet no-needle injection technique using 0.3 mL of 2%

idocaine with 1:1,000,000 epinephrine, as recommended byhe manufacturer. The other vas deferens was anesthetized withhree 1.7-mL ampules of mepivacaine using a 27-gauge needle.ilateral no-scalpel vasectomy was performed in the standardanner by one experienced, board-certified urologist (T.J.M.).fter completion of the procedure, the patient was asked to

omplete a visual analog scale questionnaire. The level of painf the injection and the subsequent procedural pain accordingo the visual analog pain scale were documented for eachechnique.

The sites of injection were randomly assigned to each pa-ient, side A or side B. The patients were not told the form ofnesthetic delivered. The urologist then randomly performedhe procedure beginning with either the needle or the jetnjector. Only the urologist knew the type of anesthetic used.he patient then rated the pain associated with the injectionnd procedure. The other investigator (M.A.W.), not the va-ectomy performing urologist (T.J.M.), analyzed the data andas unaware of the type and order in which the anesthetic hadeen delivered. Neither investigator had financial interests inhe device.

tatistical Analysissing nQuery before initiation of the study, it was determined

hat 50 patients would have to be enrolled to detect a changen the pain score of 0.5 at a standard deviation of 1.2, signifi-ance level of 5%, and power of 80%. The effect was chosenecause any smaller effect would be neither clinically nor sub-tantively significant, and because the magnitude of effect wasonsidered reasonable to expect in the field of pain research.he endpoints of the pain scores were analyzed using theonparametric Wilcoxon signed ranks test. The data were an-lyzed with Statistical Package for Social Sciences (SPSS, Chi-ago, Ill) statistical software.

ESULTShe average visual analog scale pain score for the jet

Figure 1. Visual analog scale.

njection was 1.56 of 10 (range 0 to 5) and was 2.12 s

188

range 0 to 6) for the needle injection (Fig. 2). Theatients had a statistically significant less amount of painith the jet injection (P � 0.029). The average visualnalog scale pain score for vasectomy after the jet injec-ion was 1.68 of 10 (range 0 to 7) compared 1.86 (rangeto 9) after the needle injection (Fig. 3). The difference

n pain scores was not statistically significant (P � 0.66).one of the 50 patients required any additional anesthe-

ia after the no-needle jet injection anesthetic or theraditional needle anesthetic was administered.

OMMENTasectomy is the most commonly performed urologic

urgery. Advances in this procedure have undergone sev-ral changes over the years. The most significant im-rovement has been the introduction of the no-scalpelechnique. This has resulted in decreased operative pain,rocedure time, and complication rates. In some coun-ries, it has reversed the male/female ratio in elective

Figure 2. Visual analog scale for injection pain.

Figure 3. Visual analog scale for vasectomy pain.

terilization from 1:3 to 3:1.5 This type of sterilization

UROLOGY 70 (6), 2007

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eversal has yet to be demonstrated in the United States,nd some have theorized that this is secondary to the fearf the procedure and the discomfort associated with it.

In 2001, Wilson6 introduced the no-needle anesthesiaechnique to the field of urology. Previously, dentists,odiatrists, and other medical specialists had used thisechnique successfully.7,8 Although they had achievedmproved subjective results, it was not until Weiss andi4 demonstrated objective success that this techniqueegan to achieve more widespread popularity. The feasi-ility of this method was tested, with resultant low paincores. Yet, no studies have been done to date thatompared the traditional vasal block and the no-needlenesthetic approach. We compared the no-needle anes-hetic technique and the traditional hypodermic needleasal block performed by a single experienced urologist.Weiss and Li4 demonstrated an average no-needle an-

sthesia pain score of 1.71 of 10 and an average visualnalog scale score for pain of the subsequent vasectomyuring the surgical procedure of 0.66 of 10. These resultsre similar to those of the present study for the injectionain scores, with an average no-needle anesthesia paincore of 1.56 of 10. However, our results differed whenomparing the average visual analog scale score for theain experienced during the subsequent vasectomy. Theresent study demonstrated a score of 1.68 and the pre-ious study demonstrated a score of 0.66. We believe theower pain scores demonstrated in the previous studyould have been the result of crossover anesthesia fromhe MadaJet delivery, which disperses the anesthetic inn inverted cone pattern, thereby possibly allowing ad-itional tissue to be anesthetized on the contralateralargeted side.

When comparing the no-needle anesthesia pain scoreith the traditional hypodermic needle vasal block pain

core, the values were less (1.56 for the former and 2.12or the latter; P � 0.029). When comparing the averageisual analog scale score for pain of the subsequent va-ectomy during the procedure, no-needle versus the tra-itional vasal block, the values were also less, but not asuch, 1.68 for the former and 1.86 for the latter (P �

.66).One possible reason for this effect could have been the

se of two separate anesthetics, yet we believe this isnlikely. The onset of action of mepivacaine and lido-aine are rapid, with slightly differing durations of effect.idocaine has a duration of 30 to 60 minutes and mepi-acaine, a duration of 60 to 90 minutes.9,10 In addition,he perceived pain from the vasectomy itself should notave been affected by the use of mepivacaine instead of

idocaine, because that side was always performed afterhe no-needle side of the vasectomy was completed,hereby allowing adequate time for the anesthetic to take

ffect.

ROLOGY 70 (6), 2007

The limitations of this study included the above-men-ioned use of two separate anesthetics. Ideally, we wouldave used the same anesthetic, but we believe this wasot a concern because we were comparing a new tech-ique, as it had previously been studied, with the tradi-ional approach, which had successfully been used by aingle urologist who had been in practice for longer than0 years. Additionally, we believe the use of the twoeparate anesthetics would not have affected the out-omes, because they are both fast acting and the differ-nces in their pharmacokinetics lie in their duration ofction and not in their onset.9,10

Another limitation of this study was the inability toraw a significant conclusion between the pain scoresecorded during the vasectomy. This resulted from theow power of this arm of the study. Initially, the study wasowered to 80% with 50 patients but after the calculatedtandard deviation was well above what had been esti-ated, the power was reduced significantly. Future stud-

es with additional patients would be necessary to draweaningful conclusions.

ONCLUSIONSasectomy is the most common urologic surgery and will

ikely continue a similar trend in the future. No-needlenesthesia with jet injection reduces the pain associatedith the traditional delivery of anesthesia to the skin andas deferens before no-scalpel vasectomy. Additional stud-es are needed with more subjects to evaluate whether theecrease in procedural pain is statistically significanthen comparing the two types of anesthetics.

eferences1. Barone MA, Hutchinson PL, Johnson CH, et al: Vasectomy in the

United States, 2002. J Urol 176: 232–236, 2006.2. Nirapathpongporn A, Huber D, and Krieger JN: No-scalpel vasec-

tomy at the King’s birthday vasectomy festival. Lancet 335: 894–895, 1990.

3. Li SQ, Goldstein M, Zhu J, et al: The no-scalpel vasectomy. J Urol145: 341–344, 1991.

4. Weiss RS, and Li PS: No-needle jet anesthetic technique forno-scalpel vasectomy. J Urol 173: 1677–1680, 2005.

5. Liu X, and Li S: Vasal sterilization in China. Contraception 48:255–265, 1993.

6. Wilson CL: No-needle anesthetic for no-scalpel vasectomy. AmFam Physician 63: 1295, 2001.

7. Munshi AK, Hedge A, and Bashir N: Clinical evaluation of theefficacy of anesthesia and patient preference using the needle-lessjet syringe in pediatric dental practice. J Clin Pediatr Dent 25:131–134, 2001.

8. Dialynas M, Hollingsworth SJ, Cooper D, et al: Use of a needlelessinjection system for digital ring block anesthesia. J Am Podiatr MedAssoc 93: 23–26, 2003.

9. Covino BG: Local anesthesia 2. N Engl J Med 286: 1035–1042,1972.

0. Crystal CS, and Blankenship RB: Local anesthetics and peripheralnerve blocks in the emergency department. Emerg Med Clin North

Am 23: 477–502, 2005.

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