Benzocaine

BACKGROUND. Colposcopic evaluation can cause patients to experience pain and anxiety. This study investigated the use of benzocaine spray, a topical anesthetic, and its effects on pain and anxiety associated with colposcopy and colposcopic biopsy.

METHODS. The study was a double-blind, placebo-controlled trial of the effectiveness of benzocaine spray applied to the cervix immediately before colposcopic examination, cervical biopsy, or endocervical curettage in patients of a family practice center. Prior to the gynecologic procedure the patient's cervix was sprayed with either benzocaine spray or matching placebo spray. After waiting at least 30 seconds the clinician started the procedure. Pain and anxiety, measured on 10-cm visual analog scales, were determined at the following times: (1) before the start of the gynecologic examination; (2) immediately before using the spray; (3) immediately after using the spray; and, (4) after the procedure was completed.

RESULTS. Of 58 consecutive patients who underwent colposcopy, 36 patients were eligible for the trial and were evaluated. Participants were similar to patients not participating with regard to race, gravidity, and parity. Statistical analysis found significant differences in both pain and anxiety scores over time (repeated measures multivariate ANOVA, P [is less than] .0001), but no difference between the use of active drug and placebo. Pain scores increased significantly after application of either benzocaine or placebo spray before the start of the procedure (average increase 1.3 cm, P [is less than] .0001).

CONCLUSIONS. Benzocaine, in a spray vehicle, confers no benefit when used to decrease pain and anxiety in women undergoing colposcopic procedures.

KEY WORDS. Anesthesia, local; colposcopy; benzocaine; cervix uteri. (J Fam Pract 1998; 46: 242-246)

Commonly performed gynecologic procedures can sometimes result in pain and anxiety. Several investigators have tried various methods to decrease pain with the use of a topical analgesic alone or in combination with an oral nonsteroidal anti-inflammatory agent.[1-6] Some of these trials have shown benefit but have been of limited value because of their study design.

A number of topical anesthetics are available to anesthetize mucous membranes. Benzocaine, dyclonine, lidocaine, and tetracaine are available in solution, gel, or spray formulations. Spray formulations with a disposable applicator are simple and easy to apply.

The aim of this study was to compare topical anesthesia using benzocaine 20% topical spray with placebo spray in the prevention of pain and anxiety associated with endocervical curettage and biopsy performed during colposcopic examination in a family practice office.

METHODS

A prospective, double-blind, placebo-controlled trial of topical anesthesia during colposcopy was performed at a teaching site for the Harrisburg Family Practice Residency Program. Consecutive patients scheduled for colposcopic examination were approached to participate in this study. Examinations were performed by either faculty or supervised residents. Patients were excluded if they were younger than 18 years old, pregnant, allergic to benzocaine, non-English speaking, or if they had a history of narcotic substance abuse. Informed consent was obtained from each patient. Patients also were asked to list any medications taken within the past 24 hours.

Patients were randomly assigned to receive either benzocaine 20% topical spray or placebo. To assure blinding, four identical spray bottles were used. Two bottles contained placebo and two bottles contained benzocaine. Patients in the study were allocated in blocks of four, randomly assigned using a random number table to receive treatment with the contents of one of the four bottles.

The patient was prepared for the procedure in the normal manner after the collection of demographic information and the completion of baseline pain and anxiety scales by the study nurse. Following insertion of the speculum, but before the procedure was started, a short (two-second) spray was applied to the cervix using a disposable applicator tube. Examiners waited at least 30 seconds before starting the procedure. The procedure included endocervial curettage with a curette, with a biopsy sample taken using biopsy forceps if necessary.

Pain and anxiety were measured using separate 10-cm visual analog scales (VAS). Pain scales were labeled at the left end with "no pain" and at the right end with "worst pain imaginable." Anxiety scales were labeled "no anxiety" and "extreme anxiety," and anxiety was defined as "nervousness" in the instructions. Patients were given the printed scales attached to a clipboard and were asked to represent their level of pain by drawing a single vertical line through the horizontal scale.

Pain and anxiety initially were measured at three intervals: before undressing for the examination, immediately before the spray was applied and after completion of the procedure. "Clinically significant" pain was defined as a change of [is greater than or equal to] 1.3 cm on the 10-cm VAS as documented previously.[7]

At the start of the trial several patients reported stinging when the spray was applied. To more precisely evaluate the effect of the spray itself on pain score, we changed the protocol and included a fourth set of pain and anxiety measurements. These data were obtained immediately after the spray was applied but before the procedure was started.

Statistical analysis was performed using the chi-square statistic for categorical data and the unpaired t test for continuous demographic data. Differences in pain and anxiety scores across time and between the two interventions at each time point were evaluated using the two-factor repeated measures ANOVA statistic. Using a variance based on previously reported data[4] and an expected mean difference of 2.0 cm, a minimum sample size of 32 was calculated to yield a power of 0.8 at an alpha level of 0.05.[8]

RESULTS

Colposcopy was performed in the family practice center on 58 women between March and December 1996. Of these women, 22 were excluded from participation in the study: 12 met one or more of the exclusion criteria, 8 patients declined participation, and 2 were excluded because of protocol violations. Except for age (since women younger than 18 years of age were excluded), there were no differences between participants and nonparticipants with regard to demographic characteristics. Demographic information about these patients is presented in Table 1. Patients were similar in both groups with regard to age, ethnic group, gravidity, and parity.

TABLE 1 Demographic Characteristics of 36 Women Patients Undergoing Colposcopy with Either Benzocaine Spray or Placebo to Control Pain and Anxiety

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