From the Journals

Lidocaine-prilocaine cream tops lidocaine injections for vulvar biopsy pain



The median highest pain score in a randomized trial of 38 women undergoing vulvar biopsies was 25.7 mm lower, on a 100 mm visual analogue scale, when they received 5% lidocaine-prilocaine cream instead of a 1% lidocaine injection, according to a report from Duke University, in Durham, N.C.

“In the current study, we found that application of lidocaine-prilocaine cream, alone, for a minimum of 10 minutes before vulvar biopsy on a non–hair-bearing surface results in a significantly lower maximum pain score and a significantly better patient rating of the biopsy experience,” said investigators led by Logan K. Williams, MD, of the department of obstetrics and gynecology at Duke University, Durham, N.C.

Given the “clear advantage” of the cream, it “should be considered as an anesthetic method for vulvar biopsy in a non-hair-bearing area,” Dr. Williams and colleagues concluded (Obstet Gynecol. 2020 Feb;135{2]:311-8).

Studies have pitted the cream against the injection before, but they did not compare patients’ maximal pain scores. The team wanted to do that because “comparing the highest score allows us to consider the possibility that the pain of anesthesia application” – injection versus cream – “may be greater than the pain of any other portion of the biopsy procedure.”

They randomized 19 women to the cream, approximately 5 g at the site of biopsy at least 10 minutes beforehand, and 18 others to the injection, 2 mL using a 27-gauge needle, at least 1 minute prior.

The median highest pain score in the lidocaine-prilocaine group was 20 mm, but 56.5 mm in the injection group. Patients randomized to lidocaine-prilocaine also had a significantly better (P = 0.02) experience than those receiving injected lidocaine, also assessed by visual analog scale (VAS). The median baseline pain level was 0 mm.

Anxiety was assessed after patients knew whether they were going to get the cream or the injection, but before the biopsy. The median score in the cream group was of 19 mm on another VAS, compared with 31.5 mm.

The team had planned to enroll 106 women, but given the results on interim analysis, they stopped the trial early.

Participants were 60 years old on average, and almost all had prior vulvar biopsies. Two in the cream group and three in the injection group had punch biopsies; cervical biopsy forceps were used for the rest. More than half the women had benign findings, and most of the others had vulvar intraepithelial neoplasia, but there was one invasive cancer. At Duke, the cost of the injection was $0.99, compared with $7.36 for the cream.

Dr. Williams and colleagues cited a few limitations. One is that the patients and clinicians in the study were not blinded. Another is that most of the patients had undergone vulvar biopsy before, possibly predisposing them to bias.

“In the future, consideration could be taken to studying lidocaine-prilocaine cream applications to hair-bearing surfaces, which were excluded in this study.” Also, “there is a question of the histologic effect of lidocaine-prilocaine on tissues and whether this could affect pathologic diagnoses.

“We are conducting a separate ancillary study in conjunction with our dermatopathology colleagues to investigate this question,” the investigators said.

The work was funded by Duke and the National Institutes of Health. Dr. Williams had no disclosures.

SOURCE: Williams LK et al. Obstet Gynecol. 2020 Feb;135(2):311-8.

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