A Comparison of Pain Perception Using Topical EMLA Cream Versus Lidocaine Injection for Vulvar Biopsy: a Randomized Controlled Trial

Performing minor procedures in-office is essential to gynecologic practices. In-office procedures allow for evaluation and diagnosis of a variety of conditions while avoiding the expense, anesthesia, and time associated with the operating room. Pain and discomfort are frequently associated with these procedures, and ensuring that the patient has the least amount of discomfort is a priority. Very painful or uncomfortable procedures could potentially discourage a patient from returning to clinic or receiving the follow up that they may need. Psychological, physiologic, and social factors influence a patient's experience of pain. Previous studies, though mostly related to first trimester abortion procedures in the office, indicate that the procedure type, anxiety, depression, and general anticipation of pain predict increased pain during in office gynecologic procedures (1-4). A review by Ireland et al., found that a multimodal approach that includes patient counseling with other techniques is most effective in achieving optimum pain control for procedures (5,6).

Vulvar biopsies are associated with significant discomfort, and some form of anesthesia is required. The current standard in our group is to inject local anesthesia prior to vulvar biopsy. However, the injection itself is associated with its own level of pain that is not insignificant, and for many, the anticipation of receiving an injection is anxiety provoking. The use of topical anesthesia in lieu of injection or as pre-injection analgesia is variable.

Several previous studies have examined the use of topical anesthetics in the place of or in addition to injected anesthesia. Drouault et al. compared EMLA cream alone to injected lidocaine alone for pain relief in vulvar biopsy and found that pain associated with administration of anesthesia was significantly less for EMLA cream, but better biopsy analgesia was obtained with injected anesthesia. The study considered combined pain scores for both groups for the overall procedure (anesthesia + biopsy), it comments that the combined scores were lower for the EMLA group but failed to reach statistical significance. The study ultimately concluded that EMLA is the less painful procedure to obtain anesthesia and that it can be used as an alternative to injection for biopsies of the genital mucosa (7). This prior study did not compare the highest pain score between groups. Consideration of the highest pain score allows us to assess whether the injection of lidocaine could result in causing more pain than the biopsy itself using EMLA cream alone for anesthesia. Further, the study did not assess the subjects' or the providers' perception of the tolerability and acceptability of performing the procedure using either method. This is an important factor in any in office procedure

EMLA cream is the most extensively studied topical anesthetic. It is FDA approved for use as a topical anesthetic on the genital mucous membranes for superficial, minor surgery. EMLA cream requires between 7-10 minutes of absorption time on the genital mucosa for analgesic effect, with variable duration of analgesia following, usually around 15-20 minutes (9). There is a highly variable absorption rate for EMLA cream depending on the characteristics of the epithelium upon which it is applied as well as the duration and surface area of cream applied. On hair-bearing non-mucosal surfaces it can require 60 minutes of application time to obtain analgesic affect (10). The vulvar area is unique in that it contains both mucosal and non-mucosal and hair-bearing surfaces; this could greatly affect the absorption of EMLA and therefore affect analgesia. For this reason, we will exclude from the study patients requiring vulvar biopsy on hair bearing portion of the vulva.

Several previous studies have examined the use of topical anesthetics in the place of or in addition to injected anesthesia. Drouault et al. compared EMLA cream to injected lidocaine as described above. The study found that pain associated with administration of anesthesia was significantly less for EMLA cream, but better biopsy analgesia was obtained with injected anesthesia. However, there were some limitations to this study also noted above, that we plan to expand and improve upon with the current study.