Buffered Lidocaine for Loop Electrosurgical Excision Procedures (LEEPs)

Women undergoing a LEEP procedure who receive lidocaine buffered with sodium bicarbonate for their cervical block will experience less injection pain than women who receive plain lidocaine.

Specific aims: 1. To determine whether buffering the agent used for intracervical anesthetic at the time of cervical loop excision reduces injection-related pain. (Hypothesis: buffering significantly reduces injection-related pain.) 2. To determine whether other components of pain from LEEP (procedural pain, and cramping) can be reduced by buffering of intracervical anesthetic among women undergoing cervical loop excision. (Hypothesis: only injection pain will be reduced by buffering, as procedural pain will be reduced by lidocaine equally in both arms and cramping will not be reduced in either arm.) Background: Although cervical cancer rates have been dramatically reduced by Pap test screening and the eradication of precursors, more than 100,000 U.S. women develop premalignant cervical lesions each year that require treatment (1). The cervical loop electrosurgical excision procedure (LEEP) is the most common therapy for CIN among U.S. gynecologists. LEEP is performed using one or more 1-2 cm electrosurgical diathermy loops to excise involved and at-risk cervical epithelium including underlying stroma containing glands. Destroying this tissue eliminates cells infected with human papillomavirus, the proximate cause of cervical cancer, and radically reduces the risk of later developing cervical cancer (2, 3). LEEP is usually performed as an outpatient procedure using intracervical anesthesia, most commonly combining lidocaine as an anesthetic agent with epinephrine as a hemostatic agent; final hemostasis is achieved using electrosurgical fulguration and topical hemostatic agents (4). Prior literature has suggested that pain from LEEP has 3 components: pain from injection of the anesthetic combination, pain from the excision, and cramping from reflex uterine contractions (5). While cramping can be controlled with oral nonsteroidal anti-inflammatory agents, injection and procedural pain are not. Most women categorize the pain of LEEP as 3-7 on a 0-10 Likert scale (5, 6). Studies of dermal and ocular anesthesia and bone marrow biopsy have found that buffering of acidic local anesthetic agents reduces injection pain (7-14), with up to 66% reduction in pain and significant results in randomized trials involving 30-50 participants. However, the use of buffered lidocaine has not yet been tested for LEEPs. The principal investigator has used both forms of anesthesia and considers both acceptable forms of therapy; he is unaware of any evidence to support the superiority of either arm.