Techniques for Reducing Patient Discomfort
Patients with a variety of gynecologic conditions require biopsies to establish diagnosis. Many lesions are amenable to minor surgical procedures in the office or clinic setting because of two advances in local anesthesia: topical analgesia of mucosa and intact skin and neutralized pH of injectable local anesthetic solution.1
It is well known that the vulvar skin and mucosa, especially the vestibule and clitoris, are highly sensitive to pain. Injecting these sites with even a small-gauge needle is not possible without producing considerable patient discomfort. The piercing of skin causes an immediate, sharp flash of pain followed by delayed pain of a dull or burning diffuse nature.2 Topical anesthesia to diminish needle pain is desirable.
A lidocaine-prilocaine combination water-emulsion cream is an appropriate choice for topical anesthesia in vulvar biopsy. This cream is marketed under the brand name EMLA, an acronym for eutectic mixture of local anesthetics. EMLA is non-sterile and contains no preservatives, due to the antimicrobial activity of lidocaine and prilocaine. The cream contains an equal amount of each drug base and causes dermal and mucosal analgesia by migration of the agents into skin layers, with accumulation in the vicinity of pain receptors and nerve endings. Lidocaine and prilocaine stabilize the neuronal membrane and temporarily prevent initiation and conduction of nerve impulses. The depth of analgesia depends on the time since application, the dose and the type of epithelium.3-6
Anesthesia of Vulvar Skin
Local analgesia of intact vulvar skin, such as areas lateral to Hart’s line and including hair-bearing and hairless skin, is typically achieved after 30 to 45 minutes of EMLA application under an occlusive dressing. This method enables needle prick without sensation. The farther lateral the target tissue, the more keratinized the skin, and the longer it takes the cream to penetrate. The anesthetic effect lasts about 1 to 2 hours.
Clinical experience shows that longer application time increases the duration of pain relief, but data about this is unavailable. The depth of anesthesia increases with time, but is sufficient for local anesthetic infiltration after 30 minutes.
Anesthesia of Genital Mucosa
Absorption of EMLA cream by mucosa is faster than by skin, so both analgesic onset time and duration are less when the genital mucosa is involved. The entire treatment or biopsy area, including any mucosa folds and between and around the labia, should be covered by a thick layer of EMLA cream for a minimum of 15 to 30 minutes to prepare the site for fine-needle infiltration with a modified mixture of 1% lidocaine. Maximum effect is achieved in 20 to 45 minutes. Occlusive dressing is not technically required, but if used, allows the patient to be dressed and comfortable in the waiting room during the delay time. This frees up the examining room.
Complications of EMLA Cream
Local pallor, redness or edema may occur with application of EMLA, but are not clinically significant.3,4
Local Infiltration of Anesthetic Solution
The problem with local anesthesia of the genitals goes beyond pain from the needle prick; infiltration by the anesthetizing solution produces a stinging sensation. There are probably several explanations for this phenomenon, but the pH of the drug is a significant factor.7,8
A particular solution’s acidity or alkalinity, expressed on the pH scale of 0 to 14, reflects the concentration of H+ ions. A change of +1 pH is a tenfold decrease in the number of H+ ions. If H+ ions cause pain, then increasing the pH would decrease pain. There must be other influences, since some solutions are more acidic but less painful than others. Some experts have speculated that the equilibrium between ionized and non-ionized solutions or the diffusibility of the non-ionized form is what determines infiltration pain.4
Nevertheless, it has been clinically demonstrated in a double-blind, randomized trial that adding sodium bicarbonate (NaHCO2) to lidocaine and increasing the pH to 7.37 or 7.38 significantly reduces pain from infiltration of lidocaine with or without epinephrine (see table).7
Mixing Lidocaine with NaHCO2
Mixing 1% lidocaine and sodium bicarbonate (1 mEq/mL) at a ratio of 10:1 (such as 10 cc of 1% lidocaine and 0.1 cc sodium bicarbonate) yields the pH of 7.38 (or 7.37 if lidocaine plus epinephrine is used).
Biopsy can then take place in the chronology described here. After the required time for EMLA to anesthetize the epithelium, the patient undresses and you remove her dressing and wipe off the EMLA cream using gauze. Then you can inject the modified lidocaine solution as would be done with a traditional solution. Inject the 1% solution sub-epidermally with a fine, 25-gauge needle. The amount of solution will be 4 mL to 8 mL per site.
Most biopsy sites require only a single injection. If more than one biopsy from the same site is required, lidocaine injection around the lesion may be necessary. The anesthetizing effect occurs within 60 seconds. Injection produces localized swelling and elevation of the lesion, which facilitates the biopsy. No antiseptic application on the skin is necessary.
Punch Biopsy of the Vulvar Skin
Before taking a punch biopsy of the vulva, give the patient a thorough explanation of the procedure that includes the reason for biopsy, the aftercare and the anticipated date for receiving the pathology results. Biopsy is considered part of the investigation of the lesion, especially if it is to be ablated, and is required to differentiate benign from malignant conditions. This is not always possible with colposcopic or gross inspection.
Some lesions are not suitable for punch biopsy. Well-circumscribed lesions, such as nevi, individual cysts and papules, are better excised to provide an adequate margin of normal skin in case malignancy is encountered.9 Biopsies taken from the vulva usually do not result in scarring (either hypertrophic or keloid). However, areas beyond the vulva, such as the inner thigh or buttock, may scar. Hypertrophic scarring usually fades over time, but keloid scarring is permanent.
The two most common skin biopsy instruments used in colposcopy are the punch biopsy as used on the cervix and the Keyes 4 mm to 6 mm diameter cutaneous punch.
The Keyes punch technique requires light pressure and a circular rotation to cut into the tissue. Depth of the cut should be through the dermis and end at the junction of the subcutaneous tissue. Hold the instrument in one hand between the thumb and index finger and stabilize and elevate the vulvar skin using the thumb and index finger with the other hand. When you achieve adequate depth, remove the Keyes punch. With one hand, grasp and elevate the specimen with fine-tissue forceps. With the other hand, sever the base of the cylindrical defect with a transverse cut using a scalpel or fine scissors.10 A vague sensation of decreased resistance at the dermal-subcutaneous border can be appreciated after a handful of cases.10
Biopsy with the standard cervical punch involves pressuring the open jaws onto the biopsy site and then closing the jaws. It is important not to “shave” the skin surface. You can avoid this problem by elevating the skin between the thumb and index finger of one hand while applying the forceps’ jaws orthogonally onto the skin with the other. Pick the specimen out of the jaws of the punch biopsy forceps with fine-tissue forceps. The appropriate technique and adequacy of depth can be practiced by using the instruments on a raw, unpeeled cucumber, a raw tomato or an orange.
The dimensions of the specimens will vary depending on the thickness of the epidermis and the size of the instrument used.9 Vulvar dermis thickness also varies. It is thinnest on the vestibule and thickest on the cutaneous (hair-bearing) skin but usually does not exceed 4 mm. Benign lesions like squamous cell hyperplasia or lichen sclerosus require only superficial dermis.9
Lesions that you suspect to be premalignant require deep excision into the dermis, creating a biopsy specimen containing stroma to differentiate between intraepithelial neoplasia and invasion and between the degrees of invasion (superficial or frank invasion). On the vulva, superficial invasive cancer is measured from the nearest dermal-epidermal junction. Lesions with infiltration deeper than 1.0 mm are no longer considered superficial.11 Your index of suspicion will be honed with colposcopic experience.9
Place specimens on absorbent, thin cardboard, a Telfa pad or a paper towel with its dermal side down. Serum from the specimen will cause it to adhere to the paper surface. Put the specimen and paper in fixative solution with the lesion submerged in the fluid and the paper floating. Placing the specimen by itself in the fluid could create orientation problems for the laboratory technologist and for the pathologist.9
The histology report may indicate that a further excision is required to establish the diagnosis. Biopsy may not be sufficient. Diagnoses such as superficial invasive squamous cell cancer or atypical condyloma are examples.
Management of Bleeding
A biopsy that is too deep, extending into the subcutaneous tissue—particularly with the Keyes punch—may lead to excessive bleeding. Slight bleeding can be managed by plugging the cylindrical defect with pledgets of gel foam. Bleeding from the edges may be controlled by applying a silver nitrate stick. If bleeding persists, make a figure-eight stitch using fine chromic catgut (3-0 suture).
Monsel’s solution is a powerful hemostatic agent prepared from powdered ferrous sulfate in a mixture of sulfuric and nitrate acids and water that has been heated to 100 degrees Celsius. The solution becomes therapeutic by evaporation of the water, creating a paste. It is particularly useful on the cervix. But Monsel’s paste can cause chronic inflammatory reactions when it is applied to muscle or deep tissue injuries. When applied to skin, it can cause permanent pigmentation and collagen changes as well as histologic characteristics suggesting malignancy. The histologic distortion is probably related to the inflammatory reaction it stimulates.12 Electrosurgical fulguration (electrode not in contact with tissue) or desiccation (electrode in contact with tissue) applied to the vulva after Monsel’s paste has been used to try to stop bleeding. This can precipitate elemental iron and insoluble iron compounds that can result in a cosmetic blemish like a tattoo. For these reasons, Monsel’s paste might not be a good choice for bleeding after a vulvar biopsy.
Instruct patients to take daily baths or showers to keep the biopsied area clean. Petrolatum or silver sulfadiazine may be used to cover the biopsy site, but this is usually not necessary.
The vulva heals within 5 to 7 days after biopsy. Healing and aftercare depend on the size and location of the lesion and the treatment technique used. Patients should avoid anything that may irritate the vulva, such as bike riding or sexual activity. No follow-up examination of the biopsy site is necessary unless the patient notices odor, heat, pain or swelling at the site.
Reducing Patient Discomfort
A modified lidocaine solution used in conjunction with EMLA allows a variety of diagnostic and therapeutic procedures to be carried out in an office or clinic setting with minimal patient discomfort.
Virtually all biopsies can be performed without causing significant pain. EMLA plus the lidocaine mixture eliminates the need for general anesthesia in up to 85% of patients who require conservative treatment of selected lesions of the vulva, vaginal introitus, perineum, perianal skin and perianal mucosa. This combination saves an enormous amount of time, is convenient for patients and reduces health care costs.
1. Wright VC. Colposcopy of intraepithelial neoplasia of the vulva and adjacent sites: differentiation from other lesions. In Wright VO, Lickrish GM, Shier RM (eds): Basic and Advanced Colposcopy — A Practical Handbook for Diagnosis. 2nd edition. Houston: Biomedical Communications; 1995:17-22.
2. Woolfson AD, McCafferty DF. Local anaesthesia of the skin. J Olin Pharm Ther. 1989;14:103-109.
3. Juhlin L, Evers H, Broberg F. A lidocaine-prilocaine cream for superficial skin surgery and painful lesions. Acta Dermatovener (Stockholm). 1980;60:544-546.
4. HaIlen A, Ljunghall K, Wallin J. Topical anaesthesia with local anaesthetics (lidocaine and prilocaine, EMLA) cream for cautery of genital warts. Genitourin Med. 1987;63:316-319.
5. Bjerring P, Arendt-Nielsen L. Depth and duration of skin analgesia to needle insertion after topical application of EMLA cream. Br J Anaes. 1990;64:173-177.
6. Hernandez E, Gonzalez S, Gonzalez E. Evaluation of topical anesthetics by laser induced sensation: comparison of EMLA 5% cream and 40% lidocaine in an acid mantle ointment. Lasers Surg Med. 1998;23:167-171.
7. McKay W, Morris R, Mushlin P. Sodium bicarbonate attenuates pain on skin infiltration with lidocaine with or without epinephrine. Anesth Analg. 1987;66:572-574.
8. Morris RW, Whish DKM. A controlled trial of pain on skin infiltration with local anaesthesia. Anaesth Int Care. 1984;12:113-114.
9. Wright VO, Chapman WB. Colposcopy of intraepithelial neoplasia of the vulva and adjacent sites. Obstet Gynecol. 1993;20:231-253.
10. Friedrich EG Jr. Diagnostic procedures. In Friedrich EG Jr (ed). Vulvar Disease. Philadelphia: WB Saunders; 1976:34-41.
11. Wilkinson EJ, Kneale B, Lunch PJ. Report of the ISSVD Terminology Committee. J Reprod Med. 1986;31:973-975.
12. Epstein E, Mainach HI. Monsel’s solution: chemistry and efficacy. Arch Dermatol. 1964;90:226-229.
V. Cecil Wright is a physician who is a professor emeritus in the Department of Obstetrics and Gynaecology at the University of Western Ontario in London, Ontario, Canada. He has written and edited numerous articles and textbooks on colposcopy and taught colposcopy courses in North America for 20 years.
pH of 1% Lidocaine ± Epinephrine and Sodium Bicarbonate
|Lidocaine + commercial epinephrine||4.05|
|Lidocaine + added epinephrine||6.39|
|Lidocaine + epinephrine + sodium bicarbonate||7.37|
|Lidocaine + sodium bicarbonate||7.38|