Comparison of Lidocaine With and Without Adrenaline for Reducing Ecchymosis

Background and rationale Ecchymosis at the insertion or removal site is a recognized local reaction to subdermal contraceptive implant procedures. At King Chulalongkorn Memorial Hospital, the introduction of telemedicine follow-up, in which clients submit photographs of the procedure site after the visit, revealed a higher-than-expected frequency of visible bruising. Although clinically minor, bruising is conspicuous on lighter skin, and in the Thai context, where stigma surrounds sexual and reproductive health services, visible bruising may lead women to conceal the procedure site with makeup or long-sleeved clothing.

The standard local anesthetic for implant procedures at the study site is 1% lidocaine without adrenaline, selected partly because it does not require refrigerated storage. Adrenaline added to lidocaine produces local vasoconstriction, which has been reported to reduce operative bleeding, prolong subcutaneous anesthesia in a dose-related manner, and limit systemic absorption of the anesthetic. Evidence on whether these effects reduce post-procedural ecchymosis is inconsistent: reduced bleeding or hematoma has been reported in incisional surgery and great saphenous vein stripping, whereas trials in rhinoplasty and hyaluronic acid filler injection found no significant reduction in ecchymosis. No trial has directly compared lidocaine with and without adrenaline for contraceptive implant insertion or removal. The study hypothesis is that lidocaine with adrenaline reduces the incidence and severity of ecchymosis, with a comparable profile of adrenaline-related adverse effects.

Interventions The intervention arm receives 1% lidocaine with epinephrine 1:100,000; the comparator arm receives 1% lidocaine without epinephrine. The anesthetic is infiltrated at the procedure site immediately before implant insertion or removal using standard technique, including aspiration before injection to avoid intravascular administration. The total volume administered (mL) and the procedure type (insertion, removal, or replacement) are recorded. All other aspects of the procedure follow routine clinical practice at the Family Planning Clinic.

Recruitment, consent, and allocation Clients attending the Family Planning Clinic for implant procedures are informed of the study through posters in the clinic. A trained research assistant who is not involved in the participant's clinical care provides study information and obtains written informed consent in a private area before the procedure. Eligible participants are allocated 1:1 to the two arms using sealed, opaque, sequentially numbered envelopes. The anesthetic is prepared by a single designated research assistant who has no role in recruitment, informed consent, performing procedures, or outcome assessment. Both formulations are clear, colorless solutions; each dose is drawn into an identical unlabeled syringe, which is sealed in an opaque envelope marked only with the participant's study identification number, so that the formulation cannot be distinguished by the clinician performing the procedure.

Follow-up and photographic assessment Post-procedure communication is conducted through the clinic's LINE Official Account (LINE OA), with reminder messages to support retention. Participants receive a standardized transparent ruler sticker and written instructions for photographing the procedure site: well-lit conditions without shadows, the camera held at least 30 cm from the site and within 20 degrees of perpendicular, the ruler sticker and at least 3 inches of surrounding skin included in the frame, and three photographs taken from slightly different angles. On Day 3, participants photograph the adhesive dressing pad so that residual blood staining can be measured, using the pad dimensions as a size reference.

Two independent examiners, blinded to allocation, assess ecchymosis from the submitted photographs. Before the study, the examiners complete joint training using 10 image sets from a previous telemedicine follow-up cohort at the study site; inter-rater reliability is then evaluated on 10 additional image sets using the intraclass correlation coefficient. During the study, each examiner independently measures the area and records the color of any ecchymosis. When the two area measurements differ by less than 10%, the mean is used; when the difference is 10% or greater, the examiners re-assess the image jointly to reach consensus. Severity is graded according to the area-based categories described under Outcome Measures.

Safety monitoring Pulse rate and blood pressure are measured at clinic admission and after the procedure, and participants are observed for symptoms attributable to adrenaline (e.g., nervousness, tremor, palpitations, flushing, light-headedness). Adverse events reported in the clinic or through LINE OA are documented and managed according to standard clinical care.

Sample size The sample size was calculated for a comparison of two independent proportions (two-sided alpha 0.05, power 80%, 1:1 allocation), assuming an incidence of any ecchymosis of 49.2% with lidocaine alone and 34.4% with lidocaine plus adrenaline (a 30% relative reduction), based on data from the institution's previous telemedicine follow-up study. After inflation by 30% for loss to follow-up, the target is 225 participants per arm (450 in total).

Statistical analysis The proportion of participants with any ecchymosis is compared between arms using the Pearson chi-square test (or Fisher's exact test when expected counts are small), with the relative risk and 95% confidence interval; regression models are used to adjust for potential confounders such as age and parity. Ordinal outcomes are analyzed with ordinal logistic regression and Fisher's exact test, with Bonferroni-corrected pairwise comparisons where indicated. Continuous outcomes are compared using the independent t-test or the Mann-Whitney U test according to distribution, and within-group changes in vital signs using the paired t-test or the Wilcoxon signed-rank test. Time to first analgesic use is compared using the log-rank test. Statistical significance is set at a two-sided p < 0.05.

Data management Data and photographs are labeled with study identification numbers rather than personal identifiers, stored securely, and accessible only to authorized study personnel. No biological specimens are collected or stored.