The effect of local anaesthetic spray on the pain associated with local anaesthetic injection, prior to biopsy or loop diathermy to the cervix in the outpatient colposcopy clinic
Correspondence: Dr R. J. Connell, Department of Obstetrics and Gynaecology, Elizabeth Garrett Anderson Hospital, 144 Euston Road, London NW1 2AP, UK.
We evaluated the effectiveness of local anaesthetic spray prior to injection of local anaesthetic before biopsy or large loop excision of the transformation zone of the cervix at colposcopy. This was a prospective, randomised, double-blind placebo-controlled study involving 51 women. Pain or discomfort was measured using a four-point categorical scale and a visual analogue score. Our results show that the use of local anaesthetic spray has no effect on the pain or discomfort experienced by patients having local anaesthetic injections to the cervix, and cannot be recommended.
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Guidelines produced for the NHS Cervical Screening Programme by the British Society for Colposcopy and Cervical Pathology stipulate that women whose cervical smears show moderate or severe dyskaryosis, or persistent mild dyskaryosis or borderline change should be referred for colposcopic evaluation of the cervix. Where colposcopic evaluation reveals abnormalities, a biopsy should be performed1. Large loop excision of the transformation zone with diathermy is the method most commonly used for the treatment of histologically diagnosed cervical intraepithelial neoplasia and intracervical block with local anaesthetic is an established method for effecting local anaesthesia before colposcopic procedures. In our experience many women undergoing either loop excision or biopsy stated that they had found the local anaesthetic injection the most painful or uncomfortable part of the whole procedure. We therefore sought to design a study to examine whether a local anaesthetic spray applied to the cervix before the injection, reduced the discomfort of intracervical local anaesthetic injection. The main outcome measure was pain experienced, as measured by a visual analogue score, and by a four-point categorical scale.
The study was conducted after obtaining local ethical committee approval. It was a prospective, randomised, double-blind, placebo-controlled study, performed at two consultant-led colposcopy clinics at a teaching hospital.
Women aged 20 to 64 years who were undergoing biopsy or loop excision under local anaesthetic for cyto-logical abnormalities were recruited to the study. All women were seen on the day by one investigator and consented to the study. Randomisation occurred when a decision was made to either biopsy the cervix or perform a loop excision under a local anaesthetic injection. Randomisation was by stratified computer-generated numbers. Patients were randomised to receive either the 10% lignocaine hydrochloride spray or saline. Multiple atomiser bottles were made up with solution and were labelled ‘A’ or ‘B’. To ensure blinding, the bottles were made up in the pharmacy department who also sealed the code in an envelope. The active (local anaesthetic) and placebo sprays were made up to contain identical solvents and differed only in that the active spray contained lignocaine hydrochloride.
The attending doctor, the nursing staff, the woman and the investigator were all blinded to the identification of the solution used. The woman was placed in the lithotomy position and a bivalve speculum placed in the vagina to expose the cervix. Acetic acid (3%) was used to douse the cervix to reveal anomalies. The operator was then handed an atomiser bottle after deciding to perform the procedure. The spray was primed and the operator depressed the spray four times applying approximately 0.5 mL of solution to the cervix. At least one minute later 1.1 mL of local anaesthetic (prilocaine hydrochloride 30 mg/mL with felypressin 0.54 μg/mL) was injected with a dental syringe and needle. In the biopsy group, injection was into two adjacent quadrants of the cervix, the total volume being 2.2 mL. In the large loop excision of the transformation zone group injection was into four quadrants, the total volume being 4.4 mL. Pain was measured using 100 mm visual analogue score scales. The woman was asked to mark the line with a cross as soon as the injections had been performed. We also assessed pain with a four-point categorical scale 1−4; 1 = not painful; 2 = slightly painful; 3 = moderately painful; 4 = severely painful. After the procedure, the patient was asked to score the procedure as a whole in a similar way.
Statistical analysis was performed using nonparametric Mann-Whitney U tests to determine the significance of the differences between the two groups of data. A calculation based on previously reported data2, predicted a sample size of 33 to yield a power of 80% at an alpha level of 5% to show a difference in pain scores of 20 mm. The code was broken after statistical analysis had been carried out.
Fifty-four women were randomised into the trial. Three women were excluded after randomisation due to extensive lesions requiring a general anaesthetic cone biopsy; of these, two had been randomised to receive solution A and one to receive solution B. Examinations and treatments were performed by five different clinicians, but under the supervision of one of two consultants. Of the 51 women entered into the study, 19 had a biopsy performed and 32 had a large loop excision of the transformation zone. Of the 19 women undergoing biopsy, eight were randomised to receive solution A and 11 solution B. Of the women undergoing a large loop excision of the transformation zone, 16 were randomised to receive solution A and 16 had solution B; two women in this group failed to complete the second visual analogue score scales. Solution A was the lignocaine spay, and solution B was the placebo. The results are shown in Table 1.
Table 1. Results of visual analogue scores (VAS). IQR = interquartile range; NS = not significant.
|VAS after injection (mm)|| || || |
| Median||37.5||33.0|| |
| IQR||12–59.5||10–58|| |
| || || ||0.6371|
| || || || |
|VAS after procedure (mm)|| || || |
| Median||40.0||36.0|| |
| IQR||21.25–63.25||17.5–49.5|| |
| || || ||0.3751|
Application of the lignocaine spray had no significant effect on pain scores after the injection (P= 0.6371) or after the procedure as a whole (P= 0.3751). Differences in the categorical data after the injection and after the procedure were also not significantly different (P= 0.678 and P= 0.230, respectively). None of the women in the study experienced any abnormal effects to the spray (e.g. stinging or cold sensation).
The use of topical anaesthetic agents is common to prevent noxious stimuli, whether that is from the oral cavity, urethra or skin. In the United States 20% benzocaine is commonly used and has been shown to reduce significantly the pain associated with many gynaecological procedures. Furthermore, intracervical block with local anaesthetic has been shown to reduce the discomfort associated with many cervical procedures3. Anecdotal evidence from our colposcopy clinics has shown that during either cervical biopsy or large loop excision of the transformation zone to the cervix, when local anaesthetic injection was used, a large number of women complained that the worst part of the entire procedure was the pain associated with the injection. The logical step was to undertake a study looking at whether the application of topical local anaesthetic to the cervix prior to injection, would reduce this pain.
We specifically made up the two solutions to be as similar as possible. The use of an atomiser pumped bottle enabled the omission of fluorocarbons or similar vehicle gases usually found in aerosol sprays, as Clifton et al.2 showed that the use of benzocaine spray with a fluorocarbon vehicle gas increased pain scores during cervical procedures. We also waited at least one minute after application of the spray before injecting.
In our study, pain scores varied considerably. Patients were undergoing either biopsy or large loop excision of the transformation zone. The mean pain scores were quite high, adding to the evidence that colposcopic examination and treatment is not without a significant degree of discomfort. In this study there was no benefit in the application of local anaesthetic spray before local anaesthetic injection.
Other authors have found that the use of benzocaine gel significantly reduced pain scores during cervical biopsy, insertion of intrauterine contraceptive devices, endocervical curettage, intracervical block and the placement of a tenaculum3. However, Lipscomb et al.4 showed that there was no difference in pain between 20% benzocaine gel and placebo applied before biopsy of the cervix.
There have been various studies attempting to reduce the pain and discomfort from the injection, using simple oral analgesia before the procedure, altering pH or by warming the anaesthetic solution before injection, but results have not shown any benefit5.
Davies et al.6 is the only other group to our knowledge who used lignocaine 10% in an atomiser bottle. They sprayed the cervix, cervical canal and uterine cavity during outpatient hysteroscopy. They found that women treated with active spray experienced significantly less pain when the cervix was grasped with a tenaculum at the start of hysteroscopy. If the pain stimulus originates from the cervical stroma and not the epithelium, a difference in pain scores would indeed be expected for the use of a tenaculum after application of topical local anaesthetic, while a difference in the pain scores from a deep cervical injection would not. Topical application of local anaesthetic will also have no effect on the pressure exhibited by injecting a volume of solution into the stroma.
The use of 10% lignocaine spray has no effect on reducing the discomfort felt from injection of local anaesthetic prior into the cervix and cannot be recommended.