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Objective To assess whether transcervical intrauterine instillation of local anaesthetic agent reduces pain during diagnostic outpatient hysteroscopy and endometrial biopsy.
Design Prospective, randomised, double blind, placebo-controlled trial.
Setting Outpatient hysteroscopy clinic in a university teaching hospital.
Population Ninety women undergoing outpatient diagnostic hysteroscopy with or without endometrial biopsy.
Methods Transcervical intrauterine instillation of 5 mL of 2% lignocaine into the uterine cavity before performing the procedure.
Main outcome measures Evaluation of pain at different stages of the procedure using a visual analogue scale and changes in blood pressure and heart rate.
Results The use of local anaesthetic did not alleviate pain experienced during hysteroscopy and endometrial biopsy. It did not prevent the occurrence of vaso-vagal reactions; however the incidence of these was low.
Conclusions Transcervical instillation of local anaesthesia neither reduced pain nor prevented vasovagal reaction during hysteroscopy and endometrial biopsy.
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The trial was approved by the Clinical Research Ethics Committee of the Chinese University of Hong Kong. Women scheduled for outpatient hysteroscopy were invited to participate in the study. After giving her consent, the woman was randomised into one of the two groups using random numbers generated by a computer, and the allocations placed in opaque sealed numbered envelopes. One group received 5 mL of 2% lignocaine solution and the other received 5 mL of normal saline. No premedication was given. A nurse who was not involved in the actual procedure prepared the medication. Both the women and the attending medical staff were unaware which medication was used. The woman was placed in a lithotomy position and a bimanual examination was performed to assess the size and position of the uterus. The cervix was exposed with a bivalve speculum and an 18 gauge polythene intravenous catheter (Angiocath, Becton Dickinson Vascular Access, Utah) was inserted into the cervical canal up to the internal os; the solution was then instilled into the uterine cavity. Hysteroscopy was started five minutes later. A rigid 5-mm diameter hysteroscope with a 30° oblique view (Karl Storz, Germany) was inserted into the uterine cavity under direct vision without cervical dilatation. The uterine cavity was distended by carbon dioxide using a hystero-insufflator (Wisap, Germany) at a flow rate of 40–50 mL/min and a pressure of 100 mmHg. All procedures were monitored with a video camera. Endometrial biopsy was performed using a 3-mm Karman Vacuum Aspirator Curette (Rocket Medical, England).
During the procedure the woman was asked to record the pain she felt at different stages of the procedure using a visual analogue scale (a horizontal line of 10 cm without gradations, with 0 on the left side indicating no pain and 10 on the right side indicating the worst possible pain). The assessments were made at the following times: 1. when the cervix was grasped by a single-toothed tenaculum forceps; 2. immediately after instillation of the solution into the uterine cavity; 3. at the time of insertion of the hysteroscope; 4. during hysteroscopy at maximal distension of the uterine cavity; 5. immediately after endometrial biopsy; and 6. 30 minutes after hysteroscopy. Blood pressure and pulse rate was recorded before the procedure, during the hysteroscopic examination at the time of maximal uterine distension and 30 minutes after the procedure. Vaso-vagal reaction was defined as the occurrence of bradycardia (heart rate < 60 bpm) or hypotension (reduction in blood pressure > 20% compared with baseline), associated with dizziness, faintness, sweating, nausea or vomiting.
Transcervical instillation of local anaesthesia into the uterine cavity in postmenopausal women was reported to reduce significantly the mean pain score during hysteroscopy from 13.4 to 11.5 on a 20 cm scale, with a standard deviation of 3.58. We believe that a reduction in pain score of 15% is of clinical significance and therefore estimated that a sample size of 90 would be able to detect such a difference with a power of 80% and type 1 error (α) of 0.05. Statistical analysis was performed using Student's t test or the χ2 test where appropriate. Confidence intervals were calculated for the estimates of the differences.
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Ninety women were recruited and randomised into either the anaesthetic or the placebo group. All procedures were successfully performed except in one woman in the placebo group who experienced intolerable pain when the tenaculum forceps was applied to her cervix before the introduction of the hysteroscope. There were no significant differences in demographic characteristics of the women in the two groups (Table 1). The primary indication for the procedure is shown in Table 2 and was similar in both groups. There was no difference in the mean duration of the procedure.
Table 1. Characteristics of the women in the two groups. Values are given as n (%) or mean [SD].
| ||Lignocaine (n= 45)||Placebo (n= 44)|
|Age (years)||47.8 [10.0]||44.3 [9.0]|
|Parity|| || |
| Nulliparous||3 (7)||4 (9)|
| Multiparous||42 (93)||40 (91)|
|Menopausal status|| || |
| Premenopausal||30 (67)||37 (84)|
| Postmenopausal||15 (33)||7 (16)|
|Procedure time (minutes)||11.0 [4.8]||11.3 [4.4]|
|Blood presure and pulse|| || |
| Before procedure|| || |
| Systolic (mmHg)||145 ||134 |
| Diastolic (mmHg)||78 ||80 |
| Pulse (bpm)||75 ||80 |
|During procedure|| || |
| Systolic (mmHg)||138 ||136 |
| Diastolic (mmHg)||76 ||75 1111|
| Pulse (bpm)||72 ||78 |
|After procedure|| || |
| systolic (mmHg)||124 ||126 |
| Diastolic (mmHg)||71 ||75 |
| Pulse (bpm)||73 ||74 |
Table 2. Indications for the outpatient hysteroscopy. Values are given as mean (SD)
| ||Lignocaine (n= 45)||Placebo(n= 44)|
|Postmenopausal bleeding||13 (28.9)||6 (13.6)|
|Menorrhagia||5 (11.1)||9 (20.5)|
|Irregular period||15 (33.3)||17 (38.6)|
|Intermenstrual or postcoital bleeding||10 (22.2)||8 (18.2)|
|Others||2 (4.5)||4 (9.1)|
Pain scores at various stages of the hysteroscopy are shown in Table 3. Insertion of the Teflon catheter and instillation of the solution did not result in an increase in the mean pain score. There was no significant difference in pain scores at various stages of the procedure between two groups. Endometrial biopsy was performed in 35 of the women randomised to lignocaine (78%) and 32 of the women given placebo (73%).
Table 3. Pain scores at various stages of the procedure. Values are given as mean (SD), unless otherwise indicated
| ||Lignocaine||Placebo||Mean difference (95% CI)||t||P|
|Before the procedure||0.3 (0.4)||0.4 (0.8)||−0.09 (−0.36 to 0.18)||−0.644||0.522|
|At grasping of the cervix||1.9(2.4)||2.4(2.6)||−0.52 (−1.57 to 0.54)||−0.976||0.332|
|After instillation||2.1(2.8)||1.9(2.3)||0.27 (−0.82 to 1.35)||0.487||0.627|
|At insertion of hysteroscope||3.1(3.0)||3.6(3.3)||−0.42 (−1.73 to 0.88)||−0.645||0.521|
|During hysteroscopy||4.1(3.6)||4.2(3.2)||−0.10 (−1.54 to 1.34)||−0.139||0.890|
|At endometrial sampling||4.3(3.4)||4.5(3.7)||−0.24 (−1.93 to 1.45)||−0.282||0.719|
|30 min after procedure||1.4(1.8)||1.2(1.4)||0.23 (−0.50 to 0.96)||0.632||0.530|
|Vaso-vaginal reaction||3||3|| || || |
No major complications occurred and no woman required admission to hospital after the procedure. Two postmenopausal and one premenopausal women in each group developed a vaso-vagal reaction [relative risk 0.98 (95% CI 0.21, 4.59)]; all recovered spontaneously.
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Although diagnostic hysteroscopy with endometrial biopsy can be performed in the outpatient setting under either local or no anaesthesia, pain and vaso-vagal reaction are a concern to women and their gynaecologists. In order to maximise the chance of success of the procedure and minimise the woman's discomfort, various forms of local anaesthesia have been evaluated. Paracervical and intracervical local anaesthesia are not effective in reducing pain during hysteroscopy and endometrial biopsy5,6, and the injection itself is almost as painful as the hysteroscopy6,7. We recently reported that paracervical anaesthesia could only reduce pain during insertion of the hysteroscope but failed to suppress pain during uterine distension and aspiration of the endometrium7. This is probably related to the different innervation of the uterine body and the cervix. Although innervation of the uterus is mainly confined to the uterine cervix and lower part of the uterus, nerve endings are also present in the endometrium9, and failure to block these nerve endings may account for the pain at hysteroscopy and endometrial biopsy secondary to uterine distension. Transcervical instillation of local anaesthesia into the uterine cavity may reduce pain during the procedure by directly blocking the nerve endings in the endometrium.
In a randomised, double-blind, placebo-controlled trial, Zupi et al.10 concluded that instillation of 5 mL of 2% mepivacaine into the uterine cavity reduced pain during and after diagnostic hysteroscopy and endometrial biopsy, however the trial was small and the difference was not statistically significant. In another randomised trial Cicinelli et al.8 reported that the use of topical anaesthesia significantly reduced pain at hysteroscopy and endometrial biopsy; however the study was confined to postmenopausal women and the results cannot be generalised to premenopausal women. Our results showed that transcervical instillation of local anaesthetic into uterine cavity failed to reduce the pain during diagnostic hysteroscopy and endometrial biopsy. Given that the pain associated with hysteroscopy and endometrial biopsy is of moderate intensity only, a reduction in pain score of less than 15% is probably of no clinical significance.
It was suggested that the use of topical anaesthesia for diagnostic hysteroscopy reduced the risk of a vasovagal reaction. Zupi et al.10 reported that 2 of the 22 women receiving placebo developed a vaso-vagal reaction, but none of the 23 given local anaesthesia did so. Cicinelli et al.8 found a significant reduction in the incidence of vaso-vagal reactions from 32.5% to 5% in postmenopausal women. We have recently reported that the use of paracervical block in outpatient diagnostic hysteroscopy was associated with a higher incidence of symptomatic bradycardia or hypotension (31%)7. This is probably the effect of intravasation of the anaesthetic agent rather than the development of a vaso-vagal reaction. Transcervical instillation of anaesthetic should avoid such a risk and therefore reduces the risk of bradycardia and hypotension. However the incidence of vaso-vagal reaction in our study was low (6%) and there was no difference in the incidence whether transcervical anaesthesia was used during hysteroscopy or not. Given the low incidence and that the primary outcome of the study was pain, our study therefore would not have sufficient power to detect a difference in this complication.
It has been consistently shown that endometrial biopsy is the most painful part of the whole procedure, whether local anaesthesia is used or not5–7. The mechanism of pain may be related to the local release of prostaglandins, which then induce uterine cramps. Although the use of mefenamic acid significantly reduced pain after hysteroscopy, it failed to alleviate the discomfort during the procedure11. Whether other more potent prostaglandin synthetase inhibitors confer any advantages in outpatient hysteroscopy is still unknown.
The use of transcervical intrauterine local anaesthesia neither reduces pain nor prevents vaso-vagal reaction during hysteroscopy and endometrial biopsy. Paracervical anaesthesia is also ineffective and carries a risk of inadvertent intravasation of the anaesthetic agent. As hysteroscopy has become an important and frequently performed outpatient investigation, there is a need to search for an effective method to alleviate the pain associated with the procedure.