A double-blind, randomized controlled trial on the use of a 50:50 mixture of nitrous oxide/oxygen in pain relief during suction evacuation for the first trimester pregnancy termination

Local anaesthesia for pain control in first trimester surgical abortion

BACKGROUND

Abortions prior to 14 weeks are among the most common outpatient surgical procedures performed on people capable of becoming pregnant. Various methods have been used to control pain; however, many people still experience pain with the procedure.

OBJECTIVES

To evaluate the benefits and harms of local anaesthesia given for pain control during surgical abortion at less than 14 weeks' gestation.

SEARCH METHODS

We searched CENTRAL (Ovid EBM Reviews), MEDLINE (Ovid), Embase, POPLINE, and Google Scholar to December 2022 for randomized controlled trials of pain control in surgical abortion at less than 14 weeks' gestation using suction aspiration. We searched the reference lists of related reviews and articles.

SELECTION CRITERIA

We selected effectiveness and comparative effectiveness randomized controlled trials that studied local anaesthesia with common local anaesthetics and administration routes given for pain control in surgical abortion at less than 14 weeks' gestation using uterine aspiration. Outcomes included intraoperative pain, patient satisfaction, and adverse events.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We computed mean differences (MD) with 95% confidence intervals (CI) for continuous variables reporting a mean. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

Thirteen studies with 1992 participants met the inclusion criteria. Due to heterogeneity of interventions, we could not pool more than two studies for any outcome. We used 13 mm improvement on a visual/verbal analogue scale to indicate a clinically meaningful difference in pain with surgical abortion (pain with dilation, aspiration, or during procedure). Based on type of pain control, we divided studies into three groups. Paracervical block (PCB) effectiveness trials A 20 mL 1% lidocaine PCB reduced pain with dilation (MD -37.00, 95% CI -45.64 to -28.36), and aspiration (MD -26.00, 95% CI -33.48 to -18.52) compared to a sham PCB (1 RCT, 120 participants; high-certainty evidence). A PCB with 14 mL of 1% chloroprocaine resulted in a slight reduction in pain with aspiration compared to a PCB with normal saline injected at two or four sites (MD -1.50, 95% CI -2.45 to -0.55; 1 RCT, 79 participants; high-certainty evidence). PCB comparative effectiveness trials An ultracaine PCB probably results in little to no clinically meaningful difference in pain during procedure compared to topical cervical lidocaine spray (median 1 point higher, interquartile range (IQR) 0 to 3; P < 0.001; 1 RCT, 48 participants; moderate-certainty evidence). A 1000 mg dose of intravenous paracetamol probably does not decrease pain as much as ultracaine PCB during procedure (median 2 points higher, IQR 1 to 3; P < 0.001; 1 RCT, 46 participants; moderate-certainty evidence). Various local anaesthetics in PCB comparative effectiveness trials A 10 mL buffered 2% lidocaine PCB probably does not result in a clinically meaningful difference in pain with dilation compared to a plain lidocaine PCB (MD -0.80, 95% CI -0.89 to -0.71; 1 RCT, 167 participants; moderate-certainty evidence). A buffered lidocaine PCB probably does not result in a clinically meaningful difference in pain with aspiration compared to plain lidocaine PCB (MD -0.57, 95% CI -1.01 to -0.06; 2 RCTs, 291 participants; moderate-certainty evidence). Non-PCB local anaesthesia or PCB technique effectiveness trials PCB: waiting versus no waiting Waiting three to five minutes between 1% lidocaine PCB injection and dilation probably does not result in a clinically meaningful difference in pain with dilation compared to not waiting (MD -0.70, 95% CI -1.23 to -0.17; 2 RCTs, 357 participants; moderate-certainty evidence). Topical cervical analgesia Topical 10 mL 2% lignocaine gel probably does not result in a clinically meaningful difference in pain with aspiration compared to KY Jelly (MD -0.87, 95% CI -1.60 to -0.14; 1 RCT, 131 participants; moderate-certainty evidence). In participants who also received a PCB, 20 mg topical cervical lidocaine spray probably does not result in a clinically meaningful difference in pain during the procedure compared to two pumps of normal saline spray (median -1 point, IQR -2 to -1; P < 0.001; 1 RCT, 55 participants; moderate-certainty evidence). Intravenous paracetamol 1000 mg compared to two pumps of cervical lidocaine spray probably does not results in a clinically meaningful difference in pain procedure (median 1 point, IQR -2 to 2; P < 0.001; 1 RCT, 48 participants; low-certainty evidence). Non-PCB local anaesthesia or PCB technique comparative effectiveness trials Depth of PCB The evidence suggests that a 3-cm deep PCB probably does not result in a clinically meaningful difference in pain with aspiration compared to a 1.5-cm deep PCB (MD -1.00, 95% CI -1.09 to -0.91; 2 RCTs, 229 participants; low-certainty evidence). PCB: four sites versus two sites A two-site (4-8 o'clock) 20 mL 1% lidocaine PCB does not result in a clinically meaningful difference in pain with dilation compared to a four-site (2-4-8-10 o'clock) PCB (MD 8.60, 95% CI 0.69 to 16.51; 1 RCT, 163 participants; high-certainty evidence). Overall, participants reported moderately high satisfaction with pain control and studies reported few adverse events.

AUTHORS' CONCLUSIONS

Evidence from this updated review indicates that a 20 mL 1% plain lidocaine PCB decreases pain during an abortion procedure. Evidence supports forgoing buffering lidocaine and a wait time between PCB injection and cervical dilation. A 1.5-cm deep injection as opposed to a 3-cm deep injection is sufficient. A two-site PCB injection as opposed to a four-site injection has similar effectiveness. Topical cervical anaesthesia (10 mL 2% lignocaine gel or 20 mg topical cervical lidocaine spray) as compared to placebo did not decrease pain based on moderate-certainty evidence, but then when compared to PCB, pain control was similar. Due to this inconsistency in evidence regarding the effectiveness of topical anaesthesia, its routine use is presently not supported. This review did not include studies of pain management with conscious sedation but, based on the results of our prior Cochrane review and the 2022 WHO guidelines, we recommend that the option of combination of pain management using conscious sedation plus PCB and non-steroidal anti-inflammatory drugs should be offered where conscious sedation is available as it further decreases pain.

Effectiveness of Nitrous Oxide versus Pethidine/Midazolam for Pain Relief in Minor Gynecological Operative Procedures: A Randomized Controlled Trial

Aim and Objective: To compare the analgesic effectiveness of the patient-controlled inhaled nitrous oxide (Entonox^®) with intravenous opioids (pethidine/midazolam) in reducing pain during minor gynecological operative procedures, including manual vacuum aspiration (MVA), fractional curettage and dilatation and curettage. Materials and Methods: Patients undergoing minor gynecological procedures from August 2021 to December 2022 were randomized to receive nitrous oxide or intravenous pethidine (50-75 micrograms) plus midazolam (2 mg). Pain scores during and post-procedure, satisfaction level, and side effects were assessed and compared. Results: A total of 106 patients met the inclusion criteria, including 53 in the pethidine/midazolam group and 53 in the nitrous oxide group. Baseline characteristics were comparable (p-value > 0.05). Pain scores during, immediately and 30 min after procedures were not significantly different in two groups (4.94 ± 3.15, 2.74 ± 2.57, 1.58 ± 2.13 vs. 5.47 ± 2.80, 2.98 ± 2.70, 1.64 ± 2.70; p-value: 0.174, 0.634, 0.889, for pethidine/midazolam vs. nitrous oxide group, respectively. Satisfaction scores were comparable in both groups (p-value > 0.05). However, the rate of side effects was significantly lower in the nitrous oxide group (3.8% vs. 28.3%; p-value 0.001). Additionally, the discharge scores showed a significantly faster recovery time in the nitrous oxide group at 60 and 90 min after the procedure; median (IQR): 10 (9-10) vs. 9 (8-10) and 10 (10-10) vs. 10 (8.5-10); p-value 0.002 and 0.029, respectively). Conclusions: Nitrous oxide is as effective as pethidine/midazolam for pain relief in minor gynecological operative procedures but associated with significantly lower side effects and significantly faster recovery time.

Analgesic efficacy and safety of paracervical block versus conscious sedation in the surgical evacuation of the uterus following first-trimester incomplete miscarriages: A randomised controlled trial

Objective:

To compare the analgesic efficacy and safety of paracervical block and conscious sedation in the surgical evacuation of the uterus following a first-trimester miscarriage.

Methods:

This is an open-label, randomised control trial comparing pain relief by paracervical block versus conscious sedation during manual vacuum aspiration of first-trimester incomplete miscarriages. One-hundred and sixty-two women were equally randomised into two groups. Group A (paracervical group) received a paracervical block of 4 ml of lidocaine each at the 4 and 8 o’clock positions. Group B (conscious sedation group) received intravenous 30 mg pentazocine and 10 mg diazepam. Data obtained were presented using a frequency table, student t-test, chi-square and Mann–Whitney test and bar chart. A P-value of ⩽0.05 was taken to be statistically significant.

Results:

The mean pain score was lower in the paracervical block group compared to the conscious sedation group (P < 0.05); however, there was no significant difference in women’s satisfaction between the groups (P ⩾ 0.05). Conscious sedation had more negative side effects compared to paracervical block which was significant (P < 0.05).

Conclusion:

Paracervical block has better pain control compared with conscious sedation and has a good side effect profile.

Trial registration:

Pan African Clinical Trial Registry (registered trial no. PACTR202108841661192).

Synopsis

Paracervical block for manual vacuum aspiration (MVA) during first-trimester miscarriage is associated with less pain among women compared with conscious sedation.

Nitrous oxide for pain management of first-trimester instrumental termination of pregnancy under local anaesthesia and/or minimal sedation: A systematic review and meta-analysis

BACKGROUND

Inhalation of nitrous oxide and oxygen (N₂O/O₂) is used to reduce pain that is spontaneous or induced by procedures. N₂O/O₂ could be useful in the treatment of the pain in first-trimester termination of pregnancy performed under local anaesthesia and/or minimal sedation (FTOPL).

OBJECTIVE

To evaluate the usefulness of N₂O/O₂ to reduce pain in FTOPL.

SEARCH STRATEGY

Electronic databases including PubMed, Embase, and MEDLINE were searched using keywords.

STUDY SELECTION

All studies comparing the use of N₂O/O₂ versus a placebo in the management of pain during FTOPL during the first trimester were included. Of the 199 studies identified, four were deemed eligible for this meta-analysis.

DATA COLLECTION

The extracted results were perioperative pain, immediate and delayed postoperative pain, anxiety scores, and the secondary effects (nausea, vomiting). The data were analysed using Comprehensive Meta-Analysis software version 2.2.064.

MAIN RESULTS

There was a significant difference in favour of N₂O/O₂ for perioperative pain (p = 0.006; SMD = - 0.31; 95 % CI, -0.54 - -0.09). No difference was found, however, in postoperative pain, nor was there a difference in the secondary effects (nausea, vomiting) (p = 0.61). A significant decrease in postoperative anxiety scores was seen in the pooled placebo group (p = 0.049; SMD = 0.41; and 95 % CI, 0.001-0.83).

CONCLUSIONS

N₂O/O₂ reduces the pain of FTOPL. N₂O/O₂ could be recommended in FTOPL.

Impact of music therapy before first-trimester instrumental termination of pregnancy: a randomised controlled trial

OBJECTIVES

To evaluate the impact of preoperative Music Therapy (MT) on pain in first-trimester termination of pregnancy (TOP) under local anaesthesia.

DESIGN

Randomised controlled trial comparing women undergoing a first-trimester TOP under local anaesthesia with or without a preoperative MT session.

SETTING

University Hospital of Angers from November 2016 to August 2017.

POPULATION

Women who underwent first-trimester TOP under local anaesthesia.

METHODS

Women allocated to the MT group underwent a preoperative 20-minute session of MT.

MAIN OUTCOME MEASURES

Pain was assessed using a visual analogue scale (VAS) just before the procedure, during the procedure, at the end of the procedure and upon returning to the ward.

RESULTS

A total of 159 women were randomised (80 in the MT group, and 79 in the control group). Two women were excluded from the control group and six from the MT group. Therefore, 77 women were analysed in the control group and 74 in the MT group. The intensity of pain was similar in the two groups just before the procedure (VAS 4.0 ± 2.9 versus 3.6 ± 2.5; P = 0.78), during the procedure (VAS 5.3 ± 2.5 versus 4.9 ± 2.9; P = 0.78), at the end of the procedure (VAS 2.7 ± 2.4 versus 2.6 ± 2.4; P = 0.43) and upon returning to the ward (VAS 1.8 ± 2.0 versus 1.5 ± 2.0; P = 0.84). The difference in pain between entering the department and returning to the room after the procedure was similar between the MT and control groups (difference in VAS 0.3 ± 2.5 versus 0.3 ± 2.4; P = 0.92).

CONCLUSION

An MT session before a TOP under local anaesthesia procedure resulted in no improvement in patient perception of pain during a first-trimester TOP.

TWEETABLE ABSTRACT

Music therapy before first-trimester termination of pregnancy under local anaesthesia did not improve the perception of pain.

No. 360-Induced Abortion: Surgical Abortion and Second Trimester Medical Methods

OBJECTIVE

This guideline reviews evidence relating to the provision of surgical induced abortion (IA) and second trimester medical abortion, including pre- and post-procedural care.

INTENDED USERS

Gynaecologists, family physicians, nurses, midwives, residents, and other health care providers who currently or intend to provide and/or teach IAs.

TARGET POPULATION

Women with an unintended or abnormal first or second trimester pregnancy.

EVIDENCE

PubMed, Medline, and the Cochrane Database were searched using the key words: first-trimester surgical abortion, second-trimester surgical abortion, second-trimester medical abortion, dilation and evacuation, induction abortion, feticide, cervical preparation, cervical dilation, abortion complications. Results were restricted to English or French systematic reviews, randomized controlled trials, clinical trials, and observational studies published from 1979 to July 2017. National and international clinical practice guidelines were consulted for review. Grey literature was not searched.

VALUES

The quality of evidence in this document was rated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology framework. The summary of findings is available upon request.

BENEFITS, HARMS, AND/OR COSTS

IA is safe and effective. The benefits of IA outweigh the potential harms or costs. No new direct harms or costs identified with these guidelines.

Nitrous Oxide Compared With Intravenous Sedation for Second-Trimester Abortion: A Randomized Controlled Trial

OBJECTIVE

To assess whether inhaled nitrous oxide is noninferior to intravenous (IV) sedation for pain control during outpatient surgical abortion between 12 and 16 weeks of gestation.

METHODS

We enrolled women undergoing surgical abortion at 12-16 weeks of gestation into a multisite, double-blind clinical trial. Participants were randomized to sedation with nitrous oxide (70% nitrous/30% oxygen) or IV fentanyl (100 micrograms) and midazolam (2 mg). Paracervical block was administered to both groups. The primary outcome measure was immediate postabortion recall of maximum pain on a 100-mm visual analog scale.

RESULTS

Between August 2016 and March 2017, we assessed 170 women for eligibility and enrolled 39, 19 in the nitrous group and 20 in the IV sedation group. Seven participants in the nitrous group (36.8%) required conversion to IV sedation for inadequate pain control. No participants in the IV sedation group required additional medication. The proportion of women requiring additional pain control in the nitrous group exceeded our predefined stopping rule. Intention-to-treat analysis demonstrated that immediate postabortion visual analog scale pain scores were lower by 20.1 mm (95% CI 1.6-38.6) in women randomized to IV sedation than in women randomized to nitrous.

CONCLUSION

Intravenous sedation is a better choice than inhaled nitrous oxide for pain control in second-trimester abortion.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02755090.

European Society of Anaesthesiology Task Force on Nitrous Oxide: a narrative review of its role in clinical practice

Nitrous oxide (N₂O) is one of the oldest drugs still in use in medicine. Despite its superior pharmacokinetic properties, controversy remains over its continued use in clinical practice, reflecting in part significant improvements in the pharmacology of other anaesthetic agents and developing awareness of its shortcomings. This narrative review describes current knowledge regarding the clinical use of N₂O based on a systematic and critical analysis of the available scientific literature. The pharmacological properties of N₂O are reviewed in detail along with current evidence for the indications and contraindications of this drug in specific settings, both in perioperative care and in procedural sedation. Novel potential applications for N₂O for the prevention or treatment of chronic pain and depression are also discussed. In view of the available evidence, we recommend that the supply of N₂O in hospitals be maintained while encouraging its economic delivery using modern low flow delivery systems. Future research into its potential novel applications in prevention or treatment of chronic conditions should be pursued to better identify its role place in the developing era of precision medicine.

A prospective study of the frequency of severe pain and predictive factors in women undergoing first-trimester surgical abortion under local anaesthesia

OBJECTIVE

To determine the frequency of severe pain among women and to identify the associated predictive factors during first-trimester surgical abortion under local anaesthesia (LA).

STUDY DESIGN

A prospective cohort study from November 2013 to January 2014 at the Department of Gynecology and Obstetrics, Rennes, France. The study population was composed of one hundred and ninety-four patients who underwent an elective first-trimester surgical abortion under LA. In an anonymized questionnaire, the participants were asked to self-record their perceived pain level 30 min after the completion of the procedure using a 10 cm visual analogue scale (VAS). The main outcome measure was the frequency of severe pain among women, defined as VAS ≥ 7. Secondary outcome measure was the risk factor(s) for severe pain.

RESULTS

Severe pain (i.e. VAS ≥ 7) was experienced by 46% (95% CI: 39%-53%) of the population. Multivariate analysis confirmed that >10 weeks of gestation (OR: 2.530 [95% CI: 1.1-5.81], p = .0287) and having 0 or 1 child (OR: 5.206 [95% CI: 1.87-14.49], p = .0016) were significant independent factors of severe pain.

CONCLUSION

Nearly half of the women experienced severe pain. More than 10 weeks of gestation and parity were predictive factors of severe pain. These findings should be useful in counselling women undergoing surgical abortion under LA.

Nitrous oxide versus oral sedation for pain management of first-trimester surgical abortion - a randomized study

OBJECTIVE

The objective of the study was to compare nitrous oxide with oxygen (N₂O/O₂) to oral hydrocodone/acetaminophen and lorazepam for analgesia during first-trimester surgical abortion.

STUDY DESIGN

This double-blind randomized trial assigned women undergoing first-trimester surgical abortion at<11 weeks' gestation to inhaled N₂O/O₂ vs. oral sedation for pain management. The N₂O/O₂ group received up to 70:30 ratio during the procedure and placebo pills preprocedure; the oral group received inhaled oxygen during the procedure and oral hydrocodone/acetaminophen 5 mg/325 mg and lorazepam 1 mg preprocedure. The primary outcome was maximum procedural pain, assessed on a 100-mm visual analog scale (VAS; anchors 0=no pain and 100=worst pain) at 2 min postprocedure. A difference of 13 mm on the VAS was considered clinically significant. Satisfaction with pain management was measured on a 100-mm VAS (anchors 0=very unsatisfied, 100=very satisfied).

RESULTS

We randomized 140 women, 70 per study arm. Mean age of participants was 26±6.6 years; mean gestational age was 7.3±1.5 weeks. Mean maximum procedure pain scores were 52.5±26.7 and 60.8±24.4 for N₂O/O₂ and oral groups, respectively (p=.09). Satisfaction with pain management was 69.3±28.4 and 61.5±30.4 for N₂O/O₂ and oral groups. respectively (p=.15).

CONCLUSION

We found no difference in mean procedural pain scores between women assigned to N₂O/O₂ vs. those assigned to oral sedation for first-trimester surgical abortion. Satisfaction with both options was high.

IMPLICATIONS

Women undergoing early surgical abortion experienced no differences in pain and satisfaction between those who used inhaled nitrous oxide and oral sedation. Nitrous oxide, with side effects limited to the duration of inhalation and no need for a ride home, is a viable alternative to oral sedation for first-trimester abortion pain management.

Risk Assessment of Using Entonox for the Relief of Labor Pain: A Healthcare Failure Modes and Effects Analysis Approach

INTRODUCTION

In order to prevent medical errors, it is important to know why they occur and to identify their causes. Healthcare failure modes and effects analysis (HFMEA) is a type of qualitative descriptive that is used to evaluate the risk. The aim of this study was to assess the risks of using Entonox for labor pain by HFMEA.

METHODS

A mixed-methods design (qualitative action research and quantitative cross-sectional research) was used. The modes and effects of failures in the process of using Entonox were detected and analyzed during 2013-2014 at Hefdahe Shahrivar Hospital, Mashhad, Iran. Overall, 52 failure modes were identified, with 25 being recognized as high-risk modes.

RESULTS

The results revealed that 48.5% of these errors fall into the care process type, 22.05% belong to the communicative type, 19.1% fall into the administrative type, and 10.2% are of the knowledge and skills type. Strategies were presented in the forms of acceptance (3.2%), control (90.3%), and elimination (6.4%).

CONCLUSION

The following actions are suggested for improving the process of using Entonox: Close supervision by the midwife, precise recording of all the stages of the process in the woman's medical record, the necessity of the presence of the anesthesiologist at the woman's bedside during labor, confirming the indications for use of Entonox, and close monitoring to ensure the safety of the gas cylinder guards.

Nitrous oxide for pain management of first trimester surgical abortion -- a randomized controlled pilot study

OBJECTIVE

The objective was to determine feasibility of a study comparing mean pain scores between women randomized to nitrous oxide/oxygen (NO) versus oxygen+oral analgesics for trimester surgical abortion.

STUDY DESIGN

Pilot randomized controlled trial comparing NO (n=10) versus oxygen+oral analgesics (n=10). Feasibility of subject recruitment, and pain and satisfaction scores on a visual analog scale were evaluated.

RESULTS

Fifty-seven percent of eligible women participated. Mean pain scores were similar between groups, and mean satisfaction scores were higher for the NO group (77.5 vs. 46.7, P=.048).

CONCLUSIONS

The majority of eligible women agreed to participate in this study evaluating an uncommon pain control intervention.

Comparison of remifentanil: Entonox with Entonox alone in labor analgesia

Background:

We designed a study to evaluate the effectiveness of continuous low dose infusion of remifentanil adding to self-administration of entonox administered for pain relief during the active phase of first stage of labor.

Materials and Methods:

Thirty healthy term pregnant women recruited in our randomized double-blind, cross over study. They received the study medicines during two 30-min periods with a 15-min wash-out sequence after each period. Fifteen parturient used remifentanil as a single bolus dose followed by constant low dose infusion and self-administration of entonox (group R) during the first period and entonox and saline (group P) during the second period, while the remainder of the parturient used the drugs in a reverse order. Pain and Ramsay score, maternal and fetal hemodynamic, and ventilation were assessed during each intervention.

Results:

In this study, mean pain severity scores were 8 ± 0.9 before and 5.4 ± 1.7 after intervention in group P, and 7.8 ± 0.1, 3.5 ± 1.3 in group R, respectively. Mean pain severity difference was 2.6 ± 1.5 in group P, while 4.3 ± 1.5 in group R; so, use of entonox and remifentanil can decrease labor pain two times more in comparison with entonox/placebo (normal saline). However, hemodynamic and ventilation parameter in remifentanil/entonox period were same as in entonox/placebo period. No statistical differences were seen in mean Ramsay score between group R and P. There was no episode of maternal bradycardia, hypotension, or hypoxemia.

Conclusion:

Not only adding low dose infusion of remifentanil to self-administration of entonox was notable in labor pain reduction, it did n’t make more parturient and neonatal side-effects.

Pain control in first trimester surgical abortion

BACKGROUND

First trimester abortions especially cervical dilation and suction aspiration are associated with pain, despite various methods of pain control.

OBJECTIVES

Compare different methods of pain control during first trimester surgical abortion.

SEARCH STRATEGY

We searched multiple electronic databases with the appropriate key words, as well as reference lists of articles, and contacted professionals to seek other trials.

SELECTION CRITERIA

Randomized controlled trials comparing methods of pain control in first trimester surgical abortion at less than 14 weeks gestational age using electric or manual suction aspiration. Outcomes included intra- and postoperative pain, side effects, recovery measures and satisfaction.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data. Meta-analysis results are expressed as weighted mean difference (WMD) or Peto Odds ratio with 95% confidence interval (CI).

MAIN RESULTS

We included forty studies with 5131 participants. Due to heterogeneity we divided studies into 7 groups:Local anesthesia: Data was insufficient to show a clear benefit of a paracervical block (PCB) compared to no PCB or a PCB with bacteriostatic saline. Pain scores during dilation and aspiration were improved with deep injection (WMD -1.64 95% CI -3.21 to -0.08; WMD 1.00 95% CI 1.09 to 0.91), and with adding a 4% intrauterine lidocaine infusion (WMD -2.0 95% CI -3.29 to -0.71, WMD -2.8 95% CI -3.95 to -1.65 with dilation and aspiration respectively).PCB with premedication: Ibuprofen and naproxen resulted in small reduction of intra- and post-operative pain.Analgesia: Diclofenac-sodium did not reduce pain.Conscious sedation: The addition of conscious intravenous sedation using diazepam and fentanyl to PCB decreased procedural pain.General anesthesia (GA): Conscious sedation increased intraoperative but decreased postoperative pain compared to GA (Peto OR 14.77 95% CI 4.91 to 44.38, and Peto OR 7.47 95% CI 2.2 to 25.36 for dilation and aspiration respectively, and WMD 1.00 95% CI 1.77 to 0.23 postoperatively). Inhalation anesthetics are associated with increased blood loss (p<0.001).GA with premedication: The COX 2 inhibitor etoricoxib, the non-selective COX inhibitors lornoxicam, diclofenac and ketorolac IM, and the opioid nalbuphine were improved postoperative pain.Non-pharmacological intervention: Listening to music decreased procedural pain.No major complication was observed.

AUTHORS' CONCLUSIONS

Conscious sedation, GA and some non-pharmacological interventions decreased procedural and postoperative pain, while being safe and satisfactory to patients. Data on the widely used PCB is inadequate to support its use, and it needs to be further studied to determine any benefit.

A review of the safety of 50% nitrous oxide/oxygen in conscious sedation

Few studies into conscious sedation with 50% nitrous oxide/oxygen premix (50% N2O/O2) have been conducted in accordance with Good Clinical Practice in Clinical Trials. Of the 140 articles retained in this review, the incidence of adverse events (AEs) varied in the range of 0-68% according to the indications. When other drugs and/or local anaesthesia were used concomitantly, the relative risk for nausea and vomiting increased whereas it decreased for vertigo or hallucinations. Only one study examined potential causal relationship between serious AEs and the 50% N2O/O2 gas itself, giving a risk for a serious AE directly due to the gas of 3/10,000 administrations. No analysis of the effect of the method of administration was possible, nor could conclusions be drawn relating to the risk of occupational exposure.