Does temperature of distending medium matter in outpatient hysteroscopy? A double-blinded cohort control observational study of room temperature versus warmed saline

Uterine distension media for outpatient hysteroscopy

BACKGROUND

Hysteroscopy done in an outpatient setting is the 'gold standard' method for evaluating the uterine cavity. Media used to distend the uterine cavity include gas as carbon dioxide and liquid as saline that can be used at room temperature or warmed to body temperature. Both media offer advantages as well as disadvantages.

OBJECTIVES

The objective of this review is to compare the effectiveness, tolerability, and safety of gas (carbon dioxide) and liquid (normal saline) used for uterine distension during outpatient hysteroscopy.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility (CGF) Group Specialised Register, CENTRAL, MEDLINE, Embase and PsycINFO on 28 April 2021. We checked references of relevant trials and contacted study authors and experts in the field to identify additional studies. CINAHL records and ongoing trials from the trial registries were included in the CENTRAL search.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing saline with carbon dioxide, as well as RCTs comparing saline at different temperatures, for uterine distension in outpatient hysteroscopy done for any indication.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Primary review outcomes were patient tolerability and adverse events or complications related to the distending medium. Secondary outcomes were quality of the hysteroscopic view and duration of the procedure.

MAIN RESULTS

We included 12 RCTs (1946 women). The quality of evidence ranged from very low to high: the main limitations were risk of bias due to absence of blinding due to the nature of the procedure, imprecision, and inconsistency. Saline versus carbon dioxide Analysis ruled out a clinically relevant difference in pain scores during the procedure between saline and carbon dioxide, but the quality of evidence was low (standardised mean difference (SMD) -0.07, 95% confidence interval (CI) -0.17 to 0.02; 9 RCTs, N = 1705; I² = 86%). This translates to differences of 0.39 cm (lower) and 0.05 cm (higher) on a 10-cm visual analogue scale (VAS). Evidence was insufficient to show differences between groups in the proportion of procedures abandoned due to intense pain (Peto odds ratio (OR) 0.48, 95% CI 0.09 to 2.42; 1 RCT, N = 189; very low-quality evidence). We are uncertain whether saline decreases the need for analgesia compared to carbon dioxide (Peto OR 0.34, 95% CI 0.12 to 0.99; 1 RCT, N = 189; very low-quality evidence). Saline compared to carbon dioxide is probably associated with fewer vasovagal reaction events (Peto OR 0.53, 95% CI 0.32 to 0.86; 6 RCTs, N = 1076; I² = 0%; moderate-quality evidence) and fewer shoulder-tip pain events (Peto OR 0.28, 95% CI 0.14 to 0.54; 4 RCTs, N = 623; I² = 0%, moderate-quality evidence). Evidence suggests that if 10% of women undergoing outpatient hysteroscopy experience a vasovagal reaction event with the use of carbon dioxide, this rate would be between 3% and 9% with the use of saline. Similarly, if the rate of shoulder-tip pain with carbon dioxide is 9%, it would be between 1% and 5% with saline. We are uncertain whether saline is similar to carbon dioxide in terms of endometrial bleeding (Peto OR 0.83, 95% CI 0.25 to 2.75; 2 RCTs, N = 349; I² = 0%; very low-quality evidence). Infection was not reported by any study in this comparison. Saline may result in fewer procedures with an unsatisfactory hysteroscopic view than carbon dioxide (Peto OR 0.51, 95% CI 0.32 to 0.82; 5 RCTs, N = 1082; I² = 67%; low-quality evidence). The duration of the procedure was shorter with saline in three of the four studies that reported this outcome, and duration was similar in both arms in the fourth study. Warm saline versus room temperature saline Use of warm saline for uterine distension during office hysteroscopy may reduce pain scores when compared with room temperature saline (mean difference (MD) -1.14, 95% CI -1.55 to -0.73; 3 RCTs, N = 241; I² = 77%; low-quality evidence). Evidence is insufficient to show differences between groups in either the proportion of procedures abandoned due to intense pain (Peto OR 0.97, 95% CI 0.06 to 15.87; 1 RCT, N = 77; very low-quality evidence) or the need for analgesia (Peto OR 1.00, 95% CI 0.14 to 7.32; 1 RCT, N = 100; very low-quality evidence). Analysis ruled out a clinically relevant difference in duration of the procedure between warm and room temperature saline, but the quality of evidence is low (MD 13.17 seconds, 95% CI -12.96 to 39.29; 2 RCTs, N = 141; I² = 21%). No cases of infection were reported in either group (1 RCT, N = 100). No other adverse events and no information on quality of the hysteroscopic view were reported by any study in this comparison.

AUTHORS' CONCLUSIONS

Evidence was insufficient to show differences between different distension media used for uterine distension in outpatient hysteroscopy in terms of patient tolerability, operator satisfaction, or duration of the procedure. However, saline was superior to carbon dioxide in producing fewer adverse events (shoulder-tip pain and vasovagal reaction).

Warm distension fluid reduces pain severity in office hysteroscopy: a randomized controlled trial

BACKGROUND

Abnormal uterine bleeding (AUB) affects approximately 14% to 25% of women of reproductive age. The most common use of office hysteroscopy is to evaluate pathologies related to AUB and reproductive health, but office hysteroscopy can also be used for the diagnosis and treatment of other intrauterine pathologies.

OBJECTIVE

Investigate the effects of the temperature of the distension fluid on pain severity in patients undergoing diagnostic office hysteroscopy due to AUB.

DESIGN

Randomized controlled clinical trial.

SETTING

Tertiary care center in Turkey.

PATIENTS AND METHODS

One hundred perimenopausal patients with AUB were randomly allocated according to the temperature of the distension fluid used in office hysteroscopy (37°C or 25°C). Pain intensity was assessed using a visual analog scale (VAS). Six VAS measurements were compared over the course of the hysteroscopy: pre-treatment (VAS-1), at vaginal entry (VAS-2), at the cervical ostium transition (VAS-3), while in the cavity (VAS-4), at the end of the procedure (VAS-5), and 30 minutes after the end of the procedure (VAS-6).

MAIN OUTCOME MEASURE

VAS SAMPLE SIZE: Fifty in each group enrolled, one drop out.

RESULTS

The VAS-3, VAS-4, and VAS-5 scores were significantly lower for patients in the warm fluid group than in the room temperature group (P<.05), whereas the VAS-1, VAS-2, and VAS-6 scores were similar in both groups.

CONCLUSION

The application of warm distension fluid in office hysteroscopy reduces pain severity compared with the application of an unheated fluid.

LIMITATIONS

The main limitations of the study were that a subgroup analysis could not be performed due to an insufficient number of cases, and we were unable to evaluate vasovagal symptoms.

CONFLICT OF INTEREST

None.

A Systematic Review of the Effect of Type, Pressure, and Temperature of the Distension Medium on Pain During Office Hysteroscopy

OBJECTIVE

To identify the optimal distension medium type, pressure, and temperature to minimize pain during office hysteroscopy.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and CENTRAL were searched from inception to January 29, 2020.

METHODS OF STUDY SELECTION

We included randomized controlled trials in which women undergoing office hysteroscopy were randomized to either a distension medium type, pressure, or temperature against a suitable control, where pain was an outcome. Data regarding feasibility, visualization, complications, and satisfaction were also collected.

TABULATION, INTEGRATION, AND RESULTS

The literature search returned 847 studies, of which 18 were included for systematic review and 17 for meta-analysis. There was no significant difference in intraprocedural pain when comparing the use of normal saline against carbon dioxide (standardized mean difference [SMD], -0.12; 95% confidence interval [CI], -0.36 to 0.13). Subgroup analysis of high-quality studies revealed a statistically significant reduction in postprocedural pain with normal saline (SMD, -0.65; 95% CI, -1.14 to -0.16). Side effects were less frequent (Peto odds ratio, 0.29; 95% CI, 0.20-0.40) and patient satisfaction was higher (SMD, 1.39; 95% CI, 0.51-2.28) with normal saline compared with carbon dioxide. Pressures of ≤40 mm Hg reduced intraprocedural pain (SMD, -0.67; 95% CI, -1.09 to -0.26) at the expense of a higher proportion of unsatisfactory views (81%-89% at ≤40 mm Hg vs 95%-99% at ≥50 mm Hg). Postprocedural pain was reduced with lower filling pressures. Warming saline did not reduce intraprocedural pain (SMD, 0.59; 95% CI, -0.14 to 1.33).

CONCLUSION

Normal saline, instilled at the lowest pressure to acquire a satisfactory view, should be used for uterine distension during office hysteroscopy to minimize pain.