A randomized controlled study comparing carbon dioxide versus normal saline as distension media in diagnostic office hysteroscopy: is the distension with carbon dioxide a problem?

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).

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.

Pain during diagnostic hysteroscopy: what is the role of the cervical canal? A pilot study

OBJECTIVE

To evaluate whether a correlation exists between the pain perceived during diagnostic anesthesia-free hysteroscopy and the characteristics of the cervical canal.

STUDY DESIGN

Prospective observational pilot study of 255 women undergoing diagnostic hysteroscopy. Data analysis included characteristics of the patient and the cervical canal, and the pain experience during the procedure, assessed by visual analog score (VAS). A multiple logistic regression was then carried out in order to exclude confounding factors.

RESULTS

The degree of pain during hysteroscopy was equal to a median VAS score of 2 (range 0-10). Bivariate analysis between patients with VAS>3 and patients with VAS≤3 demonstrated a significant correlation between pain and the presence of synechiae in the cervical canal (P=0.022), the patient's age (P=0.003) and parity (P=0.001). Multivariate analysis revealed that the presence of cervical synechiae (P=0.0001) [OR=4.99 (95% CI 2.13-11.70)] and parity (P=0.014) [OR=0.42 (95% CI 0.21-0.83)] were significantly correlated with pain. There was no significant correlation with the different angles of the cervical canal.

CONCLUSION

Cervical synechiae appear as a major factor influencing pain during hysteroscopy. While parity acts as a protective factor, the angle of the cervical canal does not seem to play an important role for pain during diagnostic hysteroscopy.

Hysteroscopy: guidelines for clinical practice from the French College of Gynaecologists and Obstetricians

The objective of this study was to provide guidelines for clinical practice from the French College of Obstetrics and Gynecology (CNGOF), based on the best evidence available, concerning hysteroscopy. Vaginoscopy should be the standard technique for diagnostic hysteroscopy (Grade A) using a miniature (≤3.5mm sheath) (Grade A) rigid hysteroscope (Grade C), using normal saline solution distension medium (Grade C), without any anaesthesia (conscious sedation should not be routinely used), without cervical preparation (Grade B), without vaginal disinfection and without antibiotic prophylaxy (Grade B). Misoprostol (Grade A), vaginal oestrogens (Grade C), or GnRH agonist routine administration is not recommended before operative hysteroscopy. Before performing hysteroscopy, it is important to purge the air out of the system (Grade A). The uterine cavity distention pressure should be maintained below the mean arterial pressure and below 120mm Hg. The maximum fluid deficit of 2000ml is suggested when using normal saline solution and 1000ml is suggested when using hypotonic solution. When uterine perforation is recognized during operative hysteroscopy using monopolar or bipolar loop, the procedure should be stopped and a laparoscopy should be performed in order to eliminate a bowel injury. Diagnostic or operative hysteroscopy is allowed when an endometrial cancer is suspected (Grade B). Implementation of this guideline should decrease the prevalence of complications related to hysteroscopy.

[Prevention of the complications related to hysteroscopy: guidelines for clinical practice]

OBJECTIVE

To provide clinical practice guidelines (CPGs) from the French college of obstetrics and gynecology (CNGOF), based on the best evidence available, concerning the adverse events related to hysteroscopy.

MATERIALS AND METHODS

Review of literature using following Keywords: hysteroscopy; vaginoscopy; infection; perforation; intrauterine adhesions

RESULTS

Vaginoscopy should be the standard technique for outpatient hysteroscopy (grade A) using a miniature (≤ 3.5mm sheath) (grade A) rigid hysteroscope (grade C), using normal saline solution distension medium (grade C), without any anesthesia (conscious sedation should not be routinely used), without cervical preparation (grade B), without vaginal disinfection and without antibiotic prophylaxy (grade B). Misoprostol (grade A), vaginal estrogens (grade C), or GnRH agonist routine administration is not recommended before operative hysteroscopy. Before performing hysteroscopy, it is important to purge the air out of the system (grade A). The uterine cavity distention pressure should be maintained below the mean arterial pressure and below 120 mmHg. The maximum fluid deficit of 2000 mL is suggested when using normal saline solution and 1000 mL is suggested when using hypotonic solution. When uterine perforation is recognized during operative hysteroscopy using monopolar or bipolar loop, the procedure should be stopped and a laparoscopy should be performed in order to eliminate a bowel injury. Diagnostic or operative hysteroscopy is allowed when an endometrial cancer is suspected (grade B).

CONCLUSION

Implementation of this guideline should decrease the prevalence of complications related to office and operative hysteroscopy.