Carbon dioxide versus normal saline as distension medium for diagnostic hysteroscopy: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: To appraise critically the published randomized controlled trials (RCTs) comparing carbon dioxide (CO2) with normal saline (NS) as distension medium for diagnostic hysteroscopy. DESIGN: Systematic review and meta-analysis of RCTs. SETTING: Outpatient and inpatient hysteroscopy clinics. PATIENT(S): Women undergoing diagnostic hysteroscopy. REFVENTION(S): CO2 or NS as distension medium for diagnostic hysteroscopy. MAIN OUTCOME MEASURE(S): Procedural and shoulder pain, side effects, satisfaction, quality of view, duration of procedure. RESULT(S): Ten RCTs involving 1,839 women (905 in the CO2 group, 934 in the NS group) were systematically analyzed. There was significant heterogeneity among the included trials. Compared with NS, CO2 was associated with greater procedural pain, more occurrences of shoulder pain and side effects, less satisfaction, less quality of view, and greater duration of procedure. CONCLUSION(S): A meta-analysis from the available moderate quality trials suggests that NS might be superior to CO2 for use in diagnostic hysteroscopy. Owing to problems of clinical diversity, statistical heterogeneity, and risk of bias, it is clear that additional pragmatic multicenter RCTs are needed to corroborate these findings before firm evidence-based guidelines can be given.