Optimum uterine filling pressure for outpatient diagnostic hysteroscopy: a double-blind, randomized controlled trial

This study designed a double-blind, randomized controlled trial to assess whether adequate visibility can be achieved with lower uterine filling pressures using normal saline for diagnostic outpatient hysteroscopy and whether patient discomfort can be reduced. A total of 234 patients were randomized to 40 mmHg (77 patients), 70 mmHg (78 patients) or 100 mmHg (79 patients) of uterine filling pressures. The primary outcome measure was the proportion of procedures where adequate visibility was achieved during diagnostic outpatient hysteroscopy. The secondary outcome was the level of pain experienced by the patient as assessed using a visual analogue scale. There was adequate visibility in 87.0% of cases in 40 mmHg group, 94.9% in 70 mmHg group and 97.5% in 100 mmHg group. Visibility was lower with 40 mmHg compared with 70 and 100 mmHg (P < 0.05). The mean pain score in each group was not significantly different. In conclusion, this study showed that there was a higher trend towards inadequate visibility with lower filling pressures. Pressures of 70 and 100 mmHg may be equivalent to each other but not to a pressure level of 40 mmHg. Pain scores do not differ significantly with the pressure options used.Outpatient diagnostic hysteroscopy is an endoscopic examination of the inside of the womb. In order to visualize inside the womb, a clear fluid is usually administered under pressure (100 mmHg) to distend the cavity of the womb. The aim of this study was to establish whether lower filling pressures can be used to visualize inside the womb and whether they can reduce the level of pain the woman experiences. A total of 234 women who were due to undergo an outpatient hysteroscopy procedure in Gynaecology Outpatients Department of the University College London Hospitals (UK) and were able to give informed consent were included in this trial. These women were randomly allocated to three different level of filling pressures (100, 70 or 40 mmHg). The patients and the assessors did not know which pressure level was used. Then the assessor judged whether the visualization was adequate or inadequate and the woman was asked to score the level of pain she experienced during the procedure. If the visualization was inadequate, then the standard filling pressure of 100 mmHg was used to complete the procedure. The visibility was lower in the 40 mmHg group compared with the 70 and 100 mmHg groups (P < 0.05). The mean pain score in each group was not significantly different. In conclusion, this study showed that there was inadequate visibility with lower filling pressures and the pain scores did not seem to differ significantly with the pressure options used.