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Saline best distension medium for diagnostic hysteroscopy

NEW YORK (Reuters Health) – Normal saline is superior to carbon dioxide as a distention medium for diagnostic hysteroscopy, according to a new meta-analysis of clinical trials.

Carbon dioxide led to more procedural pain, more shoulder pain and side effects, worse patient satisfaction, worse quality of view, and longer procedure duration, Dr. Laurentiu Craciunas of St. Mary’s Hospital in Manchester, UK, and his colleagues report in Fertility and Sterility, online September 6.

“Our conclusion and recommendations are based on the summated data from medium to low quality trials so we need a high-quality, well-designed trial, with adequate randomisation and allocation concealment, with blinding of participants and assessors, in order to confirm our findings and provide stronger recommendation,” Dr. Craciunas told Reuters Health by email.

Current Royal College of Obstetricians and Gynaecologists guidelines do not recommend one distention medium over the other due to lack of evidence, he added. “We conducted this systematic review in order to make this decision evidence-based.”

Dr. Craciunas and his colleagues reviewed 10 randomized controlled trials comparing carbon dioxide to normal saline in 1,839 women undergoing diagnostic hysteroscopy. Overall, 905 women received carbon dioxide and 934 were given normal saline.

While there was heterogeneity among the trials looking at procedural pain, pain was significantly worse with carbon dioxide versus normal saline, the researchers found. Among the eight trials that looked at shoulder pain, there was no heterogeneity, and the relative risk (RR) of shoulder pain was 6.25 with carbon dioxide. There also was no heterogeneity among the eight trials that looked at side effects, which found they were nearly twice as frequent with carbon dioxide.

The analysis also found greater patient satisfaction with normal saline. In the six trials that measured quality of view as incidence of unsatisfactory view, there was no heterogeneity, and the RR of unsatisfactory view was 2.51 with carbon dioxide. However, one study using a visual analog scale rated quality of view significantly higher with carbon dioxide versus normal saline.

Procedure duration was longer with carbon dioxide, although there was significant heterogeneity among the six trials that looked at this issue.

“At St. Mary’s Hospital we only use normal saline, but there are other units where carbon dioxide is the initial choice,” Dr. Craciunas told Reuters Health. “In the UK carbon dioxide is used much less compared to other European countries.”

“Before our study there was no clear evidence to support the use of one distension medium over another,” he added. “Carbon dioxide is the preferred medium for some gynaecologists due to the theoretical better view associated with its use, but as we can see in the current meta-analysis the theory is not supported by practical results. In the absence of this advantage, there is nothing to recommend the use of carbon dioxide over normal saline.”


Fertil Steril 2013.