Anaesthesia for evacuation of incomplete miscarriage

An incomplete miscarriage occurs when all the products of conception are not expelled through the cervix. Curettage or vacuum aspiration have been used to remove retained tissues. The anaesthetic techniques used to facilitate this procedure have not been systematically evaluated in order to determine which provide better outcomes to the patients.

To assess the effects of general anaesthesia, sedation or analgesia, regional or paracervical block anaesthetic techniques, or differing regimens of these, for surgical evacuation of incomplete miscarriage.

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (23 January 2012), CENTRAL (The Cochrane Library 2012, Issue 1), PubMed (1966 to 23 January 2012), EMBASE (1974 to 23 January 2012), CINAHL (1982 to 23 January 2012), LILACS (1982 to 23 January 2012) and reference lists of retrieved studies.

All published and unpublished randomised controlled trials (RCTs) or cluster-RCTs comparing the use of any anaesthetic technique (defined by authors as general anaesthesia, sedation/analgesia, regional or paracervical local block (PCB) procedures) to perform surgical evacuation of an incomplete miscarriage. We excluded quasi-randomised trials and studies that were only available as abstracts.

Two review authors independently assessed studies for inclusion and assessed risk of bias. Data were independently extracted and checked for accuracy.

We included seven trials involving 800 women. The comparisons revealed a very high clinical heterogeneity. As a result of the heterogeneity in the randomisation unit, we did not combine trials but reported the individual trial results in the 'Data and analysis' section and in the text. Half of trials have unclear or high risk of bias in several domains.We did not find any trial reporting data about maternal mortality. In terms of postoperative pain, PCB does not improve the control of postoperative pain when it is compared against sedation/analgesia or versus no anaesthesia/no analgesia. In the comparison of PCB with lidocaine versus PCB with saline solution, significant differences favouring the group with lidocaine were found in one trial (moderate or severe postoperative pain) (risk ratio (RR) 0.32; 95% confidence interval (CI) 0.18 to 0.59).When opioids were used, postoperative nausea and vomiting was more frequent in two trials comparing those versus PCB. In terms of requirement of blood transfusion, two trials showed conflicting results.

Particular considerations that influence the choice of anaesthesia for this procedure such as availability, effectiveness, safety, side effects, practitioner's choice, costs and woman's preferences of each technique should continue to be used until more evidence supporting the use of one technique or another.