Nitric oxide donors for cervical ripening in first-trimester surgical abortion: Cochrane systematic review

Abstract

Assessed as up to date: 2011/10/05

Background

Cervical priming before first-trimester surgical abortion is recommended in certain groups of women. Nitric oxide (NO) donors induce cervical ripening without uterine contractions, but the efficacy and side effects are of concern.

Objectives

To evaluate efficacy, side effects and complications of NO donors for cervical ripening before first-trimester surgical abortion.

Search methods

We searched the Cochrane Controlled Trials Register, MEDLINE, EMBASE and POPLINE. We also searched reference lists of retrieved papers. We contacted experts in the field for information on both published and unpublished trials.

Selection criteria

Randomised controlled trials comparing NO donors alone or in combination with other methods for cervical ripening in first-trimester surgical abortion.

Data collection and analysis

Two reviewers independently selected and extracted the data onto a data extraction form. We processed the data using Review Manager (RevMan5) software.

Main results

We included nine studies involving 766 participants. There were no serious complications (infection requiring antibiotic treatment, blood transfusion, complications requiring unintended operation, cervical injury, uterine perforation, death or serious morbidity) in the trials included.

NO donors were more effective in cervical ripening comparing with placebo or no treatment. Baseline cervical dilatation before the procedure was higher in NO donors group (mean difference 0.30, 95% CI 0.01, 0.58) The cumulative force required to dilate the cervix to 8 mm (mean difference -4.29, 95% CI -9.92, 1.35), headache (RR 1.73, 95% CI 0.86, 3.46), abdominal pain (RR 0.87, 95% CI 0.50, 1.50) or patient satisfaction (RR 0.95, 95% CI 0.84, 1.07) were not different. More nausea and vomiting occurred in the women who received a NO donor (RR 2.62, 95% CI 1.07, 6.45).

NO donors were inferior to prostaglandins for cervical ripening. The cumulative force required to dilate the cervix to 8-9 mm was higher (mean difference 13.12, 95% CI 9.72, 16.52) and baseline cervical dilatation was less (mean difference -0.73, 95% CI -1.01, -0.45) in the NO donor group. Side effects including headache (RR 5.13, 95% CI 3.29, 8.00), palpitation (RR 3.43, 95% CI 1.64, 7.15), dizziness (RR 3.29, 95% CI 1.46, 7.41) and intraoperative blood loss (mean difference 33.59 ml, 95% CI 24.50, 42.67) were also higher. However, abdominal pain (RR 0.33, 95% CI 0.25, 0.44) and vaginal bleeding (RR 0.14, 95% CI 0.07, 0.27) was less in the NO donor group. Patient satisfaction was not different.

One trial compared a NO donor with a NO donor plus prostaglandin. The cumulative force required to dilate the cervix to 8 mm was higher (mean difference 14.50, 95% CI 0.50, 28.50) in the NO donor group. There was no difference in headache (RR 0.88, 95% CI 0.38, 2.00), abdominal pain (RR 0.14, 95% CI 0.02, 1.07) or intraoperative blood loss (mean difference -50, 95% CI -164.19, 64.19).

Authors' conclusions

NO donors are superior to placebo or no treatment, but inferior to prostaglandins for first-trimester cervical ripening, and associated with more side effects.

Author(s)

Promsonthi Patama, Preechapornprasert Domerudee, Chanrachakul Boonsri

Summary

Preparing the cervix with nitric oxide donors before surgical abortion in the first three months of pregnancy

Possible complications of surgical abortion in the first three months of pregnancy include injury to the cervix (the neck of the womb) and the womb itself. Preparing the cervix before surgery might make the procedure safer and easier. There are several methods to prepare the cervix. This review compared drugs called nitric oxide donors with other drugs.

We did a computer search for randomised trials of nitric oxide donors used before surgical abortion. We found that nitric oxide donors are better than placebo (a sugar pill). Prostaglandins are better than nitric oxide donors for preparing the cervix.

Reviewer's Conclusions

Implications for practice

Nitric oxide donors alone were superior to placebo or no treatment in terms of efficacy for cervical ripening, but caused more nausea and vomiting. Prostaglandins were more effective than NO donors for cervical ripening with fewer incidences of headache, palpitation, dizziness and operative blood loss, but associated with higher incidence of abdominal pain and vaginal bleeding. Given the safety, wide availability, and low cost of prostaglandins, these should be the medical treatment of choice.

Implications for research

NO donors are more effective than placebo or no treatment for cervical ripening before first trimester surgical abortion. NO donors were clearly inferior to prostaglandins for cervical priming. Further researches on the optimal dose and interval of NO donors are needed. Only large randomised trials would have the power to detect clinically important differences in outcomes such as cervical injury or uterine perforation. The validity of surrogate markers used in trials to date is unknown.

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