Nitric oxide donors for cervical ripening in first‐trimester surgical abortion
Abstract
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 We contacted experts in the field for information on both published and unpublished trials.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 eight studies involving 718 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 ineffective in cervical ripening comparing with placebo or no treatment. The cumulative force required to dilate the cervix to 8 mm (mean difference ‐4.29, 95% CI ‐9.92, 1.35), baseline cervical dilatation before the procedure (mean difference 0.21, 95% CI ‐0.12, 0.53), headache (RR 1.73, 95% CI 0.86, 3.46), abdominal pain (RR 0.87, 95% CI 0.51, 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, 6.75).
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 inferior to prostaglandins for first‐trimester cervical ripening, and associated with more side effects. NO donors are comparable to placebo and no treatment for cervical ripening.
PICOs
Plain language 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 comparable to placebo (a sugar pill). Prostaglandins are better than nitric oxide donors for preparing the cervix.
