Recommendation ID

What are the most effective and acceptable methods of cervical priming before dilatation and evacuation after 16+0 weeks' gestation?

Any explanatory notes
(if applicable)

Between 14+0 and 23+6 weeks

Cervical priming is standard clinical practice for women having a surgical abortion between 14+0 and 23+6 weeks.

There was good evidence that cervical priming regimens using same day or overnight osmotic dilators either increase cervical dilation, make procedures easier to carry out, or both, compared with cervical priming without dilators. However, there was evidence that osmotic dilators are less acceptable to women than mifepristone or misoprostol. In addition, the evidence comparing single priming agents against each other was unclear on whether or not there are differences between dilators and mifepristone in a number of important outcomes, such as cervical trauma, uterine perforation and preoperative expulsion. It was also unclear whether misoprostol alone and osmotic dilators alone gave equivalent baseline cervical dilation, or whether there are clinically important differences. Therefore, the committee recommended all 3 options.

Mifepristone and misoprostol are only recommended between 14+0 and 16+0 weeks and between 14+0 and 19+0 weeks respectively because there was no evidence for them beyond these stages. There was evidence for the 200 mg oral dose of mifepristone given the day before the abortion, but not enough evidence to recommend a specific dose or timing for misoprostol.

There was no evidence for alternatives to osmotic dilators after 19+0 weeks. There was good evidence that mifepristone combined with osmotic dilators reduces procedural difficulty compared with osmotic dilators alone. However, it was unclear if there were differences in safety outcomes such as uterine perforation or cervical trauma. The committee recommended this regimen for women who were between 19+1 and 23+6 weeks' gestation, because later gestational age is associated with increased procedural difficulty.

The committee agreed that further research on whether pharmacological priming is an effective and acceptable alternative to osmotic dilators would be useful, so made a research recommendation.

Limited evidence showed that inserting osmotic dilators the day before the abortion will also make the procedure easier, compared with inserting them on the same day. However, this would involve an additional visit to the clinic, and this may not always be possible. The evidence on inserting osmotic dilators the day before the procedure only covered women having an abortion up to and including 17+6 weeks' gestation. Despite this, the committee agreed that women at later gestations may have the greatest benefit from inserting osmotic dilators the day before, as abortion becomes more complicated at later gestational ages. The committee agreed that further research comparing the timing of osmotic dilator insertion would be beneficial to inform future practice, so made a research recommendation.

Misoprostol does not provide any benefit when used in combination with osmotic dilators, and it may have additional side effects. Further, it was unclear from the evidence whether or not there was an increased risk of preoperative expulsion when the combination was used compared with dilators alone. It is feasible that this risk may increase with additional cervical priming. Therefore, the committee recommended that the combination is not used.

Source guidance details

Comes from guidance
Abortion care
Date issued
September 2019

Other details

Is this a recommendation for the use of a technology only in the context of research? No  
Is it a recommendation that suggests collection of data or the establishment of a register?   No  
Last Reviewed 30/09/2019