An ARM involves the creation of a small tear, or hole, in the membranes (or bag of waters). By releasing the amniotic fluid, the baby is expected to move down lower onto the woman's cervix, to help stimulate it to open (or dilate). Sometimes, if the cervix is already dilated slightly, (about 3 cms or more) or the woman is in early labour already, this may be all that is required to induce the labour. If you have had a baby before, an ARM is often all that is needed. Be aware that the waters will probably be
meconium stained. That is, they will be dark green or brown in colour, due to the baby opening their bowels.
Again, if you wish to labour in a birth centre, or at home, then this procedure can be done by the midwife at either of these places, and you can go on to give birth there, if no other induction method is needed.
If the cervix is tightly closed, an ARM may be difficult to achieve, and if your caregiver attempts it, it is likely to be quite uncomfortable. In this case, prostaglandins may be used first, to soften and slightly dilate the cervix (and / or induce the labour).
How is it done?
The woman is normally asked to empty her bladder and lie on her back on the bed. The caregiver then performs an internal vaginal examination, to see if the cervix is soft and open enough. If it is, then an 'amnihook', is placed into the vagina, and through the cervix, to make a small hole in the membranes (or bag of waters). If the cervix is slightly open, this should be no more uncomfortable than a normal vaginal examination.
Image 4-36 shows an amnihook that can be used to break the waters.
Intravenous oxytocin infusion (Syntocinon)
Sometimes the labour is induced, using a synthetic oxytocin hormone called 'Syntocinon'. This is a drug used to mimic the body's normal production of the oxytocin hormone that naturally starts labour. You can only be in a delivery suite to use this method.