INDUCTION OF LABOUR (IOL)
Failed induction of labour
Cord prolapse (obstetric emergency)
Uterine rupture (rare)
Induction is to start labour when there are no contractions and never have been any. Induce/persuade/bring about.
Cervidil® – (PGE2) is a continuous release prostaglandin pessary with a long tape attached to aid retrieval at the end of dosing. Cervidil® which ripens (softens and effaces – thins) the cervix and stimulates uterine contractions is used to induce labour. The active ingredient is dinoprostone. The pessary is inserted high into the posterior vaginal fornix (a large recess behind the cervix). The withdrawal tape will be removed after 12 hours as the medication is a 12 hour controlled release formula, or earlier if clinically indicated – uterine hyperstimulation/fetal distress. After administration, you will need to remain in bed for at least 30 minutes. Your baby will be monitored by a cariotocograph (CTG) machine for a period of time before and after insertion.
Prostin (prostaglandin E2) is a vaginal gel which ripens the cervix and stimulates uterine contractions and is used to induce labour. The active ingredient is dinoprostone. Prostin gel comes in a single use syringe of either 1mg or 2mgs. One or two doses may be required. Administration is intravaginally, inserted high into the vaginal posterior fornix. After administration, you will need to remain in bed for at least 30 minutes. Your baby will be monitored by a cardiotocograph (CTG) machine for a period of time before and after insertion.
Syntocinon is a synthetic form of the hormone oxytocin. A syntocinon infusion (10 units of syntocinon in a one litre flask of Compound Sodium Lactate – CSL (Hartmann’s solution – an intravenous solution used to replace body fluid and mineral salts) can be used at varying strengths to start contractions in an induction of labour, or to increase contractions in an augmentation of labour.
MECHANICAL METHODS – TRANS CERVICAL CATHERERS:
Using a Foley catheter to induce labour is a mechanical method that can ripen and dilate the cervix. A Foley’s catheter is a soft rubber catheter usually used to empty the bladder. The catheter was designed by Frederic Foley, a Boston, Massachusetts surgeion. When the catheter is used to induce labour, the tip is placed into the opening of the cervix. There is a small balloon in the end of the tubing which is inflated with water to stop the tubing from falling out. The tip of the catheter is placed into the opening of the cervix putting even pressure on the inside of the cervix aiming for direct dilatation of the cervicx. This pressure also aims to ripen the cervix through indirect prostaglandin secretion. Often an artificial rupture of membranes (ARM -break the waters surrounding the baby), will be needed to induce labour and a syntocinon infusion may also be required.
If the catheter has not spontaneously fallen out after 12 hours, obstetric review is required.
Used for pre induction cervical dilation. The double balloons x 2 are inserted through the vagina and cervix until both balloons have entered the cervical canal. The uterine balloon is inflated with 40 mls of saline (salt water) and then the device is pulled back until the balloon sits at the internal cervical opening. The vaginal balloon is then visible outside of the external cervical opening and is inflated with 20 mls of saline. Once the balloons are situated on either side of the cervix, saline is added to a maximum of 80 mls per balloon. Placement of the balloon should be timed wo that it is in place on longer than 12 hours before active labour is induced. So one balloon sits in the uterus at the internal opening of the cervix right near baby’s head, and the other balloon sits in the vagina on the external opening of the cervix – see attached diagrams.
ARTIFICIAL RUPTURE OF MEMBRANES (ARM)
ARM can be performed to either augment or induce labour. An amnihook is used to rupture the membranes (break the baby waters). An amnihook looks like a big crochet hook. Aligator forceps can also be used to confirm if ruptured membranes (broken baby waters) are suspected. The clinician will be trying to get a hair/hairs from baby’s head with the aligator forceps to confirm that the membranes have in fact ruptured.
To augment is to increase or make greater where contractions are present but are ineffective. ARM can be used to augment a labour as can a syntocinon infusion where contractions are present but are ineffective.
FETAL SCALP ELECTRODE (FSE)
This is a small clip which is attached to baby’s head after being inserted through the vagina and dilated cervix. A FSE would be used if abdominal fetal monitoring with a cardiotocograph is not adequately picking up the fetal heart rythym.