Place of induction : Where facilities for intervention and fetal monitoring is available
Preparation of patient : enema may be given
Factors to assess prior to induction
Maternal Assessment :
Confirm the indication
Exclude the contraindications
Assess Bishop score
Assess pelvic adequacy
Fetal gestational age
Fetal well being
Methods of Induction of Labor
Membrane sweeping - if the cervix has ripened enough to allow the passage of a finger - finger is inserted and the membranes separated from the uterine wall the pressure always being on the uterine wall. It strips the chorioninc membrane from the underlying decidua leading to release prostaglandins. Ensure there is no placenta previa.
Amniotomy - this is artificial rupture of the membranes. - it may be preceded by prostaglandins in prelabor and latent labor - cannot be applied in an unfavourable cervix - it is contraindicated in IUD, HIV - complications : cord prolapse, amnionitis, amniotic fluid embolism, abruptio placentae
Prostaglandins : Administration of prostaglandins sensitises the myometrium to the oxytocin and ripens the cervix. thpes of prostaglandins :
PGE1 from amnion PGE2 from amnion PGF2 from dicidua and myometrium PGI2 from myometrium.
Prostaglandin used : PGE1 (Misoprostol) and PGE2 (Cerviprime) - Contraindications bronchial asthma, pulmonary disease, previous uterine scar.
Misoprostol : Dose of 25 microgram every 4 hours to a maximum of 6 doses intravaginally/Dose of 50 micrograms every 3 hours to a maximum of 6 doses orally/Dose of 25 micrograms every 2 hours orally to a maximum of 6 doses
The chances of fetal distress is less with oral administration than with the vaginal but oral administration is less effective than the vaginal
Dinoprostone : Vaginal gel of 0.5 mg intracervically, may be repeated after 6 hours x 3-4 doses
Vaginal tabs of 3 mg in the posterior fornix; one more dose after 6-8 hours; max- 6 mg
Vaginal pessary 10 mg for 24 hours. To be removed when cervix is adequately ripened
Oxytocin: (Syntocinon) Commonly used- produces uterine contractions and effective in producing changes in cervix and in the descent of the presenting part; commonly IV route is preferred. maximum doseof oxytocin : 5IU in 500 ml of fluid at the rate of 40 drops/min. Started with 10 drops and increased to 20, 30 and 40 gradually.
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PRIOR TO COMMENCING OXYTOCIN
Oxytocin should not be started for six hours following administration of vaginal prostoglandins.
For women with intact membranes an ARM should be performed prior to commencing induction.
Establish fetal well-being immediately prior to commencement of oxytocin.
Perform a 20-30 minute cardiotocograph (CTG) prior to commencing the induction.
Women with a previous caesarean section scar should have discussion and consent to the use of oxytocin. The rupture risk (approximately 1:100) should be explained and this discussion documented in the medical notes.
Standard Dilution of Oxytocin
10 I.U. of oxytocin in 500mL of Hartmannís solution.
At this dilution, a 3mL/hr infusion rate equates to 1milli-unit (mU) of oxytocin per minute.
minus 1 to 0
It is possible only if the cervix has ripened to allow the passage of one finger
Insert a gloved finger through the cervix and rotate against the wall of the uterus
It strips the chorionic membrane from the underlying decidua which leads to release of prostaglandins
Placenta previa should be excluded. Accidental amniotomy is a disadvantage.
Deliver the oxytocin through an infusion pump and ensure the giving set has a double or triple lumen peripheral set (V-set) attached.
Note: The V-Set acts as an anti reflux valve preventing bolus administration of oxytocin.
Where the oxytocin infusion is to run as a sideline to a main intravenous line, it should be connected to the main line with a V-Set.
Ensure continuous electronic fetal heart rate monitoring and monitoring of uterine contractionsthroughout the induction using continuous electronic cardiotocography.
Place an intrauterine pressure catheter in women whose contractions cannot be adequately assessed by external monitoring or manual palpation.
Monitor fluid balance.
Ensure constant midwifery support. The woman should have one-on-one midwifery care while having oxytocin infusion.