Induction: Indication & Methods Flashcards
What is induction?
- stimulation of uterine contractions to accomplish delivery PRIOR to the onset of spontaneous labor.
What is augmentation?
- treatment of abnormal labor (i.e. contractions/labor is present).
What are the indications for induction?
- OBSTETRICAL and MEDICAL induction= delivery before the onset of labor is indicated, when the maternal/fetal risks associated with continuing the pregnancy are thought to be greater than the maternal/fetal risks associated with an early delivery.
- ELECTIVE at term= induction at patient request (no longer before 39 weeks).
What are the obstetrical and medical indications?
- post-term pregnancy
- premature rupture of membranes (PROM)
- preeclampsia, eclampsia, HELLP syndrome
- fetal demise
- maternal diabetes
- fetal growth restriction
- twins
- abruptio placentae
What are the contraindications of induction?
- prior high risk cesarean incision.
- prior uterine rupture
- prior transmural uterine incision entering the uterine cavity.
- active genital herpes infection.
- placenta previa or vasa previa
- umbilical cord prolapse or persistent funic presentation
- transverse fetal lie
- invasive cervical cancer
- category III fetal heart rate tracing
What is the problem with elective induction at term?
- COST to health care! EXPENSIVE
What things must we assess when considering induction?
- gestational age (at least 39 weeks)
- fetal weight (4500 g in DM or 5000 g in non-diabetic moms).
- presentation (vasa previa…)
- cervical assessment
- fetal heart rate pattern
- review of pregnancy and medical hx
How do we confirm term gestation?
- US at less than 20 weeks gestation supports gestational age of 39 weeks or greater.
- fetal heart tones present for 30 weeks by doppler US.
- it has been 36 weeks since a positive serum or urine hCG result
What criteria must be met to confirm gestational date with US?
- consistent if within 5 days by crown-rump length (CRL) if obtained at 6-14 weeks (1st trimester).
- within 7 days if obtained at 14-20 weeks gestation (2nd trimester)
Does mean diameter of gestational sac help in determining gestational age?
NO
*** What is the gestational week terminology for preterm, term or post term?
- preterm= 20-37 weeks
- term= 39- 41 weeks (BEST TIME TO DELIVER)
- post term= after 41 and 6/7 weeks
*** What is late preterm?
- 34-37 weeks
*** What is early term?
- 37-39 weeks
* we don’t encourage early labor induction here anymore.
How much does fetal brain cortex volume increase between 34 and 40 weeks gestation?
50%
Must the cervix be ripened before we induce labor?
YES
How do we know if the cervix is ripened?
Bishop scoring system:
- dilation
- effacement
- station (where the leading edge of skull is located in relation to the ischial spines).
- cervical consistency
- position of cervix
- based on -3 to +3 scale
What is considered a good score to induce labor using the Bishop scoring system?
- 5 or higher
What are some home remedies for induction?
- castor oil
- black cohosh
- pirmrose oil
- acupuncture
- sex
- walking
What happens with cervical ripening?
- collagen breakdown leading to weaker and softer stroma.
- increase in prostaglandins
What prostaglandins are used for cervical ripening?
- Misoprostol (prostaglandin E1)= not FDA approved for labor induction or cervical ripening, but CHEAP.
- higher rate of vaginal delivery w/o need for oxytocin.
- Cerividil and Prepidil (prostaglandin E2)= more expensive
- higher rate of need for oxytocin and tachysytole.
What are 2 mechanical methods for cervical ripening?
- cook catheter
- foley catheter
* low cost, removable, and easy to use, but possible risk of infection.
If we already have a ripe cervix, how then can we proceed with induction?
- oxytocin
- membrane stripping
- amniotomy
- prostaglandins
What are the 2 protocols for oxytocin use?
- LOW DOSE protocol= start at 1-2 munits/min and increase by 1-2 munits/min every 115-40 minutes.
- HIGH DOSE protocol= start at 6 munits/min and increase by 3-6 munits/min every 15-40 minutes (not done as much).
- remember this is given at a rate to mimic the pulsatile fashion of the pituitary. Reaches steady state at 40 mins and half-life is 1-6 mins (don’t exceed 40 munits/ml).
What are the advantages of oxytocin?
- cheap, easy to titrate, easily reversible (since it has a short half life) and it is bioidentical to natural oxytocin in the body.
What are some disadvantages of oxytocin?
- one of the most potent uterotonic agents known.
- uterine tachysystole/hyperstimulation
- uterine rupture
- amniotic fluid embolism
- hyponatremia, pulmonary edema and generalized edema (due to similarity to ADH/vasopressin).
