Induction of Labor Flashcards
Methods of labor induction
oxytocin, membrane stripping, amniotomy, nipple stimulation, prostaglandin E analogues
Cervical remodeling changes
collagen breakdown and rearrangement, changes in glycosaminoglycans, increased production of cytokines, and white blood cel infiltration
Bishop scoring system
Refer to album
Unfavorable cervix
Bishop score of 6 or less
Methods of cervical ripening
Mechanical dilation:
- hygroscopic dilators
- osmotic dilators (Laminaria japonicum)
- Foley catheters (14-26 F) with 30-80 mL inflation volumes
- double balloon devices
- extra-amniotic saline infusions with rates of 30-40 mL/hr
Non-mechanical:
- synthetic prostaglandin E1 (PGE1)
- prostaglandin E2 (PGE2)
Complication of using Laminaria japonicum
possible increased infection rate
Benefits of mechanical dilation
decreased C-section rate with all except extra-amniotic saline infusions when compared to oxytocin alone
Advantage of Foley catheter over prostaglandins
low cost, stability at room temperature, reduced rate of uterine tahcysystole with or without FHR changes
Misoprostol
PGE1 analogue, used for cervical ripening and IOL
Route: vaginally, orally, sublingually
Dose: 25 mcg?
Dinoprostone
PGE2 analogue, used for cervical ripening
Route: gel (0.5 mg) and vaginal insert (10 mg)
- Increase the likelihood of delivery within 24 hrs, don’t reduce the chance of C section, and increase the risk of tachysystole and FHR changes
Oxytocin
used for IOL
- Stimulates uterine contraction within 3-5 mins of use, steady level achieved in 40 minutes
- gradual increase in response from 20 - 30 weeks
- Maximum amount of receptors present by 34 weeks
Predictors of successful response to oxytocin induction
- Lower BMI, greater cervical dilation, parity or gestational age
Membrane stripping
Causes an increase in phospholipase A2 and PGF2alpha2
- Increases the likelihood of spontaneous labor within 48 hours
Side effects: discomfort, vaginal bleeding, and irregular contractions over the next 24 hrs
Membrane stripping in group B + patients
ify
Amniotomy
Typically used if the cervix is favorable
- When used alone, it can result in long periods before contractions start
- Unknown when the best timing is in patients being treated for group B strep
Nipple stimulation
- Used in patients with favorable cervixes
- No difference in rates of meconium stained amniotic fluid or C section rates
- Decreased rates of postpartum hemorrhage
- Not encouraged in unmonitored setting
Bishop score 0
closed, posterior, 0-30% effaced, -3 station, firm cervix
Bishop score 1
1-2 cm dilated, midposition, 40-50% effaced, -2 station, medium cervix
Bishop score 2
3-4 cm dilated, anterior, 60-70% effaced, -1,0 station, soft cervix
Bishop score 3
5-6 cm dilated, anterior, 80% effaced, 1+, 2+ station, soft
Normal contraction frequency
5 contractions or less in 10 mins, averaged over 30 mins
Tachysystole
more than 5 contraction in 10 mins, averaged over 30 mins
- Always specify presence or absence of FHR changes
Indications for IOL
placental abruption, chorioamnionitis, fetal demise, gestational HTN, preeclampsia, eclampsia, PROM, post-term pregnancy, maternal health problems, severe IUGR, isoimmunization, oligohydramnios
Contraindications for IOL
vasa previa, active genital herpes, transvere lie, classical C section, umbilical prolapse, prior myomectomy into the endometrial cavity
Confirmation of term gestation
- Ultrasound at 20 wks or less supports gestational age of 39 wks or greater
- FH tones have been documented for at least 30 weeks by Doppler
- 36 wks since a positive beta HCG
IOL risk in nulliparous pts with unfavorable cervix
twofold increased risk of C section
Failed induction time period
- Allow for at least 12-18 hours of latent labor before diagnosing failure
What is the relative effectiveness of available methods for cervical ripening in reducing the duration of labor?
both Foley catheter placement and prostaglandin administration reduced length of labor and C section rates, but prostaglandins have an increased risk of tachnysystole
Which is more effective misoprostol or dinoprostone
misoprostol
Vaginal misoprostol
less use of epidural or analgesia, more vaginal deliveries within 24 hrs, and increased rates of tachysytole
How should prostaglandins be administered?
Misoprostol: 25 mcg tablet, every 3-6 hrs with oxytocin administered not less than 4 hrs after, sometimes 50 mcg is acceptable
Dinoprostone: 1.5 mg in the cervix, 2.5 mg in the vagina
- repeat dose can be given 6-12 hrs later
- oxytocin can be given 6-12 hrs later
- No more than three doeses or 7.5 mg of the gel
Highest risk of tachysystole
vaginal misoprostol
Risks of vaginal misoprostol
tachysystole, category III FHR tracing, and uterine rupture in women with C sections
How to correct uterine tachysytole
removal of medication, terbutaline
Maternal side effects from PGE2
very rare diarrhea, fever, vomiting
- Caution should be taken in women with glaucoma, severe renal or hepatic disease, and asthma (bronchodilator though so low risk)
What are the recommended guidelines for fetal surveillance after prostaglandin use?
Patient should be recumbent for the first 30 mins
- FHR and uterine activity should be monitored for the first 30 mins to 2 hrs after admin.
- Peak contractions in the first 4 hrs
Are cervical ripening methods appropriate in an outpatient setting?
yes, in selected patients (dioprostone and mechanical dilation)
Complications of oxytocin
tachysystole, water intoxication
concentrated solutions can cause low BP
Complications of amniotomy
fetal cord compression, and umbilical cord prolapse, chorioamnionitis
- Get FHR before and after amniotomy
Membrane stripping
vaginal bleeding from undiagnosed placenta previa, accidental amniotomy
Oxytocin regimen - high dose versus low dose
trade off between shorter labor times, c section for dystocia, and chorio and tachysystole
Low-dose oxytocin dosing
0.5-2 initial dose, 1-2 mU/min, dose interval 15-40 mins
High-dose oxytocin dosing
6 initial dose, 3-6 mU/min, dose interval 15-40 mins
Are there special considerations that apply for induction in a woman with ruptured membranes?
IOL should be started at presentation to decrease risk of chorio; vaginal misoprostol ok
What methods can be used for IOL with IUFD in the late second, third trimester?
D&E in late second trimester, oxytocin, vaginal misoprostol (200-400 mcg every 4-12 hrs ) (most useful before 28 wks)
