#107 Induction of Labor Flashcards
How many gravid women undergo induction of labor in the United States?
More than 22%
What methods of induction of labor are there?
Membrane stripping, amniotomy, nipple stimulation, prostaglandin E analogues, and oxytocin
What is included in cervical remodeling (molecularly)?
Collagen breakdown and rearrangement, changes in glycosaminoglycans, increased production of cytokines, and white blood cell infiltration
What scoring system is used to determine the status of the cervix?
Bishop scoring system
An unfavorable cervix has a Bishop’s score of how much?
6 or less
What does a Bishop score of more than 8 mean?
Favorable. Probability of vaginal delivery after labor induction is similar to that after spontaneous labor
Bishop Score:
Points for closed cervix
0
Bishop Score:
Points for 1cm dilated
1
Bishop Score:
Points for 2cm dilated
1
Bishop Score:
Points for 3cm dilated
2
Bishop Score:
Points for 4cm dilated
2
Bishop Score:
Points for 5cm dilated
3
Bishop Score:
Points for 6cm dilated
3
Bishop Score:
Points for posterior cervix
0
Bishop Score:
Points for midposition cervix
1
Bishop Score:
Points for anterior cervix
2
Bishop Score:
Points for 0% effacement
0
Bishop Score:
Points for 10% effacement
0
Bishop Score:
Points for 20% effacement
0
Bishop Score:
Points for 30% effacement
0
Bishop Score:
Points for 40% effacement
1
Bishop Score:
Points for 50% effacement
1
Bishop Score:
Points for 60% effacement
2
Bishop Score:
Points for 70% effacement
2
Bishop Score:
Points for 80% effacement
3
Bishop Score:
Points for -3 station
0
Bishop Score:
Points for -2 station
1
Bishop Score:
Points for -1 station
2
Bishop Score:
Points for 0 station
2
Bishop Score:
Points for +1 station
3
Bishop Score:
Points for +2 station
3
Bishop Score:
Points for firm cervical consistency
0
Bishop Score:
Points for medium cervical consistency
1
Bishop Score:
Points for soft cervical consistency
2
Bishop Score:
2/40/-3/soft/midposition
5
Bishop Score:
1/20/-2/medium/posterior
3
Bishop Score:
4/60/-2/soft/anterior
9
Maximum Bishop score?
13
What are methods for cervical ripening?
Mechanical cervical dilators and prostaglandin E1 and prostaglandin E2
What are methods for mechanical cervical dilation for induction of labor?
Hygroscopic dilators, osmotic dilators, foley catheters (14-26 Fr) with inflation volume of 30-80cc, double balloon devices, and extraamniotic saline infusion using infusion rates of 30-40cc/h.
Which mechanical method for cervical dilation is not associated with decreased risk of cesarean delivery (when compared to oxytocin alone)?
Extraamniotic saline infusion
Which method of mechanical cervical dialtion is associated with increased peripartum infections?
Laminaria japonicum
What are the advantages of foley catheter for mechanical cervical dilation compared to prostaglandins?
Low cost, stability at room temperature, reduced risk of uterine tachysystole with or without FHR changes
What type of prostaglandin in misoprostol?
PGE1 analogue
How is misoprostol administered for cervical ripening/induction of labor?
intravaginally, orally, or sublingually
The majority of adverse maternal and fetal outcomes are associated with misoprostol therapy resulted from what dose of misoprostol?
Greater than 25mcg
What type of prostaglandin is dinoprostone?
PGE2
Do vaginal prostaglandins increase the risk of uterine tachysystole with associated FHR changes?
Yes
How soon after infusion of oxytocin does uterine response ensue?
After 3-5 minutes
How long does it take to achieve a steady level of oxytocin in the plasma?
40 minutes
What factor determines how sensitive the uterus is to oxytocin?
Gestational age. Gradual increase in response from 20 to 30 weeks, plateau from 34wk until term, when sensitivity increases
What factors are predictors of successful response to oxytocin for induction?
Lower BMI, greater cervical dilation, parity, gestational age
What happens molecularly after membrane stripping/sweeping?
Significant increases in phospholipase A2 activity and prostaglanding F2alpha levels
How does membrane stripping affect pregnancy/labor?
Increases the likelihood of spontaneous labor within 48 hours and reduces the incidence of induction with other methods
Can you strip membranes for a patient who is GBS positive?
There is insufficient evidence to guide clinical practice
Can AROM be used as a method of labor induction?
Yes, especially if the condition of the cervix is favorable
What does ACOG say about using amniotomy alone for labor induction?
Insufficient evidnece on the efficacy and safety. Can be associated with unpredictable and sometimes long intervals before the onset of contractions
When is it safe to AROM in GBS+ patient receiving intrapartum prophylaxis?
Insufficient data to guide the timing of amniotomy
True or false, breast stimulation is associated with a decrease in postpartum hemorrhage?
True
How long should a patient be in latent labor before diagnosing a failed induction of labor?
At least 12-18 hours
How can you confirm a term gestation for scheduling induction?
- Ultrasound measurement at less than 20 weeks supports gestational age of 39 wks or greater
- FHT have been documented as present for 30wks by doppler ultrasonography
- It has been 36 weeks since a positive serum or urine hcg
How does vaginal misoprostol compare to dinoprostone and oxytocin?
Less use of epidural anesthesia, more vaginal deliveries within 24 hours, more uterine tachysystole with or without FHR changes
How should misoprostol be dosed for cervical ripening and labor induction?
25mcg should be considered as the initial dose. Frequency not more than q3-6h. Can use 50mcg every 6 hours, but associated with increased risk of complications (tachysystole and decels)
How soon after misoprostol administration can you start oxytocin?
At least 4 hours after last misoprostol dose
How long after removal of dinoprostone vaginal insert can you start oxytocin?
After 30-60 minutes
What are recommendations regarding buccal or sublingual misoprostol for cervical ripening or induction of labor?
Not recommended for clinical use until further studies support their safety (2004)
What induction agent is most associated with tachysytole?
vaginal misoprostol
What induction agents should be avoided in patients with prior cesarean that desire TOLAC?
Prostaglandins
Does irrigation of the cervix and vagina after removal of PGE2 (dinoprostone) vaginal insert help resolve tachysystole?
No
What are some potential complications of foley catheter placement for mechanical cervical dilation?
Vaginal bleeding in women with low-lying placenta, rupture of membranes, febrile morbidity, and displacement of the presenting part
What are the recommended guidelines for fetal surveillance after prostaglandin use?
Patient recumbent for at least 30 minutes. FHR and uterine activity should be monitored continuously for 30 min to 2 hours after administration of PGE2 gel. FHR monitoring should be continued if regular uterine contractions persist.
Can cervical ripening methods be performed outpatient?
In carefully selected patients. Evidence for intravaginal PGE2 gel for 5 days for women with Bishops score of 6 or less. Evidence for outpatient foley catheter placement (decreased hospital stay of 9.6 hours)
What are potential consequences of uterine tachysystole?
Fetal heart rate abnormalities, placental abruption, uterine rupture (rare)
Does oral or vaginal route of misoprostol administration, at equivalent dosage, produce greater clinical efficacy?
Vaginal
What are potential risks of amniotomy?
Umbilical cord prolapse, chorioamnionitis, significant umbilical cord compression, rupture of vasa previa
What should you remember when considering amniotomy for HIV+ patient?
Duration of ruptured membranes has been identified as an independent risk factor for vertical transmission of HIV infection
What is a risk of rapid IV injection of oxytocin?
Hypotension
Can you use prostaglandins in the setting of PROM for cervical ripening/induction oflabor?
Yes
Can you use mechanical dilation in setting of PROM for cervical dilation/induction of labor?
Insufficient evidence to guide the physician
What are management options for late second or third trimester IUFD?
D&E (if comfortable provider available) or labor induction
At what gestational age cut off do you manage an IUFD with misoprostol alone vs a typical induction of labor with usual obstetrical protocols?
28 weeks
What are the typical misoprostol doses for an IUFD <28wks?
200-400mcg vaginally q4-12 hours
In patients with prior uterine scar up to how many weeks can you use misoprostol induction for IUFD?
28wks (can use 400mcg q6h)
In patients with prior uterine scar how can you manage induction for IUFD after 28 weeks?
Cervical ripening with transcervical foley and pitocin.