PB#107: Induction of Labor Flashcards
Physiologic goal of cervical ripening
Facilitate process of cervical softening/thinning/dilating
Clinical goals of cervical ripening (2)
Reduction in rate of failed IOL, reduction in IOL-to-delivery time
Observed histologic changes during cervical ripening (4)
Collagen breakdown/rearrangement, changes in glycosaminoglycans, increased cytokine production, WBC infiltration
Bishop score signifying unfavorable cervix
6 or less
Bishop score signifying favorable cervix
8 or more
What a “favorable” cervix indicates
Probability of vaginal delivery after IOL is similar to spontaneous labor
Bishop score points for dilation
Closed = 0; 1-cm = 1; 3-4cm = 2, 5-6cm = 3
Bishop score points for position
Post = 0; mid = 1; ant = 2
Bishop score points for effacement
0-30% = 0; 40-50% = 1; 60-70% = 2; 80+% = 3
Bishop score points for station
-3 = 0; -2 = 1; -1–0 = 2; +1 or more = 3
Bishop score points for consistency
Firm = 0; med = 1; soft = 2
General categories for cervical ripening methods (3)
Mechanical dilators, synthetic PGE1, synthetic PGE2
Mechanical cervical ripening options (5)
Hygroscopic dilators, osmotic dilators (Laminaria japonicum), Foley catheters, double balloon devices, EASI balloon
Typical size and inflation volume of cervical Foley balloon
14-26F, 30-80mL
Routes of administration of miso (3); incremental dosages of miso
Vaginal, PO, sublingual; 25mcg increments
Is intrapartum miso exposure associated w/ long-term adverse fetal consequences?
No (in absence of fetal distress)
Available formulations and dosages of PGE2 (2)
2.5mL syringe containing 0.5mg dinoprostone gel, 10mg dinoprostone vaginal insert
Which formulation of PGE2 releases prostaglandins at a slower rate?
Insert (0.3mg/h) over gel
Effect of vaginal prostaglandins for cervical ripening compared to placebo or pit alone on time to delivery; effect on C/S rate; effect on tachysystole
Increase likelihood of delivery within 24h; do not reduce C/S rate; increase risk of tachysystole w/ associated FHR changes
Time from pit onset to uterine response; time of pit onset to steady level in plasma
3-5 mins; 40 mins
Changes in response to pit by gestational age
Gradual increase from 20-30wga, followed by plateau from 34wga until term, then further increase in sensitivity
Predictors for successful response to pit IOL (4)
Lower BMI, greater cervical dilation, higher parity, greater EGA
Cytokines increases associated w/ membrane stripping (2)
Increase in phospholipase A2 activity, increase in PGF2alpha levels
Clinical benefits of membrane stripping (2)
Increases likelihood of spontaneous labor within 48h, reduces incidence of IOL w/ other methods
Risk associated w/ membrane stripping
Increased risk of PROM
Disadvantage of AROM when used alone for IOL
Can be associated w/ unpredictable and sometimes long intervals before onset of ctxs
Only “natural” method for IOL
Nipple/Unilateral breast stim
Clinical advantage of nipple stim; caveat
Associated w/ significant decrease in pts not in labor at 72h; only in pts w/ favorable cervices
Percentage of pts doing nipple stim who experienced tachysystole w/ or w/o FHR changes
0%
Does nipple stim increase or decrease mec-stained fluid; C/S rates?
No change; no change
PP benefit of breast stim for IOL
Decrease in PPH rates
How to quantify ctxs
Number present in 10-min window, averaged over 30-min period
Normal ctx rate
5 or fewer ctxs in 10 mins, averaged over 30-min period
Tachysystole
> 5 ctxs in 10 mins, averaged over 30-min period
How to qualify tachysystole
Presence or absence of decels
Does tachysystole apply to spontaneous or stimulated labor, or both?
Both
Logistical reasons for IOL (3)
Risk of rapid labor, distance from hospital, psychosocial indications
Methods to confirm gestational age for logistical IOL (3)
US measurement at <20wga supports age of 39+wga, FHT documented as present for 30+ weeks, positive serum/urine hCG pregnancy test 36+ weeks ago
General contraindications to IOL
The same as for spontaneous labor
Examples of contraindications to IOL (7)
Vasa previa, complete placenta previa, transverse lie, cord prolapse, hx classical C/S, active genital HSV, hx myo entering endometrial cavity
Risk of C/S for nulliparous pts undergoing IOL w/ unfavorable cervices
Twofold increased risk
Criteria prior to diagnosing failed IOL in order to reduce risk of C/S
At least 12-18h latent labor
Requirements prior to cervical ripening and IOL (4)
Assessment of cervix, maternal pelvis, EFW, fetal presentation
Clinical benefits of cervical balloon prior to pit (2)
Significantly reduced duration of labor, reduced risk of C/S
Does addition of pit along w/ cervical balloon shorten time to delivery?
No
Disadvantage of prostaglandin ripening agents compared to cervical balloon
Increased risk of tachysystole w/ or w/o FHT changes
Effectiveness of vaginal miso compared to dinoprostone gel
Superior to or as effective as
Clinical benefits of vaginal miso compared to dinoprostone and pit (2)
Less epidural use, more vaginal deliveries within 24h
Clinical disadvantage of vaginal miso compared to dinoprostone and pit
More tachysystole w/ or w/o FHT changes
Do pharmacologic methods for cervical ripening decrease likelihood of C/S?
No
Typical initial cervical ripening miso dose/frequency
25mcg q3-6h
Soonest pit can be administered after last miso dose
4h
When can second dose of intracervical dinoprostone be given if inadequate cervical change and minimal uterine activity?
6-12h after first dose
Soonest pit can be given after cervical (1.5mg) dinoprostone or vaginal (2.5mg) dinoprostone, and why?
6-12h, because effect of prostaglandins may be higher w/ pit
Soonest pit can be given after sustained-release dinoprostone is removed
30-60 mins
When should C/S be considered w/ miso use?
If tachysystole + Cat 3 FHT and no response to routine corrective measures
Med that can be used to correct Cat 3 FHT and/or tachysystole
SubQ terb
Pts for whom miso should be avoided in 3rd tri, and why
Pts w/ prior C/S or major uterine surgery, because of increased risk of uterine rupture
Fetal outcome associated w/ miso use
Increase in mec-stained amniotic fluid
Rate of tachysystole w/ associated FHT changes seen in intracervical dinoprostone 0.5mg gel
1%
Rate of tachysystole w/ associated FHT changes seen in intravaginal dinsoprostone 2-5mg gel or vaginal insert
5%
Typical timing of onset of tachysystole s/p dinoprostone gel/insert placement
1h (but may occur up to 9.5h after)
Method to help reverse effects of tachysystole associated w/ dinoprostone vaginal insert
Removal of insert (irrigation of cervix/vagina is not beneficial)
Common maternal side effects assocaited w/ low-dose dinoprostone (3)
Fever, vomiting, diarrhea
Pts in whom caution should be exercised w/ dinoprostone use (3)
Glaucoma, severe hepatic/renal dysfunction, asthma
Clinical disadvantage of Laminaria japonicum/hygroscopic dilators over dinoprostone analogs
Increased maternal/neonatal infections
Clinical risks associated w/ cervical balloon (4)
Significant VB in pts w/ low-lying placenta, ROM, febrile morbidity, displacement of presenting part
Positioning rec after prostaglandin placement
Pt should remain recumbent x30 mins
Fetal surveillance s/p dinoprostone gel placement
FHT/TOCO monitoring continuously x30 mins-2h
When are ctxs usually first seen, and when do they exhibit peak activity, following prostaglandin placement?
Within first hour, in first 4 hours
Pts for whom outpatient dinoprostone gel is safe and effective for IOL
Term pts w/ Bishop score 6 or less
By how much time does outpatient cervical balloon reduce hospital stay?
9.6h
Most common adverse effects of pit (2)
Tachysystole, Cat 2-3 FHT (typically dose-dependent)
Potential catastrophic effects of tachysystole (2)
Abruption, uterine rupture (rare, even in parous pts)
Rare risk that occur w/ high concentrations of pit infused w/ large quantities of hypotonic solutions
Water intoxication
Which route of miso produces greater clinical efficacy at equivalent dosage?
Vaginal (over PO)
Benefits of PO miso administration over vaginal (2)
Fewer abnormal FHT patterns, fewer episodes of tachysystole w/ associated FHT changes
Does tachysystole w/o decels portend any significant increase in adverse fetal outcomes?
No
Potential risks associated w/ AROM (4)
Cord prolapse, chorio, significant cord compression, rupture of vasa previa
Precautionary measures to take at time of AROM (3)
Palpate for cord, avoid dislodging fetal head, FHT assessed before and immediately after AROM
Pts in whom AROM is contraindicated, and why
HIV+ pts, since duration of ROM has been identified as independent risk factor for vertical HIV transmission
Risks associated w/ membrane stripping (2)
Bleeding (if undiagnosed placenta previa/low-lying placenta), accidental AROM
Risk associated w/ bilateral nipple stim
Tachysystole w/ associated decels
Pit regimens/management strategies that are associated w/ decreased tachysystole w/ associated FHT changes
Low-dose regimens/less frequent increases in dose
Clinical benefits of high-dose pit regimens/more frequent dose increases (3)
Shorter labor, less frequent cases of chorio, less frequent cases of C/S for labor dystocia
What is max dose of recommended pit?
Not established
Example of low-dose pit regimen
0.5-2mU/min starting dose > increase 1-2mU/min q15-40 mins
Example of high-dose pit regimen
6mU/min starting dose > increase 3-6mU/min q15-40 mins
Initial management strategies for tachysystole w/ Cat III FHT (3)
Decrease/discontinue pit, turn pt on side, IVF resuscitation if hypotensive, supplemental O2 if hypoxic
Management strategy for persistent tachysystole despite initial measures
Terb
Clinical benefits to pit IOL for PROM pts (4), w/o increasing rate of C/S or neonatal infections
Reduce time interval between PROM and delivery, decrease frequency of IAI, decrease frequency of PP febrile morbidity, decrease frequency of neonatal abx txs
When should pts w/ term PROM be induced w/ pit, and why?
At time of presentation, in order to reduce risk of IAI and NICU admissions
Does use of miso/dinoprostone increase risk of infection in pts w/ PROM?
No
When can D&E be offered to pts w/ IUFD?
In 2nd tri if experienced provider is available (though D&E may limit efficacy of autopsy)
When is IOL appropriate for pts w/ IUFD (3)?
At later gestational ages, if 2nd tri D&E unavailable, per pt preference
When should vaginal miso be recommended for IOL in pts w/ IUFD?
Use in nonviable pregnancies at <24wga, recommend for IUFD pregnancies at <28wga (regardless of Bishop score) though high-dose pit is an acceptable alternative
Typical dosing protocol for vaginal miso in pts w/ IUFD
200-400mcg q4-12h
Preferred option for pts w/ IUFD w/ prior LTCS and <28wga
VTOL w/ miso at 400mcg q6h (because no increased risk of uterine rupture/complication)
Additional ripening option for pts >28wga w/ IUFD and unfavorable cervices
Cervical balloon
