11. Induction of Labour Flashcards
1
Q
Define: Induction of labour (1)
A
artificial initiation of labour in a pregnant woman prior to spontaneous initiation to deliver the fetus and placenta
2
Q
Name Prerequisites for Labour Induction (3)
A
- capability for C/S if necessary
- maternal: inducible/ripe cervix: short, thin, soft, anterior cervix with open os
- fetal:
- normal fetal heart tracing
- cephalic presentation
- adequate fetal monitoring available
3
Q
If cervix is not ripe for induction of labour, what to do? (4)
A
- prostaglandin vaginal insert (Cervidil®)
- prostaglandin gel (Prepidil®)
- misoprostol (Cytotec®)
- Foley catheter
4
Q
Induction is indicated when? (1)
A
when the risk of continuing pregnancy exceeds the risks associated with induced labour and delivery
5
Q
Likelihood of success of induction of labour determined by what? (3)
A
Bishop score
- cervix considered unfavourable if <6
- cervix favourable if ≥6
- score of 9-13 associated with high likelihood of vaginal delivery
6
Q
Name cervical characteristics in Bishop score (5)
A
- Position
- Consistency
- Effacement (%)
- Dilatation (cm)
- Station of Fetal Head
7
Q
Describe Bishop Score 0
- Position
- Consistency
- Effacement (%)
- Dilatation (cm)
- Station of Fetal Head
A
- Position: Posterior
- Consistency: Firm
- Effacement (%): 0-30
- Dilatation (cm): 0
- Station of Fetal Head: -3
8
Q
Describe Bishop Score 1
- Position
- Consistency
- Effacement (%)
- Dilatation (cm)
- Station of Fetal Head
A
- Position: Mid
- Consistency: Medium
- Effacement (%): 40-50
- Dilatation (cm): 1-2
- Station of Fetal Head: -2
9
Q
Describe Bishop Score 2
- Position
- Consistency
- Effacement (%)
- Dilatation (cm)
- Station of Fetal Head
A
- Position: Anterior
- Consistency: Soft
- Effacement (%): 60-70
- Dilatation (cm): 3-4
- Station of Fetal Head: -1,0
10
Q
Describe Bishop Score 3
- Position
- Consistency
- Effacement (%)
- Dilatation (cm)
- Station of Fetal Head
A
- Position: -
- Consistency: -
- Effacement (%): _>_80
- Dilatation (cm): _>_5
- Station of Fetal Head: +1, +2, +3
11
Q
Differentiate: Induction vs. Augmentation (2)
A
- Induction is the artificial initiation of labour
- Augmentation promotes contractions when spontaneous contractions are inadequate
12
Q
Name indications of induction (4)
A
- post-dates pregnancy (generally >41 wk) = most common reason for induction
- maternal factors
- maternal-fetal factors
- fetal factors
13
Q
Name MATERNAL indications of induction (5)
A
- DM = second most common reason for induction
- gestational HTN ≥37 wk
- preeclampsia
- other maternal medical problems, e.g. renal or lung disease, chronic hypertension, and cholestasis
- maternal age over 40
14
Q
Name MATERNAL-FETAL indications of induction (3)
A
- isoimmunization
- preterm premature rupture of membranes PROM
- chorioamnionitis
15
Q
Name FETAL indications of induction (3)
A
- suspected fetal jeopardy as evidenced by biochemical or biophysical indications
- macrosomia, fetal demise, intrauterine growth restriction IUGR, oligo/polyhydramnios, anomalies requiring surgical intervention, and twins
- previous stillbirth or low pregnancy-associated plasma protein A (PAPP-A)
16
Q
Name risks of induction (4)
A
- failure to achieve labour and/or vaginal birth
- uterine hyperstimulation with fetal compromise or uterine rupture
- maternal side effects to medications
- uterine atony and postpartum hemorrhage (PPH)
17
Q
Name maternal contraindications (5)
A
- prior classical or inverted T-incision C/S or uterine surgery (e.g. myomectomy)
- unstable maternal condition
- active maternal genital herpes
- invasive cervical carcinoma
- pelvic structure deformities
18
Q
Name maternal-fetal contraindications (2)
A
- placenta previa or vasa previa
- cord presentation
19
Q
Name fetal contraindications (3)
A
- fetal distress
- malpresentation/abnormallie
- preterm fetus without lung maturity
20
Q
Consider the Following Before Induction… (8)
A
- Indication for induction
- Contraindications
- GA
- Cervical favourability
- Fetal presentation
- Potential for CPD
- Fetal well-being/FHR
- Membrane status
21
Q
Describe: Cervical ripening (2)
A
- use of medications or other means to soften, efface, and dilate the cervix; increases likelihood of successful induction
- ripening of an unfavourable cervix (Bishop score <6) is warranted prior to induction of labour
22
Q
Name methods of cervical ripening (4)
A
-
intravaginal prostaglandin PGE2 gel (Prostin® gel): long and closed cervix
- recommended dosing interval of prostaglandin gel is every 6-12 h up to 3 doses
-
intravaginal PGE2 (Cervidil®): long and closed cervix, may use if rupture of membranes ROM
- continuous release, can be removed if needed
- controlled release PGE2
- intracervical PGE2 (Prepidil®)
-
intravaginal PGE1 misoprostol (Cytotec®): long and closed cervix
- inexpensive, stored at room temperature
- more effective than PGE2 for achieving vaginal delivery and less epidural use
- Foley catheter placement to mechanically dilate the cervix
23
Q
Name theoretical advantages of Intravaginal PGE2 Cervidil® (4)
A
- Slow, continuous release
- Only one dose required
- Ability to use oxytocin 30 min after removal vs. 6 hours for gel
- Ability to remove insert if required (i.e. excessive uterine activity)
24
Q
A
25
Q
Describe: Amniotomy (3)
A
- artificial ROM (amniotomy) to stimulate prostaglandin synthesis and secretion; may try this as initial measure if cervix is open and soft, the membranes can be felt, and if the head is present at the cervix
- few studies address the value of amniotomy alone for induction of labour
- amniotomy plus intravenous oxytocin: more women delivered vaginally at 24 h than amniotomy alone (relative risk = 0.03) and had fewer instrumental vaginal deliveries (relative risk = 5.5)
26
Q
Describe oxytocin for induction of labor (5)
A
- oxytocin (Pitocin®): 10 U in 1L NS, run at 0.5-2 mU/min IV increasing by 1-2 mU/min q20-60min
- reduces rate of unsuccessful vaginal deliveries within 24 h when used alone (8.3% vs. 54%, RR 0.16)
- ideal dosing regimen of oxytocin is not known
- current recommendations: use the minimum dose to achieve active labour and increase q30min as needed
- reassessment should occur once a dose of 20 mU/min is reached
27
Q
Name potential complications of oxytocin in induction of labor
A
- hyperstimulation/tetanic contraction (may cause fetal distress or uterine rupture)
- uterine muscle fatigue, uterine atony (may result in postpartum hemorrhage PPH)
- vasopressin-like action causing anti-diuresis
