INDUCTION AND AUGMENTATION OF LABOR Flashcards
implies stimulation of contractions before the spontaneous on set of labor, with or without ruptured membranes
induction
refers to enhancement of spontaneous contractions that are considered inadequate because of failed cervical dilation and fetal descent
augmentation
pharmacologic or other means to soften, efface or dilate cervix to increase likelihood of a vaginal delivery with labor induction
Cervical ripening
induction of labor indications
When the risk of continuing the pregnancy exceeds the risk of induction
maternal indications
•Membrane rupture without labor
•Severepre-eclampsia,eclampsia
•Significantmaternaldiseaseunresponsive totreatment (DM, Chronic renal ds, pulmods)
Induction of Labor
FETAL INDICATIONS
- IUGR
- Chorioamnionitis
- Suspectedfetalcompromise
- Term/near termPROM
- Oligohydramnios
- Post term pregnancy
RELATIVE INDICATIONS
- Chronic hypertension
- Gestational DM
- Logistic factors: risk of rapid labor, distance from hospital
- Psychosocial indications
Indications–Unacceptable
•Suspected fetal macrosomia
•Absence of fetal or maternal indication
•HCP or patient convenience
Induction of Labor
- gestation of >42wks
- approximately6% ofbirths
- Accurate dating of pregnancy very important
- Significance
- increased perinatal mortality, increased perinatal morbidity
- increased operative delivery rates
Post-term pregnancy
Why induction is recommended
in order to avoid the risks associated with ‘post-term’ pregnancy
If induction not chosen
- daily fetal movement counts
- twice weekly fetal surveillance
contraindication to induction
- Any contraindication to labor
- Absence of indication for induction
contraindication to induction: any contraindication to labor
- placenta previa, vasaprevia, cord presentation
- abnormal fetal lie
- prior CCS or inverted T C/S significant uterine surgery
- active genital herpes, invasive cervical CA
- previous uterine rupture
Strategies to Reduce the Need for Induction
- Use of dating ultrasound
2. Sweeping of membranes
MOST Likelihood of Successful Vaginal Delivery
favorable cervix
multiparous
previous vaginal delivery
LEAST Likelihood of Successful Vaginal Delivery
unfavorable cervix
nulliparous
previous CS
this Bishop score conveys a high likelihood for a successful induction
9
this Bishop score identifies an unfavorable cervix and may be an indication for cervical ripening
4 or less
Maternal parameters/assessment prior to IOL
- Confirm indication for IOL
- Review contraindications to labor and/or vaginal delivery
- Assess shape and adequacy of the bony pelvis
- Assess cervix (Bishop score)
Fetal parameters/assessment prior to IOL
Confirm AOG
Estimate fetal weight
Determine fetal position
Confirm fetal well-being
METHODS OF INDUCTION OF LABOR for UNFAVORABLE CERVIX
–Mechanical methods
–Pharmacological methods
METHODS OF INDUCTION OF LABOR for FAVORABLE CERVIX
–Amniotomy
–Oxytocin
cervical ripening
unfavorable cervix –> favorable cervix
Options for Cervical Ripening with an Unfavourable Cervix
1.Mechanical methods
•Transcervical balloon devices
•Extraamnionic saline infusion
•hygroscopic dilators
2.Pharmacologic options
•prostaglandins
usually needed after cervical ripening
oxytocin
- Effective (but not as effective as vaginal prostaglandins)
- No. 14-18, sterile technique, insert past internal os, inflated to 30-80 cc water
- Contraindication: low placenta-relative contraindications: APH, PROM, cervicitis
Foley catheter
- effective
- Increased risk of neonatal infection
Hygroscopic dilators
Prostaglandin Preparations
Cervical ripening
- vaginal PGE2
- endocervical PGE2
Prostaglandin Preparations
Labor induction
-vaginal PGE2
Precautions with Prostaglandins
- Vaginal gel should not be put in cervical canal
- Should not be used to augment labour
- Should not be followed by oxytocin in women with previous C/S
- Use cautiously in the setting of ruptured membranes
Guidelinesfor PGE2 Use
- Done in controlled setting by experienced staff with resuscitation and delivery capabilities
- Normal electronic fetal surveillance prior to application
- PGE₂ applied by experienced caregiver
- Monitor FHR and uterine activity (1-2 hours)
- If no labor, reassess, repeat as necessary or choose an alternative induction method
Prostaglandin E2 –Advantages
- Improved patien tacceptance
- Lower operative deliveryrate
- Less need for oxytocin induction
Prostaglandin E2 –Disadvantages
•Adverserveactions -hyperstimulation -CVSevents -nausea,vomiting, diarrhea •Gel preparations are difficult to remove •No cervical preparations in PROM
- Ideal dose, route & frequency of administration not firmly established
- Only available in an oral form but tablet is readily absorbable trans-mucosally (sublingually, buccally, vaginally, or rectally)
Prostaglandin E1 (Misoprostol)
Misoprostol –Disavantages
- increased risk of uterine rupture with previous C/S
* Nausea, vomiting, diarrhea, shivering and chills
Options for Induction–Favourable Cervix
- Amniotomy
- Oxytocin
- Vaginal prostaglandins
MECHANISM OF ARM
- Stretching of the cervix
- Separation of membrane (liberation of PGs)
- Reduction of amniotic fluid volume
- Fetal head serves as a more solid wedging pressure
RISKS OF AMNIOTOMY
- Cord prolapse
- Intraamniotic nfection
- Accidental injury to the placenta, cervix, uterus, fetal parts or vasaprevia
- Creates commitment to delivery
- Effective with favourable cervix
- Often used in conjunction with oxytocin
- Caution in cases of high presenting part
- After amniotomy note amount and color of the fluid and assess fetal well being
Amniotomy
Oxytocin Effects
•Myometrialcontraction
•Cervix -no direct effect
•Vasoactive
-hypotension possible with bolus IV administration
•Antidiureticactivity
-water intoxication possible with high dose oxytocin
Oxytocin Protocol
•Cervix is ideally favourable (except can be used with PROM with unfavourable cervix)
•Experienced caregivers and adequate resources available to manage dystocia and other emergencies
•EFM according to guidelines for FHS
•Administration
-infusion pump into a mainline IV
-rates in milliUnits per minute (mU/min)
-concentrations vary but avoid large free water load
Oxytocin endpoint
- effective contractions leading to labor progress
- maternal and fetal well-being
Oxytocin Dosage Low dose protocol
-Less hyperstimulation & overall smaller dose
Oxytocin Dosage High dose protocol
-May shorten the length of labour
Oxytocin Adverse Effects on Fetus
with hyperstimulation or / with normal contraction pattern
Oxytocin Adverse Effects on Mother
- discomfort secondary to contractions
- uterine rupture
- water intoxication
if there is Excessive Uterine Activity
•Discontinue oxytocinor remove prostaglandinfrom vagina
•Intrauterine resuscitation
•Be prepared for emergency delivery
•Consider tocolyticagentsnitroglycerin 50 mcg IV push, repeatq3 to5 minutes to maximum of 200 mcg
Induction of Labor
Induction for Term PROM
consider induction with oxytocin (rather than prostaglandin or expectant management)
Conclusions in inducing labor
•Indication must be VALID •Match the method with the cervical status •Ripen the cervix as much as possible •Discuss risk and benefits with patient Induction of Labor
