Induction of Labor

1. Induction of Labor C. T. Allred, M.D. 8/7/09

2. Standard Maternal Indications • Preeclampsia, eclampsia • Term premature rupture of membranes • Suspected chorioamnionitis • Maternal medical condition (DM, HTN, renal disease, ht. disease, etc.) • Risk for precipitous delivery • Fetal demise

3. Standard Fetal Indications • Postterm pregnancy (Is it 41 or 42 wks?) • Oligohydramnios (AFI < 5) • IUGR • Rh sensitization • Prior term stillborn infant • Known fetal anomalies • Not on here is macrosomia, Joe. More on that in a bit.

4. Preventive Labor IndicationsAMOR-IPAT • Active Management of Risk in Pregnancy at Term. • A system that assumes 38 to 41 weeks is the ideal time to deliver. • Days are subtracted from 41 weeks depending on the mother’s underlying risk factors. E.G. – wt. gain > 30 pounds, induce 6 days before 41 weeks. • Relies on confirmation of EDC with US done between 8 and 20 weeks. • Relies on cervical ripening. • One small study shows section rate of 4%!! (retrospective study) • Not standard of care at this time.

5. AMOR-IPAT references • Nicholson, J.M., et al, Grand Rounds: Will active management of obstetric risk lower C/S rates?, Contemporary OB/GYN, 9/1/05 • Nicholson, J.M., et al, Active Management of risk . . . Am J Obstet Gynecol. 2004:191:616-625 • Sanchez-Ramos L., et al, Labor induction vs expectant management for postterm pregnancies: a systematic review with meta-analysis. Obstet Gynecol. 2003;101:1312-1318.

6. Maternal contraindications • Placenta previa (complete) • Previous classical c-section • Uterine scar other than LTCS x 1 • Invasive cervical cancer • Relative contraindications: • 1 LTCS, narrow pelvis, significant maternal medical conditions (cardiac, pulmonary, neuro), polyhydramnios, grand multiparity

7. Fetal contraindications • Active maternal genital herpes • Untreated maternal HIV • Transverse lie • Vasa previa • Severe IUGR with abn. Doppler studies • Significant hydrocephalus • Specific nonreassuring FHT patterns • Relative: presenting fetal part above the inlet

8. Risk of induction • Unintentional preterm delivery • To infer fetal maturity (ACOG) – ultrasound measurement before 20 weeks supports gestational age of > or = 39 weeks. • FHTs documented as present for 30 weeks by doppler. • >36 weeks since a positive urine or serum HCG

9. Risk of induction • ACOG Practice Bulletin, # 107, 8/09 • Nulliparous women with unfavorable cervices should be counseled about a TWO FOLD increased risk for c-section

10. Risk of induction • Requires continuous electronic fetal monitoring. • Most agents carry the risk of tachysystole leading to nonreassuring fetal heart patterns. • Rupture of membranes > 12 hours increases risk of maternal and neonatal infection.

11. Risk of induction • All of these factors need to be discussed with the mother prior to induction as well as alternatives and those risks. • Document!

12. Factors predicting success • Bishop score > 5 to 7. Dilation is most important factor. • Gestational age. • Multiparity. • Lack of factors leading to large baby/uteroplacental insufficiency

13. Leads to an increased likelihood of successful induction if Bishop > 5 in multips, > 7 in primips. Multiple methods: Membrane stripping Amniotomy Mechanical Breast stimulation (not recommended) Prostaglandins Oxytocin Cervical ripening

14. Amniotic membrane stripping • Works to cause spontaneous labor and decrease the need for induction. Shortens pregnancy by 3 days. • NNT = 8 to prevent one induction. • Sweep by placing finger(s) through the cervix and freeing the membranes from the uterus in a circular pattern. • Begin at 38 weeks and do weekly. • Hurts, can cause SROM, prolapse of cord, promotion of infection, bleeding. (Only the first and last are common.) Discuss with pt. first!

15. Mechanical • Foley # 16 with tip removed through the cervix. Inflate with 30 to 80 cc of water. • Retract so it rests against the internal os. Some attach to a liter of saline and suspend from the end of the bed. Not shown to improve success. • It works to improve Bishop score and decrease time to delivery. • Can cause AROM, injury to placenta, pain.

16. Prostaglandins • PGE1 – misoprostol. Optimal dose appears to be 25 micrograms q 3 to 6. • 50 works but seems to increase tachysystole more than 25. • 100 microgram pill = $1. • Works. Improves Bishop score and decreases time to delivery. • Associated with more FHT abnormalities and thick meconium than PGE2.

17. Prostaglandins • PGE2 – dinoprostone • Prepidil – vaginal gel. .5 mg q 6-8 hours to max of 3 doses. • Cervidil – vaginal insert. 10 mg pladget inserted in vagina x 12 hours. Not approved for use > 1 x, but some do. Advantage is has a string and can pull if tachysystole and FHT problems. • Both seem to be gentler than misoprostol. • Both work. Cost > 100 x more than misopros.

18. Induction • Misoprostol can be used q 3 to 6 hours for induction. Is effective but increase in tachysystole and thick meconium. • Pitocin • Effect after 5 minutes but steady state is reached in 40 minutes. • High dose vs. low dose: both work. High dose accomplishes delivery faster with more FHT problems but equal outcomes.

19. SRHC – Smoky Hill • Baseline FHT tracing. Is it reactive? What is variability? • Pitocin 10 units in 500 ml Normal Saline, 1 mu/3ml. (Triple concentration when reach 36 mu/min – makes for 1 mu/ml) • Increase gradually to achieve 3 to 5 contractions over a 10 minute period. If the cervix is changing > 1 cm/hr, you do not need to increase the pit!

20. Tips for a successful induction • Know your dates. • Ripen the cervix. If not > 5-7, consider continued ripening. • Be patient. Do not consider the induction a failure until the pt. is through the latent phase (cx at least 4 cm) • AROM early if committed.