Induction of labor

Labor induction

1. Induction of Labor M. Kamil

2. Outline Definition Indication Preinduction assessment Techniques of induction Monitoring during induction Complication and side effects of induction

3. Definitions Induction of labor: Artificial initiation of labor before spontaneous onset for purpose of delivery of fetus and placenta. Success of induction: Achieved vaginal delivery. Failed induction: Failure to generate regular contractions approx. every 3 to 5 minutes and cervical change after at least 24 hours of oxytocin administration. Cervical ripening: Use of medications or other means to soften, and dilate the cervix to increase likelihood of induction success.

4. Indication Urgent Elective/ Non-urgent Maternal Worsen of preeclampsia Significant maternal disease Infection: Chorioamnionitis PPROM and PROM Isoimmune disease near term Postterm pregnancy DM at term Fetal Fetal compromise: Marked oligohydramnios Severe IUGR Unstable lie (when the lie becomes stable) IUFD

5. Contraindication Placenta previa or vasa previa Active genital herpes Prior classical C- section Previous uterine surgery involving full thickness of myometrium Abnormal lie Invasive cervical carcinoma Category III FHR tracing

6. Types of cesarean section

7. Preinduction assessment Through maternal and fetal condition evaluation Indications for and alternatives to the procedure Techniques for cervical ripening labor induction Explained to the patient

8. American College of Obstetricians and Gynecologists. Patient Safety Checklist no. 5: scheduling induction of labor. Obstet Gynecol 2011; 118:1473.

9. Prerequisite for labor induction Capability for C/S if necessary Maternal Short, thin, soft, anterior cervix with open os (“inducible” or “ripe”) If cervix is not ripe, use prostaglandin vaginal insert ( Cervidil ), prostaglandin gel ( Prepidil ), or Foley catheter. Fetal Normal fetal heart tracing Cephalic presentation Adequate fetal monitoring available Likelihood of success determined by Bishop score Cervix considered unfavorable if < 6 Cervix favorable if > 6 Score 9-13 associated with high likelihood of vaginal delivery

10. Predicting successful induction Population of being induced Nulliparous/multiparous Intact/ ruptured membranes Baseline cervical status Placental insufficiency present/ absent Gestational age Previous vaginal delivery Mean newborn size Maternal height and BMI Management of induction Choice of endpoints Delivery within 24 hours Delivery within 48 hours dose/duration of oxytocin Interval from preinduction cervical ripening to delivery vs time from induction to delivery Route of delivery Maternal and neonatal morbidity

11. Techniques Preinduction cervical ripening Early amniotomy (ARM) as long as the head is engaged Oxytocin infusion

12. Bishop score Position Consistency Effacement (%) Dilation (cm) Station of fetal head

13. Unfavorable cervix First step – cervical ripening 2 options Pharmacological Mechanical

14. Unfavorable cervix - Pharmacologic option Prostaglandin E2 Many different routes: Intracervical (Prepedil) Intravaginal (Prostin) Intravaginal is better efficacy Regime: Primigravida: 3 mg Multigravida: 1.5 mg Max: 2 Prostin per day 6 hourly for the first day. The 3 rd Prostin inserted early morning of the 2 nd day

15. Unfavorable cervix - mechanical options (1) A Foley Catheter: inserted into the cervix and blown up with saline

16. Unfavorable cervix - mechanical options (2) Hygroscopic mechanical dilator: Laminaria Mechanical options: Places where PG is not available Concern of uterine hyperstimulation

17. Favorable cervix 1. Artificial rupture of membrane (ARM) Study: 2001 systemic review of randomized trials: The combination of amniotomy plus IV oxytocin was more effective than oxytocin alone. Recommendation - to do early ARM during oxytocin induction if fetus is engaged. Other means: “stripping/ sweeping” the amniotic membranes Study:2005 meta-analysis of 22 trials: Weekly membrane stripping at term shortens the time to onset of spontaneous labor and reduces the need for formal induction. Membrane stripping to patients 39 weeks of gestation who wish to accelerate the onset of spontaneous labor.  

18. “stripping/ sweeping” the amniotic membranes

19. Favorable cervix 2. Induction of labor by oxytocin Start the oxytocin infusion at 2 mill units/ min (12 mL/ hr ) Increase the rate every 30 minutes aiming for 4 contractions in 10 minutes lasting 40 – 90 seconds each. Once 4 contractions in 10 minutes are achieved maintain the infusion rate.

20. Other Oxytocin regimens Low dose Dose of oxytocin is initiated at 0.5 to 1 milliunits /min and increased by 1 milliunits /min at 30 – 40 minutes intervals Slightly higher doses Begin at 1 to 2 milliunits /min and increase by 1 to 2 milliunits /min with shorted incremental time intervals (15 to 30 minutes) High dose: Active management of labor regimens, and others, use a high dose oxytocin infusion with short incremental time intervals. Most labor and delivery units do not go above 40 milliunits /min Most common complication: uterine tachysystole

21. Monitoring during induction Monitoring after PGE2 Continuous CTG Monitor the progress by reassess bishop score: 6 hours after vaginal PGE2 tablet or gel insertion OR 24 hours after vaginal PGE2 controlled release pessary insertion Monitor after oxytocin infusion Continuous CTG Assess uterine contraction Assess the strength of uterine contraction

22. Tachysystole: > 5 contraction in 10 minutes, average over a 30 minutes window Uterine hypersystole/hypertonus : Contraction lasting at least 2 minutes with a normal FHR Must noted: Present/absent of FHR changes. Complication and side effects - Abnormal or excessive uterine contractions

23. Management: Perform vaginal examination CTG is mandatory to exclude fetal distress Flush posterior fornix with NS to remove remaining Prostin Oxytocin: discontinue the infusion accompany by FHR changes to back to normal. Place the woman in the left lateral position Administer oxygen (10L/min via nonrebreather mask) Increase IV fluids (fluid bolus 500 mL of lactated Ringer’s solution or more) No prompt response: Administer tocolytic SC/IV Terbulatine 250 mcg for fetal resuscitation OR IV Atosiban 6.75 mg over 1 min for fetal resuscitation For intractable cases: IV nitroglycerin 60 to 90 mcg Complication and side effects - Abnormal or excessive uterine contractions (continued)

24. Complication and side effects (continued) Failed induction: Failure to establish labor after one cycle of treatment consisting of: The insertion of 2 vaginal PGE2 tablets (3mg) or gel (1-2 mg) at 6 hourly intervals, OR One PGE2 pessary (10 mg) within 24 hours. Managements: C/S Cord prolapse Uterine rupture Hyponatremia

25. Uterine hyperstimulation without FHR changes To describe uterine tachysystole (> 5 contraction in 10 minutes for at least 30 minutes) Uterine hypersystole/hypertonus A contraction lasting at least 2 minutes with a normal FHR Uterine hyperstimulation with FHR changes Uterine hyperstimulation with FHR changes such as persistent decelerations, tachycardia, or decreased short-term variability.

26. References Coates T. Malpositions of the occiput and malpresentations . In: Marshall J, Raynor M, editors. Myles textbook for midwives. 16th ed. Edinburgh: Churchill Livingstone Elsevier; 2014. p. 435-54 Callahan, T., & Caughey , A. (2007). Blueprints obstetrics & gynecology (4th ed. / Tamara L. Callahan, Aaron B. Caughey . ed., Blueprints). Philadelphia ; London: Lippincott Williams & Wilkins. http://www.acog.org/Resources-And-Publications/Patient-Safety-Checklists American College of Obstetricians and Gynecologists. Patient Safety Checklist no. 5: scheduling induction of labor . Obstet Gynecol 2011; 118:1473. Porreco RP, Clark SL, Belfort MA, et al. The changing specter of uterine rupture. Am J Obstet Gynecol 2009; 200:269.e1. Cunningham, F., & Williams, J. (2014). Williams obstetrics. (24th ed. / [edited by] F. Gary Cunningham et al. ed.). New York ; London: McGraw-Hill Medical. Lilien AA. Oxytocin-induced water intoxication. A report of a maternal death. Obstet Gynecol 1968; 32:171. Beckmann, C., Herbert, W., Laube , D., Ling, F., Smith, R., & American College of Obstetricians Gynecologists. (2014). Obstetrics and gynecology (7th ed.). Bilek W, Dorr P. Water intoxication and grand mal seizure due to oxytocin. Can Med Assoc J 1970; 103:379. Moen V, Brudin L, Rundgren M, Irestedt L. Hyponatremia complicating labour --rare or unrecognised ? A prospective observational study. BJOG 2009; 116:552.