Induction and Augmentation of Labor 1222020 1 Outline

Induction and Augmentation of Labor 12/2/2020 1

Outline • Define induction and augmentation of labor • List indications for labor induction • Discuss procedures and preconditions for labor induction/augmentation • Discuss methods of labor induction and augmentation • Describe complications of induction and augmentation 12/2/2020 2

Definitions • Induction of labor – artificial initiation of labor after fetal viability for clear maternal and fetal indications • Augmentation of labor- artificial stimulation of uterine contractions in cases of inefficient uterine contractions to attain required efficiency to effect delivery • Induction and augmentation of labor can be achieved through medical and surgical means or a combination of both • Induction and augmentation interventions incur maternal and fetal risks and should be institute with clear medical indications and after informed maternal consent 12/2/2020 3

Indications for Induction of Labor Maternal • Intrauterine fetal death • Pre-eclampsia/Eclampsia • Chronic hypertensive disease • Antepartum hemmorhage • Premature rupture of the membranes Fetal • Congenital anomaly incompatible with life • RH Isoimmunization • Fetal growth restriction • Post term pregnancy • Diabetes mellitus in pregnancy • Abnormal fetal well being tests suggesting chronic intrauterine asphyxia Indications are classified as maternal and fetal based on the predominant reason for termination. In most cases maternal and fetal indications overlap and may be difficult to classify as maternal and fetal. 12/2/2020 4

Methods of Labor Induction and Augmentation Medical Surgical Combination of both 1. Oxytocin infusion • Low dose regimenbeginning at 1 mu/min and doubling every 20 -30 mins to a maximum of 40 mu/min • High dose regimen- start at 6 mu/min and escalate every 20 -30 mins to a maximum of 42 mu/in 2. Prostaglandin E 1( Misoprostol) induction – intravaginal or intracervical 3. Prostaglandin E 2 ( Dinoprostone) – 3 mg vaginally every 6 hours for two – four doses 1. Amniotomy – artificial rupture of the membranes 2. Stripping of the fetal membranes 3. Foley catheter method 1. Amniotomy with oxytocin induction 2. Stripping of fetal membranes with oxytocin induction 3. Foley catheter method with oxytocin induction …. . Etc 12/2/2020 Surgical methods are often used in conjunction with medical methods and not alone for labor induction. Most methods of labor induction are also used for augmentation of labor as well. 5

Pre requisites for labor induction • Valid indication • Obtain informed consent of the mother • Assure fetal maturity - > 39 completed weeks or fetal lung maturity tests • Rule out contraindications for vaginal delivery • Assess pelvic adequacy • Assess favorability of cervix by the Bishop’s Score • Assess presentation ( vertex) and fetal size • Induction to be conducted mostly as an elective planned procedure with maternal preparation – hemoglobin determination, NPO except fluids etc • Sometimes emergency inductions may also need to be conducted due to obstetric emergencies such as eclampsia and abruptio placenta 12/2/2020 6

The Bishop Score Parameter 0 1 2 3 Cervical dilatation Closed 1 -2 3 -4 >5 Cervical effacement 0 -30% 40 -50% 60 -70% >80% Cervical position Posterior Midposition Anterior _ Cervical consistency Firm Medium Soft _ Fetal station -3 -2 -1, 0 +1, +2 The Bishop score indicates the ripening of the cervix for labor indirectly indicating the possibility of success of an induction. Scores > 9/13 indicate a ripe cervix; 5 -8 intermediate cervix and < 4 an unripe cervix and a high probability of unsuccessful induction. 12/2/2020 7

Methods of Cervical Ripening Pharmacological Mechanical • Prostaglandin E 2 (dinoprostone)intravaginal, intracervical – repeated 3 -5 mg doses applied until the cervical status improves or a maximum of three to four doses • Prostaglandin E 1 (misoprostol) – intravaginal or oral • Foley catheter method • Stripping of the fetal membranes • Laminaria insertion into the cervix – hygroscopic dilators that dilate and soften the cervix by absorbing its water content. Extracts of laminaria sea weeds. Un unripe cervix needs to be ripened by these cervical ripening methods in order to be softened and more ripe. The pharmacologic methods are the most preferred but in cases where these are not accessible, mechanical agents can also be used to ripen the cervix. A ripe cervix indicates a dilated, soft, anterior and effaced cervix that is easily pliable to uterine contractions. 12/2/2020 8

Procedures of Labor induction Procedure Description Complications Amniotomy After ascertaining the fetal station and ruling out cord presentation membrane is ruptured with an amnion hook or a kocker and controlled release of amniotic fluid effected • Cord prolapse • Infection – chorioamnionitis • Abruptio placentae- if sudden decompression of uterus occurs due to excessive release of amniotic fluid Oxytocin infusion An IV line is opened and oxytocin infusion administered gradually by either a graduated perfusor prepared for the purpose or by IV drip method manually calibrated – dosage expressed in mu/min • Uterine hypertonus – fetal distress; uterine rupture • Water intoxication – sodium retention and fluid overload • Hypersensitivity reaction to oxytocin • Higher risk of atonic PPH 12/2/2020 9

Procedures for Labor Induction Procedure Description Complications Prostaglandin Usually applied for cervical ripening E 1, E 2 induction but also used for induction of labor. Tablet or gel or cream inserted at the posterior fornix or near the cervix repeatedly at 6 hourly intervals until labor is established Nausea, vomiting, diahorrea, fever, chills, respiratory complications ( rare), uterine hypertonusfetal distress, uterine rupture Stripping of the fetal membranes The membranes are separated from the lower uterine segment by the examining finger for 3 -4 cms from the os and await for labor onset in hours or days. Possibility of placenta previa and bleeding. Placenta should be localized before membrane stripping. Foley catheter method Foley catheter inserted into the uterus Infection above the internal os, balloon inflated Membrane rupture with 30 cc of normal saline and pressure applied by hanging weight of 1 kg ( e. g. IV fluid bag). 12/2/2020 10

Complications of Labor Induction • Prematurity • Infection- chorioamnionitis; neonatal sepsis; puerperal sepsis • Water intoxication • Uterine hypertonus- fetal distress, uterine rupture • Hypersensitivity reactions • Side effects of prostaglandins • Post partum hemmorhage risk • Unforeseen cephalopelvic disproportion 12/2/2020 11

Contraindications to induction of labor • Fetal distress – acute or chronic asphyxia • Gross cephalopelvic of feto pelvic disproportion • Gross contracted pelvis • Malpresentations • Fundal uterine scars • Multifetal gestations • Uterotonics hypersensitivity 12/2/2020 12