Induction of labour (2)
- 1. INDUCTION AND AUGMENTATION OF LABOUR Prof. M.C.Bansal MBBS,MS,MICOG,FICOG Professor OBGY Ex-Principal & Controller Jhalawar Medical College & Hospital Mahatma Gandhi Medical College, Jaipur.
- 2. INTRODUCTION •The culmination of normal pregnancy involves three stages: prelabour, cervical ripening and labour. •Endogenous prostaglandins play a part in all these processes. •Interventions to artificially ripen the cervix, induce uterine contractions and augment labour once it is in progress also lack distinct boundaries. •Labour induction and augmentation may be a source of conflict and distress. •For most health workers they are seen as routine, technical procedures.
- 3. INTRODUCTION •For many women, they have emotive connotations, evoking a sense of personal inadequacy and eroded self-esteem. •It is important for health workers to approach the question of labour induction with sensitivity, and to involve women in the decision-making process. •Labour induction is one of the most frequent medical procedures in pregnant women. •It is a major intervention in the normal course of pregnancy, with the potential to set in motion a cascade of interventions, particularly Caesarean section. •However, with modern methods of labour induction, this risk appears to have diminished.
- 4. Definition: Induction of Labor (IOL) is defined as artificial stimulation of uterine contractions before the onset of labor. Augmentation refers to stimulation of spontaneous contractions that are considered inadequate because of failed cervical dilation and fetal descent.
- 5. The goal of IOL is to eliminate the potential risks to the fetus with prolonged intrauterine existence while minimizing the likelihood of operative delivery The overall incidence of IOL has increased globally. In a survey by the National Center for Health Statistics the rate of labor induction was noted to have increased from 90 per 1,000 live births in 1989 to 184 per 1,000 live births in 1997 (1).
- 6. Indications For induction: •Hypertensive disorders of pregnancy ( pre-eclampsia, eclampsia, chronic hypertension) •Diabetes, renal disease, chronic pulmonary disease •Premature rupture of membranes •Chorioamnionitis •Fetal growth restriction •Rh isoimmunization •Postdated pregnancy •Fetal demise •Abruptio placentae •Fetal malformations incompatible with life •Logistic factors: Risk of rapid labor, distance from hospital, psychosocial indications
- 7. Contraindications to the induction of labor: •Major degree of Placenta praevia •Vasa praevia •Previous classical uterine incision or incision because of metroplasty or extensive myomectomy when the cavity is opened •Cephalopelvic disproportion because of malpresentation or abnormal pelvic bone structure •Active genital Herpes infection •Invasive cervical carcinoma •Hypersensitivity to cervical ripening agents Transverse lie
- 8. Conditions where IOL is not a true contraindication but where special caution is required : •Multiple pregnancy •Polyhydramnios •Grand multiparity •Maternal heart disease. •Severe hypertension. • Breech presentation •One or more previous cesarean section •Abnormal fetal heart rate not requiring emergency cesarean section
- 9. Risks of IOL: Maternal Risks : •Failure leading to Cesarean section •Uterine hyperstimulation •Rupture uterus •Intrauterine infection, Chorioamnionitis •Amniotic Fluid Embolism •Precipitate labor , Dysfunctional labor •Increased risk of operative vaginal delivery •Increased risk of post partum hemorrhage •Abruptio Placentae •APH from undiagnosed placenta praevia •Water intoxication
- 10. Fetal Risks : •Fetal distress . •Fetal death •Neonatal sepsis •Iatrogenic delivery of a preterm infant •Cord prolapse •Neonatal jaundice •Increased risk of birth trauma
- 11. Pre- requisites for IOL: •Evaluate the indication •Explain the indication of induction to the patient along with details of the method to be used and take a written informed consent •Assess adequacy of the pelvis and fetal size •Confirm the gestational age, fetal lie, and assess the fetal lung maturity # where ever indicated Uterine activity and fetal heart rate should be continuously monitored. In case of clinical auscultation, FHR should be heard during and for 30 seconds after a contraction at least every 15 minutes during the active phase of labor and after every contraction in the second stage . Otherwise electronic fetal monitoring is preferable · Partogram is to be maintained for active labour · Trained personnel and well equipped center
- 12. # According to the ACOG Committee Opinion (2) , if one of the following criteria are met then fetal maturity may be assumed and amniocentesis need not be performed to confirm fetal maturity: - Fetal heart tones have been documented for 20 weeks by non electric fetoscope or for 30 weeks by Doppler - It has been 36 weeks since a positive serum or urine human chorionic gonadotropin pregnancy test was performed by a reliable method - An ultrasound measurement of the crown rump length, obtained at 6- 11 weeks, supports a gestational age of 39 weeks or more - An ultrasound scan obtained at 12 to 20 weeks confirms the gestational age of 39 weeks or more determined by clinical history and physical examination
- 13. Structures of the cervix and Physiology of cervical ripening : The uterine cervix has broadly two components which are: a) cellular portion and, b) extracellular matrix The distal portion has greater connective tissue as compared to the part close to the myometrium which is richer in the cellular component. The cellular component has: smooth muscle cells, fibroblasts, epithelium, and blood vessels. Cervical stromal cells produce collagenases, elastases and metalloproteinaeses which are involved in remodeling of the cervix. Fibroblasts also secrete cytokines like interleukin 1 beta and interleukin -8
- 14. Extracellular matrix is composed of : a) Collagen: collagen is in two forms Type I (70%) and type II (30%) and is arranged in the form of a triple helix. In the non pregnant cervix these are arranged in a dense and irregular fashion b) Elastin: these fibres are arranged parallel to and between the collageAn fibres and play an important role in taking the pregnancy to term by keeping the os closed c) Decorin: is a glycosaminoglycan and its relative proportion to collagen is important in the remodeling of the cervix at labor d) Hyaluronic acid: is the most important proteoglycan which is responsible for the increased water content of the cervix
- 15. Changes during pregnancy: a) Collagen is reorganized and consolidated in early pregnancy with proliferation and hyperplasia of the cellular component b) Near the onset of labor, an overall decrease in the concentration of collagen occurs with dispersion and remodeling into fine fibres , making the cervix softer in consistency c) Increases in decorin levels and physiologic cell death are in part responsible for this process d) Hyaluronic acid levels increase thereby increasing the water content of the cervix and causes a loosening and dispersal of the fibres e) Chemotactic response at term leads to an influx of neutrophils and an increased levels of cyokines (interleukin 1 beta and interleukin – 8 ) which in turn release collagenases and elastases to allow effacement f) Mechanical forces of uterine contractions extend the elastin and allow dilatation
- 16. PRE INDUCTION CERVICAL ASSESSMENT: It is known that success of labor induction is closely related to ripeness of the cervix . Various scores have been proposed to evaluate the cervical status. a) Bishop’s Score : This was proposed by Bishop in 1964 (3) and is the most widely used score. It was originally proposed to determine the suitability of a patient for IOL in patients who were parous, at term , had an uncomplicated pregnancy and the fetus was in cephalic presentation.
- 17. Table 1. Bishop Score for Assessing Favor ability for Induction of labour. Score Factor 0 1 2 3 Dilatation (cm) 0 1-2 3-4 5-6 Effacement(%) 0-30 40-50 60-70 80 Station -3 -2 -1 or 0 +1 or +2 Consistency Firm Medium Soft - Position Posterior Mid Anterior - * A score of 9 or more ensured a safe and uniformly successful induction
- 18. * Induction with a score of 16 more is considered favorable Burnett (5) later on modified the original Bishop’s score giving a maximum score of 2 to each of Bishop's five categories, giving a total maximum score of 10. He considered effacement in terms of length and not percentage and considered previous term birth and cephalic presentation to be pre-requisites for induction.
- 19. * Outcome of patients with a score of less than 6 was unfavorable, with a score of 9- 10 all patients could be delivered within 4 hours and most within 24 hours. Evaluating the performance of Bishop's score, Lange et al (6) observed that cervical dilatation was twice as important as the other factors and proposed a modification of the original score which predicted successful induction equally well.
- 20. Table 4. Pelvic Score Proposed by Lange et al Score Factor 0 1 2 3 Multiply by Dilatation (cm) 0 1-2 3-4 >4 X2 Length (cm) 3 2 1 0 X1 Station(cm) -3 -2 -1 or 0 +1 or +2 X1
- 21. METHODS OF CERVICAL RIPENING AND LABOR INDUCTION: Cervical priming before labor induction in an unfavorable cervix increases the success rates and shortens the induction to delivery interval. Methods for cervical ripening and labor induction can be broadly classified as : •Pharmacological methods (Prostaglandins, Oxytocin & others) •Non pharmacological methods (Natural, Surgical , Mechanical and others)
- 22. PHARMACOLOGICAL METHODS PROSTAGLANDINS : PG E2 gel has been widely used for pre-induction cervical ripening. Local applications of PGE2 causes cervical ripening by three mechanisms: •Alteration of extracellular grounds substance of cervix by increasing collagenase , elastase, glycosaminoglycans , dermatan sulfate, and hyaluronic acid levels •Relaxation of smooth muscle of cervix •Gap junction formation leading to initiation of uterine contractions
- 23. Preparations available, Dosage and Usage Guidelines : Intracervical PGE2 gel: ( Cervigel , Dinoripe , Prepidil ) •Contains 0.5 mg of PGE2 •Bring the gel to room temperature before use and instill in the cervical canal below the internal os •The patient lies supine for 15-30 minutes after the insertion . •If no response occurs in one use a repeat insertion may be required after 6 hours •Maximum of 1.5 mg or three insertions are allowed over a period of 24 hours. •If required oxytocin is to used only after 6- 12 hours of the last insertion.
- 24. Intravaginal PGE2 gel: •Vaginal PG E2 gel : - contains 2.5 mg PGE2 - 2 doses 6 hours apart are used •Vaginal controlled release insert : (Cervidil ) - 10 mg insert which releases 0.3 mg / hr of the prostaglandin - No need to pre warm the insert . - The patient should lie supine for 2 hours following the insertion - The insert is to be removed after 12 hours or when active labor begins or in case of hyperstimulation.
- 26. PGE 2 Routes : Controlled trials : Some observations (10-13) •Intracervical use is technically more difficult •Vaginal route ( gel or insert ) is superior to intracervical route for cervical ripening but it causes higher uterine activity •Controlled release vaginal insert use gives a better post ripening score, decreased the time to delivery, time to active labor and need for oxytocin use as compared to vaginal gel 2 doses 2.5 mg six hours apart. •The overall incidence of hyperstimulation is 4.8% - same as with oxytocin. However , the incidence is more when used in active labor (12.5 %) , more with vaginal gel (5%) than intracervical (1%) and least with controlled release insert which can be reversed with terbutaline administration or removal of the vaginal insert. Washing the vagina does not offer any benefit . •Use of PGE 2 does not alter C. S. rates
- 27. Contraindications: Established uterine activity, glaucoma, asthma, severe hepatic or renal impairment , known hypersensitivity to prostaglandins , active vaginal bleeding
- 28. Side Effects Uterine tachysystole has been reported to follow vaginally administered prostaglandin E2 in 1 to 5 percent of women . Although definitions may vary among studies, most use the terms defined by the American College of Obstetricians and Gynecologists (1999a) to describe increased uterine activity as follows: 1.Uterine tachysystole is defined as 6 contractions in a 10-minute period. 2.Uterine hypertonus is described as a single contraction lasting longer than 2 minutes. 3.Uterine hyperstimulation is when either condition leads to a nonreassuring fetal heart rate pattern. Because hyperstimulation that can cause fetal compromise may develop when prostaglandins are used with preexisting spontaneous labor, such use is not recommended. If hyperstimulation occurs with the 10-mg insert, its removal by pulling on the tail of the surrounding net sac will usually reverse this effect. Irrigation to remove the gel preparation has not been helpful.
- 29. ACOG Guidelines : (14,15) Bishop’s score should be less than 4. Drug should be administered near the delivery suite. Patient should lie recumbent for 30 minutes after the instillation. FHR and uterine activity should be monitored for 30 minutes to 2 hours after the instillation. After this , patient may be transferred elsewhere, if there is no increase in uterine activity and FHR is normal. The controlled release insert should be removed at the onset of labor. Oxytocin should be avoided for initial 6-12 hours
- 30. RCOG Guidelines : (16) Intravaginal PGE2 should be used in preference to intracervical preparations as they are equally effective and administration of intravaginal PGE 2 is less invasive of the vaginal preparations. Tablets should be preferred over the gel as they are more cheap and equally effective.
- 31. MISOPROSTOL: Mioprostol is a synthetic PG E1 analogue which has been used as a gastric cytoprotective agent since 1988 for patients of peptic ulcer. Studies in late 1980’s and early 1990’s noted that oral administration of this drug causes uterine contractions in early pregnancy. Subsequent studies showed that intravaginal misoprostol causes first and second trimester abortion and there has been recent evidence of its use for cervical ripening and labor induction.
- 32. Pharmacokinetics: The pharmacokinetics of misoprostol have been extensively studied by Ziemann et al (17). They have observed that peak plasma concentration is higher and achieved earlier after an oral administration. Peak levels with vaginal administration are attained more slowly and sustained for longer periods because of the presystemic gastrointestinal and hepatic metabolism that occurs with oral route . Overall the systemic bioavailability is three times higher with the vaginal route.
- 33. Dosage schedules and usage guidelines: •Cheap drug •Does not require storage conditions •Can be given by oral, buccal or vaginal routes although vaginal route is the most extensively used •Tablets are available as either 100 mcg or 200 mcg •Dosage: 25 –50 mcg is administered 4-6 hourly •The tablet is inserted into the posterior vaginal fornix , one may or may not wet the tablet with saline prior to insertion
- 34. Misoprostol : Controlled trials : some observations: (18) •Oral route is not recommended at this point of time •Misoprostol shortens the Induction delivery interval as compared to PG E2 and oxytocin •25 mcg vaginal dose has less hyperstimulation but a longer IDI as compared to 50 mcg •It effectively lowers the cesarean rates •However it is not recommended as an outpatient setting or with previous C. S. •An increase in the incidence of meconium staining of amiotic fliud and tachysystole is noted •Overall the use of misoprostol is not associated with an increased rate of operative intervention for fetal distress and NICU admission.
- 35. ACOG Guidelines 25mcg should be the initial dose for labor induction at term , should not be administered more frequent than 3-6 hours , oxytocin should not be administered < 4 hours after the last misoprostol use and the drug should be avoided in patients with previous cesarean delivery or major uterine surgery. Use of higher dosage 50 mcg may be appropriate in some situations and have a greater likelihood of vaginal delivery within 12 hours, such doses increase the risk of hyperstimulation and rupture. There is at present insufficient clinical evidence to address the safety of misoprostol in patients with multiple gestations and suspected fetal macrosomia.
- 36. RCOG Guidelines : (16) Misoprostol appears to be more effective than oxytocin or vaginal PG E2 in presence of ruptured membranes for induction of labor. Use of misoprostol in obstetrics must be restricted to RCTs. Oral misoprostol appears to be less effective than vaginal misoprostol, however, oral route is associated with less incidence of uterine hypercontractility but a higher incidence of meconium stained liquor. Its use is associated with increased uterine hypercontractilty but this is not translated in increased operative delivery rates. The safety issues surrounding the use of misoprostol have not been clearly evaluated. * Despite a lot of clinical use, misoprostol is still not approved by the Drug Controller of India for use in induction of labor.
- 37. OXYTOCIN: Oxytocin is a polypeptide hormone secreted from the posterior pituitary gland which acts as a potent uterotonic agent. The drug was used intravenously in 1948 by Theobald et al (21) to induce labor. Later in 1958 Du Vigneaud et al (22) synthesized the drug. Since then it has been the most commonly used drug for induction and augmentation of labor. Routes of administration: Oxytocin can be administered by any parenteral route, intravenous route being the most widely used. It can be absorbed from the nasal or buccal mucosa, however when given orally it is rapidly inactivated by trypsin.
- 38. Pharmacokinetics and mechanism of action: The half life of oxytocin is 3-5 minutes. Once absorbed it is distributed in the extracellular fluid and does not bind to plasma proteins and is excreted by the liver and kidneys. The action is mediated by oxytocin receptors (OTR) which are present on the myometrium. Myometrial response to oxytocin begins at 20 weeks , increases through out pregnancy and peaks just before initiation of labor. The response varies according to the status of the cervix, uterine sensitivity, variability in oxytocin clearance rate, duration of pregnancy and the pre-existing myometrial contractions. The OTR concentration is the rate limiting step for oxytocin action. Oxytocin on binding to the OTR increases the intracellular concentration of calcium causing myometrial cell contraction. Uterine contractions are also stimulated by a calcium independent mechanism involving the prostaglandins. PGE and PGF are increased during oxytocin administration. It has been postulated that Prostaglandin release by oxytocin is necessary for fully efficient uterine contractions during labor.
- 39. Dosing and Usage Guidelines: 10 –20 units are dissolved in 1000 ml of balanced salt solution ( Ringer Lactate solution or Normal saline ) making it as 10-20 mu/ml and it is preferable to give it through an infusion pump. Further increments are made according to the low dose or high dose protocol given below (15 ) : Regimen Starting dose Incremental dose Dosage interval (mU/ min) (mU/ min) ( min) Low Dose 0.5 – 1 1 30-40 1 –2 2 15 High dose 6 6 15 6 6, 3*, 1* 20-40 * The incremental increase is reduced to 3 mU/min in presence of hyperstimulation and reduced to 1mU/min with recurrent hyperstimulation .
- 40. After intravenous infusion , uterine response occurs within 3- 5 minutes and a steady state plasma concentration is reached in about 40 minutes. The end point to be achieved is uterine contractions every 2- 3 minutes lasting for 60-90 seconds and a uterine pressure of 50- 60 mm Hg or 150 Montevideo units.
- 41. Risks of Oxytocin: · Hyperstimulation , with or without fetal heart rate changes · Failed induction with need for repeat induction or possibly cesarean · Increased risk for uterine rupture in some studies · Hypotension if administered by IV bolus · Hyponatremia if administered with large amounts of sodium poor fluids · Antidiuretic hormone like effect if administered at high doses · Increased risk for neonatal hyperbilirubinemia
- 42. In the management of active-phase arrest, and with no contraindication to intravenous oxytocin, decisions must be made with knowledge of the safe upper range of uterine activity. Importantly, despite no labor progression, there were no adverse maternal or perinatal effects in those undergoing cesarean delivery. There are no data regarding safety and efficacy of contraction patterns in women with a prior cesarean delivery, with twins, or with an overdistended uterus.
- 43. Duration of Oxytocin Administration—Active Phase Arrest First-stage arrest of labor is defined by the American College of Obstetricians and Gynecologists (1989, 1995a) as a completed latent phase along with contractions exceeding 200 Montevideo units for more than 2 hours without cervical change. Some investigators have attempted to define a more accurate duration for active-phase arrest.
- 44. Rouse and colleagues (1999) prospectively managed 542 women at term with active-phase arrest and no other complications. Their protocol was to achieve a sustained pattern of at least 200 Montevideo units for a minimum of 4 hours. This time frame was extended to 6 hours if activity of 200 Montevideo units or greater could not be sustained. Almost 92 percent of these women were delivered vaginally. These and other studies support the practice to allow an active-phase arrest of 4 hours (Rouse and associates, 2001).
- 45. How do we calculate uterine activity ? MONTEVIDEO UNITS : No of contractions / 10 MIN X Avg, intensity of contractions in mm of hg Eg : 3 X 60mmHg = 180 Uterine activity – Spontaneous labour - 200 MVs Induction of labour - 250 – 275 MVs
- 46. RCOG Guidelines : (16) · Oxytocin should not be started for 6 hours following administration of vaginal prostaglandins · In women with intact membranes , if feasible amniotomy should be performed prior to commencement of oxytocin infusion · Minimum possible dose of oxytocin should be used and titrated against uterine contractions. Maximum licensed dose is 20 mU/min and should not be exceed 32 mU/min · Local protocols should specify the dose , dilution of oxytocin and preferably be delivered via infusion pump or syringe driver with non-return valve
- 48. Infusion pumps is an electronic apparatus designed to deliver drugs and 'biologicals', at low doses. The delivery process of these pumps are associated with local hemolysis which consists the potential benefits of a calibrated delivery system. infusion pumps are easy to use as these are designed keeping in mind the requirements of patrons at our vendors' end.
- 49. Oxytocin Administration via the Infusion Pump 1. Oxytocin for the purpose of induction or augmentation of labor, will be ordered by the physician and administered by an RN. 2. Oxytocin administered for induction or augmentation of labor will be performed only in L&D after a minimum 30 minute baseline FHR and UA tracing is obtained. 3. A registered nurse is responsible for the operation of the pump (adjustments to infusion rate per MD order). 4. Continuation of an oxytocin infusion beyond 20 milliunits/min requires an MD order. 5. In accordance with ACOG recommendations, the practice of elective* delivery prior to 39 weeks gestation is prohibited (unless approved by Chairman/Clinical Chief).
- 50. CONTRA-INDICATIONS: Contraindications include but are not restricted to: 1. Unfavorable fetal positions 2. Uterine tachysystole 3. Hypersensitivity to the drug 4. Cases where vaginal delivery is contraindicated, such as complete placenta previa, vasa previa, and cord prolapse
- 51. EQUIPMENT: Infusion pump Premixed 500ml bag of D5W with 20 units of oxytocin Infusion pump tubing
- 52. PROCEDURE: ACTION 1. Place patient on external electronic fetal monitor to establish a continuous fetal heart rate (FHR) tracing and uterine activity (UA) pattern. 2. The determination of cervical dilation, effacement, station and position should be performed either prior to the initiation of the infusion or within the first 2 hours after the initiation of the infusion. 3. Assist with the placement of internal fetal monitoring and intrauterine pressure catheters when ordered by 3. Provide additional information regarding fetal status and uterine contractions.
- 53. 4. Piggyback oxytocin infusion to main IV line as close to venipunture as possible. It may be necessary to remove or add different IV tubing so the oxytocin can be placed close to the venipuncture site. 4. Piggybacking the solution away from the venipuncture site can result in an oxytocin bolus. 5. Program infusion pump. Select Intrapartum pitocin concentration (20 units oxytocin in 500 ml) 6. Confirm pitocin concentration. 6. Concentration is 40 milliunits/ml. 7. Select dose in milliunits/min. 8. Enter the volume to be infused. 9. Begin infusion at 2 milliunits/min and increase by 2 milliunits/min every 30 minutes or as ordered by the physician until an adequate labor pattern is established. When the infusion rate reaches 20 milliunits/min notify the physician. 9. Continuation of the infusion beyond 20 milliunits/min requires a physician’s order.
- 54. 10. Decrease oxytocin if: Tachysystole is present The uterine resting tone is increased by palpation assessment or Intrauterine Pressure Catheter (IUPC) For fetal heart rate tracing concerns as assessed by nurse or physician. MD should be notified. 11. Discontinue oxytocin if: Uterine tetany Fetal indications as assessed by nurse or physician 10. Notify physician. 12. If restarting oxytocin is indicated, begin with the following guidelines: If the oxytocin was discontinued for less than 30 minutes because of: Uterine tachysystole restart oxytocin 4 milliunits/min lower than the previous level
- 55. Fetal indications: restart oxytocin at 2.0 milliunits/min or at the discretion of the physician If the oxytocin discontinued for more than 30 minutes, restart at 2.0 milliunits/min or at the discretion of the physician
- 56. Other Pharmacological methods: a) Mifepristone: 200 mg misoprostone for 2 days has been recently used for cervical priming (23). However this method is not cost effective and needs further trials. b) Relaxin : Relaxin has been demonstrated to causes changes in the collagen resulting in cervical softening . Both purified porcine and DNA produced human relaxin have been tried with success in promoting cervical ripening with no adverse maternal and fetal outcomes (24,25) . It is not yet commercially available. c) Nitric Oxide: Animal studies have shown it to be a cervical ripening agent but it is unlikely to be used for human use unless safety of NO in late pregnancy is established d) Cytokines: Theses are chemotactic agents which also can promote cervical ripening by causing changes in the extracelllulaar matrix
- 58. NATURAL MODALITIES: a) Herbal supplements: Commonly used herbal cervical ripening agents include evening primrose oil, black cohosh, raspberry leaves. The liquid of black cohosh is given as 10 drops sublingually hourly until the cervical change occurs. Evening primrose oil is given as 3 capsules orally daily for one week, this can be repeated for three such administrations.. red raspberry leaves also enhance uterine contractions in a synchronous manner b) Intercourse : results in a 10-50 fold increase in cervical mucus prostaglandin concentrationswhich occurs after 2-4 hours and remains for more than 12 hours duration . There is an associated increase in the uterine contractile activity .
- 59. SURGICAL METHODS: AMNIOTOMY: Ideally amniotomy or ARM is performed when the cervix is effaced and 2 cm dilated but it can be performed with minimal cervical dilatation. Methodology of ARM: •Auscultate the FHR •Evaluate the cervix and station of head. The cervix should be well applied to the head •Introduce two fingers into the cervix , sweep away the membranes from the cervix •Pass an Allis or Kocher’s forceps in between the groove of your two fingers , hook the membranes and rupture them ; look for the clarity of liquor •Risks: Cord prolapse FHR deceleration Bleeding through vasa praevia Fetal injury Maternal and fetal infection Advantages: - It shortens duration of labor - Allows for early diagnosis of meconium staining of amniotic fluid,specially in high risk pregnancy - Facilitates invasive fetal monitoring
- 60. MECHANICAL MODALITIES: a) Hygroscopic dilators: These are natural or synthetic rods inserted through the cervical os and left in situ for a particular time wherein because of their osmotic properties they absorb endocervical and local tissue fluids . This swelling causes a controlled dilatation of the cervix along with releasing prostaglandins. Natural dilators are obtained from the seaweed Laminaria japonicum. b) Balloon devices : Foley’s catheter or designer balloon devices when inserted intracervically can facilitate cervical ripening. Once properly placed ( beyond the internal os) balloon or the catheter is inflated with 30-50 ml saline. It is recommended to either attach a defined weight to the catheter end ( 1litre of i.v. fliud ) or to use “gentle tugs” – 2 to 4 each hour until the catheter or the balloon passes out (26,27) . Some recommend infusion of extra-amniotic saline at the rate of 1 cc/minute. There is no infection associated with balloon devices
- 61. Mechanical -- Double balloon
- 62. MISCELLANEOUS: a) Castor Oil (28 ) : It is an extract from “Ricinus communis” and is mainly crude ricinoleic acid .It is known to stimulate gut peristalsis and labor most likely is stimulated due to release of prostaglandins. The method is no longer used now. One study has reported an increased incidence of meconium staining of amniotic fluid. b) Accupuncture and TENS( Transcutaneous electric nerve stimulation) : Few studies ( 29-31) have reported successful induction of labor with these methods but further trials are needed before planning a large scale use.
- 63. CERVICAL RIPENING AND IOL IN SPECIAL CIRCUMSTANCES: a) Previous C. S. : · One or more previous C. S. are not a contraindication to the induction of labor. · Cervical ripening can be done in these situations with PGE2 gel – either intravaginal or intracervical · Misoprostol is an absolute contraindication · Oxytocin can be safely used in low doses with close monitoring of uterine contractions and FHR. · It is preferable to have continuous electronic fetal monitoring.
- 64. b) Twin pregnancy: · PGE 2 gel can be safely used for cervical ripening · ARM facilitates induction · Oxytocin in low doses can be used c) Premature rupture of membranes (PROM) : · Use of PGE2 gel– 2 doses 6 hours apart is not associated with higher incidence of infection · Misoprostol can also be used in 25 mcg dose · Oxytocin infusion should be closely monitored · Beware of hyperstimulation
- 65. d) Intrauterine fetal demise (IUFD ) : · Oxytocin is effective for IOL near term with a favorable cervix. · All prostaglandins can safely be used in recommended dosages for cervical ripening remote from term.
- 66. Induction of labor : Summary of evidence based ACOG recommendations: Recommendations based on good and consistent scientific evidence ( Level A) Prostaglandin E analogues are effective in promoting cervical ripening and inducing labor Women in whom induction of labor is indicated may be appropriately managed with either a low or high dose oxytocin regimen Fetal heart rate and uterine activity should be continuously monitored from the time the PGE 2 vaginal insert is placed until at least 15 minutes after it is removed High dose PGE 2 vaginal suppositories may be used in the management of intrauterine fetal demise in the second trimester of pregnancy Although the optimal dose and timing interval of misoprostol is unknown , lower doses ( 25 mcg every 3-6 hours) are effective for cervical ripening and induction of labor
- 67. Recommendations based on evidence that may be limited or inconsistent ( Level B): Misoprostol use in women with prior cesarean birth should be avoided because of the possibility of uterine rupture The use of higher doses of misoprostol ( 50 mcg every 6 hours) to induce labor may be appropriate in some situations , although there are reports of increased risk of complications, including uterine hyperstimulation.
- 68. Recommendations based onconsensus and expert opinion ( Level C) : For women with third trimester intrauterine fetal demises, intravaginal misoplrostol can be used to induce labor. Fetal heart rate and uterine activity should be continuously monitored from 30 minutes to 2 hours after administration of PG E2 gel
- 69. Failure of Induction It is defined when Cx failed to dilate up to 3-4 cm in 24 hrs of induction. What to do now ? - Option to wait-- if No PROM and postponement is not harmful for fetus as well as mother. - Review the case and if there is urgency, Caesarean delivery is performed.
- 70. What's new in monitoring of labour ? MONITORING UTERINE CONTRACTIONS : Intra uterine pressures FETAL MONITORING Fetal pulse oximetry Fetal electrocardiogram wave form analysis Intermittent measurement of lactate by FBS As an adjuvant to EFM as it has high False positive rates