Updates on Induction & Augmentation - 2021
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The document provides detailed guidelines for labor induction and augmentation, including definitions, indications, contraindications, methods for cervical ripening, and the Bishop scoring system. It discusses various pharmacologic and mechanical agents used for induction, highlighting their mechanisms of action, administration protocols, and potential side effects. Additionally, it covers factors influencing the success of induction and outlines non-pharmacological methods like amniotomy.
![Pharmacologic Ripening
Synthetic Prostaglandin E1
(misoprostol - Cytotec)
• MOA
– Approved for treatment and prevention of gastric
ulcer disease related to chronic NSAIDs use
• As it produces a dose-related inhibition of gastric acid and
pepsin secretion and enhances mucosal resistance to injury
• approved by the U.S. FDA for Peptic ulcer prevention
– binds to myometrial cells to cause strong myometrial
contractions leading to expulsion of tissue
– also causes cervical ripening with softening and dilation
of the cervix
• Its use for cervical ripening and labor induction is considered
an off-label use in the United States
• Rapidly absorbed from both oral & vaginal
routes
SPHMMC 2020 – PG E2
• If no response after 2 dozes of 25 mcg → 50 mcg
every 6 hours for a total of 200 mcg
(place into the posterior fornix):
– Do not divide or cut a 200-mcg tablet – since
inaccurate
– 25 mcg → redosing intervals of 3 – 6 hours
25 mcg; if required repeat after 3 hours.
– If no 25 mcg tablet → 25 mL of [200 mcg in 200 mL
of water]
– Re dose after 2 hour if necessary
– The concentration peaks sooner and declines more
rapidly than with vaginal route
– Preferred in patients with PROM
- investigational
• No better route
• Discontinue misoprostol and begin oxytocin
infusion if
– ROM / cervical ripening has been achieved or
– 12 hours have passed since 1st dose of prostaglandin
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Updates on Induction & Augmentation - 2021
- 1. Updates on Induction and Augmentation : https://t.me/OBGYN_Note_Book https://t.me/Hanybal2021 : https://www.facebook.com/obgyn.books : https://www.slideshare.net/bjlomsecond : bjlomsecond@gmail.com
- 2. Contents • Induction – Definition – Indications Vs Contraindications – Cervical Ripening – Bishop Scoring System – Labor induction without initial use of Oxytocin – Induction with Oxytocin – Failed Induction • Augmentation 2
- 3. Induction Definition • artificial stimulation of uterine contractions before the spontaneous onset of true labor to achieve vaginal delivery • can – Planned (elective) or – Emergency 3
- 4. IndicationsVs Contraindications Indications • Hypertensive disorders of pregnancy • Maternal medical complications (DM, severe cardiac disease) • Chorioamnionitis • Term PROM, IUFD • Post term • Abruptio placenta • Congenital anomaly • RH isoimmunization Preconditions • Get informed consent • Document the indication • Make sure that there are no contraindications • Determine Bishop score – if unfavorable ➔ ripen cervix • Ascertain availability of labor ward staff and also the capacity to do emergency caesarean section 4
- 5. Contraindications ABSOLUTE Gross CPD, Macrosomia Transverse and oblique lie, Footling breech Scar o Upper segment uterine scar o previous uterine scar (e.g. myomectomy, CS) o ≥ 2 previous lower uterine segment cesarean scar Active or culture proven genital herpes (with intact membranes or ROM < 6 hrs duration) Extensive genital wart Invasive cervical Ca. Pelvic tumor obstructing the birth canal Placenta previa (major degree) Vasa previa Acute fetal distress Severe IUGR with confirmed fetal compromise RELATIVE Grande multi-parity Bad obstetric history Twin pregnancy One previous lower segment c/s • NB: Mothers with relative contraindications will be managed with the discussion between the mother and the most senior person 5
- 6. Cervical Ripening Definition • The use of pharmacological / mechanical means to soften the cervix • Indications – In women with unfavorable BISHOP (≤ 5) • Method – Mechanical: Balloon / Foley catheter; Osmotic (hygroscopic) dilators – Pharmacological • Prostaglandin E1 (Misoprostol), Prostaglandin E2 (Dinoprostol) • In patientVs Out patient Cervical ripening (UTD 2021) – If maternal and/or fetal monitoring is not otherwise necessary during the ripening phase • Outpatient ripening could reduce the duration of hospitalization and costs of medical care – Reactive nonstress test or reassuring biophysical profile, vertex presentation 6
- 7. Pharmacologic Ripening Synthetic Prostaglandin E1 (misoprostol - Cytotec) • MOA – Approved for treatment and prevention of gastric ulcer disease related to chronic NSAIDs use • As it produces a dose-related inhibition of gastric acid and pepsin secretion and enhances mucosal resistance to injury • approved by the U.S. FDA for Peptic ulcer prevention – binds to myometrial cells to cause strong myometrial contractions leading to expulsion of tissue – also causes cervical ripening with softening and dilation of the cervix • Its use for cervical ripening and labor induction is considered an off-label use in the United States • Rapidly absorbed from both oral & vaginal routes SPHMMC 2020 – PG E2 • If no response after 2 dozes of 25 mcg → 50 mcg every 6 hours for a total of 200 mcg (place into the posterior fornix): – Do not divide or cut a 200-mcg tablet – since inaccurate – 25 mcg → redosing intervals of 3 – 6 hours 25 mcg; if required repeat after 3 hours. – If no 25 mcg tablet → 25 mL of [200 mcg in 200 mL of water] – Re dose after 2 hour if necessary – The concentration peaks sooner and declines more rapidly than with vaginal route – Preferred in patients with PROM - investigational • No better route • Discontinue misoprostol and begin oxytocin infusion if – ROM / cervical ripening has been achieved or – 12 hours have passed since 1st dose of prostaglandin 7
- 8. Asthma - (G 7th) • PGE2 or PGE1 can be used for cervical ripening, – management of spontaneous or – induced abortions, or – postpartum hemorrhage, – although the patient’s respiratory status should be monitored Contraindications for PGs • Ruptured membranes • known hypersensitivity to prostaglandins • Unexplained vaginal bleeding • Women already receiving oxytocin • Those with a contraindication to vaginal delivery 8
- 9. Prostaglandin E2 (Dinoprostone) • Two drugs: Prepidil & Cervidil • vaginal tablet is superior to vaginal gel • also stimulates osteoblasts to release factors which stimulates bone resorption by osteoclasts • Prepidil - Gel – 0.5 mg of dinoprostone in 2.5 mL of gel for endocervical administration – 2nd dose after 6 to 12 hours if inadequate cervical change – Maximum cumulative dose: 1.5 mg/24 hr (3 doses) – Oxytocin: after 6 to 12 hours due to the potential for uterine tachysystole with concurrent oxytocin and PGE2 prostaglandin administration • Cervidil -Vaginal insert – 10 mg of dinoprostone: a timed-release - 0.3 mg/hour – left in place until active labor begins for 12 hr – Oxytocin: 30 minutes after removal of the insert – Theoretical advantage over the Gel: it can be removed in cases of uterine tachysystole or abnormalities of the FHR tracing • Efficacy – Intravaginal PGE2 is more likely to result in vaginal delivery within 24 hours than endocervical PGE2, but both preparations are associated with similar rates of cesarean delivery and tachysystole • Side effects of prostaglandins – tachysystole, fever, chills, vomiting, and diarrhea – Uterine contractile abnormalities occur in up to 30 percent of cases • Do not use misoprostol / Dinoprostone for cervical ripening in women with a previous cesarean delivery (ACOG, SOGC) 9
- 10. General guideline for PG use in cervical ripening (SPHMMC 2020) • Insertion - @ hospital – kept patient in recumbent for at 30 minutes • Monitor FHB and uterine activity – for 30 minutes to 2 hours after insertion – ? contractions • Repeat doses of PGE – After an interval of 6-12 hours of the last dose only if the cervical change is insufficient • Discontinue use of PG and begin oxytocin infusion – if membranes ruptures; cervical ripening has been achieved; contractions are achieved; or 6 hours have passed from last planned dose. • Effects of PGE2 may be exaggerated with oxytocin, so oxytocin induction should be delayed for 6 hours after the last dose 10
- 11. Mechanical Ripening • Mechanism of mechanical agents – directly causing cervical dilation → cause releasing endogenous prostaglandins & oxytocin Balloon / Foley catheter • Catheter size16 / 18) - above the IO (about 5-8 cm) - @ SPHMMC 2020 • through the endocervical canal and into the extraamniotic space • 30 - 50 ml of sterile saline and pulled gently to the level of the IO - @ SPHMMC 2020 – moderate traction to the inner aspect of thigh – It is left for 12 hours or labor starts and expelled spontaneously • Inflate with (30 to 80 mL) of saline (UTD 2021) o Single (30 to 80 ml)Vs o Double (1st – 40 ml + 2nd – 20 ml) balloon catheter • It is not known if more fluid in the balloon is more effective without being more dangerous – Volumes of 80 mLVs 30 mL • 30 ml: required oxytocin more frequently • 80 ml: more scar dehiscence occurred, with no significant difference • Mechanism of action – direct physical pressure on internal cervical os – by causing the release of prostaglandins from the decidua, adjacent membranes, and/or cervix • keep for at least 12 hours / until contractions begin – oxytocin infusion can be started with a balloon catheter in place or after it has been removed • Induction-to-delivery times may be decreased compared with prostaglandins • no or minimal side effects • CI: If history of bleeding, ROM, vaginal infection 11
- 12. Contraindications for balloon catheter • No absolute CI • GBS colonization is not a CI, but standard chemoprophylaxis should be used • Polyhydramnios: we can prime with great caution • CI o Placenta previa: Since edge of the placenta may be disrupted by manipulation during placement of the device o Active herpes lesions o Vasa previa o Malpresentation o Maternal refusal o Ruptured membranes o Signs of fetal compromise on cardiotocography o Any contraindication to vaginal birth • Efficacy of balloon catheter o Similar - PGE2 o Slightly less effective than low- dose vaginal (oral) misoprostol o Resulted in a lower risk of uterine tachysystole with FHR changes compared with PGE2, vaginal misoprostol, and oral misoprostol o Resulted in less serious neonatal morbidity or perinatal death compared with PGE2 Balloon catheter combined with a prostaglandin or oxytocin • does not increase adverse obstetric or perinatal outcomes • may have modest benefits over the use of a single method alone 12
- 13. Hygroscopic dilators • as safe and effective as other cervical ripening agents • more commonly used during pregnancy termination than for preinduction cervical ripening of term pregnancies • hydrophilic agents – absorb water (moisture) → gradually expand within the cervical canal • Two types 1. Laminaria tents • Extracted from natural seaweed • Can be removed 12 to 24 hours after placement 2. Dilapan-S • synthetic product • Can be removed after 6 to 8 hours • Efficacy – Lower risk of tachysystole with adverse FHR changes compared with those who received prostaglandins – cesarean delivery rate was similar with those receiving any prostaglandin (vaginal PGE2, intracervical PGE2, or misoprostol) or balloon catheters 13
- 14. Other cervical ripening drugs and techniques Relaxin Nitric oxide donors Hyaluronidase Corticosteroids Castor oil Sexual intercourse Breast stimulation and Herbal preparations • Nitric oxide (NO) donor agents – isosorbide mononitrate, Isosorbide dinitrate, nitroglycerin & sodium nitroprusside – it probably helps in causing the cervix to be more favourable at 12 to 24 hours after administration – Less effective when compared to vaginal misoprostol • resulted in a higher rate of maternal headache when used for induction of labor – compared to placebo, vaginal or intracervical prostaglandins, vaginal misoprostol and intracervical Foley catheter • Available data suggests that NO donors can be a useful tool in the process of induction of labor causing the cervix to be more favorable in comparison to placebo. However, additional data are needed to assess the true impact of NO donors on all important labor process and delivery outcomes 14
- 15. • Compared with prostaglandin E2 in clinical trials, which of the following is true of NO donors? – A.They increase the cesarean delivery rate. – B.They result in more uterine hyperstimulation. – C.They are less effective for cervical ripening – D.They cause more fetal distress. • In theory, nitric oxide (NO) donors should be effective agents to stimulate labor based on which of the following facts? – A. NO is a mediator of cervical ripening. – B. NO metabolites are increased in early labor. – C. NO production is low in post term pregnancies. – D.All of the above • Which regiment is more effective to improve Bishop score? – A- vaginal misoprostol 50 mcg B- intracervical PGE2 (dinoprostone)0.5 mg – C- Oral Misoprostol 50 mcg D-NS extra amniotic infusion • Which is wrong in PGE2 administration for labor induction? – A-It reduces submucosal water content – B- vaginal tablet is superior to vaginal gel – C- It better affects on a cervix with Bishop score below 4 – D-It can be used instead of oxytocin for cervical Bishop score of 5-7 15
- 16. • Which is wrong about PGE2 gel? – A-The intracervical dose is 0.3-0.5 mg – B-The vaginal dose is 3-5 mg – C- The vaginal application releases 10 mg Q4h – D-If contractions and FHR are normal in a 2 hour observation, the patient can be discharged • Common side effects of Dinoprostone (prostaglandin E2) include which of the following? – A. Fever B. Dysuria C.Arthralgias D. Somnolence • Most women who undergo membrane stripping at term enter labor within how many hours? 72 • When administering dinoprostone using the device shown here, which of the following should be avoided? – A.The patient remaining recumbent for the first 2 hours after insertion – B. Subsequent use of oxytocin – C.The use of lubricants during insertion – D. Removal of the device with the onset of labor 16
- 17. Bishop Scoring System 0 1 2 3 Dilation, cm Closed 1 to 2 3 to 4 ≥5 to 6 Effacement , % 0 to 30 40 to 50 60 to 70 ≥80 Station* -3 -2 -1, 0 +1, +2 Cervical consistenc y Firm Medium Soft Position of the cervix Posteri or Midposit ion Anterior • No universally accepted definition of favorable or unfavorable cervix (UTD 2021) • many obstetricians use a Bishop score (UTD 2021) – ≥ 6: Favorable cervix • cervical condition and induction is likely to succeed • no need for cervical ripening • Induction using Oxytocin can be planned – Score ≤ 5: Unfavorable • cervix is unlikely to yield for induction • Cervical ripening is needed for success with induction • Postpone induction for next week if possible or use cervical ripening and plan induction for next day • Unfavorable cervix – Use mechanical cervical ripening → amniotomy & oxytocin administration ❑ A term pregnancy- 3cm / 50%, station @ -2; soft cervix in mid position has a Bishop score of: – A-5 B-7 C-9 D-10 17 * Based on a -3 to +3 scale AAU - 2010 • Score ≤ 4: unfavorable • Score 5-8: intermediate • Score ≥ 9: favorable
- 18. SPHMMC 2020 Protocol • Bishop score ≥ 8: favorable – indicates a similar likelihood of vaginal birth whether labor is spontaneous or induced • Low Bishop score <8: unfavorable – is associated with a higher rate of failed induction of labor, particularly in nulliparous women • Admit the woman the day before the oxytocin induction • Asses Bishop score • Monitor every 2-4 hours once on cervical ripening • Provide light sedation the night before procedure • Allow fluid diet in the evening before the day of induction and keep her NPO in the morning. • Initiate elective induction at 8:00 am • Discontinue PG and begin oxytocin infusion if membranes ruptures; cervical ripening has been achieved; contractions are achieved; or 6 hours have passed from last planned dose 18
- 19. Noncervical factors associated with a higher chance of successful induction • Multiparity • Ruptured membranes • Lower body mass index (BMI) • Taller height • Lower estimated fetal weight • Absence of comorbidities associated with placental insufficiency (eg, preeclampsia) • Q:Which of the following women would be most likely to have a successful induction of labor? – A. G2P1 with a body mass index of 34 and a neonatal birthweight of 3,250 g – B. G1P0 with a body mass index of 25 and a neonatal birthweight of 3,800 g – C. G2P1 with a body mass index of 27 and a neonatal birthweight of 3,150 g – D. G1P0 with a body mass index of 31 and a neonatal birthweight of 2,900 g Risk factors for uterine rupture during induction • No previous vaginal delivery • Unfavorable cervix • Use of prostaglandins – Induction with prostaglandins appears to be associated with a higher risk for uterine rupture than induction with oxytocin or cervical ripening with mechanical methods followed by oxytocin administration 19
- 20. Labor induction without initial use of Oxytocin Amniotomy (Artificial Rupture of Membranes) • non-pharmacological method • amniotic membranes can be ruptured artificially to induce or augment labor • contraindicated in – known or suspected vasa previa, – any contraindications to vaginal delivery or – unengaged presenting part • this obstacle may be overcome with the use of a controlled amniotomy or the application of fundal or suprapubic pressure • performed if the fetal head is well opposed to the cervix; – if not, it is delayed until the head is well opposed in order to reduce the risk of cord prolapse 20
- 21. • Mechanism - remains unclear – it is thought that when the membranes are ruptured, the production and release of prostaglandins and oxytocin increases resulting in stronger contractions and quicker cervical dilatation • combination of amniotomy and intravenous oxytocin administration is more effective • Classification – Early amniotomy: soon after successful cervical ripening • After expulsion of Foley balloon, cervical dilation 3 cm, or favorable Bishop score – Late amniotomy: after the onset of the active phase of labor • Complications: rupture of a vasa previa and umbilical cord prolapse • Elective amniotomy increases the risk for which of the following? – A. Late decelerations B. Placental abruption – C. Chorioamnionitis D. Cesarean delivery 21
- 22. Others techniques for induction • Prostaglandin E1 or E2 • Membrane stripping – Insert examiner's finger beyond the internal cervical os and then rotating the finger circumferentially along the lower uterine segment to detach the fetal membranes from the decidua – has not been associated with demonstrable improvements in many clinically important outcomes (lower cesarean rates, better perinatal outcomes) – Group B Streptococcus colonization is not a contraindication to membrane sweeping as there is no direct evidence of harm – Mechanism • Increased local production of prostaglandins 22
- 23. Induction with Oxytocin Mechanism of Action • Oxytocin stimulates uterine contraction by activating G-protein-coupled receptors that trigger increases in intracellular calcium levels in uterine myofibrils • Oxytocin also increases local prostaglandin production, further stimulating uterine contraction • Myometrial responsiveness increases with advancing gestational age until 34 weeks, at which time it levels off until spontaneous labor begins, when it increases rapidly – Increases in myometrial sensitivity are due primarily to increases in myometrial oxytocin receptor binding sites – Receptor activation triggers signaling events that stimulate contractions, primarily by elevating intracellular calcium levels Pharmacodynamics and Pharmacokinetics • Onset of uterine contractions: IM - 3 to 5 minutes; IV - 1 minute • Duration: IM: 2 to 3 hours; IV: 1 hour • Half-life elimination: 1 to 6 minutes; decreased in late pregnancy and during lactation – What is the mean half-life of oxytocin? 5 minutes • Excretion: Urine (small amount unchanged) 23
- 24. Timing of oxytocin administration (UTD 2021) • After prostaglandins – 6 to 12 hours after the final dose of dinoprostone gel – 30 minutes after removal of dinoprostone insert – 4 hours after the final misoprostol dose • After cervical ripening with a balloon catheter – oxytocin can be initiated while the catheter is in place or after it has been removed 24
- 25. UTD 2021 • No previous cesarean – concurrent use of a balloon catheter & oxytocin is sometimes employed to decrease the time to delivery • Previous cesarean – least 60% of inductions in women with one or two prior cesarean deliveries results in vaginal births, with the highest chance of success in women with a prior vaginal delivery and favorable cervix • amniotomy and administration of oxytocin rather than oxytocin alone (Grade 2C) 25
- 26. Oxytocin infusion protocols Regimen Starting dose, milliunits/ minute Incremental increase, milliunits/minute Dose interval, minutes Low-dose 0.5 to 1 1 30 to 40 Alternative low-dose 1 to 2 1 to 2 15 to 30 High-dose 6 6 The incremental increase should be reduced to 3 milliunits/minute if hyperstimulation is present and reduced to 1 milliunit/minute if recurrent hyperstimulation. 15 to 40 Some clinicians limit to a maximum cumulative dose of 10 units and a maximum duration of 6 hours. Alternative high-dose 4 4 15 • Different oxytocin regimens didn’t show significant association with success • High-dose regimens – starting doses: 4 to 10 mU/min • Our: 5 IU / 1000 ml for PG – 5 mIU/ml – increases in dose: 4 to 7 mU/min every 20 min – maximum rates: 4 to 90 mU/min • Low-dose regimen – starting doses: 1–4 mU/min • Our: 2.5 IU/1000 ml for multigravida – 2.5 mIU/ml – increases in dose: 1 to 2 mU/min every 30 min up to a maximum of 40 mU/minute – maximum rates: 1 and 32 mU/min High versus low dose oxytocin regimens (May 2021) • Both are used for labor induction and augmentation • Either approach is acceptable • whether one of these regimens is superior is unclear Dose titration • there is no evidence-based optimal upper limit – most regimens limit the infusion dose to no more than 40 milliunits/minute • There is no maximum cumulative dose limit for oxytocin known to be associated with improved outcomes 26
- 27. Our practice @ SPHMMC • 2.5 IU for multipara: Low-dose regimen – 2500 mU/1000 ml = 2.5 mU/ml = 2.5 mIU / 20 drop • 5 IU for PG: High-dose regimens – 5000 mU / 1000 ml = 5 mU/ml = 5 mIU / 20 drop • Three rounded dose increment – First round: 20 drop → 40 → 60 → 80 – Second round: 40 drop → 60 → 80 – Third round: 60 drop → 80 drop (Maintenance) 27
- 28. Fluids & rate (FMOH 2020) • Use 0.9% N/S or R/L for infusion • To ensure even mixing, the bag must be turned upside down several times before use • The initial infusion rate should be set at 1 to 2 mIU/ minute – The infusion rate is increased every 30 minutes up to a maximum of 40 mU / min (250 ml/hour) • As alternative, for induction of a primigravid woman only, oxytocin with starting dose of 3.0 to 6.0 mU / min can be used – Aim to maintain the lowest possible dosage consistent with regular uterine contraction that is until 3-5 contractions are achieved in 10 min, each lasting 40 - 60 sec • An adequate contraction consists of 3 - 5 strong contractions in 10 min, each lasting for 45-60 sec 28
- 29. SPHMMC 2020 • Once a good contraction pattern is established (3/10’/ ≥ 40” seconds, each lasting > 40 seconds), • maintain the rate; continue to monitor the woman’s pulse, BP and contractions, and the FHR • If a good contraction pattern still has not been established using the higher concentration of oxytocin: – Multigravida & previous caesarean scars → failed induction → CS – primigravida: – Infuse oxytocin at a higher concentration (10 units in 500 mL) – If good contractions are not established at the maximum dose, perform a caesarean. • Do not use oxytocin 10 units in 500 mL (i.e. 20 mIU/mL) in multigravidae and women with a previous caesarean birth • After the labor has entered the active phase, plan to deliver within 8-12 hr • Continue the oxytocin infusion for 1 hr post-partum 29
- 30. • In high dose oxytocin labor stimulation, what is the maximum dose (mu/min) of oxytocin ? – A-20 B-30 C-42 D-60 • Which of the following is true about oxytocin? – A. It is as effective orally as it is intravenously. – B. It is a powerful diuretic that could cause dehydration in large doses. – C.The half-life with intravenous infusion is 3 minutes. – D. Oxytocin should not be given prior to delivery of the placenta because this could prolong the third stage of labor. • Potential benefits of a high-dose oxytocin regimen (4.5–6 mU/mL) compared with a low- dose regimen (0.5–1.5 mU/mL) include which of the following? – A. Decreased admission-to-delivery intervals – B. Fewer failed inductions – C. Lower rates of intrapartum chorioamnionitis – D.All of the above • At what oxytocin infusion dosage does free-water clearance begin to decrease markedly? 20 mU/mL 30
- 31. Should oxytocin be discontinued in the active phase? UTD 2021 • Previously: meta-analysis – discontinuation resulted in lower cesarean birth rates • April 2021 – no consensus regarding discontinuation versus continuation of oxytocin in the active phase – in a new large randomized trial comparing the two approaches in >1200 patients, the cesarean birth rate was similar in both arms of the trial – Discontinuation • lengthened the active phase and reduced the frequency of hyperstimulation and fetal heart rate abnormalities, this did not lead to differences in maternal infection or neonatal intensive care unit admission – In the active phase, we consider either discontinuation or continuation of oxytocin reasonable, • as long as patients are monitored, with appropriate intervention for slow progress or abnormal cardiotocography 31
- 32. Other approaches to dosing • "Oxytocin rest" or break – Don’t routinely stopping oxytocin and then restarting – It has been hypothesized that stopping oxytocin if labor is not progressing and then restarting the drug several hours later will improve myometrial contractility, no randomized trials have shown clear evidence of benefit of this approach • Pulsatile dosing – pulsatile administration of IV oxytocin at 6- to 10-minute intervals – does not improve outcomes such as reducing the frequency of cesarean delivery 32
- 33. Administration and use of oxytocin • Check - uterine contraction frequency and intensity before administration – delaying or avoiding administration if the patient is having ≥2 painful contractions/10 minutes may reduce the risk of tachysystole • Uterine activity & FHR monitoring – continuously for at least 30 minutes after administration • Timing of Amniotomy – soon after the last dose of misoprostol or removal of a dinoprostone insert shortens the time interval from induction to delivery compared with waiting until spontaneous rupture of membranes 33
- 34. Side effects of Oxytocin 1:Tachysystole • > 5 contractions in 10 minutes, averaged over a 30-minute window (UTD 2021) • further subdivided into two categories – With FHR changes → Hypertonus – Without FHR changes → Hyperstimulation Hypertonus • Uterine hypersystole/hypertonus: a contraction lasting at least 2 minutes with a normal FHR • This term should be abandoned and has been replaced by tachysytole without FHR changes. Hyperstimulation • Excessive uterine contractions (tachysystole or hypertonus) with abnormal FHR changes. • FMOH 2020: ≥ 6 contractions in 10 min each lasting for ≥ 60 seconds • This term should be abandoned and has been replaced by tachystole with FHR changes Treatment • Rx: Hold Pitocin - until the tachysystole resolves • delaying or avoiding administration if the patient is having ≥ 2 painful contractions/10 minutes may reduce the risk of tachysystole • SPHMMC – 2020: If any contraction lasts > 60 seconds, or if there are > 5 contractions in 10 minutes, stop the infusion and manage as hyperstimulation 34
- 35. 2: Hyponatremia (Water intoxication) • Oxytocin has a similar structure to vasopressin (antidiuretic hormone) and can cross-react with the renal vasopressin receptor • Risks for excessive water retention – higher doses: ≥ 50 milliunits/minute – > 3 liters of hypotonic solutions: D5W – Excessive oral, rather than intravenous (IV), intake of hypotonic liquids can have the same effect. – Occur as high as 5 percent when the conditions described above are met • Clinical presentation – Symptoms of severe acute hyponatremia • headache, anorexia, nausea, vomiting, abdominal pain, lethargy, drowsiness, unconsciousness, grand mal type seizures, and potentially irreversible neurologic injury • similar to the syndrome of inappropriate antidiuretic hormone secretion • Rx – Stop hypotonic solutions – Correction of hyponatremia must be performed carefully – Consists of restricting water intake and careful administration of hypertonic saline if the patient is symptomatic 35
- 36. 3: Hypotension • Because oxytocin relaxes vascular smooth muscle, hypotension and tachycardia can result from rapid IV injection 4:Amniotic fluid embolism • 10.3 per 100,000 births with medical induction versus 5.2 per 100,000 births without medical induction 5: Uterine rupture • Rare 6: Other issues • allergic reactions to oxytocin 36
- 37. Elective induction versus expectant management at 39 weeks gestation (February 2021) – UTD 2021 • Evidence of the benefits of induction rather than expectant management at 39 weeks of gestation continue to accrue – Composite perinatal adverse outcome • 39 weeks: 5.1 percent • 40 weeks: 5.9 percent • 41 to 42 weeks: 8.2 percent – Cesarean rates also increased • 39 weeks – 17% • 40 weeks – 22% • 41 to 42 weeks - 38 percent, respectively • So have a shared decision-making regarding elective induction at 39 weeks, taking into account the values and preferences of the patient as well as the availability of labor unit beds and staffing • ACOG, SMFM Potential advantages of elective induction at ≥ 39 weeks include • Reduction in cesarean delivery • Reduction in other adverse neonatal and maternal outcomes (eg, preeclampsia) • Reduction in macrosomia (and its consequences) • Reduction in stillbirth 37
- 38. Complications MATERNAL • Failed induction • Unforeseen CPD leading to obstructed labor • Uterine hyper stimulation/tetanic contractions • Sepsis • Placental abruption • Water intoxication • Amniotic fluid embolism • PPH • Uterine rupture FETAL • Iatrogenic prematurity • Fetal asphyxia • Cord prolapse • Fetal hemorrhage from vasa previa • Fetal pneumonia • Neonatal jaundice 38
- 39. Failed Induction • not been strong consensus as to the standard for defining a failed induction • ACOG, SMFM (UTD 2021) – failure to generate regular (eg, every 3 minutes) contractions and cervical change after at least 24 hours of oxytocin administration, with artificial membrane rupture as soon as feasible and safe – The time devoted to cervical ripening is not included when calculating the length of induction or diagnosing failed induction • Gabbe 7th - Failed induction – Inability to achieve cervical dilation of 4 cm and 80% effacement or 5 cm (regardless of effacement) after a minimum of 12 to 18 hours of both oxytocin & ROM • SPHMMC 2020 – failure to generate regular contractions and cervical change with oxytocin administration for 12 hours after ROM • FMOH 2020 – failure to achieve regular contractions and cervical change after at least 6 - 8 hours of the maintenance dose of oxytocin administration, with artificial rupture of membranes if feasible 39
- 40. Management • If the induction is not for an emergency condition and the fetal membranes are intact – (E.g. IUFD with unruptured membranes), the induction can be postponed and ripening of the cervix considered • If the pregnancy has to be terminated on the day of the induction or the membranes are ruptured, cesarean section is the only available option • Failed induction as an indication for cesarean section should be differentiated from other indications detected after achieving good uterine contraction – Protraction of labor after achieving adequate uterine contraction is managed as abnormal labor 40
- 41. Augmentation • Definition – Correction of dystocia due to inefficient uterine contractions (power) by the use of oxytocin • Indications – Protracted labor is associated with hypotonic uterine dysfunction • Contraindications – are similar to the contraindications of oxytocin (+ ARM) use as detailed in the section of induction above – Breech, scared uterus, multiple pregnancy etc. are contraindication for oxytocin use – Oxytocin should not be used for secondary hypotonic contractions due to obstructed labor • Methods for augmentation are – ARM and oxytocin 41