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Preterm Labor International Preterm Labor Preterm Labor International Objectives • Definition and Incidence • Etiology • Diagnosis • Management - Delaying delivery - Promoting fetal maturity - When to transfer - Delivery Preterm Labor International Definition • regular uterine contractions accompanied by progressive cervical dilatation and/or effacement at less than 37 weeks gestation 20 to 50% of PTL diagnosis is incorrect Preterm Labor International Dilemma • interventions to stop preterm labor are not particularly effective - especially when not instituted early 'Solution' • diagnosis based on some degree of uterine activity combined with a single cervical exam suggesting early dilatation or effacement Preterm Labor International Diagnosis • establish dates • history of contractions, risk factors • abdominal exam for uterine activity • cervical exam - serial if reasonable • sterile speculum exam alone should be done in PPROM • defer digital exam if there is undiagnosed vaginal bleeding until _______ of placenta is known Preterm Labor International Establishing the EDD - LMP • Naegele's Rule can be used in conjunction with the LMP if: - first day of last menses is known - period was 'normal' - cycle is regular and between 24 and 35 days - no recent hormonal contraception, lactation or pregnancy (3 subsequent spontaneous periods) Preterm Labor International Establishing the EDD - When ultrasound is available • Ultrasound should be used when the LMP is unknown or criteria are not fulfilled for its use in calculating the EDD • U/S dating accuracy decreases as gestational age increases - 7 - 12 weeks GA ± 5 days - 13 - 20 weeks GA ± 1 week - 21 - 30 weeks GA ± 2 weeks - > 30 weeks GA ± 3 weeks Preterm Labor International Establishing the EDD • please tell someone the EDD! - inform woman of EDD from LMP if appropriate and reinforce at time of dating and/or 18 week ultrasound - document EDD on antenatal forms - document dates and findings of each ultrasound on antenatal (include placental location) • good dating is useless if no one but you knows the EDD and you are not available Preterm Labor International Incidence • preterm delivery occurs in about 7% of pregnancies • there has been little change in this rate despite new technologies Preterm Labor International Significance • preterm birth accounts for 75% of perinatal mortality • significant longterm neonatal/pediatric sequelae - CNS and neurodevelopmental - respiratory - blindness and deafness Preterm Labor International Etiology • • • • • • • • Idiopathic Antepartum haemorrhage Preterm prelabor rupture of membranes Chorioamnionitis Multiple pregnancy / Polyhydramnios Incompetent cervix / Uterine Anomaly Maternal disease Fetal anomaly Preterm Labor International Management of Preterm Labor Four Objectives: 1. Early diagnosis of preterm labor 2. Identify and treat the underlying cause of preterm labor if possible 3. Attempt to stop labor when appropriate 4. Minimize neonatal morbidity and mortality Preterm Labor International Management - Prolongation of Pregnancy less than 40% of patients in preterm labor will be candidates for tocolysis Goal of Tocolytic Therapy • Delay delivery when appropriate - gain 48 hours for corticosteroids - transport - optimize personnel Preterm Labor International Management - Tocolysis Contraindicated • contraindication to continuing pregnancy e.g. severe pregnancy induced hypertension, chonoamnionitis intrauterine fetal death • contraindication to specific tocolytic agents Preterm Labor International Tocolytics - No strong evidence for efficacy • Fluid bolus - small trial (n=48), no detected effect • Ethanol - small trials, no benefit over placebo - ritodrine more effective in comparative trials - concerns re: adverse effects • Sedation - no evidence, concern re: adverse effects Preterm Labor International Tocolytics - No strong evidence for efficacy • Magnesium sulfate - small, poor quality trials; placebo and comparative - no benefit shown Preterm Labor International Tocolytics - Good evidence for efficacy • -sympathomimetics (ritodrine) - highly effective for delaying delivery in the short term - no demonstrated effect on neonatal outcome • PG synthetase inhibitors (indomethacin) - more effective than placebo in delaying delivery >48 hours and beyond - no demonstrated positive effect on neonatal outcome - small trials, concern re: adverse effects • Calcium channel blockers (e.g. nifedipine) Preterm Labor International Side Effects of -mimetics • • • • • tachycardia - maternal and/or fetal headache and nasal congestion hyperglycemia / hypokalemia hypotension pulmonary edema - multiple gestation - other interventions - infection • myocardial ischemia Preterm Labor International Contraindications to -mimetics • Maternal cardiac disease - structural, ischemic, rhythm • Significant antepartum haemorrhage • Poorly controlled medical condition - type I diabetes mellitus - hyperthyroidism • Contraindication to prolongation of pregnancy - preeclampsia or other medical indication - chorioamnionitis, suspected fetal compromise - mature fetus / imminent delivery / IUFD or anomaly Preterm Labor International Minimizing Neonatal Adverse Outcomes • Respiratory distress syndrome (RDS) is a major concern with preterm delivery • Incidence of RDS has improved due to newer therapies • RDS plays a role in several other conditions - intraventricular haemorrhage (IVH) - necrotising enterocolitis (NEC) - persistent pulmonary hypertension (PPHN) - other respiratory conditions Preterm Labor International Meta-analysis of Antepartum Steroids • 15 trials evaluating antenatal glucocorticoids for the reduction of RDS in preterm infants (>24 weeks and < 34 weeks) • an incomplete course of steroids may still be beneficial P. Crowley CCPC Review No. 02955 Preterm Labor International Effect of Corticosteroids on Neonatal Outcomes RDS IVH NEC Perinatal Infection Neonatal Death 0.1 P. Crowley CCPC Review No. 02955 1 10 Odds Ratio (95% Confidence Interval) Preterm Labor International Recommendations Which steroid ? • betamethasone 12 mg IM q 24h x 2 doses (or q 12h) • dexamethasone 6 mg IV q 12h x 4 doses (or q 6h) Beware • steroids in the presence of infection • steroids in combination with tocolytics in multiple gestation or diabetes Preterm Labor International Recommendations When should steroid therapy be instituted? • lower gestation limit 22 - 24 weeks • upper gestation limit 34 - 36 weeks • prophylactic administration depends on diagnosis and risk • repeated administration unknown Preterm Labor International Recommendations Who is a candidate for antenatal steroid therapy? preterm labour preterm PROM hypertensives diabetics IUGR multiple gestation YES YES YES YES YES YES Considerations cause infection urgency type, sugars urgency pulmonary edema Preterm Labor International Decision to Transport • • • • • Available level of neonatal or obstetrical care Available transport and skilled personnel Travel time Risk of journey - maternal and fetal/neonatal well-being Risk of delivery en route - Parity, length of previous labour - State of cervix - Contractions - Response to tocolytics Preterm Labor International Transport Plan • Copies of antenatal forms, lab results, ultrasounds • Communication - with patient and family - with receiving physician re: indication, stabilization, optimization, mode of transport, E.T.A. • Appropriate attendant • IV access, indicated medications, appropriate equipment • Assess patient immediately prior to transport Preterm Labor International Preterm Delivery • caesarean not indicated on basis of prematurity • recommendation for C/S of breech < 31 weeks not based on good evidence • prophylactic outlet forceps not indicated • routine episiotomy not indicated • personnel skilled in neonatal resuscitation present Preterm Labor International Conclusion • Prompt and accurate diagnosis • Identify and treat underlying cause if possible • Attempt to prolong pregnancy if appropriate • Intervene to minimize neonatal mortality and morbidity - antenatal steroid therapy - maternal transport - optimize local resources if unable to transport Preterm Labor International Prelabor Rupture of the Membranes (PROM) Preterm Labor International Objectives • Definition • Diagnosis • Management - Preterm and Term Preterm Labor International Definition • rupture of the membranes before the onset of labor – preterm - < 37 weeks gestation (PPROM) – term - 37 weeks gestation (TPROM) Preterm Labor International Latent Period • time from rupture until onset of labor • earlier the gestation the longer the latent period • At term - 90% go into labor within 24 hours • At 28 - 34 weeks – 50% go into labor within 24 hours – 80 - 90% go into labor within 1 week Preterm Labor International Etiology of PROM • idiopathic • infection (e.g. bacterial vaginosis) • polyhydramnios • cervical incompetence • uterine abnormality • following cervical cerclage or amniocentesis • trauma Preterm Labor International Diagnosis of PROM • history • sterile speculum exam ( avoid digital exam) – glistening, washed out vagina – fluid pooling in posterior fornix – free flow from cervix – pH testing of fluid (nitrazine paper) - non specific – ferning • ultrasound - PROM less likely if normal fluid volume Preterm Labor International Complications of PROM - Term • fetal / neonatal infection • maternal infection • umbilical cord compression / prolapse • failed induction resulting in cesarean section Preterm Labor International Complications of PROM - Preterm • preterm labor and delivery • fetal / neonatal infection • maternal infection • umbilical cord compression / prolapse • failed induction resulting in cesarean section • pulmonary hypoplasia (early, severe oligohydramnios) • fetal deformation Preterm Labor International Management - General • assess maternal and fetal well-being • confirm diagnosis • assess cervical status by speculum exam (sterile) • avoid digital cervical exam • assess for conditions requiring concurrent management e.g. presence of temperature or maternal or fetal tachycardia • assess for indications for immediate delivery Preterm Labor International Management - Term (> 37 weeks) • avoid digital cervical exam • assess for infection • consider need for antibiotics if prolonged PROM • expectant or active management depending on circumstances and patient preference Preterm Labor International Management - Preterm (34-37 weeks) • avoid digital cervical exam • consider antenatal steroids • intrapartum antibiotic prophylaxis • surveillance for infection - clinical (monitor maternal temperature and pulse, fetal heart rate) • appropriate antibiotics for chorioamnionitis if develops Preterm Labor International Management - Preterm (< 34weeks) • avoid digital cervical exam • steroids • antepartum and intrapartum antibiotics to mother • surveillance for infection - clinical (monitor maternal pulse and temperature, fetal heart rate, presence of uterine irritability) • appropriate antibiotics for chorioamnionitis if develops • consider transfer to higher level of care center if appropriate • expectant management (possibly outpatient) Preterm Labor International Antibiotic options are: Iv Penicillin G 5 million units q 4-6h preferred or Iv Ampiullin 2g followed by 1 g q 4h or IV Clindamyin 600 ng q 8h Women with suspected chorioamnitonitis require broader range spectrum antibiotic coverage
