Management of Preterm labor

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1. Management of Preterm L abour Sunil Kumar Daha

2. Obstetrics  :   All issues, physiological and pathological, related to pregnancy and child bearing . Gynaecology :     All diseases of the female, and specific to the female, not related to pregnancy. While these may occur in the gravid lady, they are neither a cause nor effect of pregnancy. E.g. A fibroid or ovarian cyst present in a female who is carrying a foetus . As such, the treatment of Infertility, and all forms of contraception, also fall in gynaecology .  Obstetrics is used only when the uterus or an ectopic site is gravid, and continues till the end of puerperium, which is six weeks from the delivery of the placenta.

3. : When the labor starts before 37 th completed weeks (< 259 days) counting from the first day of the last menstrual period. Preterm Birth : defined as delivery before 37 completed weeks . E arly preterm , Those before 36/7 weeks are labeled L ate preterm ; T hose occurring between 34 and 36 completed weeks. Preterm Labor

4. S mall for gestational age ; N ewborns whose birthweight is usually < 10th percentile for gestational age. L arge for gestational age ; N ewborns whose birthweight is > 90th percentile for gestational age. Appropriate for gestational age ; N ewborns whose weight is between the 10th and 90th percentiles. Low birthweight N eonates weighing 1500 to 2500 g; Very low birthweight Neonates weighing between 500 and 1500 g; and E xtremely low birthweight Neonates weighing between 500 and 1000 g.

5. Etiology: It is multifactorial High risk factors History Complication in present pregnancy Iatrogenic Idiopathic

6. History Previous history of induced/ spontaneous abortion/ Preterm delivery Pregnancy followed by assisted reproductive techniques Asymptomatic bacteriuria / Recurrent UTI Smoking habit Low socio-economic and nutritional status Maternal stress

7. Complication in present pregnancy Maternal: Preeclampsia Antepartum hemorrhage Premature rupture of membrane Polyhydramnios C ervical incompetency Malformation of uterus Acute fever Acute appendicitis Toxoplasmosis Abdominal operation

8. Complication in present pregnancy Maternal: 8. Hypertennsion 9. Nephritis 10. Diabetes 11. Low BMI 12. Genital tract infections 13. Bacterial vaginosis 14. B Hemolytic streptococcus 15. Bacteriodes 16. Chlamydia

9. Complication in present pregnancy Fetal Complications: Multiple pregnancy Congenital malformation Intrauterine death Placental complication Infraction Thrombosis Placenta previa Abruption

10. Iatrogenic: 1. Indicted preterm delivery due to medical or obstetric complication Idiopathic: 1. Premature effacement of the cervix 2. Early engagement of head

11. Etiopathogenesis of preterm labor:

12. ↑ CRH Choriodecidual bacterial colonization Pathologic uterine enlargement ↑ ↑ ↑ Cortisol ↑ TNF, ↑ IL-1,6,8 ( Polyhydramnios , Multiple pregnancy) ↑ Mechanical strength ↑ IL -8 ↑ Gap junction and PG sythatase Chorion , amnion, and decidua ↑ PGE2, F2alpha, ↑TXA2, ↑Leukotrienes, ↑ PG dehydrogenase, ↑ Proteases, ↑ Collagenase, ↑Leukocyte elastase ↑ Myometrial contraction, ↑ Cerviacal ripening, ↑Cervical insufficiency Preterm Labour and delivery

13. Predictors of preterm labor Clinical predictors : ( i ) Multiple pregnancy ; (ii) History of preterm birth ; ( iii) Presence of genital tract infection ; (iv) Symptoms of PTL Biophysical predictors: ( i ) Uterine contractions (UC) > 4/ hr ; ( ii) Bishop score > 4; ( iii) Cervical length (TVS) < 25 mm .

14. Biochemical predictors : Fetal fibronectin ( fFN ) in cervico vaginal discharge Others IL-6 , IL-8, TNF-a . Fibronectin

15. Diagnosis Preterm labor is primarily diagnosed by symptoms and physical examination.

16. Diagnosis Symptoms Uterine contractions, (Irregular, N onrhythmical , and either painful or painless ( at least one in every 10 min)) Pelvic pressure Menstrual-like cramps Watery vaginal discharge Lower back pain

17. Diagnosis Cervical Change Dilatation : ≥ 2 cm Effacement: 80 % of the cervix Length of cervix (measured by TVS) ≤ 2.5 cm Funelling of the internal OS

18. Management To prevent preterm onset of labor, if possible To arrest preterm labor Appropriate management of labor Effective neonatal care

19. Prevention of preterm labor Risk of delivery of LBW baby against risk to fetus and mother Adopt following guidelines: 1. Primary care is aimed to reduce incidence of preterm labor by reducing high risk factors 2. Secondary care : Screening test for early detection and prophylactic treatment ( Tocolytics ) 3. Tertiary care : Aimed to reduce perinatal morbidity and mortality after diagnosis (corticosteroids)

20. Investigations: Full blood count Urine for routine analysis culture and sensitivity Cervical vaginal swab for culture and fibronectin USG for fetal well being, cervical length, placental localization Serum electrolyte and glucose level when tocolytics used

21. Measures to arrest preterm labor Bed rest in left lateral position Adequate hydration Prophylactic cervical circlage : Women with prior preterm birth and short cervix in present pregnancy Tocolytics : Inihibit uterinc contraction Commonly used: prostaglandin synthetase inhibitors, magnesium sulphate , calcium channel blockers, oxytocin receptor antagonists, NO

22. Drugs MOA Dose S/E CCB ( nifidipine , verapamil ) Blocks the entry of calcium inside cell 10-20mg every 3-6 hours Hypotension, headache, nausea Magnesium sulphate Competitive inhibition of calcium ions 4-6 g IV over 20 minutes followed by infusion of 1-2gm/hour Relatively safe Flushing, perspiration, muscle weakness Betamimetics Activation of intracellular enzyme( adenylate cyclase , cAMP ) reduces intracellular free calcium Ritrodin : 50ug/min IV every 10 minute till contraction cease and infusion 12 hours after that Terbutalin : subcutaneous, 0.25 mg every 3-4 hours Headache, palpitation, hypotension, cardiac arrest, hypokalemia Oxytocin antagonist Blocks myometrial oxytocin receptors 300ug/min IV Nausea, vomiting, chest pain (rare) Nitric oxide Smooth muscle relaxant Patches Headache

23. Principles of management 1. Glucocorticoids: To reduce neonatal RDS, IVH and NEC Helps fetal lung development Dexamethasone: 6 mg IM every 12 hourly for 4 doses Betamethasone: 12mg IM 24 hours apart for 2 doses Betamethasone better than dexamethasone but betamethasone is not available.

24. Risk of antenatal corticosteroid use: Prelabor rupture of membrane Insulin dependent diabetes mellitus Transient reduction of fetal breathing and body movement

25. 2. Antenatal transfer of the mother with fetus in utero to a center equipped with NICU 3. Tocolytics drugs to the mother for short period unless contraindicated Commonly used: prostaglandin synthetase inhibitors, magnesium sulphate , calcium channel blockers, oxytocin receptor antagonists, NO

26. 4. Antibiotics to prevent neonatal infection with Group B Streptococcus : 18 hour after leaking Crystalline penicillin ( Penicilin G ) 5 million unit, IV, one dose at the onset of labour 2.5 million unit, IV, every 4 hourly till delivery.

27. Short-term therapy :It is commonly employed with success . The objectives: To delay delivery for at least 48 hours for glucocorticoid therapy to the mother to enhance fetal lung maturation ; In utero transfer of the patient to a unit with an advanced NICU. Contraindications: A . Maternal: Uncontrolled diabetes, thyrotoxicosis, severe hypertension, cardiac disease , hemorrhage in pregnancy, e.g. placenta previa or abruption. B . Fetal : Fetal distress, fetal death, congenital malformation, pregnancy beyond 34 weeks. C . Others : Rupture of membranes, chorioamnionitis , cervical dilatation more than 4 cm.

28. First stage Second stage The patient is put to bed to prevent early rupture of membranes. To ensure adequate fetal oxygenation by giving oxygen to the mother by mask. Epidural analgesia is of choice. Labor should be carefully monitored. Cesarian delivery is done for obstetric reasons. NICU The birth should be gentle and slow to avoid rapid compression and decompression of the head Episiotomy may be done to minimize head compression if there is perineal resistance The cord is to be clamped immediately at birth to prevent hypervolemia and hyperbilirubinemia To shift the baby to neonatal intensive care unit. Principals in management of preterm labor are: To prevent birth asphyxia and development of RDS To prevent birth trauma. Duration of labor is usually short.

29. Cesarean Section: Routine CS not recommended. Only for Preterm fetuses before 34 weeks presented by breech. Lower segment vertical/ J shaped incision made to minimize trauma during delivery. Prognosis: Preterm labor and delivery of low birth weight baby results in high perinatal mortality and morbidity. If NICU care given, survival rate is more than 90% for (1000g- 1500g).

30. Cunningham et.al., Williams OBSTETRICS, 24E, McGraw-Hill Education, 2014, DC Dutta’s textbook of Obstetrics References

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