Induction of labour

Induction of labour: it is the use of drugs or interventions to help start of labour. This leads to progressive effacement & dilatation of the cx & delivery of the baby. The guidelines recommended that Id of labour is indicated when it is agreed that the fetus or mother will benefit from a higher probability of a healthy outcome than if birth is delayed. Incidence: of Id at term about 15-20%.

Indications of induction of labour: 1-pregnancy passing 41wk. 2-pprom(premature- prelabour rupture of mem.) 3-maternal diseases:DM,HT,Renal or Autoimmune diseases. 4-pregnancy related conditions:e.g PE,intrahepatic cholestasis ,APH. 5-fetal indications:IUGR, oligo.,IUD,

Mechanisms of parturition: The exact mechanism underling the onset of labour in human are not fully understood, some theories suggest that the production of fetal cortisol causes an increase in the production of placental estrogen & PG which sensitize the myometrium to circulating oxytocin & in turn initiate labour. These changes are mediated by the hypothalamic- pituitary axis.

Induction methods: 1-Methodes traditionally used by women: caster oil, herbal remedies, breast or nipple stimulation ,sexual intercourse(little evidence to support their role in induction ) 2-Mecanical interventions: i- membrane sweeping ii-extra-amniotic infusion of saline: infusion of NS into extra-amniotic space via folly's catheter iii- Mechanical dilators 3-Surgical interventions:amniotomy(rupturing of memb.)

4-Medical interventions: i-Oxytocin: it is an octapeptid hormone secreted from the supraoptic & Para ventricular nuclei of the hypothalamus & transported to the post. Pituitary gland along the axons of the neurons when it is released in a pulsatile manner. Despite its short half life in the circ. It stimulates uterine activity with the freq. & force of cont. being proportional to it’s conc. It is given in infusion pump (iv). S.E: antidiuretic effect (fluid over load),uterine rupture & tetanic contraction.

ii-PG: long chain FA derived from arachidonic acid via the cyclooxygenase path-way. Types :PGE2 ,PGF2α , PGE1 Oral ,im ,uterine (extra-amniotic , intra-amniotic),intravaginal S.E: 1-GIT 2-uterine hyper stimulation 3- precipitated labour 4-uterine rupture 5-PPH

Complications of induction of labour: 1-Failed induction. 2-cord prolapse. 3-abraptio-placentae. 4-maternal complication: hyponitraemia , uterine hyper stimulation , PPH, & uterine rupture. 5- fetal complication : prematurity ,hyperbilirubinemia , fetal distress(cord compression or prolapse) , oligohydramnious.

Pain relief methods during labour & delivery Obstetrical analgesia: multiple techniques useful for alteration of pain asso.with labour or delivery. Advantages: more co-operative women & can tolerate labour Disadvantages:-risk of fetal resp. depression -may interfere with uterine contraction -increase the risk of operative delivery

Methods of pain relief: 1- Non- pharmacological methods: -relaxation & breathing exercise -acupuncture & hypnosis -transcutaneous electron nerve stimulation(TCNS) 2-Pharmacological methods: 1-systemic analgesia 2-regional analgesia 3-inhalation analgesia 4-GA

Nerve supply of GT: Upper GT:sensory fibers from the Ux ,Cx ,upper Vx →T10,11,12,&L1. 1st stage pain mainly due to :uterine ischemic pain &cx dilatation pain. Lower GT:painfull stimuli pass mainly through pudendal n. ,iliofemoral n. ,genitofemoral n. ,&post. Femoral cutaneous n. 2nd stage pain mainly due to stretching of the perineum & vx.

pharmacological methods: i- Systemic analgesia: -pethidine : IM 100-150mg . Fetal S.E:respiratory center depression ,inhibition of sucking reflex ,cold intolerance Maternal S.E;n&v ,risky in fulminating PE -Morphine: cause fetal resp. depression used in IUD or fetus with cong.abn Narcotic antagonist is naloxone to the fetus through the umbilical cord.

ii- Regional analgesia : 1-spinal A. 2-epidural A 3-caudal A 4-local infiltration 5-Pudendal nerve block 6-paracx block Indication: prolonged labour ,multiple G ,PIH,high risk of operative delivery. CI:coagulation disorder,sepsis,hypovolemia ,aortic stenosis

Complication of regional analgesia: 1-Hypotension 2-Accidental dural puncture. 3-Respiratory failure & death if over dose or error in the technique. 4-Post-dural puncture headache. 5-bladder dysfunction 6-Backache. 7- Increase risk of instrumental delivery.

Local analgesia: as local infiltration of analgesic agent around laceration or episiotomy (perineal infiltration) Pudendal nerve block: S2,3,4 ,blocked by injection of xylocain 1% bilaterally. iii- Inhalation analgesia: using O2 &N2O ,cylinder ,it does not interfere with ux contraction.

iv- General Anesthesia: Induction (thiopental ) ,Maintenance & intubation Disadvantages of GA: 1-depresse maternal & fetal CNS 2- inhalation of gastric content (Mendelsohn's syndrome):aspiration of gastric content →obstruction of airway & death or chemical pneumonitis. Avoidance: Fasting ,antacid ,intubation under cricoid pressure RX: suction & bronchoscopy -corticosteroid -O2 & ventilation to maintain adequate oxygen. -antibiotics to prevent pneumonitis.