Labour

Labour “Braxton Hicks” contractions – irregular, low frequency, high amplitude, occasionally painful Pro-pregnancy factors Progesterone (from corpus luteum until 8 weeks, then placenta). ▼sensitivity to oxytocin therefore à uterine relaxation Nitric Oxide, Catecholamines & Relaxin (role unclear) Pro-labour factors Oxytocin (from post pituitary) is potent stimulator of uterine contractions (levels constant through preg) Oestrogen à ▲ expression of oxytocin receptors Prostaglandins promote cervical ripening & stimulate contractility directly & upreg oxytocin receptors Mifepristone = progesterone antagonist increases myometrial contractility à induction Normal Labour Diagnosis – requires cervical change, regular painful contractions & show Cervical Ripening – prostaglandins inhibit collagen synthesis &simulate collagenase 1st stage – onset à fully dilated cervix Latent phase = Effacement – thinning of the cervix (from onset of contractions). Use Bishops score Active phase = Dilatation – opening of external os, should occur at min 1cm/hr. Fully dilated = 10cm or when cervix no longer palpable. Fetal head also descends (measured in relation to ischial spines) 2nd stage – fully dilated to delivery of baby, progress measured by descent & rotation propulsive/passive phase – until head reaches pelvic floor (head is occipito-transverse, lower vagina not stretched, no urge to push) expulsive/active phase – begins when head reaches pelvic floor & strong urge to push, head rotates (usually to OA), then resititutes to occipito-transverse to allow delivery of shoulders. Apply lateral traction to head towards mothers back to allow anterior shoulder delivery (give syntometrine – see later) then lift head anterior to deliver post shoulder & body will follow. Give baby to mum 3rd stage – delivery of placenta – usually actively (pharmacologically) managed clamp & cut cord give syntometrine (syntocinon + ergometrine) i.m. when ant shoulder delivers à tonic uterine contraction (minimises PPH risk) Controlled cord traction using “Brandt-Andrews” method (cord upwards whilst pressure on fundus) to avoid uterine inversion Placental separation = lengthening of cord + gush of dark blood pv. Check for tears (suture if req) & examine placenta to check complete Partogram Fetal condition HR should be checked every 15 minutes Liquor colour Moulding of head Progress Dilataion (should be 1cm/hr) Descent (engagement) Maternal condition Pulse, BO (every ½ hr) Temp Urine Output Oxytocin / other drugs given Contractions Fetal Monitoring Meconium liquor = 15% of cases @ term, 40% @ 42 weeks Can be due to normal vagal stimulation / fetal distress if CTG is abnormal à lowers threshold for interventions because risk meconium aspiration syndrome. Grading: 1=lightly stained, 2=heavy suspension, 3=pea soup Fetal HR (normal 110-150). If low risk auscultate every 15 mins + after contractions in 1st stage, every 5-10 mins in 2nd stage. If tachy/brady/decelerations à continuous CTG CTG Paper moves at 1cm/min Baseline at term 110-160bpm Tachy = prem, acidosis, maternal pyrexia & exogenous Beta agonists Brady = severe acidosis, hypotension, maternal sedation Baseline variability (10-25) via US or scalp clip (gives ecg) Fetal heartblock assoc with maternal SLE (Anti Ro Ab) Accelerations (>15bpm for >15s) = healthy. Can sum together for prolonged tachy if very active, but abnormal if baby is quiet Decelerations (>15bpm for >15sec) early if during contraction, late if >15 sec after. Late = abnormal Cord Compression variable deceleration with “shoulders”. Accelleration as vein occluded (drop BP, increased HR), then deceleration as arteries occuluded (increased afterload, decreased HR) Hypoxia --> acidaemia --> sudden drop in HR --> activates sympathetic NS --> progressive increase in HR (with eventual crash as decompensation occurs) Acidosis with sick myocardium if deceleration starts after peak of contraction (eg anaemia) Sinusoidal baseline indicates anaemia, or Rh disease Fetal Blood/Scalp Sampling (FBS / FSS) - to assess for fetal acidosis Indications: persistent early/late/variable decelerations on CTG, prolonged fetal tachycardia, grade 2/3 meconium staining + abnormal CTG, loss of CTG baseline variability Contraindications: maternal HIV, HepB, Herpes, Grp B strep, fetal bleeding disorder, prem (<32 weeks) Method: ethyl chloride to induce hyperaemia, Vaseline, nick scalp & collect with capillary tube Interpretation: >7.25 – continue 7.2-7.25 – repeat in 30 minutes <7.2 – deliver immediately (10-15% risk of permanent neuro damage pH can be as low as 7.20 (in hypoxia fetus à anaerobic glycolysis à lactic acid) if < 7.20 deliver immediatley Bloods Important to know mothers blood group & Rh Ab status in case transfusion required. If mother is RhKleinhauer test (looking for fetal cells in maternal blood) Retest Ab status Check fetal blood group (direct coombs test) – if Rh+ give mother AntiD until Kleinhauer -ve Complications Pre-labour ROM 6-12% cases. Digital VE should NOT be performed (Infection risk) if left 70% à labour in 24hrs & 90% by 48hrs (with risk of chorioamnionitis) Manage based on maternal & fetal health, Meconium staining of liquor etc Episiotomy Usually right posterolateral. Indications: rigid perineum (preventing delivery), tear imminent, instrumental delivery, shoulder dystocia, breech. . Procedure: lidocaine into subcut perineum & vagina, right mediolateral cut (with pressure on fetal head to prevent further tear) Repair: absorbable synthetic (vicryl), good perineal hygiene, ice packs & analgesia Perineal Tears 1st degree – vaginal epithelium & vulval skin only 2nd degree – perineal muscles but not anal sphincter 3rd degree – includes anal sphincter (require Abx, laxatives & good dietary fibre) 4th degree – includes rectal mucosa (require Abx, laxatives & good dietary fibre)