What is Labor ? (: work) Regular painful uterine contractions accompanied by progressive effacement and dilatation of the cervix

Timing of Labor 40 weeks 8% deliver on E.D.C. 7% premature < 37 weeks 10% post-mature > 42 weeks

Signs of Onset of Labour “Show” Rupture of membranes Contractions

Detection of ruptured membranes Nitrazine Test - alkaline pH of fluid turns blue Ferning - high Na+ content causes “ferning” on air dried slide

Stages of Labor 1st stage - Onset to ‘full dilatation Latent active 2nd stage -Full dilatation to delivery of baby 3rd stage-Delivery of placenta 4th stage-Bonding

DR.

Table Characteristics of Labor Nulliparas and Multiparas* CharacteristicAll patientsIdeal LaborAll patientsIdeal labor NulliparasMultiparas Duration of first stage (hr) Latent phase6.4(±5.1)6.1 (±4.0)4.8 (±4.9)4.5 (±4.2) Active phase4.6(±3.6)3.4(±1.5)2.4(±2.2)2.1 (±2.0) Total 11.0(±8.7)9.5(±5.5)7.2(±7.1)6.6(±6.2) Maximum rate of descent (cm/hr)3.3(±2.3)3.6(±1.9)6.6(±4.0)7.0(±3.2) Duration of second stage (hr)1.1(±0.8) 0.76(±0.5) 0.39(±0.3) 0.32(±0.3) * All values given are ± SD. (Data from Friedman EA: Labor: Clinical Evaluation and Management. 2nd ed. New York, Appleton-Century-Crofts, 1978).

Cesarean Section Indications Failure to progress Repeat (Failed VBAC) Fetal Distress Breech Presentation Placenta Previa Cord prolapse Abruption Diabetes Social...

DYSTOCIA

DYSTOCIA DIAGNOSIS Abnormal progression of labour in the ACTIVE Phase –Cervical dilatation of <0.5 cm/hr over a 4 hr period –arrest of progress in the ACTIVE phase either in the first or second stage of labour This includes a failure in the descent of the presenting part

OUTCOME OF PROLONGED LATENT PHASE NCPP 1965  Apgar  perinatal death and poor outcome where latent phase greater than 15 hours Chelmow are  for labour intervention and low apgars where latent phase greater than 12 hours in nullip and 6 hours in multips Piezner 1985 found that length of latent phase related to cervical dilatation on admission Roemer 1996 found lower I.Q.’s in siblings with dystocia greater than 12 hours.

CAUSES OF DYSTOCIA PowerIncoordinate uterine action Dysfunctional Labour PassengerCPD Relative disproportion PassagesDiameters

DYSTOCIA A 4 cm cut off separates latent from active labour Abnormal progress never diagnosed before 4cm dilatation Women not in active labour ‘triaged’ from the labour floor

CESAREAN SECTION FOR DYSTOCIA Timing of procedureRate Latent phase41% Active phase38% Second stage21% Source: Stewart CMAJ 1990:142;

DYSFUNCTIONAL LABOUR - FACTORS OF INTEREST Age Parity Infection Epidural Position in labour Cervix Induction Macrosomia

INITIAL MEASURE TO TREAT DYSTOCIA –Comfort –wellbeing –hydration B. Amniotomy C. Oxytocin if A+B fail D. Wait long enough to see a response A. Attention to

OXYTOCIN USAGE Initial dose: 1 to 2 mlu/min Rate increased by 1 to 2 mlu/min every 30 min Until contractions are considered adequate and cervical dilatation achieved Clinical response usually seen at dose levels of mlu/min

REDUCTION OF RISK OF DYSTOCIA Factors to avoid Induction for large fetal weight Oxytocin use with unfavourable cervix No admission to Labour and Delivery at <4cm dilatation Discontinuation of epidural at full dilatation Immediate pushing after full dilatation

SUPPORTIVE STRATEGIES Cervical evaluation for ripening prior to booking induction Obstetrical triage Continuous professional support in active labour Mobilisation of women in active labour Minimisation of motor blockage with epidural Use of amniotomy and oxytocin prior to C/S for dystocia

APPROPRIATE MANAGEMENT FOR SLOW LABOUR ASSOCIATED WITH AN OCCIPITO POSTERIOR DURING THE FIRST STAGE OF LABOUR WOULD INCLUDE: a) immediate cesarean section b)forceps c)augmentation with oxytocin d)external cephalic version e)fetal blood sampling

NS C C C C C C C