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 dilatationLatent active
2nd stage - Full dilatation to deliveryof baby
3rd stage - Delivery of placenta
4th stage - Bonding
DR. DR.
Table 30-1. Characteristics of Labor Nulliparas and Multiparas*
Characteristic All patients Ideal Labor All patients Ideal laborNulliparas Multiparas
Duration of first stage(hr)Latent phase 6.4(±5.1) 6.1 (±4.0) 4.8 (±4.9) 4.5 (±4.2)Active phase 4.6(±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 secondstage (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 SectionIndications
Failure to progressRepeat (Failed VBAC)Fetal DistressBreech PresentationPlacenta PreviaCord prolapseAbruptionDiabetesSocial...
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 outcomewhere latent phase greater than 15 hours
• Chelmow are 1993 - 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
Power Incoordinate uterine action Dysfunctional Labour
Passenger CPDRelative disproportion
Passages Diameters
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 procedure Rate
• Latent phase 41%• Active phase 38%• Second stage 21%
• Source: Stewart CMAJ 1990:142; 459-463
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 USAGEInitial dose: 1 to 2 mlu/min
Rate increased by 1 to 2 mlu/min every 30 min
Until contractions are considered adequateand
cervical dilatation achieved
Clinical response usually seen at dose levels of 8 - 10 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 LABOURASSOCIATED WITH AN OCCIPITO POSTERIORDURING THE FIRST STAGE OF LABOUR WOULDINCLUDE:
a) immediate cesarean section
b) forceps
c) augmentation with oxytocin
d) external cephalic version
e) fetal blood sampling
NS NS
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C C C C C C C