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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