ABNORMAL PROGRESS OF LABOUR

expected patterns of descent of the presenting part and cervical dilatation fail to occur in the appropriate time frame can occur in a...

1. expected patterns of descent of the presenting part and cervical dilatation fail to occur in the appropriate time frame
2. can occur in all stages of labour
3. traditionally three causes of abnormal labour have been recognized
   
   • Power: poor, inadequate or uncoordinated uterinecontractions
   • Passenger: fetus too large in size or unusual presentation
   • Passage: cephalopelvic disproportion (CPD) = pelvis of inadequate size, shape or consistency, or maternal soft tissue resistance relative to fetus
4. initial diagnosis of CPD requires progression into the active phase and the presence of adequate uterine contractions

A. Average Multipara                              C Arrest of active phase
B. Average Primigravida                          D. Protracted active phase
E. Prolonged latent phase


Prolonged Latent Phase (Curve E)

1. A period of 20 hours or more in the primigravida or 14 hours or more in the multigravida during which labour has not progressed to the active phase
2. Most often patient not really in labour (avoid amniotomy for fear of false labour and increased risk of intrauterine infection)
3. too early and too heavy sedation is present in 30-40% of these patients
4. careful search for factors of CPD should be made
5. treatment: oxytocin augmentation if diagnosis of labour is certain
   otherwise rest +/- sedation

Protraction Disorders (Curve D)

1. of dilatation: when slope of cervical dilatation is less than 1.2 cm/hour in the primigravida or 1.5 cm/hour in the multigravida
2. of descent: a rate of descent of less than 1.0 cm/hour in the primigravida or 2.0 cm/hour in the multigravida
3. in about 1/3 CPD will be present so that secondary arrest of dilatation usually develops
4. 2/3 will progress steadily through labour with ultimate uneventful
   vaginal delivery
5. treatment: oxytocin augmentation if contractions are inadequate(see Augmentation of Labour )  and/or amniotomy

Arrest Disorder (Curve C)

1. of dilatation: progress in dilatation does not occur for a period of 2 hours or more in a patient who has entered the active phase
2. arrest usually occurs at a cervical dilatation of 5 to 8 cm
3.  of descent: no progress in station for > 1 hour during second stage
4. should search for factors causing CPD (nearly 50%; requires C-section)
5. CPD if adequate contractions measured by intrauterine pressure catheter (IUPC) and no descent/dilatation for > 2 hours
6. if CPD ruled out, IV oxytocin and amniotomy can be attempted