E.Naghshineh M.D

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labor abnormalities :•protraction disorders (ie, slower than normal progress) •arrest disorders (ie, complete cessation of progress)•most common indication for primary cesarean delivery(68%)•Prevalence :20 %•The risk is highest in nulliparous women with term pregnancies

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three stages of labor:•First stage :from onset of contractions to complete cervical dilation.

•Second stage :from complete cervical dilation to expulsion of the fetus

•Third stage :from expulsion of the fetus to expulsion of the placenta

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two phases:•Latent phase :regular contractions, typically mild and infrequent,change in cervical dilation and effacement is gradual, less than 1 cm dilation over a single hour.

•Active phase :painful contractions of increasing frequency, intensity, and duration accompanied by more rapid cervical change (at least 1 cm/hour)

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Friedman divided labor :first and second stagefirst stage :latent phase, acceleration phase, phase of

maximum slope, and a deceleration phase( figure 1 .)acceleration phase :occur at 3 to 4 cm cervical dilation

minimum rate of acceptable cervical dilation during the active phase of labor :

1.2cm/hour for nulliparous ,1.5 cm/hour for multiparous

-relatively slow rate of cervical dilation until approximately 4 cm (ie, latent labor), followed by an abrupt acceleration in the rate of dilation until a deceleration phase at approximately 9 cm

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Friedman versus contemporary data Labor curve :The shape of the labor curve generated from Zhang’s data (figure 2) is different from

Friedman’s( figure 1.)

Zhang’s curves: increase more gradual, greater than 50 % do not dilate at a rate of >1 cm/hour until 5 to 6 cm dilation, not observe a deceleration phase

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Other authors’ : rate of cervical change between 3 and 6 cm much slower than previously thought , less

than 1 cm per hour prior to 5 to 6 cm( table 1 .)

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Duration of the latent phase :•Average latent phase: -nulliparous:6.4 hours-multiparous:4.8 hours

•Prolonged latent phase:-nulliparous ≥20 hours-multiparous ≥14hours

The duration of latent phase in the induced labor is controversial, but appears to be longer than in spontaneous labor

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Duration of the active phase: nulliparous =4.6 hour Friedman :

multiparous=2.4hours Zhang :nulliparous=5.3hours- multiparous=3.8hours

-duration of the first stage (defined as from 4 to 10 cm) was significantly longer in induced labor than in spontaneous labor

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Duration of the second stage :Induction does not affect the duration of the second stage of labor

Friedman: nulliparous =3 hours, multiparous=1hours Zhang :nulliparous=0.6hours, multiparous=0.2hours

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DIAGNOSIS OF LABOR ABNORMALITIES:  Protraction and arrest can occur anytime

during labor. The thresholds are defined according to the phase or stage of labor when they occur.

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Active phase: Friedman: minimum rate of acceptable cervical dilation during

the active phase of labor : 1.2cm/hour for nulliparous ,1.5 cm/hour for multiparous

Zhang’s: rates of dilation in the first stage slower,

Labor accelerates much faster after 6 cm, and is significantly faster inregardless of parity. multiparas

compared to nulliparas .

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Second stage: longer than 2 hours in nulliparas , 1 hour in

multiparas Zhang: in nulliparous over 2.5 to 3 hours ; in multiparous 1 hour

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Precipitous labor : labor that lasts no more than 3 hours from

onset of contractions to delivery

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Etiology And Risk Factors :Hypocontractile uterine activity : most common cause ،either not sufficiently strong or not appropriately coordinated to dilate the cervix and expel the fetus ، 3 to 8%of parturientsNormal uterine activity : palpation, external tocodynamometry, or internal uterine pressure catheter

Cephalopelvic disproportion (CPD)

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Neuraxial anesthesia : uterine activity, fetal malposition, ultimately arrest disorders, significant increases in the second stage of labor and use of oxytocin , more likely to undergo operative vaginal delivery Bandl's ring : An hourglass constriction ring of the uterus, not clear if it is the cause or the result of the associated dystociaOcciput posterior (OP) position : longer duration of active labor and the second stage, higher risk of arrest of descent requiring operative delivery Maternal obesity : increasing length of the first stage of labor, not independently correlated with the second stage of labor

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Management Patients With Protracted Latent Phase:

•Therapeutic rest•Uterotonic drugs 

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Therapeutic rest Morphine SC (15 to 20 mg) or IM (10 mg), 85%wake up in the active phase of labor, 10 % will not be in labor ( false labor),5 % will have a persistent dysfunctional;

zolpidem (5 mg PO) and secobarbital (100 mg PO) are two commonly prescribed agents.

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Oxytocin Friedman :oxytocin and therapeutic rest equally efficacious and safe,average interval between initiation of oxytocin and active labor was 3.4 hours

Prostaglandins not been studied as a treatment for women diagnosed with prolonged latent phase

Amniotomy increase in maternal plasma prostaglandin concentration , the effects on the uterus and cervix are probably insufficient to result in significant augmentation of labor

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Cesarean delivery should not be performed in women in latent phase unless evidence of maternal or fetal deterioration necessitating prompt delivery, a contraindication to vaginal delivery, or induction of labor with oxytocin fails

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Consequences Of Prolonged Latent Phase associated with a higher risk of C/S

Friedman : not more prone to developing active phase protraction and arrest disorders, perinatal mortality was not increased

Others:associated with a higher risk of subsequent labor abnormalities, newborns are more exposed to thick meconium, have depressed five-minute Apgar scores, and require NICU admission

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Patients with protracted active phase :confirm that the patient is in the active phase (cervix is at least 5 to 6 cm), administer oxytocin, and wait four hours

Oxytocin augmentation : Oxytocin is the only medication (FDA approved) for labor stimulation in the active phase.•Decreased the c/s rate , increased rate NVD•Decreased the total duration of labor •Increased the frequency of tachysystole •Resulted in similar maternal and neonatal morbidities

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Assessing progress after initiating oxytocin : the 2hour threshold is not highly predictive that the patient will fail to deliver vaginally. A better threshold is a minimum change in cervical dilation of 2 cm over4 hours , safe and increased the rate of vaginal delivery Intrauterine pressure catheter : no reduction in the rate of operative delivery or improvement in perinatal outcome

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Other approaches•Amniotomy —not accelerate spontaneous labor •Prostaglandins —not •Evaluation of maternal hydration status and increased intravenous fluids(250 ml/h) DW5%:lower frequency of prolonged labor,less need for oxytocin•Ambulation and continuous labor support : increase the comfort of the parturient, no effective

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OUTCOME • increased risk of chorioamnionitis and cesarean delivery, not at significantly increased risk of adverse outcome

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PREVENTION•no strong evidence any intervention prevent protracted labor. •The best evidence is for the combination of early initiation of oxytocin and amniotomy

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