Transcript Abnormal labor: Protraction and arrest disorders

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 stage
first 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 :
Friedman: nulliparous =4.6 hour
multiparous=2.4hours
Zhang :nulliparous=5.3hoursmultiparous=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 parturients
Normal 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 dystocia
Occiput 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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