MCN LEC

Dystocia - difficult labor

four main components of the labor process:
(a) the power, or the force that propels the fetus (uterine contractions)
(b) the passenger (the fetus)
(c) the passageway (the birth canal)
(d) the psyche (the woman’s and family’s perception of the event)

COMPLICATIONS WITH THE POWER (THE FORCE OF LABOR)

Inertia - is a time-honored term to denote sluggishness of contractions, or that the force of
labor, is less than usual.
Dysfunctional labor - more current term, can occur at any point in labor
Generally classified as;
primary (occurring at the onset of labor)
secondary (occurring later in labor)
Prolonged labor appears to result from several factors but Is most likely to occur if a fetus is
Hypotonic - Large
Hypertonic - uncoordinated contractions occur
Ineffective Uterine Force
Uterine contractions - are the basic force that moves the fetus through the birth canal.
- occur because of the interplay of the contractile enzyme;
• adenosine triphosphate
• Influence of major electrolytes such as calcium, sodium, and potassium, specific
contractile proteins (actin and myosin), epinephrine and norepinephrine, oxytocin (a
posterior pituitary hormone), estrogen, progesterone, and prostaglandins. In about 95% of
labors, contractions follow a predictable, efficient course.
Common Causes of Dysfunctional Labor
• Primigravida status
• Pelvic bone contraction that has narrowed the pelvic diameter so a fetus cannot pass
(cephalopelvic disproportion [CPD]) such as could occur in a woman with Rickets
• Posterior rather than anterior fetal position or extension rather than flexion of the fetal head
• Failure of the uterine muscle to contract properly or overdistention of the uterus, as with a
multiple pregnancy, polyhydramnios, or an excessively oversized fetus (macrosomic fetus)
• A nonripe cervix
• Presence of a full rectum or urinary bladder that impedes fetal descent
• A woman becoming exhausted from labor
• Inappropriate use of analgesia (excessive or too early administration)
Hypotonic Contractions

hypotonic uterine contractions

– number of contractions is unusually infrequent (not more than two or three occurring in a 10-
minute period).
- Resting tone of the uterus remains less than 10 mmHg, and the strength of contractions
does not rise above 25 mmHg
- Occur during the active phase of labor and tend to occur after the administration of
analgesia, especially if the cervix is not dilated to 3 to 4 cm or if bowel or bladder
distention is preventing descent or firm engagement.
- Occur in a uterus that is overstretched by a multiple gestation, a larger than usual single
fetus, polyhydramnios, or in a uterus that is lax from grand multiparity.
- Not exceedingly painful because of their lack of intensity.
Hypotonic contractions will increase the length of labor because more of them are necessary to
achieve cervical dilatation.
  If the uterus becomes exhausted, this can cause it to not contract as effectively during
the postpartal period, thus increasing a woman’s chance for postpartal hemorrhage.
 In the first hour after birth following a labor of hypotonic contractions, it is very
important
- to palpate the uterine fundus
- the woman’s blood pressure
- the amount of lochia every 15 minutes for the first hour to ensure postpartal
contractions are not also hypotonic and therefore not adequate to halt postpartal
hemorrhage.
Hypertonic Contractions
Hypertonic uterine contractions - are marked by an increase in resting tone to more than 15
mmHg.
- In contrast to hypotonic contractions, these occur frequently and are most commonly
seen in the latent phase of labor.
- Occur because more than one uterine pacemaker is stimulating contractions or because
the muscle fibers of the myometrium do not repolarize or relax after a contraction,
thereby “wiping it clean” to accept a new pacemaker stimulus.
- They tend to be more painful than usual, because the myometrium becomes tender
from constant lack of relaxation and the anoxia of uterine cells that results.
- Danger of hypertonic contractions is that the lack of relaxation between contractions
may not allow optimal uterine artery filling; this can lead to fetal anoxia early in the
latent phase of labor.
- FHR is not showing late deceleration.
- If deceleration in the FHR, an abnormally long first stage of labor or lack of progress with
pushing (“second-stage arrest”)occurs, cesarean birth may be necessary.
- Although contractions are strong, they are ineffective and are not achieving cervical
dilatation.
Uncoordinated Contractions
- Normally, all contractions are initiated at one pacemaker point high in the uterus.
- Contraction sweeps down over the organ, encircling it; repolarization occurs; relaxation
or a low resting tone is achieved; and another pacemaker-activated contraction begins.
Uncoordinated contractions - more than one pacemaker may be initiating contractions, or
receptor points in the myometrium may be acting independently of the pacemaker.
- Occur so closely together that they can interfere with the blood supply to the placenta.
Because they occur so erratically, such as one on top of another and then a long period
without any, it may be difficult for a woman to rest between contractions or to breathe
effectively with contractions.
- Applying a fetal and a uterine external monitor and assessing the rate, pattern, resting
tone, and fetal response to contractions for 15 minutes (or longer if necessary in early
labor) reveals the abnormal pattern.
- Oxytocin administration may be helpful in uncoordinated labor to stimulate a more
effective and consistent pattern of contractions with a better, lower resting tone.
Dysfunctional Labor and Associated Stages Of Labor

Dysfunction at the First Stage of Labor

Dysfunction that occurs with the first stage of labor involves a prolonged latent phase,
protracted active phase, prolonged deceleration phase, and secondary arrest of dilatation.
Prolonged Latent Phase - when contractions become ineffective during the first stage of labor,
a prolonged latent phase can develop. How long the stages of labor take is affected by
individual circumstances and whether a woman has received analgesia or an epidural
anesthesia.

- Latent phase that lasts longer than 20 hours in a nullipara or 14 hours in a multipara.
This may occur if the cervix is not “ripe” at the beginning of labor. It may occur if there is
excessive use of an analgesic early in labor.
- Uterus tends to be in a hypertonic state. Relaxation between contractions is inadequate,
and the contractions are only mild (less than 15 mmHg on a monitor printout) and,
therefore, ineffective. One segment of the uterus may be contracting with more force
than another segment.
Management:
- Helping the uterus to rest
- Providing adequate fluid for hydration
- Pain relief with a drug such as morphine sulfate.
- Changing the linen and the woman’s gown
- Darkening room lights
- Decreasing noise and stimulation can also be helpful.
These measures usually combine to allow labor to become effective and begin to progress. If it
does not, a cesarean birth or amniotomy (i.e., artificial rupture of membranes) and oxytocin
infusion to assist labor may be necessary.
Protracted Active Phase - usually associated with fetal malposition or cephalopelvic
disproportion (CPD) (the diameter of the fetal head is larger than the woman’s pelvic
diameters), although it may reflect ineffective myometrial activity.
 - This phase is prolonged if cervical dilatation does not occur at a rate of at least 1.2
cm/hr in a nullipara or 1.5 cm/hr in a multipara.
- If the active phase lasts longer than 12 hours in a primigravida or 6 hours in multigravida
- If the cause of the delay in dilatation is fetal malposition or CPD, cesarean birth may be
necessary.
- Dysfunctional labor during the dilatational division of labor tends to be hypotonic, in
contrast to the hypertonic action at the beginning of labor.
- After an ultrasound to show CPD is not present, oxytocin may be prescribed to augment
labor.
Prolonged Deceleration Phase - a deceleration phase has become prolonged when it extends
beyond 3 hours in a nullipara or 1 hour in a multipara. A prolonged deceleration phase most
often results from abnormal fetal head position.
- A cesarean birth is frequently required.
Secondary Arrest of Dilatation - a secondary arrest of dilatation has occurred if there is no
progress in cervical dilatation for longer than 2 hours.
- A cesarean birth may be necessary.
Dysfunction at the Second Stage of Labor
Dysfunction that occurs with the second stage of labor involves prolonged descent and arrest
of descent.
Prolonged Descent - occurs if the rate of descent is less than 1.0 cm/hr in a nullipara or 2.0
cm/hr in a multipara. It can be suspected if the second stage lasts over 2 hours in a multipara.
- With both a prolonged active phase of dilatation and prolonged descent, contractions
have been of good quality and duration, effacement and beginning dilatation have
occurred, but then the contractions become infrequent and of poor quality, and
dilatation stops.
- If everything else is within normal limits except for the suddenly faulty contractions and
CPD and poor fetal presentation have been ruled out by ultrasound.
- Then rest and fluid intake, as advocated for hypertonic contractions, also applies. If the
membranes have not ruptured, rupturing them at this point may be helpful.
- Intravenous (IV) oxytocin may be used to induce the uterus to contract effectively (see
later discussion on induction of labor by oxytocin).
- A semi-Fowler’s position, squatting, kneeling, or more effective pushing may speed
descent.
Arrest of Descent - results when no descent has occurred for 2 hours in a nullipara or 1 hour in
a multipara.
- Failure of descent occurs when expected descent of the fetus does not begin or
engagement or movement beyond 0 station does not occur.
- The most likely cause for arrest of descent during the second stage is CPD.
- Cesarean birth usually is necessary
- If there is no contraindication to vaginal birth, oxytocin may be used to assist labor.