Dystocia literally means difficult labor and is characterized by abnormally
slow labor progress.
DYSTOCIA
ABNORMALITIES OF THE EXPULSIVE FORCES
PREMATURELY RUPTURED MEMBRANES AT TERM
PRECIPITOUS LABOR AND DELIVERY
FETOPELVIC DISPROPORTION
FACE PRESENTATION
BROW PRESENTATION
TRANSVERSE LIE
COMPOUND PRESENTATION
COMPLICATIONS WITH DYSTOCIA
2. DYSTOCIA
ABNORMALITIES OF THE EXPULSIVE FORCES
PREMATURELY RUPTURED MEMBRANES AT TERM
PRECIPITOUS LABOR AND DELIVERY
FETOPELVIC DISPROPORTION
FACE PRESENTATION
BROW PRESENTATION
TRANSVERSE LIE
COMPOUND PRESENTATION
COMPLICATIONS WITH DYSTOCIA
3. DYSTOCIA
Dystocia literally means difficult labor and is characterized by abnormally
slow labor progress.
Causes are grouped into three distinct categories. Mechanistically, these simplify into
abnormalities of the powerspoor uterine contractility and maternal expulsive effort; of the
passengerthe fetus; and of the passagethe pelvis and lower reproductive tract.
These three groups act singly or in combination to produce dysfunctional labor
6. ABNORMALITIES OF THE EXPULSIVE
FORCES
Types of Uterine Dysfunction
Uterine contractions are needed to dilate the cervix and to expel the fetus. A
contraction is initiated by spontaneous action potentials in the membrane of
smooth muscle cells. Unlike the heart, a single pacemaker or its site remain
unresolved (Young, 2018).
Resulting uterine contractions in normal labor show a rising and falling gradient of myometrial
activity (Reynolds, 1951).
Normal spontaneous contractions can exert pressures approximating 60 mm
Hg (Hendricks, 1959). Even so, the lower limit of contraction pressure
required to dilate the cervix is 15 mm Hg (Caldeyro-Barcia, 1950).
7. In abnormal labor, two physiological types of uterine dysfunction may
develop.
In the more common hypotonic uterine dysfunction, basal tone is
normal and uterine contractions have a normal gradient pattern
(synchronous). However, pressure during a contraction is insufficient to
dilate the cervix.
In the second type, hypertonic uterine dysfunction or
incoordinate uterine dysfunction, either basal tone is elevated appreciably
or the pressure gradient is distorted.
8. Risk Factors for Uterine Dysfunction
Neuraxial analgesia
Chorioamnionitis
A higher station at the onset of labor
maternal age
Maternal obesity l
9. Labor Disorders
Latent-phase Prolongation
Uterine dysfunction can in turn lead to labor abnormalities (Table 23-2).First, the latent phase
may be prolonged, which is defined as >20 hours in the
nullipara and >14 hours in the multipara
11. PREMATURELY RUPTURED MEMBRANES
AT TERM
Membrane rupture at term without spontaneous uterine contractions complicates approximately
8 percent of pregnancies.
labor induction with intravenous oxytocin was preferred management
In those with an unfavorable cervix, no or few contraction, and no significant fetal heart rate
decelerations, prostaglandin E1 (misoprostol) is chosen to promote cervical
ripening and contractions.
The benefit of prophylactic antibiotics in women with ruptured membranes before labor at term
is unclear (Passos, 2012).
However, in those with membranes ruptured longer than 18 hours, antibiotics
are instituted for group B streptococcal infection prophylaxis
12. PRECIPITOUS LABOR AND DELIVERY
Precipitous labor terminates in expulsion of the fetus in <3 hours.
Complications
uterine rupture or extensive lacerations of the cervix, vagina, vulva, or perineum
Amniotic fluid embolism
Uterine atony
13. As treatment, analgesia is unlikely to modify these forceful contractions
significantly.
The use of tocolytic agents such as magnesium sulfate or
terbutaline is unproven in these circumstances.
A single, intramuscular 250-ug terbutaline dose may be reasonable in an attempt to resolve a
nonreassuring fetal heart rate pattern. This is balanced against the risk of
associated uterine atony if delivery is imminent.
Certainly, oxytocin administration should be stopped.
14. FETOPELVIC DISPROPORTION
Pelvic Capacity
Fetopelvic disproportion arises from diminished pelvic capacity or from
abnormal fetal size, structure, presentation, or position. Commonly, both are
present.
The pelvic inlet, midpelvis, or pelvic outlet may be contracted
solely or in combination. Any contraction of the pelvic diameters that
diminishes pelvic capacity can create dystocia.
15. Face Presentation
With this presentation, the neck is hyperextended so that
the occiput is in contact with the fetal back, and the chin
(mentum) is presenting.
The rate is approximately 0.1 percent of births
16. During labor, fetal heart rate monitoring is best done with external devices to
help avoid face or eye injury.
Because face presentations among term-size
fetuses are more common with some degree of pelvic inlet contraction,
cesarean delivery rates are substantially higher than with occiput
presentation.
If indicated, low or outlet forceps delivery of a mentum anterior
face presentation can be completed (Chap. 29, p. 542). Vacuum extraction
has been associated with eye trauma and is not recommended
17. Brow Presentation
This uncommon presentation is diagnosed when that portion of
the fetal head
between the orbital ridge and the anterior fontanel presents at the
pelvic
inlet.
the fetal head thus occupies a position midway between full
flexion (occiput) and full extension (face).
Rates range from 0.1 to 0.2 percent of births
18. The presentation may be recognized by abdominal palpation when both the occiput and chin
can be palpated easily, but vaginal examination is usually necessary.
The frontal sutures, large anterior fontanel, orbital ridges, eyes, and root of the nose are felt
during vaginal examination, but neither the mouth nor the chin is palpable.
Except when the fetal head is small or the pelvis is unusually large, engagement of the fetal
head and subsequent delivery cannot take place as long as the brow presentation persists.
19. Transverse Lie
the fetus long axis lies approximately perpendicular to that of the
mother. In a transverse lie, the shoulder is usually positioned over the
pelvic
inlet. The head occupies one iliac fossa, and the breech the other. This
creates a shoulder presentation in which the side of the mother on which
the
acromion rests determines the designation of the position as right or left
acromial. In addition, the back may be directed anteriorly or posteriorly
and
also superiorly or inferiorly. Thus, it is customary to further distinguish
right
or left varieties as dorsoanterior and dorsoposterior
20. Umbilical Cord Prolapse
umbilical cord prolapse may be more common with pelvis contraction.
Most risks stem from an unengaged presenting part and include hydramnios, breech
presentation, transverse lie, premature or small fetus with weight <2500 g, preterm rupture of
membranes, and multifetal gestation
21. Umbilical cord prolapse is usually diagnosed clinically.
The cord loop is palpated in a position lower in the vaginal canal than the head or beside it.
For most cases, prompt manual elevation of the fetal head relieves cord
compression.
Concurrently, expeditious transfer to an operating room and preparations for cesarean delivery
are completed.
Rarely, vaginal or operative vaginal birth is reasonable if it can be completed much more rapidly
than emergent cesarean birth
22. Compound Presentation
an extremity prolapses alongside the presenting part, and both
present simultaneously in the pelvis
23. In most cases, the prolapsed part should be left alone. It typically does
not impede labor and often retracts out of the way with descent of the
presenting part. If it fails to retract and if it appears to prevent descent of the
head, the prolapsed part can be pushed gently upward and the head
simultaneously downward by fundal pressure. In cases with a co-presenting
hand, the fetus may reflexively retract the hand if pinched by the provider.
In general, rates of perinatal mortality and morbidity are increased, but
these mainly stem from effects of associated preterm birth, prolapsed
umbilical cord, and traumatic obstetrical procedures. Tebes and coworkers
(1999) described a rare case of pressure-induced forearm ischemia and later
surgical amputatio
24. COMPLICATIONS WITH DYSTOCIA
Dystocia, especially if labor is prolonged, is associated with a higher incidence of several
common obstetrical and neonatal complications
Maternal infection, either intrapartum chorioamnionitis or postpartum endomyometritis,
Postpartum hemorrhage from atony
Uterine tears second stage caesarean section
Uterine rupture prolonged labour
the upper segment of the uterus contracts, retracts, and expels the fetus.
In response, the softened lower uterine segment and cervix dilate and thereby form a greatly expanded,
thinned-out tube through which the fetus can pass.
The boundary between these segments is the physiological retraction ring the pathological retraction
ring of Bandl
25. Fistula formation
Lower-extremity nerve injury
Caput succedaneum and molding develop commonly and may be impressive
Mechanical trauma
such as nerve injury, fractures, and cephalohematoma also are more frequent