DYSTOCIA
OB 2
Mechanisms of Dystocia
1st stage: Factors influencing the progress of
Dr. Aguada Uterine contractions:
1. Cervical Pressure
2. Forward pressure exerted by the leading fetal
Normal Labor part
1st stage- Regular contractions to full cervical 2nd stage: Fetopelvic disproportion
dilatation (10cm) • Mechanical relationship between the fetal
2nd stage- Full cervical Dilatation to delivery of fetus head size and position and the pelvic
3rd stage- delivery of fetus to delivery of placenta capacity after cervical dilation.
4th stage- 1 hour from delivery of placenta • Ineffective labor: possible warning sign of
Cardinal movements of Labor fetopelvic disproportion
1. Engagement • Uterine muscle malfunction can result to:
2. Descent o Uterine overdistention
3. Flexion o Obstructed labor
4. Internal Rotation o Both
5. Extension
6. External Rotation Labor abnormalities
7. Expulsion • Uterine dysfunction
• fetopelvic disproportion
Diameters of fetal head at term
-Occipitofrontal Diameter (Greatest circumference) Uterine contractions
-Occipitomental Diameter • cervical dilation
-Suboccipitobregmatic diameter (smallest • propulsion and expulsion of the fetus
circumference)
-Biparietal diameter (Greatest transverse diameter) Pushing- contractions are reinforced by voluntary
-Bitemporal Diameter or involuntary muscular action of the abdominal
wall.
Thoms Rule (Pelvic outlet)
Transverse Bituberous 3 Significant advances have aided treatment of
Diameter diameter uterine dysfunction
+ 1. Undue labor: contributes to maternal and
Posterior perinatal morbidity and mortality
Sagittal 2. Dilute IV infusion of oxytocin: treat certain types
Vaginal delivery is >15cm >8cm of uterine dysfunction
allowed w/ Episiotomy 3. Caesarian delivery: selected when oxytocin fails,
and low forceps or its use is inappropriate.
Caesarian Delivery <15cm <8cm
Uterine contraction
Asynclitism -gradient of myometrial activity.
-Majority of Labor Dystocia is due to Asynclitism -Fundal dominance: Forces are greatest and last
longest at the fundus
Types of Asynclitism:
1. Anterior Asynclitism- Sagittal suture approaches Montevideo units
to Sacral Promontory -method of measuring uterine performance during
2. Posterior Asynclitism- Sagittal suture lies close to labor.
symphysis (Extreme P.A- posterior ear can easily -15mmHg: lower limit of contraction pressure
palpated) required to dilate the cervix.
3. Normal asynclitism -180 Montevideo units in 10 min. window:
threshold for adequate labor
Dystocia ->180 Montevideo units-inadequate uterine
-Difficult Labor contactions
-abnormally slow labor progress
-Cephalopelvic disproportion or failure to progress Two physiological types of uterine dysfunction:
3 distinct abnormality categories: Hypotonic uterine Hypertonic uterine
1. Power- Uterine dysfunction dysfunction dysfunction
2. Passenger Tone No basal tonus basal tone is
• fetal abnormalities elevated
• fetal presentation Uterine normal gradient Pressure gradient is
• fetal position contraction pattern(synchronous) distorted
• fetal anatomy (incoordinate uterine
3. Passages dysfunction)
• soft tissue abnormalities ineffective to dilate complete
• structural changes can contract the the cervix asynchrony, more
maternal bony pelvis. forceful contraction
of the uterine
midsegment than the
fundus
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• Longer durations may be appropriate as
long as progress is documented.
Labor disorders • Maternal and fetal status should be
1. Latent phase Prolongation reassuring.
• >20 hrs in nullipara
• >14 hrs in multipara Maternal Pushing efforts
• -treated with oxytocin stimulation. • Combined force created by contractions of
2. Active phase disorder uterus and abdominal musculature propels
*Protraction disorder (Active phase protraction) the fetus downward.
• Slower than normal progress • Force of abdominal musculature
• defined as <1cm/hr cervical dilation for a o Slow or prevent spontaneous
minimum of 4 hours vaginal delivery
• not be an indication for caesarian delivery • Heavy sedation and regional anesthesia:
• oxytocin augmentation is initiated. reduce the reflex urge to push, impair the
*Arrest disorder (Active phase arrest) ability to contract abdominal muscles
• Complete cessation of progress effectively.
• defined as no dilation for 2 hours or more.
• oxytocin augmentation Risks for Uterine dysfunction
Labor factors causes uterine dysfunction:
Other criteria of Arrest phase disorder 1. Neuraxial anesthesia- lengthening 1st and
• latent phase completed; cervix is dilated 2nd stages of labor
>4cm 2. Chorioamnionitis- associated with
• contraction pattern of 200 Montevideo prolonged labor
units; 2 hours or more w/o cervical change. 3. Maternal intrapartum infection
• " 2-hour rule": at least 4 hours is necessary 4. Infection diagnosed late in labor- marker of
before concluding that the active phase has caesarian delivery for dystocia,
failed. consequence of dysfunctional, prolonged
labor rather than a cause of dystocia.
Four recommendations by the Obstetric Care 5. Maternal position during labor
Consensus Committee (2016) 6. Water immersion
1. Prolonged latent phase is not an indication for
caesarian delivery Prematurely Ruptured Membranes at Term
2. Protraction disorder
• recommends against caesarian delivery (PROM)
• managed with observation, assessment of • Membrane rupture at term without
uterine activity and stimulation of spontaneous uterine contractions.
contractions. • Labor stimulation was initiated if
3. Recommended cervical dilation threshold- 6cm contractions did not begin after 6-12 hours
4. Active phase arrest: Caesarian delivery (in the past)
• reserved for women at or beyond 6cm of • IV Oxytocin: preferred management
dilation with ROM who fail to progress • Oxytocin- hypotonic contractions or with
despite 4 hours of adequate uterine advanced cervical dilation.
activity, or 6 hrs of oxytocin administration • Prostaglandin E1 (Misoprostol)-
with inadequate contraction and no cervical unfavorable cervix and no few contraction.
change. • Antibiotics- membranes ruptures for more
than 18 hrs; group B streptococcal
prophylaxis.
Slow stage Descent disorders
• longer first stage labor was associated with Precipitous labor and delivery
maternal and neonatal complications • Extreme rapid labor and delivery
• Neuraxial analgesia delays the active phase • Results from:
of spontaneous labor and flattens the o Abnormally low resistance of the
curve. Slows the active phase of first stage soft parts of the birth canal
labor o Abnormally strong uterine and
• When regional anesthesia is used abdominal contractions
o Nullipara- 2 hours and extended to o Absence of painful sensation
3 hours • Terminates in expulsion of fetus in less than
o Multipara- 1 hour extended to 2 3 hours
hours • Accompanied by serious maternal
• Epidural anesthesia- commonly used; complications:
prolonged second stage o Uterine rupture
o Extensive lacerations of the cervix,
Newer Guidelines have been promoted by the vagina and vulva
Consensus Committee for second stage labor o Uterine atony
• Allowing a nullipara to push for at least 3 • Linked with cocaine abuse
hours and multipara to push at least 2 • Associated with placental abruption,
hours before second stage labor arrest is meconium, postpartum hemorrhage, and
diagnosed. low APGAR scores.
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▪ The spines are prominent
• Adverse perinatal outcomes increased due ▪ The pelvic sidewalls
to: converge
o Tumultuous uterine contraction- ▪ Sacrosciatic notch is
prevents uterine blood flow and narrow
fetal oxygenation • Contracted Outlet
o Resistance of the birth canal- o May cause dystocia not so much of
cause intracranial trauma itself but by often associated
o Unattended birth- may fall into the midpelvic contraction
floor, may need resuscitation that o Play important part in perineal
is not immediately available. tears
o General anesthesia/ agents that o Perineum- increasingly
impair uterine contractibility- distended→ exposed to risk of
heroic laceration.
o Oxytocin- should be stopped
immediately Pelvic fractures
• Trauma from automobile collisions was the
Fetopelvic disproportion most important cause.
• Diminished pelvic capacity from abnormal • Fracture pattern, minor malalignment, and
fetal size or presentation or both. retained hardware are not absolute
• Contraction of the pelvic diameters that indications for cesarean delivery.
diminishes pelvic capacity can create • Fracture healing- 8 to 12 weeks (vaginal
dystocia during labor. delivery)
Contracted plane Measurement of Pelvic Capacity Estimation
contraction
Pelvic Inlet • Anteroposterior • 2/3 of the neonates who required caesarian
Diameter: <10cm delivery after failed forceps weighted
• Greatest transverse <3700g
diameter: <12cm • Other factors:
• Diagonal o Obstruct fetal passage through the
Conjugate: birth canal, these includes
<11.5cm asynclitism, occiput posterior
Midpelvis • Interspinous position and face or brow
diameter: <10cm presentation.
• Interspinous + • Mueller-Hillis Maneuver- a clinical
posterior sagittal maneuver to predict disproportion.
diameter: <13cm o The fetal brow and the suboccipital
Pelvic outlet • Interischial region are grasped through
Diameter: <8cm abdominal wall with the fingers,
and firm pressure is directed
Notes: downward in the axis of the inlet.
• Cervical dilation is aided by hydrostatic o No disproportion→ vaginal
action of the unruptured membranes or delivery can be predicted.
after rupture, by direct application of the o no relationship between failed
presenting part against the cervix. descent during the maneuver and
• After membrane rupture, absent pressure subsequent labor dystocia.
by the head against the cervix and lower • no current method of measurement
uterine segment predisposes to less satisfactorily predicts fetopelvic
effective contractions. disproportion based on head size.
• Mechanical adaptation of the fetal
passenger: the better the adaption, the Presentation is in the table page **
more efficient the contractions.
• Contracted Inlet Leopolds Maneuver
o Plays an important part in the 1st Maneuver: Fundal • Head: round, more
production of abnormal Grip mobile
presentations • Breech: large,
o In women with contracted pelvis- nodular mass
▪ face and shoulder 2nd Maneuver: Lumbar •Back: hard, resistant
presentation encountered Grip structure, Directed
3x. anteriorly, posteriorly,
▪ Cord prolapse- 4x to 6x transversely
• Contracted Midpelvis • Fetal extremities:
o More common than inlet numerous small
contraction. 3rd Maneuver: Pawlik’s Used to confirm fetal
o Causes transverse arrest of the Grip presentation (cephalic
fetal head vs breech)
o Suggestion of contraction of • Not engaged-
Midpelvis movable mass is felt
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4th Maneuver: Pelvic When the head has
Grip
descended, can feel
anterior shoulder or
the space created by
the neck from the head
Complications with Dystocia
Maternal complications
1. Infection
2. Postpartum hemorrhage
3. Uterine tears with hysterectomy
4. Uterine rupture
5. Contraction ring (ring of Bandl)
6. Fistula formation
7. Pelvic floor injury
8. Lower extremity nerve injury
Perinatal complications
1. Incidence of peripartum fetal sepsis (longer
labors)
2. Caput succedaneum
3. Molding
4. Mechanical trauma
• nerve injury
• fractures
• cephalohematoma
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Labor pattern Nullipara Multipara
Prolongation >20 hours >14 hours
Disorder
-Prolonged latent
phase
Protraction disorder
-Protracted active <12cm/hr 1.5cm/hr
phase dilation
-Protracted descent <1cm/hr <2cm/hr
Arrest disorders
-Prolonged >3hrs >1hr
deceleration phase
-Secondary arrest of >2hrs >2hrs
dilation
-Arrest of Decent >1hr >1hr
-Failure of Descent No decent No decent
in in
deceleration deceleration
phase or phase or
second second
stage stage
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Picture Presentation Etiology Management
Face Presentation • fetal malformations • In the absence of a
▪ the neck is and hydramnios contracted pelvis
hyperextended so were risk factors and with effective
that the occiput is for face or brow labor, successful
in contact with the presentations. vaginal delivery
• Anencephalic usually will follow.
fetal back, and the
fetuses naturally • Fetal heart rate
chin (mentum) is present by the monitoring is
presenting face. probably better
▪ mentum posterior • High parity is a done with external
presentation is predisposing factor devices to avoid
undeliverable for face damage to the face
except with a very presentation. and eyes.
preterm fetus • Preterm fetuses, • Some degree of inlet
with their smaller contraction→
head dimensions,
can engage before caesarian delivery
conversion to vertex • Low or outlet
position forceps delivery
Brow presentation ▪ The causes of • In the absence of a
• portion of the fetal persistent brow contracted pelvis
head between the and with effective
orbital ridge and presentation are
the anterior the same as those labor, successful
fontanel presents at vaginal delivery
for face
the pelvic inlet usually will follow.
• Unstable and often presentation. • Fetal heart rate
converts to a face monitoring is
or an occiput
presentation probably better
• may be recognized done with external
by abdominal devices to avoid
palpation when both damage to the face
the occiput and chin and eyes.
can be palpated • Some degree of inlet
easily, but vaginal contraction→
examination is caesarian delivery
usually necessary. • Low or outlet
forceps delivery
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Picture Presentation Etiology Management
Transverse Lie • After rupture of the • Active labor in a
• long axis of the membranes, if labor woman with a
fetus is continues, the fetal transverse lie is
approximately shoulder is forced usually an indication
perpendicular to into the pelvis, and for cesarean
that of the mother the corresponding delivery.
• the long axis forms arm frequently • With cesarean
an acute angle, an prolapses delivery, because
oblique lie (unstable • After some descent, neither the feet nor
lie) results. the shoulder is the head of the fetus
• Shoulder presenting arrested by the
occupies the lower
• A transverse lie is margins of the
usually recognized pelvic inlet. uterine segment, a
easily, often by • uterus then low transverse
inspection alone contracts vigorously incision into the
(No fetal pole is in an unsuccessful uterus may lead to
detected in the attempt to difficult fetal
fundus, and the overcome the extraction. This is
ballottable head is obstacle. With time, especially true of
found in one iliac a retraction ring dorsoanterior
fossa and the rises increasingly
presentations.
breech in the other) higher and becomes
• the “gridiron” feel more marked→ Therefore, a vertical
of the ribs. uterine rupture hysterotomy incision
• Neglected shoulder is often indicated.
presentation
• Conduplicato
corpore
Compound • Causes of • the prolapsed part
compound
presentation presentations are should be left alone,
conditions that because most often it
• an extremity prevent complete will not interfere with
occlusion of the
prolapses alongside pelvic inlet by the labor.
the presenting part, fetal head, including • the prolapsed arm
preterm labor. should be pushed
and both present gently upward and the
simultaneously in the head simultaneously
pelvis. downward by fundal
pressure.
• the condition should
be observed closely to
ascertain whether the
arm retracts out of the
way with descent of
the presenting part.
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