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Abnormal labor and abnormal uterine contractions (dystocia) Dr Samar Sarsam

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Abnormal labor and abnormal uterine contractions (dystocia) Dr Samar Sarsam DEFINITION Dystocia is defined as difficult labor or childbirth. – PowerPoint PPT presentation

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Title: Abnormal labor and abnormal uterine contractions (dystocia) Dr Samar Sarsam


1
Abnormal labor and abnormal uterine contractions
(dystocia)Dr Samar
Sarsam
2
  • DEFINITION
  • Dystocia is defined as difficult labor or
    childbirth.
  • It may be associated with abnormalities
    involving
  • Abnormalities of the Passage
  • Abnormalities of the Passenger
  • Abnormalities of the Powers
  • or a combination of these factors

3
  • INCIDENCE
  • Over the last quarter of a century, the cesarean
    section rate in the United States has risen to
    approximately 25 of deliveries done each year.
    Dystocia is currently the most common indication
    for primary cesarean section, and is about three
    times more common than either non reassuring
    fetal status or malpresentation.
  •  

4
  •  

5
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6
Cervical dilatation (cm)
Friedman labor curve in nulliparous
2nd stage
1st stage
dec
max slope
acceleration
Active phase
Latent phase
Time (hours)
7
  • ABNORMAL PATTERNS OF LABOR 
  • The progress of labor is evaluated primarily
    through estimates of cervical dilatation and
    descent of the fetal presenting part. Normal
    labor patterns in primigravidas and multiparas
    have been described in detail by Friedman and
    others.

8
  • Friedman also described four abnormal patterns of
    labor (1) prolonged latent phase, (2)
    protraction disorders (protracted active-phase
    dilatation and protracted descent), (3) arrest
    disorders (prolonged deceleration phase,
    secondary arrest of dilatation, arrest of
    descent, and failure of descent), and (4)
    precipitate labor disorders.

9
  • 1. Prolonged Latent Phase
  • The latent phase of labor begins with the onset
    of regular uterine contractions and extends to
    the beginning of the active phase of cervical
    dilatation. The duration of the latent phase
    averages 6.4 hours in nulliparas and 4.8 hours in
    multiparas.
  • Causes of prolonged latent phase include
  • excessive sedation or sedation given before the
    end of the latent phase.
  • labor beginning with an unfavorable cervix.
  • uterine dysfunction characterized by weak,
    irregular, uncoordinated, and ineffective uterine
    contractions.
  • fetopelvic disproportion.

10
  • Treatment options
  • therapeutic rest with sedation and hydration.
  • active management of labor.
  • 85 of patients spontaneously enter the active
    phase of labor.
  • Ten percent of patients will have been in false
    labor, and may be allowed to return home to await
    the onset of true labor if fetal status is
    reassuring.
  • In the remaining 5 of patients, uterine
    contractions remain ineffective in producing
    dilatation in the absence of any
    contraindication, active stimulation of labor
    with oxytocin infusion may be effective in
    terminating the latent phase of labor.
  •  

11
  • 2. Protraction Disorders
  • Protracted cervical dilatation in the active
    phase of labor
  • Protracted descent of the fetus constitute the
    protraction disorders.
  • Protracted active-phase dilatation is
    characterized by an abnormally slow rate of
    dilatation in the active phase, ie, less than 1.2
    cm/h in nulliparas or less than 1.5 cm/h in
    multiparas.
  • Protracted descent of the fetus is characterized
    by a rate of descent under 1 cm/h in nulliparas
    or under 2 cm/h in multiparas.
  • The second stage of labor, which normally
    averages 20 minutes for parous women and 50
    minutes in nulliparous women, is protracted when
    it exceeds 2 hours in nulliparas or 1 hour in
    multiparas, or 3 and 2 hours respectively in the
    presence of conduction anesthesia.

12
  • The underlying pathogenesis of protracted labor
    is probably multifactorial.
  • Fetopelvic disproportion.
  • minor malpositions such as occiput posterior.
  • improperly administered conduction anesthesia.
  • excessive sedation.
  • pelvic tumors obstructing the birth canal.

13
  • Treatment of protraction disorders
  • Cesarean section is indicated in the presence of
    confirmed fetopelvic disproportion.
  • In the absence of fetopelvic disproportion,
    conservative management, consisting of support
    and close observation, and therapy with oxytocin
    augmentation both carry a good prognosis for
    vaginal delivery.
  •  

14
  • 3. Arrest Disorders
  • The four patterns of arrest in labor
  • (1) prolonged deceleration, with deceleration
    phase lasting more than 3 hours in nulliparas or
    more than 1 hour in multiparas.
  • (2) secondary arrest of dilatation, with no
    progressive cervical dilatation in the active
    phase of labor for 2 hours or more.
  • (3) arrest of descent, with descent failing to
    progress for 1 hour or more.
  • (4) failure of descent, with descent failing to
    occur during the deceleration phase of dilatation
    and during the second stage.

15
  • Causes
  • About 50 of patients with arrest disorders
    demonstrate fetopelvic disproportion.
  • various fetal malpositions (eg, occiput
    posterior, occiput transverse, face, or brow).
  • inappropriately administered anesthesia, or
    excessive sedation.
  • If fetopelvic disproportion is established,
    cesarean section is done.
  • If fetopelvic disproportion is not present and
    uterine activity is less than optimal, oxytocin
    stimulation is generally effective in producing
    further progress.

16
  • 4. Precipitate Labor Disorders
  • Precipitate dilatation occurs if cervical
    dilation occurs at a rate of 5 or more
    centimeters per hour in a primipara or at 10 cm
    or more per hour in a multipara. Precipitate
    descent occurs with descent of the fetal
    presenting part of 5 cm or more per hour in
    primparas and 10 cm or more per hour in
    multiparas.

17
  • Causes
  • 1-extremely strong uterine contractions
  • 2-low birth canal resistance.
  • abnormal contractions may be associated with
    administration of oxytocin and abruptio
    placentae.
  • If oxytocin administration is the cause of
    abnormal contractions, it may simply be stopped.
    The problem typically resolves in less than 5
    minutes.
  • If excessive uterine activity is associated with
    fetal heart rate abnormalities, and this pattern
    persists despite discontinuation of oxytocin, a
    b-mimetic such as terbutaline or ritodrine can be
    given and magnesium sulfate also
  • Lacerations of the birth canal are common.
  • maternal amniotic fluid embolism.
  • predisposing to postpartum hemorrhage.
  • Perinatal mortality is increased secondary to
    hypoxia, possible intracranial hemorrhage, and
    risks associated with unattended delivery.

18
  • PATHOGENESIS TREATMENT
  • --Abnormalities of the Passage
  • Causes
  • bony abnormalities (pelvic dystocia).
  • soft tissue obstruction of the birth canal.
  • abnormal placental location.
  • Pelvic dystocia, is the most common cause of
    passage abnormalities.
  • The etiology and diagnosis of pelvic
    abnormalities begins with the shape,
    classification, and clinical assessment of the
    adult female pelvis..
  • Ultrasound, magnetic resonance imaging (MRI), and
    x-rays have been used to investigate pelvic size
    and shape for evidence of pelvic contraction
    obstructing the normal progress of labor.

19
  • X-ray pelvimetry has now fallen into limited use.
  • Clinical pelvimetry has been largely used in the
    routine evaluation of most obstetric patients.
  • The diagnosis of fetopelvic disproportion has
    generally become a diagnosis of exclusion, after
    fetal factors and uterine dysfunction have been
    ruled out.
  • However, x-ray pelvimetry retains a role in the
    evaluation of a pelvis for the feasibility of
    vaginal breech delivery and in the assessment of
    gross bony distortion such as previous pelvic
    fracture or rachitic deformity.
  • Contractions of the pelvis are generally
    classified as
  • contractions of the inlet, midpelvis, or outlet,
    or as a combination of these elements.

20
  • Inlet contraction is suspected if the
    anteroposterior diameter of the pelvis is less
    than 10 cm, the transverse diameter is under 12
    cm, or both.
  • floating vertex presentation with no descent
    during labor,
  • abnormal presentation,
  • prolapsed cord or extremity.
  • considerable molding of the fetal head,
  • caput succedaneum formation,
  • and prolonged rupture of the membranes.
  • If allowed to continue, abnormal thinning of the
    lower uterine segment may occur, with development
    of a Bandl's retraction ring, or even frank
    uterine rupture.
  • Cesarean section is the treatment of choice in
    true inlet contraction.

21
  • Midpelvis contraction it is more frequent than
    inlet dystocia because the midpelvis is smaller
    than the inlet and positional abnormality is more
    common at this level.
  • Presentation
  • Arrest of descent
  • Poor application of the head to the cervix
  • Abnormal rate of cervical dilatation
  • Contraction of the outlet is extremely unusual
    unless found in association with a Midpelvis
    contraction.
  • Criteria for assessing pelvic outlet adequacy
    include intertuberous diameter greater than 8 cm
    and a sum of the intertuberous diameter and the
    anteroposterior diameter greater than 15 cm.

22
  • Midpelvic outlet obstruction is detected
    clinically on the basis of convergent side walls,
    prominent ischial spines, or a narrow pelvic
    arch.
  • It may present as a prolonged second stage,
  • persistent occiput posterior position,
  • deep transverse arrest.
  • Molding of the fetal head and caput succedaneum
    formation are common.

23
  • Uterine rupture may occur in prolonged labor
    complicated by midpelvic outlet obstruction, and
    vesicovaginal or rectovaginal fistula formation
    may result with pressure necrosis of the
    surrounding tissues of the birth canal by the
    fetal head.
  • Cesarean section is therefore the delivery method
    of choice in this complication.
  • Other anatomic abnormalities of the reproductive
    tract may cause dystocia is soft tissue dystocia
    may be caused by uterine or vaginal congenital
    anomalies, scarring of the birth canal, pelvic
    masses, or low implantation of the placenta.

24
  • --Abnormalites of the Passenger 
  • A. malposition and malpresentation
  • Fetal malpresentations are abnormalities of fetal
    position, presentation, attitude, or lie. They
    collectively constitute the most common cause of
    fetal dystocia, occurring in approximately 5 of
    all labors.
  • 1. Vertex malpositions
  • a. Occiput posterior
  • b. Occiput transverse
  • 2. Brow presentationBrow presentations usually
    are transient fetal presentations with deflexion
    of the fetal head.

25
  • 3. Face presentationIn face presentation, the
    fetal head is fully deflexed from the
    longitudinal axis.
  • 4. Abnormal fetal lieIn transverse or oblique
    lie, the long axis of the fetus is perpendicular
    to or at an angle to the maternal longitudinal
    axis.

26
  • 5. Breech presentation
  • B. fetal macrosomia
  • C. fetal malformation
  • The most common malformation is hydrocephalus,
    enlargement of the fetal abdomen caused by
    distended bladder, ascites, or abdominal
    neoplasms or other fetal masses, including
    meningomyelocele or cystosarcoma.

27
  • Abnormalities of the Powers
  • Normal uterine activity during labor
  • (1) the relative intensity of contractions is
    greater in the fundus than in the midportion or
    lower uterine segment (this is termed fundal
    dominance) (2) the average value of the
    intensity of contractions is more than 24 mm Hg.
    (3) contractions are well synchronized in
    different parts of the uterus (4) the basal
    resting pressure of the uterus is between 12 and
    15 mm Hg (5) the frequency of contractions
    progresses from one every 35 minutes to one
    every 23 minutes during the active phase (6)
    the duration of effective contraction in active
    labor approaches 60 seconds and (7) the rhythm
    and force of contractions are regular.

28
  • Quantification of uterine activity during labor
    by
  • -external tocodynamometry
  • -intrauterine pressure catheter measurement.
  • Uterine dysfunction generally comprises 3
    categories
  • hypotonic dysfunction,
  • hypertonic dysfunction,
  • uncoordinated dysfunction.

29
  • Hypotonic dysfunction is uterine activity
    characterized by contraction of the uterus with
    insufficient force (gt 24 mm Hg), irregular or
    infrequent rhythm, or both. Seen most often in
    primigravidas in the active phase of labor, it
    may be caused by excessive sedation, early
    administration of conduction anesthesia, twins,
    polyhydramnios, or overdistention of the uterus.
  • Hypotonic dysfunction responds well to oxytocin
    however, care must be taken to first rule out
    cephalopelvic disproportion and malpresentation.
    Active management of labor has been shown to
    decrease perinatal morbidity and cesarean section
    rates.

30
  • hypertonic uterine contractions and uncoordinated
    contraction often occur together and are
    characterized by elevated resting tone of the
    uterus, dyssynchronous contractions with elevated
    tone in the lower uterine segment, and frequent
    intense uterine contractions. It is generally
    associated with abruptio placentae, overuse of
    oxytocin, cephalopelvic disproportion, fetal
    malpresentation, and the latent phase of labor.
  • Treatment
  • tocolysis, decrease in oxytocin infusion
  • cesarean section as indicated for concomitant
    malpresentation, cephalopelvic disproportion, or
    fetal distress.

31
  • When these patterns occur in the latent phase of
    labor
  • sedation may be effective in converting
    hypertonic contractions to normal labor patterns.
  • Inadequate pushing in the second stage of labor
    is common and may be caused by conduction
    anesthesia, oversedation, exhaustion, or
    neurologic dysfunction such as paraplegia or
    hemiplegia of various causes, or by psychiatric
    disorders.
  • Mild sedation may improve expulsive efforts.
  • outlet forceps or vacuum delivery may be of help.
  •  
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