Post term Pregnancy (PowerPoint) by qingyunliuliu

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									Post-term Pregnancy

      Khalid A. Yarouf

Gestational age at pregnancy
  Abortion:      < 24 weeks from LMP.
  Preterm delivery:   24-37 weeks.
  Term:               38-42 weeks.
  Post-term:          > 42 weeks.
        10% of pregnancies.
        Occur more frequently in primigravida, who are
         younger or older than average childbearing age,
         and in grandmultiparas (women who have had ≥ 6
         successful pregnancies).

What is the best estimate for
gestational age?
 1. Hx:
  LMP tends to be reliable if LMP was definite,
    cycle was normal, and pregnancy was
  Quickening (maternal perception of fetal
    movement) occurs at about 16-20 weeks.
 2. P/E:
  Size of uterus at early examination in 1st
    trimester should e consistent with dates.


 3. Apply Naegele’s rule:
  Add 7 days to the date of the first day
    of the LMP  count back 3 months.
  e.g. LMP was March 7, 2001  EDD
    would be January 14, 2002.
  Note that the length of gestation
    increases approx. 1 day for each day
    the menstrual cycle is > 28 days.


 4. Obtain US (confirmatory):
  Fetal heart can be heard starting at 11
  Crown-rump length (CRL):
        Most accurate in 1st trimester to within ± 5 days.
        At ≥ 12 weeks, fetus begins to curve & this
         measurement becomes < accurate.
    Biparietal diameter (BPD) from 12-18 weeks
     is most accurate to ± 7 days.

What are the causes of post-term
    Potential causative factors:
        Deficiency of ACTH in fetus & placental sulfatase
    Exact mechanism of spontaneous onset of
     labor in unclear, but fetus, placenta & mother
     are all involved. The longest pregnancy on
     record is 1 year & 24 days, ending in a
     liveborn anencephalic infant. CNS
     abnormalities, e.g. anencephaly, are a/w
     prolonged pregnancy.

What are the complications of
prolonged pregnancy?
    Incidence of fetal mortality for all groups is as
        40-41 weeks’ gestation:                 1.1%
        43 weeks’ gestation:                    2.2%
        44 weeks’ gestation:                    6.6%
 1. Macrosomia:
        Commonest outcome (75%).
        Occurs if placental function is maintained.
        Cx of large uterus:
            Arrest of labor + Cesarean delivery + Traumatic vaginal

 2.       Dysmaturity syndrome:
         Normally, there’s little growth of fetus post-term.
         This syndrome is observed in 30% of post-term
          infants & in 3% of term infants.
         CFx:
            Loss of subcutaneous fat.
            Dry, wrinkles, cracked skin.
            Long nails.
            Unusual degree of alertness.
            Cx: Fetal hypoxia & Meconium aspiration syndrome.


 3. Placental aging / senescence          
    Critically ↓ nutritional & O2 supply  
    Fetal compromise 2 to placental
    insufficiency (major concern in post-
    term pregnancy).
 4. Oligohydramnios:
       Morbidity increased with HTN/
        preeclampsia, DM, abruption, IUGR,
        multiple gestation.

How can you assess the post-term
fetus antenatally?
 A. FHR testing:
  NST (non-stress test):
        Non-invasive test of fetal activity that correlates
         with fetal well-being.
        Fetal heart rate accelerations are observed during
         fetal movement.
        External monitor is used to record FHR & mother
         precipitates by indicating fetal movement.
        NST can be reactive or non-reactive.
    Contraction Stress test: not used anymore.


 B. Biophysical profile (BPP):
  Composite of tests designed to identify
    a compromised fetus during
    antepartum period.

Biophysical Profile (BPP)
       Parameter           Normal (2 points)              Abnormal
                                                           (0 point)
 Amniotic Fluid Volume   Fluid pockets of 2 cm in   Oligohydramnios
 (AFV)*                  2 axes.

 NST                     Reactive.                  Non-reactive

 Breathing               At least 1 episode of      No breathing
                         breathing lasting at
                         least 30 sec.
 Limb movement           3 discrete movements.      ≤2

 Fetal tone              At least 1 episode of      No movement
                         limb extension followed
                         by flexion.
        Score      Interpretation             Mx

 8-10           Normal              Repeat BPP as
                                    clinically indicated

 6              Suspect chronic     Repeat BPP in 4-6
                hypoxia             hours

 0-4            Strongly suspect    Deliver fetus if
                chronic asphyxia    mature

How can you manage suspected
post-dates pregnancy?
 1. Determine gestational age dating.
 2. Establish how favorable cervix is
    (dilated, effaced, soft).
 3. Assess fetal well-being [e.g. with NSTs
    & amniotic fluid indices (AFIs)]. If fetal
    jeopardy is evident, immediate delivery
    is appropriate.

 4. Use the following triage method:
       Dates are certain & cervix is favorable. Neither the
        mother nor the fetus benefits from waiting  induce
        labor promptly with IV oxytocin & rupture of
       Dates are certain but cervix is unfavorable. Risk of failed
        induction is high. If fetal macrosomia is suspected,
        induce labor with PGE2. Alternatively, if the estimated
        fetal weight (EFW) is normal, manage expectantly with
        twice-weekly NSTs & AFIs.
       Dates are unsure. Because it’s not known if the patient
        is post-dates, delivery is not indicated. Manage
        expectantly with twice-weekly NSTs & AFIs awaiting
        spontaneous labor.

 5. Intrapartum Mx of Cx:
  Meconium staining:
  Prior to delivery  Amnio-infusions:
        = infusion of NS thru intrauterine catheter.
        to dilute meconium.
    After delivery of fetal head  suctioning
     meconium from nose & pharynx to prevent
    After delivery of entire fetus, but before the
     first neonatal breath  aspirate neonatal
     tracheal meconium using laryngoscope.


  When macrosomia is suspected, US
   should be performed to estimate fetal
   weight. Clinician should always be
   prepared to deal with a potential
   shoulder dystocia.
  Intrapartum asphyxia: Careful
   monitoring should be instituted when this
   is suspected.


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