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Forth stage
Obstetric
Lec-8
.د
ا
سماء
1/1/2016
Post Term Pregnancy
The student at the end of this lecture should be able to :
Diagnose post term pregnancy in suspected case.
Determine the consequences of prolongation of pregnancy beyond the expected
date.
Planning delivery in a post term pregnancy depending on fetal well being and bishop
score.
Describe labor in postterm pregnancy
Post term pregnancy (prolonged)
:
is that pregnancy persist beyond 42 weeks (294 days) from the onset of last menstrual
period.
Incidence : 6 – 12 % of all pregnancies .
The risks of post term pregnancy :
Are because of Postmaturity (dysmaturity) syndrome :
Occuring in 20-30% of post term pregnancies related to aging and infarction of the
placenta result into placental insufficiency.
Intrauterine hypoxia may be manifested as meconium staining.
Fetus with postmaturity syndrome may have loss of subcutaneous fat ,long finger
nails ,dry peeling skin and abundant hair.
; may results in abnormal
somia
Other wise the fetus grow in uterus to a point of macro
labor ,shoulder dystocia , birth trauma and increased incidence of caesarean section.
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Etiology :
-Initiation of human labour is by complex maternal and fetal factors.The cause of
postdate pregnancy is unknown in most instances and occurs in healthy pregnancy.
-Rare association is with : Anencephalic pregnancy (hypoplastic Adrenal gland), placental
sulfatase deficiency and extrauterine pregnancy.
Diagnosis:
-The diagnosis is difficult . Accurate dating of gestation is the key for diagnosis and perinatal
management .
-There are factors to be evaluated in dating a pregnancy to determine whether it’s a
misdated or postdated pregnancy .
Factors evaluated in dating pregnancy
1) Accurate date of Lmp.
2) Uterus size by (bimanual Pelvic examination 1st trimester).
3) Uterus size/date discrepancy during antenatal care.
4) Gestational age when the fetal heart tones first heard (doppler ultrasound at 12-14
weeks).
5) Gestational age when the fetal heart first heard (DeLee stethoscope 18-20 weeks).
6) Date of quickening(18-20 w in primi 16-18 in multi)
7) Sonographic parameters (bipariatal diameter between 16-20 weeks)
If there is no concordance between 2 factors this mean the patient have poor date .
Management of post term pregnancy
Antepartum management ; Decision of delivery :
If the patient is <42 weeks with engaged head and favorable cervix then labour should be
induced .
Patient with <42 week and unfavorable cervix:
Twice weekly NST and BPP.
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AFI amniotic fluid index (sum of 4 pocket of liquor in 4 quadrant).
If the result is reassuring then follow up and delivery is indicated :
-until the cervix is favorable .
-result is abnormal (deceleration, AFI is oligohydramnia <=5) .
-Fetal macrosomia .
-43 weeks regardless of other factors because of increased perinatal morbidity and
mortality .
Patient present late in gestation with the label of prolonged pregnancy in question,
expectant approach is acceptable and risk of intervention with delivery of preterm infant
must be considered.
Intrapartum management:
Continuous electronic fetal monitoring during induction of labour.
Membranes should be ruptured early in labour to assess the color of amniotic fluid and to
apply internal electrodes.
If there is fetal distress (fetal blood sampling) then C.S. is indicated.