Preterm Labor, PROM and Postterm Pregnancy - Hibbs Flashcards
(37 cards)
What are the causes of preterm labor?
1) activation of maternal/fetal HPA axis
2) inflammation
3) decidual hemorrhage
4) pathological uterine distension
What are risk factors for preterm labor?
1) multiple gestations
2) prior history
3) cervical insufficiency
4) uterine distortion
5) placental abnormalities
6) maternal smoking (PROM)
7) bacterial vaginosis
What can be used as a prediction of preterm labor?
1) fFN - fetal fibronectin
a) glycoprotein produced by the amnion
2) cervical length
What are the limitations with using fetal fibronectin as a prediction for preterm labor?
1) poor positive predictive value (PPV)
2) great negative predictive value (NPV)
3) used bw 22-34 weeks
4) can’t be done if the patient has had a manual exam, had sex in the last 24 hours etc
What about the cervical length is useful in assessing risk for preterm labor?
1) less than 2.5 cm is shortened (avg @ 24 weeks is 3.5 cm)
2) dynamic changes
What is not proven effective in preventing preterm labor?
1) prophylactic therapy with tocolytic drugs
2) bed rest
3) hydration
When do you used 17-alpha-hydroxyprogesterone caproate to prevent preterm labor?
1) start @ 16-20 weeks until 36 weeks
2) used in patients with documented preterm deliveries
Why are steroids given if preterm labor is threatened and which steroid is given?
1) Betamethasone
2) maturation of lungs (and other complications)
What is the baby most at risk for after a preterm birth?
1) RESPIRATORY DISTRESS
2) intraventricular hemorrhage
3) necrotizing enterocolitis
What is tocolysis?
The inhibition of uterine contractions
What is the diagnosis of preterm labor?
1) uterine contraction
2) cervical change
3) before 37 weeks (up to 36 w 2 d)
How does Magnesium Sulfate cause tocolysis and what are side effects?
1) competes with calcium for entry into the cells
2) side effects:
a) flushing
b) headaches
c) respiratory depression at high levels
How do prostaglandin synthetase inhibitors (indomethacin) cause tocolysis and what are the side effects?
1) decreases PG production by blocking conversion of free AA to PG
2) side effects:
a) premature constriction of ductus
arteriosus (esp after 34 weeks)
b) oligohydramnios
How do CCB (Nifedipine) cause tocolysis and what are the side effects?
1) prevents entry of calcium into muscle
2) side effects
a) hypotension and headache
b) decrease in uteroplacental blood flow
c) DO NOT use with Mg Sulfate
How do beta-adrenergic agents (terbutaline) cause tocolysis and what are the side effects?
1) increases cAMP concentration in cells therefore decreasing free Ca2++
2) side effects
a) hypotension
b) tachycardia
c) anxiety
d) increased pulmonary edema
What is the definition of a postterm pregnancy?
pregnancy that persists beyond 42 weeks
What is the most common cause of postterm pregnancy?
inaccurate dating
How is a pregnancy dated?
1) gestational age always dated from first day of last menstrual period (LNMP)
2) assumes a 28 day cycle
3) first trimester ultrasound very helpful
How accurate is pregnancy dating with ultrasound?
1) Ultrasound at 6-12 weeks accurate within 3-5 days
2) ultrasound at 12-20 weeks accurate within 10 days
What are the babies risks with a postterm pregnancy?
1) macrosomia
2) shoulder dystocia
3) meconium aspiration syndrome
4) oligohydraminos
What is the definition of macrosomia and what is a common cause?
1) fetal weight greater than 4,000-4,5000 g
a) 8lbs 13 oz to 10lbs
2) diabetes and genetic factors
Does induction at 39 weeks or elective C section reduce to birth trauma from macrosomia?
NO - except in diabetics
What is shoulder dystocia?
impaction of anterior shoulder against the pubis symphysis during delivery
What are the consequences of shoulder dystocia?
1) Erb-Duchenne Palsy (waiters tip)
a) C5 and C6
b) paralysis of infraspinatus, deltoid and
flexor muscles of the forearm
2) Klumpke’s Palsy
a) C8 and T1
b) hand paralysis
