Preterm labor
Terms
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Fetal fibronection (fFN)
sensitivity & specificity - The presence of fFN is associated with PTL from 24-34 weeks. Screening shows test only has 61% sensitivity and 83% specificity. But, a negative test is 95% predictive for NOT delivering in the next 14 days. It can be used to rule out imminent PTB and avoid unnecessary intervention, as well as provide reassurance to parents. The test should not be used for routine screening of low-risk, asymptomatic women,
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Fetal fibronection (fFN)
rules of test -
Should be used in high-risk groups only with:
1.membranes intact,
2.less than 3 cm dilated
3.no earlier than 24 weeks and no later than end of 34th week. - PTL preventative measures (list given to patients following return to home):
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a.Limit activity; don’t do heavy work; avoid STRESS
b.Arrange for someone to help in the house and c the other children
c.No sexual activity until the next visit (one week); if it’s resumed after that visit, then USE CONDOMS to prevent infection
d.Return for reevaluation in 1 week
e.Follow previous instruction on nutrition s/sx of PTL, stress reduction, cease use of alcohol, cigarettes, drugs… -
Beta agonists (Ritodrine, Terbutaline)
Mechanism of action - B2 receptors in the uterus are the targets of these drugs. Stimulation of the B2 receptors leads to smooth muscle relaxation- (inhibiting contractions). Given IV, SQ, po
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Nifedipine
Mechanism of action - Calcium channel blocker-so it reduces transmembrane calcium influx, thus controlling muscle contractility and pacemaker activity in cardiac, vascular and uterine tissue. Given sublingual
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Indomethacin
Mechanism of action - Prostaglandin inhibitor-given PO or PR. Since it is thought that something triggers prostaglandin formation (be in a reversal in esto/progest ratio or something else) which leads to a further cascade of events to culminate in labor, a prostaglandin inhibitor intervenes to prevent labor
- Corticosteroids (Betamethasone)
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Both glucocorticoids (GC) and thyroid hormones (TH) accelerate fetal lung maturation. Though GC are used clinically, the mechanisms of GC-induced fetal lung maturity remain unclear. Prenatal GC increase fetal TH activity in humans and in animals. Thus, it is possible that increased fetal TH activity after prenatal GC plays a role in accelerating fetal lung maturation.
Prevents respiratory distress syndrome in neonates.
12 mg IM 12 hours apart (x 2) give between 24 and 34 weeks
- Beneficial effect only noted if birth is >24 hours and <7 days after last dose
significantly decreases RDS, NEC, IVH in neonate. - Define cervical insufficiency
- “The inability of the cervix to retain a pregnancy in the absence of uterine contractions or labor.†“…cervical function is viewed more as a continuous variable range of degrees of competency that may be expressed differently in subsequent pregnancies.â€
- cervical insufficiency etiology
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⬢ Congenital mullerian anomalies
⬢ Deficiencies of cervical collagen and elastin
⬢ Utero exposure to DES
⬢ Cervical trauma: cone biopsy, intrapartum cervical laceration, forced cervical dilation (TAB) - cervical insufficiency risk factors
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⬢Cervical trauma: cone biopsy, intrapartum cervical laceration, forced cervical dilation (TAB)
⬢HX of painless cervical dilation up to 4-6cm
⬢Hx of two or more 2nd trimester pregnancy losses
⬢Absence of clinical findings consistent with placental abruption
⬢Hx of losing each pregnancy at an earlier GA - Signs and Symptoms of PTL
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⬢Painful menstrual-like cramps
⬢Dull low back ache
⬢Suprapubic pain/pressure
⬢Sensation of pelvic pressure or heaviness
⬢Change in character/amount of vaginal discharge
⬢Diarrhea
⬢Unpalpated uterine contractions (painful or painless)
⬢PROM - Plan for PTL
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History: S/Sxs of PTL, UTI, Vaginitis, STDs, viral/bacterial infection, PROM
PE: VS, GA, UCs, FHTs, EFW, fetal presentation, CVAT, low back and suprapubic pain
Pelvic Exam: vaginitis, cervicitis, STDs, ROM, bloody show, meconium
Laboratory Tests: Micro UA, Urine C&S, wet mount, GBS, GC-CT, CBC, fern test, nitrazine test.
CONSULT with MD