Term
| what can both premature rupture of membrane (PROM) and preterm labor (PTL) lead to? |
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Definition
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Term
| what is preterm birth? what is the risk for this in the general population? |
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Definition
| delivery before 37 wks gestation - which may be the result of preterm labor. risk for PTB in the general population: ~ 4% |
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Term
| when does preterm labor occur? how does it present? |
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Definition
| after 20 wks and before 37. this will present w/regular, painful uterine contractions of 2+ contractions per 10 min for at least 30 min, demonstrating *cervical changes in effacement* and/or *dilatation w/intact membranes* (key is that preterm labor has cervical involvement). labor before 20 wks = spontaneous abortion. |
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Term
| what is cervical effacement? |
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Definition
| shortening of the cervix (which is normally ~ 4 cm), typically from the inside out - as the baby is on the vertex, it creates funneling. also - as the cervix goes through effacement, it also dilates. |
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Term
| what is the difference between preterm labor and preterm contractions? |
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Definition
| preterm labor has cervical involvement |
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Term
| what is premature rupture of the membranes (PROM)? |
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Definition
| rupture of the membranes before the onset of labor |
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Term
| what is preterm premature rupture of the membranes (PPROM)? |
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Definition
| rupture of the membrane before 37 wks of gestation |
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Term
| what is most of perinatal mortality (60-80%) related to? |
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Definition
| preterm birth, with ~15% of those having low birth weight (relative to gestational week) |
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Term
| what demographics are at risk for preterm labor? |
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Definition
| blacks > native americans > hispanics > whites |
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Term
| what are the top 2 causes of infant mortality? |
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Definition
| birth defects, followed by preterm birth/low birth weight |
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Term
| what are important risk factors for preterm birth? |
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Definition
| prior preterm birth, incompetent cervix, cervical dilatation, signs/symptoms, fetal fibronectin (FF), bacterial vaginosis (BV), and periodontal disease |
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Term
| what characterizes prior preterm birth as a risk factor for future preterm birth? |
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Definition
| hx of 1 PTB = 4x greater risk for another, hx of 2 PTB = 6x greater risk for another. when obtaining this hx, it is important to know how soon before 37 wks the prior PTB occurred to determine future risk. |
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Term
| what characterizes cervical factors as a risk factor for future preterm birth? |
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Definition
| 1) cervical incompetence/insufficiency - which is only discovered retrospectively. look for hx of painless cervical dilatation and spontaneous mid-trimester birth in the absence of spontaneous membrane rupture, bleeding or infection. 2) cervical dilatation: asymptomatic cervical dilatation after mid-pregnancy - mean cervical length at 24 wks is 2.5 cm. 3) cervical length: this is assessed w/transvaginal US, and pts w/cervical length < 25 mm between 16-15 wks have an increased risk of PTB (this risk is even greater for a pt w/a hx of PTB < 32 wks). |
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Term
| what characterizes signs + symptoms as a risk factor for future preterm birth? |
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Definition
| symptoms such as pelvic pressure, menstrual-like cramps, watery vaginal discharge and pain in low back have been associated with preterm labor |
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Term
| what characterizes fetal fibronectin as a risk factor for future preterm birth? |
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Definition
| fetal fibronectin is a glycoprotein formed in the endothelial cells and by fetal amnion, and is thought to maintain the placental adhesion to the decidua. its presence in the cervicovaginal secretion prior to ROM is a possible marker for impending PTL. *a positive FF is not very predictive for PTL, but a negative FF is very reassuring that PTL is not going to happen.* |
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Term
| what characterizes bacterial vaginosis as a risk factor for future preterm birth? |
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Definition
| this can predispose for PTL and thus needs to be treated |
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Term
| what characterizes periodontal disease as a risk factor for future preterm birth? |
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Definition
| oral bacteria, fusobacterium nucleatum and capnocytophaga spp have an association w/upper genital infections and periodontal disease increase PTB risk 7x. |
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Term
| how is gestational age determined? how does gestational age inform tx for pts w/PTL? |
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Definition
| LMP/US. gestational age is very important to determine how to correctly tx PTL, b/c survival at 24 wk gestation is 20% - but at 25 wks it is 50%. |
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Term
| what is the quick and dirty method of determining gestational age? |
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Definition
| if the fundus of the uterus is at the umbilicus = 20 wks gestation (w/fingerbreadths going either way for +/- wks). |
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Term
| why does gestational age have more of an influence on neonatal morbidity/mortality than birthweight? |
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Definition
| low birth weight could be due to IUGR |
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Term
| how does the mortality rate of neonates born at < 32 wks compare to term neonates? |
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Definition
| neonates born < 32 wks have a mortality rate 70x higher than term neonates |
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Term
| what characterizes morbidity associated with PTB neonates? |
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Definition
| higher incidence of chronic neurodevelopment/sensory disabilities, grade 3-4 intraventricular hemorrhage, periventricular leukomalacia, cerebral palsy, respiratory distress syndrome, sepsis, and necrotizing enterocolitis |
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Term
| what is the current approach for when to aggressively tx a possibly PTB? |
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Definition
| infants delivered before 24 wks have a very poor prognosis (20% survive, 50% of which will have disabilities in mental and psychomotor development, neuromotor function, or sensory and communication function). therefore, aggressive tx is usually saved for possible PTB mothers past 24 wks. |
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Term
| what is the point at which a PTB can be allowed to occur w/a good chance of a positive outcome? |
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Definition
| 34 wks (survival rate is within 1% of neonates born at 37 wks) |
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Term
| how is PTL/PTB managed if there is a previous hx of PTL? |
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Definition
| IM administration of progesterone 1x/wk if hx of PTL (keeps uterus quiescent, blocks initiation of labor) until 34 wks. |
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Term
| how is PTL managed if no hx/risk factors? |
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Definition
| first, make the dx, which is: contractions of 4 in 20 min OR 8 in 60 min + progressive cervical change (cervical dilatation > 1 cm and effacement of 80%+). once dxed, avoid delivery prior to 34 wks if possible. |
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Term
| what is therapy used to delay PTL? |
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Definition
| glucocorticoid injection IM (accelerates lung maturity and stabilizes brain parenchyma in the neonate), tocolytics (beta-mimetics, Ca++ channel blockers, Mg sulfate (if aggressive PTL), indomethacin), and antimicrobial therapy (esp if labor is progressing, prevents group B strep) |
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Term
| what is the goal of PTL/PTB management? |
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Definition
| avoid delivery prior to 34 weeks if possible |
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