Obstetric Complications Flashcards
Preterm birth is defined as a birth that occurs after 20 weeks but before 37 completed weeks of gestation. How is preterm labor (PTL) diagnosed?
Uterine contractions accompanied with cervical change or cervical dilation of 2 cm and/or 80% effaced
Etiologies of preterm labor
Spontaneous Multiple gestations Preterm premature rupture of membranes Pregnancy-associated HTN Cervical incompetence or uterine anomalies Antepartum hemorrhage Intrauterine growth restriction (IUGR)
Risk factors for PTL
SES factors: African American 2x more likely than Caucasian; Decreased access to prenatal care; High stress levels, poor nutrition
Medical/obstetric factors: previous hx of PTL, hx of 2nd trimester abortion, repeated 1st trimester abortions, bleeding in first trimester, UTI/genital tract infection, multiple gestation, uterine anomalies, polyhydramnios, incompetent cervix
4 main pathways addressed in prevention of PTL
Infection (cervical)
Placental-vascular
Psychosocial stress/work strain
Uterine stretch
How is PTL prevented via infection-cervical pathway?
Treat bacterial infections associated with preterm labor: Bacterial vaginosis, Group B strep, Gonorrhea, Chlamydia
[there is a link between infection and progressive changes in cervical length, and cervical length is a predictor for preterm birth risk]
The relative risk of PTL increases as cervical length decreases. What are screening methods to determine cervical length?
Routine screening with US
Fetal fibronectin (FFN) — released in response to disruption of membranes as with uterine activity, cervical shortening, or infection [negative predictive value is good, positive predictive value is low]
How is the placental vascular pathway involved in risk for PTL?
Alteration of placental vasculature at the level of placental-decidual-myometrial interface may result in poor fetal growth, which is a risk factor for PTL as well as growth restriction and preeclampsia
How is the stress-strain pathway involved in risk for PTL?
Mental and physical stress induce release of cortisol and catecholamines, which are associated with uterine contractions
Symptoms of preterm labor
Menstrual like cramping, low/dull backache, pelvic pressure, increase in discharge/bloody discharge, and uterine contractions
Management of PTL
Initial assessment with cervical exam to assess dilation, effacement, and fetal presenting part
Evaluate for underlying correctable problems such as infection (culture for group B strep)
External monitoring for uterine activity and fetal HR
Reevaluate cervix hourly and administer oral or IV hydration
CBC, urinalysis, and urine culture
Obtain US (fetal presentation, growth, amniotic fluid volume, r/o congenital anomalies)
Consider tocolytics
Indications/criteria to begin tocolytics in PTL
2 cm dilation and/or 80% effaced, or made cervical change; and gestational age <34 weeks and no contraindications
3 tocolytics used in PTL
Magnesium sulfate
Nifedipine
Prostaglandin Synthetase Inhibitors (Indomethacin)
In the US, the tocolytic agent of choice in PTL is magnesium sulfate. Therapeutic serum levels range from 5.5 to 7.0 mg/dL. Typically a 6g loading dose is given IV, then 3g/hr for continuous maintenance. Therapy is continued until both doses of _____ are administered, and may be titrated down if uterine activity stops. Some studies have shown magnesium sulfate may play a role in _______ and possibly protects against cerebral palsy. It is currently indicated for use in less than 32 weeks gestation PTL.
Steroids
Neuroprotection
Side effects of magnesium sulfate
Maternal: feeling of warmth and flushing, N/V, respiratory depression (with high serum levels), cardiac conduction defects and arrest (high serum levels)
Neonate: loss of muscle tone, drowsiness, lower apgar scores
Oral agent effective in suppressing PTL with minimal maternal and fetal side effects including HA, cutaneous flushing, hypotension, and tachycardia
Nifedipine
Tocolytic used on short term basis, mostly for extreme prematurity
Prostaglanin synthetase inhibitors
Complications of prostaglandin synthetase inhibitor (indomethacin) when used as PTL tocolytic
Oligohydramnios
Premature closure of fetal ductus arteriosus —> pulmonary HTN and heart failure
Increased risk of necrotizing enterocolitis and intracranial hemorrhage
When is ibuprofen indicated for tocolysis?
Not used for primary tx of preterm labor, but used to decrease uterine activity not associated with labor — to the point that hyperactive contractions are interfering with pt’s life
Drug given to accelerate premature fetal lung maturation
Glucocorticoids (betamethasone, dexamethasone)
Given between 22-34 weeks gestation
Effects last 7 days
A single course of ______ is recommended for pregnant women between 34-36 weeks of gestation at risk of preterm birth w/i 7 days, and who have not received a previous course of antenatal corticosteroids
Betamethasone
Lower limit of preterm viability in weeks and grams
23-24 weeks or 500 grams
PTL intervention used in women with previous hx of spontaneous PTL/PPROM, given weekly from 16-36 wks
IM progesterone (Makena)
PTL intervention used in women with a shortened cervix (<2.5cm)
Vaginal progesterone (prometrium or crinone)
Pessary (arabin pessary)
The etiology of PROM is unknown. What are some risk factors?
Vaginal/cervical infections
Abnormal membranes
Incompetent cervix
Nutritional deficiencies
Why shouldn’t you check the cervix of a presumed ruptured preterm patient?
Increases the risk of infection, especially with prolonged latency before delivery
3 tests used for confirmation of PROM
Pooling
Nitrazine paper
Ferning
[may also use US to evaluate amniotic fluid volume]
Note: false positives on nitrazine may be caused by urine, semen, cervical mucous, blood, or vaginitis; false negatives may occur with remote PROM with no remaining fluid or with minimal leakage
In the management of preterm premature rupture of membranes (PPROM), the risk of preterm delivery must be balanced with the risk of infection, as an intact amnionic sac provides a barrier to ________, an infection of the membranes and fetal infection associated with about 30% of preterm deliveries
Chorioamnionitis
Management of PPROM depends on gestational age at time of rupture, amniotic fluid index, fetal status, and maternal status. The goal is to continue the pregnancy until lung profile is mature. Most will deliver at ____ weeks regardless of fetal lung maturity (earlier with dx of chorioamnionitis)
34
Signs/symptoms of chorioamnionitis
Maternal temp >100.4
Fetal or maternal tachycardia
Tender uterus
Foul smelling amniotic fluid/purulent discharge
ACOG recommendations for abx and tocolytic usage in PPROM
For abx, ACOG recommends 48 hr course of ampicillin and erythromycin/azithromycin followed by 5 days of amoxil and erythromycin
For tocolytics, ACOG does not recommend for or against, they may be used if there is no evidence for chorioamnionitis and primary purpose is to have time to get steroid tx to baby
Define intrauterine growth restriction (IUGR) vs. small for gestational age (SGA)
IUGR: birth weight of newborn is below 10% for given gestational age
SGA: birth weight at lower extreme of normal birth weight distribution
Growth restricted fetuses are at risk for what complications?
Meconium aspiration Asphyxia Polycythemia Hypoglycemia Mental retardation Adult onset of conditions such as HTN, diabetes, and atherosclerosis
Maternal causes of IUGR
Poor nutritional intake/maternal low body weight
Cigarette smoking, drug abuse, alcoholism
Cyanotic heart disease
Pulmonary insufficiency (i.e., poorly controlled asthma)
Antiphospholipid syndrome
Hereditary thrombophilias
Collagen vascular dz
Placental causes of IUGR involve insufficient substrate transfer through placenta as well as defective trophoblastic invasion. What conditions may result in placental insufficiency?
HTN (preexisting or gestational)
Renal disease
Placental or cord abnormalities such as velamentous cord insertion
Diabetes
Fetal causes of IUGR
Intrauterine infections — listeriosis, TORCH
Congenital anomalies/genetic disorders
Multiple gestations
Chromosomal abnormalities
How is IUGR diagnosed?
Primary screening test is PE of fundal height. If fundal height lags more than 3 cm behind the gestational age, then order an ultrasound
US is used routinely for high risk conditions that predispose to IUGR such as HTN, renal dz, diabetes, drug abuse, antiphospholipid syndrome, lupus
Pre-pregnancy management of IUGR involves optimization of disease processes (i.e., blood sugar control, HTN control)
Antepartum management of IUGR involves decreasing any modifiable risk factors (improve nutrition, stop smoking, etc.) with the goal of delivering before fetal compromise but after fetal lung maturity. What tests are monitored in antepartum period?
Non-stress test 2x/week
Biophysical profile
Doppler studies of umbilical a. (Umbilical flow velocity waveform of normally growing fetuses is characterized by high-velocity diastolic flow, whereas with intrauterine growth restriction there is diminution of umbilical a. diastolic flow)
T/F: Babies with IUGR require C-section delivery
False — IUGR is not an indication for C-section, but fetuses have less reserve and may have intolerance of labor
Require continuous fetal monitoring and other factors may necessitate C-section
What tests should be monitored after birth of baby with IUGR?
Monitor neonatal blood glucose, as these babies have less hepatic glycogen stores
Monitor respiratory status as RDS is more common
