• Labor beginning before 37th week of pregnancy
• Preterm, regular, rhythmic contractions 5 minutes apart
• Cervical dilatation, effacement, or both occur
• Risk factors
– History of preterm labor
– Premature rupture of membranes
– Multiple gestation
– African American race
– Intrauterine infection
– Müllerian anomalies
– Substance abuse
– Bacterial vaginosis
– Certain socioeconomic conditions, such as limited access to prenatal care
– Shortened cervical length
• Fetal fibronectin measurement in cervicovaginal specimens can differentiate true from false labor
• A level < 50 ng/mL has a negative predictive value of 93–97% for delivery in 7–14 days among women with a history of preterm delivery currently having contractions
• However, fetal fibronectin is not recommended as a screening test in asymptomatic women because of its low sensitivity
• Low rates of preterm delivery are associated with successful education of patients in identifying regular, frequent contractions
• Magnesium sulfate
– Magnesium levels may be determined every 4–6 hours to monitor for evidence of toxicity
• Terbutaline (2.5 mcg/min intravenously titrated to a maximum 20 mcg/min or 2.5–5.0 mg orally every 4–6 hours)
• Oral terbutaline
– No longer recommended because of the lack of proven efficacy and concerns about maternal safety
– Side effects include tachycardia, pulmonary edema, arrhythmias, metabolic derangements (such as hyperglycemia and hypokalemia), and even death
– If it is used to treat preterm labor, the FDA recommends this medication be administered exclusively in a hospital setting and be discontinued within 48–72 hours
• Nifedipine, 20 mg orally every 6 hours, and indomethacin, 50 mg orally once then 25 mg orally every 6 hours up to 48 hours, have also been used with limited success
• Weekly injections of 17α-hydroxyprogesterone capote from 16 to 36 weeks of gestation can reduce the rate of recurrent preterm birth in women with singleton pregnancies and history of preterm delivery
• Nifedipine should not be given in conjunction with magnesium sulfate
• Women with shortened cervices (< 25 mm before 24 weeks gestation) may benefit from placement of a cervical cerclage
Content adapted from CURRENT Medical Diagnosis & Treatment 2014.
• Partial to complete lactose intolerance affects ~50 million people in the United States
• Occurs in 90% of Asian Americans, 70% of African Americans, 95% of Native Americans, 50% of Mexican Americans, 60% of Jewish Americans, < 25% of Caucasian adults
• Also occurs secondary to Crohn disease, sprue, viral gastroenteritis, giardiasis, short bowel syndrome, malnutrition
• Diarrheal stool specimens have an increased osmotic gap and pH < 6.0
• Hydrogen breath test: After ingestion of 50 g lactose, a rise in breath hydrogen of > 20 ppm within 90 minutes is a positive test
• Empiric trial of a lactose-free diet for ...
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