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Key Features

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  • • Labor beginning before 37th week of pregnancy

    • Preterm, regular, rhythmic contractions 5 minutes apart

    • Cervical dilatation, effacement, or both occur

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Clinical Findings

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  • • Risk factors

    • – History of preterm labor

      – Premature rupture of membranes

      – Multiple gestation

      – African American race

      – Intrauterine infection

      – Müllerian anomalies

      – Smoking

      – Substance abuse

      – Bacterial vaginosis

      – Certain socioeconomic conditions, such as limited access to prenatal care

      – Shortened cervical length

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Diagnosis

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  • • 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

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Treatment

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  • • Low rates of preterm delivery are associated with successful education of patients in identifying regular, frequent contractions

    • Magnesium sulfate

    • – 4–6 g intravenous bolus followed by infusion of 2–3 g/h

    – 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

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Content adapted from CURRENT Medical Diagnosis & Treatment 2014.

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Key Features

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  • • 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

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Clinical Findings

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  • • Bloating, abdominal cramps, and flatulence with mild to moderate amounts of lactose malabsorption

    • Diarrhea

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Diagnosis

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  • • 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 2 weeks ...

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