A 41-year-old woman, gravida 2 para 1, at 35 weeks gestation comes to the emergency department with contractions. The patient began to have contractions 5 hours ago after spending the day at the beach. She is now having 3-5 contractions every hour that sometimes are relatively painful. The patient has had no vaginal bleeding or leakage of fluid. She has iron deficiency anemia, for which she takes a prenatal vitamin and iron supplementation. The patient had a positive rectovaginal culture for group B Streptococcus at her prenatal visit earlier this week. She had a vaginal delivery at term with her prior pregnancy. Blood pressure is 110/80 mm Hg and pulse is 92/min. A contraction is palpated on abdominal examination, but the uterus is nontender between contractions. The cervix is closed on digital cervical examination. A nonstress test has a baseline of 120/min, moderate variability, and multiple accelerations. Tocodynamometry reveals irregular uterine contractions. Which of the following is the best next step in management of this patient?
Contractions can occur due to benign conditions (eg, mild dehydration) or serious etiologies (eg, preterm prelabor rupture of membranes, abruptio placentae); therefore, all patients with contractions (regardless of gestational age) require evaluation.
Contraction onset, frequency, duration, and pain level can help distinguish between labor and false labor (ie, Braxton-Hicks contractions). Patients in labor have regular, painful contractions (eg, palpable) that cause cervical changes (eg, dilation, effacement) and may have associated vaginal bleeding or leakage of fluid. In contrast, those in false labor have mild, irregular contractions that cause no cervical change. Fetal monitoring is typically via nonstress test, which evaluates fetal acid-base status and risk for fetal hypoxemia. Those with a reactive nonstress test (eg, moderate variability, accelerations) require no additional evaluation.
Although this preterm patient has risk factors for preterm labor (eg, advanced maternal age, iron deficiency anemia), she has irregular contractions, a closed cervix, and a reactive nonstress test. Therefore, she is in false labor and can be discharged home with labor precautions as her contractions will likely resolve without intervention.
(Choices A and E) Patients in preterm labor have regular, painful contractions causing cervical change; management is based on gestational age. In patients at <32 weeks gestation, magnesium sulfate is administered for fetal neuroprotection (eg, cerebral palsy prevention), and indomethacin is started for tocolysis. Indomethacin is contraindicated after 32 weeks gestation due to the risk of premature fetal ductus arteriosus closure. In patients at <37 weeks gestation, betamethasone may be administered to prevent neonatal respiratory distress syndrome. This patient is not in preterm labor.
(Choice B) Maternal group B Streptococcus (GBS) screening is performed in the third trimester to prevent fetal infection (ie, vertical transmission) during passage through the vaginal canal. Treatment of GBS prior to delivery offers no benefit as GBS rapidly recolonizes the maternal perineum, requiring retreatment during labor.
(Choice C) Ultrasound cervical length measurements are performed in the second trimester for patients with a prior spontaneous preterm birth. They are not performed in the third trimester as the cervix undergoes physiologic dilation and effacement closer to term, and therefore measurements do not predict preterm delivery.
Educational objective:
Labor is painful, regular contractions that cause cervical change. False labor is mild, irregular contractions that cause no cervical change and ultimately resolve without intervention. Patients in false labor can be discharged home with labor precautions.