A 33-year-old woman, gravida 2 para 1, at 33 weeks gestation comes to the emergency department due to continuous leakage of fluid that began 2 hours ago. The fluid is clear and not malodorous, and she has had no contractions or vaginal bleeding. Fetal movement is normal. This pregnancy was complicated by bacterial vaginosis in the first trimester that resolved after a course of antibiotics. Her previous pregnancy ended in a vaginal delivery at 37 weeks gestation after induction of labor for prelabor rupture of membranes. The patient has no chronic medical conditions and has had no previous surgeries. Temperature is 36.7 C (98.1 F), blood pressure is 110/68 mm Hg, and pulse is 92/min. The uterine fundus is nontender. On speculum examination, there is a clear pool of fluid that is nitrazine positive and crystallizes in a fern-like pattern after drying on a slide. The cervix appears visibly closed; digital cervical examination is deferred. The fetal heart rate tracing demonstrates a normal baseline, moderate variability, accelerations, and no decelerations. Transabdominal ultrasound reveals a fetus in vertex presentation and an amniotic fluid index of 3 cm. Which of the following is the best next step in management of this patient?

Question

A 33-year-old woman, gravida 2 para 1, at 33 weeks gestation comes to the emergency department due to continuous leakage of fluid that began 2 hours ago.  The fluid is clear and not malodorous, and she has had no contractions or vaginal bleeding.  Fetal movement is normal.  This pregnancy was complicated by bacterial vaginosis in the first trimester that resolved after a course of antibiotics.  Her previous pregnancy ended in a vaginal delivery at 37 weeks gestation after induction of labor for prelabor rupture of membranes.  The patient has no chronic medical conditions and has had no previous surgeries.  Temperature is 36.7 C (98.1 F), blood pressure is 110/68 mm Hg, and pulse is 92/min.  The uterine fundus is nontender.  On speculum examination, there is a clear pool of fluid that is nitrazine positive and crystallizes in a fern-like pattern after drying on a slide.  The cervix appears visibly closed; digital cervical examination is deferred.  The fetal heart rate tracing demonstrates a normal baseline, moderate variability, accelerations, and no decelerations.  Transabdominal ultrasound reveals a fetus in vertex presentation and an amniotic fluid index of 3 cm.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c038_a25d_8f63_e334a9234d8d_MD0005_00 Preterm prelabor rupture of membranes (PPROM) is membrane rupture (eg, leakage of fluid) at <37 weeks gestation in the absence of associated contractions. Presenting features include a gush of fluid, a nitrazine-positive pool of vaginal fluid that "ferns" on microscopy, and oligohydramnios. Although the pathophysiology is multifactorial, PPROM is likely due to a subclinical intrauterine infection (eg, no fever, uterine tenderness, or maternal/fetal tachycardia). Risk factors include genital tract infection (eg, bacterial vaginosis), tobacco use, first-trimester bleeding, and a history of PPROM in a prior pregnancy. Management of PPROM depends on gestational age: At ≥34 weeks gestation, delivery is indicated as the risks of prematurity no longer outweigh the risks of pregnancy prolongation (eg, intraamniotic infection, umbilical cord prolapse, abruptio placentae) (Choice D). At <34 weeks gestation with no signs of clinical infection or fetal compromise (eg, late decelerations), as seen in this patient, expectant management is indicated as the risks of prematurity outweigh the risks of pregnancy prolongation. In patients <34 weeks gestation, prophylactic latency antibiotics (eg, ampicillin plus azithromycin) are administered to prevent overt intrauterine infection (ie, intraamniotic infection), which can result from progression of the subclinical infection that caused PPROM or from ascent of vaginal bacteria through the ruptured membranes. Antibiotics increase the latency period (the time between membrane rupture and delivery), thereby increasing gestational age at delivery and improving neonatal outcomes. Ampicillin covers group B Streptococcus, aerobic gram-negative bacilli, and anaerobes; azithromycin covers Ureaplasma. Corticosteroids are also administered to decrease the risk of neonatal respiratory distress syndrome. (Choice A) Intramuscular progesterone is indicated to reduce the recurrence risk of preterm delivery in patients with a previous preterm birth. It is not indicated in the management of PPROM. (Choice B) Magnesium sulfate is indicated in patients at <32 weeks gestation who are at risk for preterm delivery as it decreases the risk of fetal neurologic complications (eg, cerebral palsy). This patient is at ≥32 weeks gestation. (Choice E) Emergent cesarean delivery is indicated in patients with PPROM who require immediate delivery due to impending fetal compromise (eg, umbilical cord prolapse) or evidence of fetal distress (eg, recurrent late fetal decelerations); not seen in this patient. Educational objective: Patients with preterm prelabor rupture of membranes at <34 weeks gestation are managed conservatively with prophylactic latency antibiotics (ampicillin plus azithromycin) to prolong the interval between membrane rupture and delivery, thereby improving neonatal outcomes. References: Clinical course of preterm prelabor rupture of membranes in the era of prophylactic antibiotics. (http://www.ncbi.nlm.nih.gov/pubmed/22999078) Practice bulletin no. 172: premature rupture of membranes. (http://www.ncbi.nlm.nih.gov/pubmed/27661655)

A 33-Year-Old Woman, Gravida 2 Para 1, at 33 Weeks