A 26-year-old primigravid woman at 25 weeks gestation comes to the hospital due to preterm labor. For the last 6 hours, the patient has had intermittent, painful contractions but no vaginal bleeding or leakage of fluid. Temperature is 36.7 C (98.1 F), blood pressure is 110/66 mm Hg, and pulse is 90/min. BMI is 23 kg/m2. Cardiopulmonary examination is normal. The uterus is nontender. On sterile speculum examination, the cervix is visibly 2 cm dilated and the amniotic membranes are intact. Fetal heart rate monitoring shows a baseline of 150/min, no decelerations, no accelerations, and minimal variability. Contractions occur every 2-3 minutes on tocodynamometry. The patient is administered indomethacin for tocolysis. This intervention increases this patient's risk for which of the following obstetric complications?
This patient with frequent contractions causing cervical dilation at 25 weeks gestation is in preterm labor. Management of preterm labor depends on gestational age, with increased intervention required at earlier gestations due to the risks of neonatal prematurity. Patients at <32 weeks gestation in preterm labor require:
Although the benefits typically outweigh the risks, indomethacin tocolysis can have adverse fetal effects. Indomethacin, a nonspecific cyclooxygenase inhibitor, decreases prostaglandin production and leads to fetal vasoconstriction (eg, premature closure of the ductus arteriosus). The subsequent decreased renal perfusion and fetal oliguria can result in oligohydramnios (ie, amniotic fluid index ≤5 cm), particularly with prolonged administration; therefore, patients typically receive indomethacin for ≤48 hours. The oligohydramnios associated with indomethacin use is typically transient and resolves without intervention once the medication is discontinued.
(Choice A) Although betamethasone, a corticosteroid, may transiently increase maternal glucose levels, it does not increase the risk of gestational diabetes mellitus (GDM). Indomethacin does not increase the risk of GDM.
(Choice B) Although this patient has a dilated cervix, the amniotic membranes are intact, making the risk of intraamniotic infection (IAI) exceedingly low. In contrast, the risk is increased in patients with preterm prelabor rupture of membranes (ie, amniotic membranes not intact). Indomethacin does not increase the risk. Tocolysis is typically avoided in patients with symptomatic IAI (eg, fever, tachycardia).
(Choice D) Risk factors for preeclampsia include chronic hypertension, diabetes mellitus, and multiple gestation but not indomethacin use.
(Choice E) The most common cause of pulmonary edema in pregnancy is preeclampsia due to increased vascular permeability and hemodynamic dysfunction. Although indomethacin, like other nonsteroidal anti-inflammatory drugs, can lead to some degree of fluid retention, its use is not associated with pulmonary edema.
Educational objective:
Indomethacin tocolysis (ie, to inhibit contractions) is indicated in patients with preterm labor at <32 weeks gestation. Indomethacin tocolysis can cause oligohydramnios and premature closure of the fetal ductus arteriosus, although its benefits typically outweigh these risks.