Review Question - QID 216562

This patient at 37 weeks of gestation who presents with tachycardia, uterine tenderness, leakage of purulent amniotic fluid (confirmed by positive nitrazine test), leukocytosis, fever, and an FHR tracing showing fetal tachycardia with normal reactivity most likely has premature rupture of membranes (PROM) complicated by intraamniotic infection (chorioamnionitis). The most appropriate next step in management is the administration of ampicillin and gentamicin, followed by delivery.

Intraamniotic infections (IAI) encompass infections of the amniotic fluid, membrane, placenta, and umbilical cord. IAIs are generally polymicrobial due to the migration of gram-positive, gram-negative, and anaerobic cervicovaginal flora into these structures. IAI should be suspected in patients with fever, fetal tachycardia, maternal leukocytosis, or purulent amniotic fluid. The diagnosis can be confirmed by examination of the amniotic fluid for evidence of infection or histopathologic evidence of infection or inflammation. Empiric treatment of IAI is with coverage of cervicovaginal flora with a regimen typically consisting of ampicillin and gentamicin. Prompt induction of labor after the administration of antibiotics is also recommended to definitively remove infected tissues. Antipyretics and continuous fetal monitoring should be used during delivery. Postpartum treatment of IAIs is not well established, but it may be reasonable to administer a short course of postpartum antibiotics.

The American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal-Fetal Medicine (SMFM) outline guidelines for the diagnosis and management of intraamniotic infections. The authors note that IAI should be suspected in cases of a maternal temperature greater than 39.0°C or 38.0-38.9°C with an additional risk factor. The authors recommend the administration of intrapartum antibiotics in all cases of suspected or diagnosed IAI.

Figure A/Illustration A is a fetal tracing showing fetal heart rate and maternal uterine contractions. Variability between 6-25 beats per minute around the baseline rate of 180 is shown in the blue box, indicating fetal tachycardia with moderate variability.

Incorrect Answers:
Answer 1: Administering amoxicillin is incorrect as this would provide insufficient anaerobic coverage for IAIs. Amoxicillin may be a reasonable choice for acute cystitis in pregnancy which presents with hematuria, dysuria, and increased urinary frequency. However, cystitis is less likely given this patient’s presentation with purulent amniotic fluid.

Answer 3: Artificial rupture of membranes (AROM) is unnecessary in this patient who most likely has PROM. AROM can be used for better monitoring of labor, to assess for the presence of meconium, and to possibly induce labor or augment uterine activity. In addition, AROM is associated with a higher risk of IAI.

Answer 4: Induction of labor with oxytocin is incorrect as the patient with suspected IAI should first receive antibiotics. However, some experts recommend that prompt induction of labor should occur after antibiotic administration as IAI can only be cured by the removal of the infected products of conception.

Answer 5: Performing an emergent cesarean section is incorrect as antibiotics should be given first in IAI. IAI alone is not an indication for urgent delivery and is almost never an indication for cesarean section. The choice of the route of delivery in the majority of cases of IAI should be based on standard obstetric indications.

Bullet Summary:
Intraamniotic infection should be suspected in pregnant patients with fever, maternal leukocytosis, and purulent vaginal fluid discharge and should be promptly treated with antibiotics such as ampicillin and gentamicin.