Evaluation and Management of Ruptured Membranes with Amnionitis at Term
Intraamniotic infection (IAI), or amnionitis, is an inflammatory or infectious disorder involving any combination of amniotic fluid, placenta, fetus, fetal membranes, or decidua. IAI complicates approximately 2-5% of term deliveries and is often a polymicrobial infection ascending from the lower genital tract.
The greatest risk factor for developing IAI is prolonged labor with ruptured membranes. Other associated factors include multiple vaginal exams, meconium, group B streptococcus, and sexually transmitted infections.
Potential maternal consequences of IAI include dysfunctional labor, postpartum hemorrhage due to atony, endometritis, sepsis, and rarely death. Neonates can suffer acute events such as pneumonia, meningitis, sepsis, and death, as well as long-term sequelae of bronchopulmonary dysplasia and cerebral palsy.
Establishing concern for IAI is key to initiating appropriate treatment and minimizing adverse outcomes. IAI should be suspected in the setting of maternal fever 38-38.9 C without a clear source AND at least one of the following clinical findings: baseline fetal tachycardia (>160 bpm for at least 10 min), maternal leukocytosis (>15,000 per mm2 in the absence of corticosteroids), and purulent cervical discharge. Additionally, ACOG recommends that IAI be suspected in patients with an isolated fever of 39 C or greater. Fundal tenderness and maternal tachycardia are no longer considered among diagnostic criteria as these features may be altered by labor and analgesia or anesthesia. IAI can be confirmed after delivery by placental pathology findings of chorioamnionitis or growth of bacteria in culture.
Isolated fever between 38C and 39C warrants an evaluation for extra-uterine infections (e.g. pyelonephritis or pneumonia), as well as for non-infectious causes (e.g. epidural anesthesia, dehydration, and prostaglandin induction agents). Once IAI is preliminarily diagnosed, antibiotic therapy is recommended. Antibiotics should be considered in the setting of isolated maternal fever unless another source is identified. Ampicillin and gentamicin are standard treatment for IAI to decrease the risk of neonatal sepsis and maternal morbidity. In patients with a mild penicillin allergy, cefazolin and gentamicin are recommended and in patients with a severe penicillin allergy gentamycin and either clindamycin or vancomycin are recommended. Alternative regimens include ampicillin-sulbactam or piperacillin-tazobactam. Appropriate hydration and antipyretics should also be given. Amnionitis alone is not an indication for immediate cesarean, and labor should be actively managed following standard guidelines. The decision to proceed with cesarean delivery should be based on maternal or fetal indications.
Regardless of whether or not antibiotics are initiated, it is essential to notify the pediatric care team of the maternal fever, as this greatly impacts the evaluation and treatment of the neonate, who may warrant additional laboratory analysis, antimicrobial treatment, and hospitalization in the intensive care unit.
Postpartum management should be individualized based on route of delivery. Continuation of antibiotics is not required after vaginal delivery, as risk of endometritis is low. Patient’s undergoing cesarean should receive at least one additional dose of the antimicrobial therapy they received intra-partum, with the addition of clindamycin or metronidazole to cover intraabdominal anaerobes. Duration of therapy and antimicrobial regimen should be based upon clinical risk factors including persistent maternal fever and bacteremia.
Committee on Obstetric Practice. Committee Opinion No. 712: Intrapartum Management of Intraamniotic Infection. Obstet Gynecol. 2017 Aug;130(2):e95-e101. doi: 10.1097/AOG.0000000000002236.
Higgins RD, Saade G, Polin RA, et al. Evaluation and Management of Women and Newborns with a Maternal Diagnosis of Chorioamnionitis: Summary of a Workshop. Obstet Gynecol. 2016 Mar;127(3):426-36. doi: 10.1097/AOG.0000000000001246.
Initial approval March 2018; Revised November 2019; Revised July 2021. Minor Revision March 2023.
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