Introduction
Intraamniotic infection, frequently referred to as chorioamnionitis, is a condition characterized by infection and subsequent inflammation affecting various combinations of the amniotic fluid, placenta, fetus, fetal membranes, or decidua. This common obstetric complication, particularly among term patients in labor, carries significant risks of acute neonatal morbidity, including neonatal pneumonia, meningitis, sepsis, and in severe cases, death. Maternal health is also at risk, with potential complications ranging from dysfunctional labor and postpartum hemorrhage to endometritis, peritonitis, sepsis, and even adult respiratory distress syndrome. Recognizing intrapartum intraamniotic infection and promptly implementing treatment guidelines are critical steps in mitigating risks for both mothers and their newborns. Timely management and effective communication with neonatal care providers are essential to ensure appropriate evaluation and empiric antibiotic treatment when indicated. Importantly, intraamniotic infection itself is rarely, if ever, a reason for cesarean delivery. This article delves into the ACOG (American College of Obstetricians and Gynecologists) recommendations for diagnosing and managing intraamniotic infection, providing a comprehensive overview for healthcare professionals.
ACOG Recommendations for Intraamniotic Infection
The American College of Obstetricians and Gynecologists (ACOG) has established clear recommendations to guide the diagnosis and management of intraamniotic infection, also known as chorioamnionitis:
- Definition: Intraamniotic infection, or chorioamnionitis, is defined as an infection leading to inflammation of the amniotic fluid, placenta, fetus, fetal membranes, or decidua, in any combination.
- Neonatal Risks: Intraamniotic infection is associated with severe acute neonatal morbidities, including neonatal pneumonia, meningitis, sepsis, and death. It can also lead to long-term infant complications like bronchopulmonary dysplasia and cerebral palsy.
- Suspected Intraamniotic Infection Diagnosis: A diagnosis of suspected intraamniotic infection is made when a mother’s temperature reaches 39.0°C (102.2°F) or higher. Alternatively, if the maternal temperature is between 38.0°C and 38.9°C (100.4°F and 102.0°F), and at least one additional clinical risk factor is present, suspicion of intraamniotic infection is warranted.
- Isolated Maternal Fever Definition: Isolated maternal fever is defined as any maternal temperature between 38.0°C and 38.9°C (100.4°F and 102.0°F) without any other identified clinical risk factors. This can occur with or without persistent temperature elevation.
- Intrapartum Antibiotic Administration: Antibiotic administration during labor is recommended whenever intraamniotic infection is suspected or confirmed. In cases of isolated maternal fever, antibiotics should also be considered unless an alternative source of fever, other than intraamniotic infection, is identified and clearly documented.
- Cesarean Delivery: Intraamniotic infection alone is rarely, if ever, an indication for cesarean delivery. The decision for cesarean delivery should be based on standard obstetric indications.
- Communication with Neonatal Care Team: When intraamniotic infection is diagnosed, or when other risk factors for early-onset neonatal sepsis are present (such as maternal fever, prolonged rupture of membranes, or preterm birth), effective communication with the neonatal care team is crucial. This ensures optimized neonatal evaluation and management.
Understanding Intraamniotic Infection: Background and Pathophysiology
Intraamniotic infection, synonymous with chorioamnionitis, involves infection and consequent inflammation within the amniotic cavity. Recent discussions have proposed renaming this condition to “intraamniotic infection and inflammation” to more accurately reflect the comprehensive nature of the disease process. However, for clarity and consistency, the term intraamniotic infection is retained in many clinical guidelines, particularly when focusing on the management of suspected or confirmed infection.
The infection is often polymicrobial, typically involving a mix of aerobic and anaerobic bacteria originating from the vaginal flora. The most common route of infection is ascending bacterial invasion from the lower genital tract into the amniotic cavity, which is usually sterile. Less frequently, intraamniotic infection can occur following invasive procedures like amniocentesis or chorionic villus sampling, or through hematogenous spread secondary to maternal systemic infection, such as Listeria monocytogenes. Most clinically significant cases of intraamniotic infection are observed in term patients during labor. Statistical data suggests that approximately 2–5% of term deliveries are complicated by clinically apparent intraamniotic infection. Recent studies also indicate a potential increase in the risk of intraamniotic infection and neonatal infection after 40 completed weeks of gestation.
Table 1: Common Antibiotic Regimens for Intraamniotic Infection Management. This table outlines recommended antibiotic options for obstetrician–gynecologists and other obstetric care providers in treating suspected intraamniotic infection.
Risks and Complications Associated with Chorioamnionitis
Intraamniotic infection poses significant risks for both neonates and mothers.
Neonatal Morbidity: Acute neonatal morbidities directly linked to intraamniotic infection include neonatal pneumonia, meningitis, sepsis, and death. The implementation of intrapartum antibiotic treatment, whether for maternal group B streptococcal colonization or in response to signs of intraamniotic infection during labor, has dramatically reduced group B streptococcal-specific neonatal sepsis cases by nearly tenfold. Decreases in neonatal infections from other non-group B streptococcal pathogens have also been observed. The protective effect of maternal intrapartum antibiotic administration is well-documented in risk models assessing individual infant risk of neonatal sepsis.
Furthermore, intraamniotic infection is associated with long-term infant complications such as bronchopulmonary dysplasia and cerebral palsy, potentially due to the inflammatory processes involved. A meta-analysis of 15 studies highlighted a significantly elevated relative risk of cerebral palsy among primarily premature infants exposed to either histologic chorioamnionitis (OR, 1.8; 95% CI, 1.17–2.89) or clinical chorioamnionitis (OR, 2.4; 95% CI, 1.52–3.84). Despite this increased relative risk, it’s crucial to note that the overall absolute risk of cerebral palsy remains low (approximately 2 per 1,000 live births).
Maternal Morbidity: Maternal morbidity from intraamniotic infection is also substantial. Complications can include dysfunctional labor requiring increased obstetric intervention, postpartum uterine atony leading to hemorrhage, endometritis, peritonitis, sepsis, adult respiratory distress syndrome, and in rare instances, maternal death.
Risk Factors: Several obstetric risk factors for intraamniotic infection at term have been identified. These include low parity, frequent digital examinations, use of internal uterine and fetal monitors, meconium-stained amniotic fluid, and the presence of certain genital tract pathogens such as group B streptococcal infection and sexually transmitted infections. It is important to consider that many of these factors are also associated with prolonged labor and membrane rupture and may not be independently predictive of intraamniotic infection. For example, while increased cervical examinations during labor have been linked to intrapartum fever, this association may not be significant when adjusted for factors like spontaneous labor, Bishop score, and rupture of membranes at admission.
It’s also important to recognize that maternal intraamniotic infection, while reasonably sensitive, lacks specificity in diagnosing neonatal sepsis, particularly in preterm infants. Predictive models for neonatal sepsis risk in term and late-preterm infants have been developed using objective data such as gestational age, duration of membrane rupture, highest maternal intrapartum temperature, group B streptococcal colonization status, and the timing and type of intrapartum antibiotic administration. These models, while not altering maternal intrapartum management, underscore the importance of communication with pediatric care providers and thorough documentation in maternal medical records.
Presumptive Diagnosis of Intraamniotic Infection: Clinical Criteria
While amniotic fluid culture, Gram stain, and biochemical analysis can objectively confirm intraamniotic infection, clinical diagnosis is predominantly used for term women in labor. A consensus panel of maternal and neonatal experts convened by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the Society for Maternal–Fetal Medicine, the American Academy of Pediatrics, and the American College of Obstetricians and Gynecologists, has categorized intraamniotic infection into three distinct groups:
- Isolated Maternal Fever: Defined as either a single oral temperature of 39°C (102.2°F) or greater, or an oral temperature between 38–38.9°C (100.4°F and 102.0°F) that persists upon repeat measurement after 30 minutes.
- Suspected Intraamniotic Infection: Diagnosed based on clinical criteria: maternal intrapartum fever accompanied by one or more of the following—maternal leukocytosis, purulent cervical drainage, or fetal tachycardia.
- Confirmed Intraamniotic Infection: Requires positive amniotic fluid test results (Gram stain, glucose level, or culture) consistent with infection, or placental pathology showing histologic evidence of placental infection or inflammation. In term labor, confirmed intraamniotic infection is often diagnosed postpartum via placental histopathology.
In practical clinical settings, particularly for obstetrician–gynecologists managing patients in labor, the distinction between suspected and confirmed intraamniotic infection is more relevant for research purposes than immediate patient management. Postpartum diagnosis of confirmed histologic intraamniotic infection does not alter post-delivery maternal treatment. Although the expert workshop initially categorized patients with a temperature of 39°C or greater without other risk factors into the isolated maternal fever group, ACOG recommends including these patients in the suspected intraamniotic infection group. This approach is based on the understanding that markedly elevated maternal temperatures are highly likely indicative of infection, whereas lower temperature elevations might be transient, spurious, or related to non-infectious causes like dehydration or epidural analgesia.
Management Strategies for Suspected or Confirmed Intraamniotic Infection
Intrapartum antibiotic therapy for intraamniotic infection has been proven to significantly reduce the incidence of neonatal bacteremia, pneumonia, and sepsis. Multivariate models of neonatal sepsis risk corroborate the positive impact of intrapartum antibiotics on reducing culture-confirmed neonatal infections. Furthermore, intrapartum antibiotics have been shown to decrease maternal febrile morbidity and shorten hospital stays. Therefore, unless there are clear contraindications, intrapartum antibiotic administration is recommended whenever intraamniotic infection is suspected or confirmed. In addition to antibiotics, antipyretics should be administered to manage maternal fever.
Given the association between intraamniotic infection and dysfunctional labor, ensuring proper labor progression is crucial. In the absence of contraindications, augmentation of protracted labor in women with intraamniotic infection is advisable. However, it is critical to reiterate that intraamniotic infection alone is not an indication for immediate delivery, and the mode of delivery should be determined by standard obstetric indications. Cesarean delivery is almost never indicated solely for intraamniotic infection.
Management of Isolated Maternal Fever
Isolated maternal fever is defined as a temperature between 38°C and 38.9°C (100.4°F and 102.0°F) without other clinical signs of intraamniotic infection. Managing isolated maternal fever presents a clinical challenge, as limited data is available to guide optimal approaches. Even in the absence of other signs of infection, isolated intrapartum fever has been linked to adverse short-term and long-term neonatal outcomes. The precise mechanism for this association remains unclear, although fetal hyperthermia and related metabolic changes are hypothesized to exacerbate the effects of tissue hypoxia.
Currently, due to the potential benefits for both mother and newborn, antibiotics should be considered in cases of isolated maternal fever, unless an alternative non-intraamniotic infection source is identified and documented. This approach may enhance the detection and diagnosis of intraamniotic infection, influencing subsequent newborn management. Regardless of whether intrapartum antimicrobial therapy is initiated, the occurrence of maternal intrapartum fever should always be communicated to the neonatal care team. Contemporary pediatric guidelines increasingly focus on a broader range of risk factors and newborn clinical status, rather than solely on the clinical diagnosis of suspected intraamniotic infection, to guide neonatal management.
Postdelivery Recommendations and Neonatal Implications
Postpartum antimicrobial therapy following intrapartum treatment for suspected or confirmed intraamniotic infection should not be routine. Instead, the continuation of antibiotics should be guided by risk factors for postpartum endometritis. Studies suggest that women who have vaginal deliveries are at lower risk of endometritis and may not require postpartum antibiotics. For women undergoing cesarean deliveries, at least one additional dose of antimicrobial agents post-delivery is recommended. However, the presence of other maternal risk factors such as bacteremia or persistent fever postpartum should guide the duration and continuation of antimicrobial therapy for both vaginal and cesarean deliveries.
Guidelines from the Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend laboratory studies and empiric antibiotic therapy for all newborns delivered from mothers with suspected or confirmed intraamniotic infection. However, these recommendations are currently under re-evaluation, considering recent data on neonatal microbiome development and the potential adverse effects of early antibiotic exposure. Emerging evidence suggests that multivariate risk assessment and a greater emphasis on clinical observation may safely reduce the number of well-appearing term newborns who are empirically treated with antibiotics. In all scenarios involving maternal isolated fever or suspected/confirmed intraamniotic infection, thorough communication with neonatal caregivers at birth is essential. Regardless of evolving national guidelines and local practices, these infants require heightened clinical surveillance for any signs of developing infection.
Conclusion
Intraamniotic infection remains a prevalent condition in both preterm and term pregnancies. Effective recognition of intrapartum intraamniotic infection and adherence to treatment recommendations are crucial for minimizing morbidity and mortality in mothers and newborns. Prompt maternal management and timely communication with neonatal health care providers facilitate appropriate evaluation and the judicious use of empiric antibiotic treatment when indicated. It is important to emphasize that intraamniotic infection alone is almost never an indication for cesarean delivery.
References
[List of references as provided in the original document]
Disclaimer: This information is for educational purposes and is not a substitute for professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment.
