Infections During Pregnancy

Chorioamnionitis

Overview

• Chorioamnionitis (also known as intraamniotic infection or IAI) is defined as infection and inflammation of the amniotic fluid, fetal membranes, fetus, placenta, and/or decidua.²
• It is one of the most common infections in pregnancy, affecting 2-5% of term deliveries.^1,2
• Infection commonly results from ascending bacterial invasion of the uterine cavity after rupture of membranes1, but can also occur from invasive fetal procedures or via hematogenous spread of certain maternal infections (e.g. listeria monocytogenes).²
• Most commonly, a polymicrobial infection (anaerobic + aerobic bacteria) originating from vaginal flora:²
  • Bacteroides sp., Group B streptococci, Mycoplasma sp., Ureaplasma sp., E. Coli

Risk Factors

• Low parity, multiple digital examinations, use of internal monitors, meconium-stained amniotic fluid, and presence of maternal genital tract infections (i.e., group B streptococci, sexually transmitted infections)⁷

Complications

• Maternal
  • Preterm labor, placental abruption, postpartum infection, uterine atony, postpartum hemorrhage, peripartum hysterectomy, sepsis, death¹
• Fetal
  • Pneumonia, meningitis, cerebral palsy, bronchopulmonary dysplasia, sepsis, death^1,2

Anesthetic Management

• Chorioamnionitis can be complicated by bacteremia; thus, there is a theoretical concern of seeding bacteria into the neuraxial space, leading to meningitis or an epidural abscess.¹
• There is currently no evidence to suggest that neuraxial anesthesia should be contraindicated.
  • A large retrospective review in 2022 showed no increase in maternal or fetal complication rates among patients with chorioamnionitis who received an epidural, other than an increased risk of instrumental delivery.³
• Recommendations:
  • Consider delaying neuraxial anesthesia until antibiotics are initiated.¹
  • Avoid neuraxial anesthesia in untreated patients with clinical signs of sepsis.¹
    • Presence of two or more of the following:
• Temperature < 36 °C or > 38 °C
• Tachycardia (heart rate > 90 bpm)
• Tachypnea (respiratory rate > 20 bpm)
• White blood cell count > 12,000/ml or < 4,000/ml

HSV

Overview

• Genital herpes is characterized by painful vesicular or papular lesions on mucous membranes of the genital tract due to infection with HSV type 2 (HSV-2), but also HSV type 1.
  • Primary infection: virus gains access to sensory neurons
  • Recurrent (secondary) infection: local reactivation of the virus from the sensory ganglia
• One of the most common sexually transmitted infections.
  • 15.9% of women aged 14-49 years are infected with HSV-2⁴
  • Three-fourths of women with genital HSV will have recurrent infection during pregnancy, with 14% occurring at the time of delivery.⁴
• The major risk is vertical transmission to the newborn, which can occur either via direct neonatal exposure to the virus during delivery or via viral ascent following rupture of membranes.¹
• Suppressive therapy reduces clinical recurrence and asymptomatic shedding

Anesthetic Management

• Primary HSV infection can be complicated by viremia; thus a neuraxial procedure could introduce the virus into the cerebrospinal fluid, leading to HSV meningitis/encephalitis.⁵
• The safety of neuraxial anesthesia in primary infection is unknown; the risk of potential central nervous system (CNS) infection should be weighed against the risk of alternative anesthetic options.¹
• Neuraxial anesthesia is generally considered safe in patients with recurrent infection, as it is rarely associated with viremia.¹
• Of note, neuraxial morphine administration has been shown to be associated with reactivation of oral HSV.⁶

HIV

Overview

• HIV is a retrovirus that results in impaired cell-mediated immunity characterized by a long latency period and persistent viremia that, if left untreated, can progress to acquired immune deficiency syndrome.⁷
• A multi-organ disease with associated opportunistic infections and neoplasms. However, due to the effectiveness of combined antiretroviral therapy, many patients have a normal life expectancy.⁷
• Sequelae of HIV infection (Table 3) can affect pregnancy and anesthetic considerations.

• There is a risk of vertical transmission to the fetus/neonate, which can occur in utero (30%) or during labor and delivery (70%). This can occur via transplacental blood exchange or with direct exposure of the neonate to maternal secretions/blood during delivery.⁸
• Strict adherence to treatment regimens can reduce the risk of transmission to less than 1-2% if viral load (VL) is less than 1,000 copies/mL.⁸
  • If VL is < 1,000 copies/mL at the time of delivery, the patient can have a vaginal delivery; otherwise, if VL is higher or unknown, a cesarean delivery is indicated.

Anesthetic Management

• HIV infection alone is not a contraindication to neuraxial anesthesia and is preferred when feasible to reduce aerosol exposure and hemodynamic swings, per American Society of Anesthesiologists/Society for Obstetric Anesthesia and Perinatology consensus.
• However, the presence of the following should be considered at the time of labor and delivery⁷:
  • Peripheral neuropathy
  • Thrombocytopenia/coagulopathy
  • CNS infection and/or systemic infection
• In the event of post-dural puncture headache, limited evidence suggests there is no increased risk of neurologic complications from epidural blood patch in HIV+ patients.⁷
• Patients will be on antiretroviral drug therapies that have numerous medication interactions, including with commonly used obstetric anesthesia medications, due to inhibition or induction of the CYP450 system (Table 4).^7,8

• Methergine should be avoided for the treatment of uterine atony in patients on protease inhibitors or cobicistat unless prostaglandin F2-alpha, misoprostol, or oxytocin are contraindicated.⁸

Emerging Infections (Zika Virus)

• Single-stranded RNA Flavivirus; transmitted via a vector, predominantly the Aedes mosquito
  • Sexual and vertical transmission may occur as the virus can cross the placenta.⁹
• Symptoms include fever, maculopapular rash, joint pain, conjunctivitis, as well as potentially Gullian-Barré syndrome.⁹
• Active Zika infection should prompt multidisciplinary discussion before proceeding with neuraxial anesthesia, given the potential for neurologic involvement and thrombocytopenia.
• In utero transmission can occur at any point in pregnancy, but fetal outcomes likely vary based on gestational age.⁹
  • Early pregnancy: microcephaly, ocular/optic nerve abnormalities
  • Late pregnancy: intrauterine growth restriction, placental insufficiency
• Anesthetic Management
  • Active symptoms of Zika virus at the time of labor and delivery is a relative contraindication to neuraxial anesthesia.⁹
  • Neuraxial anesthesia is generally safe in patients without active symptoms at delivery, but the following should be considered:
    • Platelet count: Zika virus is associated with thrombocytopenia.⁹
    • Gullian-Barré Syndrome
    • Smaller doses of local anesthesia may be required.⁹