Sepsis is a rare, but important, cause of maternal morbidity in the antenatal period. The physiological adaptations of pregnancy can mask the early signs of sepsis and can predispose to rapid maternal deterioration. A high index of suspicion is required to identify women with sepsis, and allow prompt treatment, including appropriate antibiotics.

The leading antenatal causes of sepsis are urinary tract infection (including pyelonephritis), pneumonia and genital tract infections. Causative organisms depend on the site of the infection (Table 1); however, in a significant proportion of infections, no organism is isolated.

Table 1. Infections that may lead to septic shock and common pathogens in pregnancy. (Adapted from Joseph 2009).¹

Approach to antenatal presentation of sepsis

A pregnant woman presenting with fever or infective symptoms should be assessed with thorough history and examination to identify the potential source of infection and evaluated for signs of sepsis and septic shock. Screening for causes should evaluate risk factors such as diabetes mellitus with poor glycaemic control, immunomodulating medications, malnutrition, smoking, obesity, unwell contacts, recent travel and animal exposure.

Alarm signs include hypoxia, hypotension, oliguria, hyperglycaemia, decreased capillary refill and impaired mentation. Initial assessment should also include evaluation for metabolic acidosis, coagulopathy, renal and liver dysfunction and fluid balance. Blood cultures and swab or culture samples from probable sources should be sent for culture. Monitoring should include close observation of haemodynamic parameters, fluid balance and consideration of the need for invasive blood pressure monitoring and haemodynamic support. Broad spectrum antibiotic coverage as per local guidelines should be commenced, with the spectrum of therapy narrowed, pending culture results when available. Antibiotics should not be delayed as early administration has been shown to improve outcomes.⁵

Fetal monitoring should be performed with intermittent heart rate or continuous cardiotocographic (CTG) monitoring depending on gestation. CTG changes may serve as an early warning sign for maternal haemodynamic or metabolic decompensation.

Septic antenatal patients should be managed in a tertiary centre with access to intensive care facilities and monitoring; retrieval should be urgently arranged if required. Multidisciplinary supports should include intensivists, anaesthetists, microbiologists, physicians and neonatologists. Consideration should be given to the administration of corticosteroids for fetal lung maturation as delivery may be indicated if beneficial to the woman or her infant. In sepsis from extra-uterine infection, the maternal condition should be stabilised prior to attempting delivery, otherwise maternal and fetal mortality rates are increased.¹⁰ The mode of delivery should be individualised based on gestation and the severity of maternal illness.

Urinary tract infection/pyelonephritis

The physiological changes of pregnancy predispose to urinary tract infections and pyelonephritis,² with pyelonephritis being the leading cause of septic shock in pregnancy.³ Pyelonephritis complicates approximately 2 per cent of pregnancies overall, but in the 5–7 per cent of pregnant women who have asymptomatic bacteriuria, the rates of pyelonephritis are reported at 20–30 per cent.⁴ Presenting symptoms are usually fever, tachycardia, flank pain and the typical symptoms of urinary tract infection may or may not be present.

E. coli accounts for 70–80 per cent of cases, with the majority of the remainder being due to Klebsiella, Proteus and Enterobacter organisms. Pyelonephritis is associated with a 15–20 per cent risk of bacteraemia and, hence, initial evaluation for suspected pyelonephritis should encompass blood cultures.³ There is also a risk of endotoxin-mediated renal dysfunction and assessment of glomerular filtration should be performed, as dosing of antibiotics may need to be adjusted.

Pyelonephritis has been associated with an increased risk of preterm birth; both spontaneous and iatrogenic.⁶ There is also a risk of recurrence and prophylactic antibiotics are recommended for all women who present with an episode of pyelonephritis during pregnancy.

Pneumonia

The physiological changes of pregnancy predispose to the development of pneumonia. The incidence of pneumonia during pregnancy is approximately 1–1.5 per cent.⁷ Pre-existing lung disease, most commonly asthma, increases maternal risk of pneumonia, along with anaemia and cigarette smoking. Pneumonia may also complicate severe sepsis from another causes⁸ or be caused by aspiration.⁹

Community-acquired pneumonias most commonly present with a productive cough, fevers, pleuritic chest pain and shortness of breath. Bacterial pneumonia is most commonly caused by streptococcus pneumonia, haemophilus influenzae and mycoplasma pneumonia.³ Viral infections, in particular influenza and varicella, can be associated with a severe acute respiratory distress syndrome, and may predispose to secondary bacterial pneumonia.²

Evaluation should include assessment of oxygenation and supplementation if needed. Sputum samples can be cultured, but swabs for viral PCR testing and serologies for atypical infections or viruses should also be considered. Chest x-ray may be performed with abdominal shielding with the estimated fetal dose of absorption well below the level associated with adverse short- or long-term effects.¹¹

Chorioamnionitis

Chorioamnionitis is typically an ascending polymicrobial infection and most commonly occurs in the setting of ruptured membranes. Less commonly, procedures such as cervical cerclage or amniocentesis may precipitate infection; haematogenous spread can also rarely occur. The infection may present with fevers and maternal and/or fetal tachycardia. Uterine tenderness and malodorous discharge are commonly late signs of infection.

Causative organisms include genital myocplasmas, ureaplasma urealyticum, Gardnerella vaginalis, E. coli and group B streptococcus. High vaginal swab culture has been shown to be the best predictor of causative organism; however, antibiotic cover should be broad initially to cover for polymicrobial infection. Chorioamnionitis is an indication for delivery and the mode of delivery should be determined based on the usual obstetric indications.¹²

Listeriosis

Listeriosis is an uncommon infection with significant implications for pregnant women. The illness most commonly presents with flu-like or gastrointestinal symptoms, but may be asymptomatic. Infection during pregnancy is complicated by high rates of intrauterine fetal demise, preterm birth and neonatal meningitis. Listeria can be cultured from blood or genital swabs and prompt treatment with appropriate antibiotics can prevent the associated adverse neonatal outcomes.¹³

Sepsis with unclear origin

In the workup of a septic antenatal patient, other uncommon causes should also be considered (Table 2).

Table 2. Uncommon causes of sepsis.

Summary

Sepsis is a severe and life-threatening complication of pregnancy. A broad range of causes should be considered and antibiotic therapy initiated promptly with early consideration of transfer to tertiary centres and monitoring in intensive care settings if required. Sepsis alone does not indicate delivery except in the case of chorioamnionitis.

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