9.4 Maternal Sepsis, MEOWS Escalation & Maternal Resuscitation (Modified BLS/ALS)

Maternal Sepsis, MEOWS Escalation & Maternal Resuscitation (Modified BLS/ALS)

Maternal sepsis remains a leading direct cause of maternal death in the United Kingdom. According to confidential maternal death enquiries (MBRRACE-UK), delays in recognizing sepsis, failure to appreciate the significance of abnormal vital signs, and delays in administering empirical antibiotics are recurring contributors to preventable mortality. Midwives must possess mastery of physiological surveillance using the Modified Early Obstetric Warning System (MEOWS), rapid execution of the Sepsis Six bundle, and the physiological adaptations governing maternal cardiopulmonary resuscitation (CPR).

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Maternal Sepsis & Pathogen Profiles

Maternal sepsis is defined by the World Health Organization (WHO) and UK guidelines as a life-threatening condition defined by organ dysfunction resulting from infection during pregnancy, childbirth, post-abortion, or the puerperium (up to 42 days postpartum).

Primary Pathogens

• Group A Streptococcus (GAS / Streptococcus pyogenes): The most lethal pathogen in modern obstetrics. GAS produces potent pyrogenic exotoxins that trigger fulminant necrotising fasciitis, myometritis, and toxic shock syndrome. Women can deteriorate from mild flu-like symptoms into catastrophic septic shock and multi-organ failure within 2 to 4 hours.
• Escherichia coli (E. coli): The primary gram-negative organism, predominantly originating from ascending urinary tract infections (pyelonephritis), chorioamnionitis, or pelvic peritonitis. Produces endotoxins (lipopolysaccharide) triggering septic vasodilatation.
• Staphylococcus aureus (including MRSA): Associated with wound infections, mastitis, and staphylococcal toxic shock syndrome (TSS).
• Anaerobes (Bacteroides, Clostridium sordellii, Peptostreptococcus): Frequently implicated in polymicrobial pelvic sepsis, prolonged rupture of membranes, and necrotic tissue infections.

Why Pregnancy Masks Early Sepsis

Midwives must recognize that normal maternal physiological adaptations can obscure the early clinical features of sepsis:

• Elevated Baseline Heart Rate: A heart rate of 85–90 bpm is physiologically normal in pregnancy, masking early compensatory septic tachycardia.
• Physiological Hyperventilation: Pregnancy induces a baseline compensated respiratory alkalosis (PaCO2 3.7–4.2 kPa), blunting maternal ability to compensate further when lactic acidosis develops.
• Physiological Leukocytosis: White blood cell counts can normally rise to 15 × 10^9/L in the third trimester and up to 20–25 × 10^9/L during active labour, rendering WBC counts unhelpful as an isolated marker.
• Vascular Compliance: Young, healthy pregnant women compensate haemodynamically through intense peripheral vasoconstriction, maintaining a normal blood pressure until they enter sudden, decompensated septic shock.

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The Modified Early Obstetric Warning System (MEOWS)

The Modified Early Obstetric Warning System (MEOWS) is a bedside physiological tracking chart designed to detect early deterioration in pregnant and postnatal women. Charts and trigger thresholds have historically varied between units; NHS England is now rolling out a single national Maternity Early Warning Score (MEWS) to standardise practice. The thresholds below are typical examples, and midwives must always use their own unit's chart.

Core MEOWS Trigger Parameters

Midwives record routine vital signs on dedicated MEOWS charts, which utilize colour-coded thresholds (Yellow for mild-to-moderate deviation, Red for severe deviation):

Clinical Escalation Rules

• A Single RED Trigger or Two Concurrent YELLOW Triggers: Mandates immediate bedside clinical evaluation by a registered midwife and urgent medical review by the duty obstetric registrar within 30 minutes.
• If sepsis is suspected, immediate implementation of the Sepsis Six pathway is triggered without waiting for laboratory results.

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The Sepsis Six Pathway: The "Golden Hour"

When maternal sepsis is diagnosed or suspected, national guidance (NICE guideline NG255 [Suspected sepsis in pregnant or recently pregnant people], published November 2025, and the UK Sepsis Trust) expects rapid assessment and, for high-risk women, broad-spectrum antimicrobials within 1 hour. The Sepsis Six bundle is commonly used to deliver this within the first hour ("The Golden Hour"):

                    ┌──────────────────────────────────────────────┐
                    │         THE SEPSIS SIX (WITHIN 1 HOUR)       │
                    └──────────────────────┬───────────────────────┘
                                           │
         ┌──────────────────┬──────────────┴─────┬──────────────────┐
         ▼                  ▼                    ▼                  ▼
┌─────────────────┐┌─────────────────┐┌─────────────────┐┌─────────────────┐
│  TAKE THREE     ││  GIVE THREE     ││  RE-ASSESS       ││   ANTITOXIN     │
│                 ││                 ││                 ││   CLINDAMYCIN   │
│ 1. Blood        ││ 1. Oxygen       ││ • Check lactate  ││ • If GAS        │
│    Cultures     ││    (Target      ││   clearance      ││   suspected,    │
│ 2. Serum Lactate││    94–98%)      ││ • Hourly urine   ││   add IV        │
│    & FBC        ││ 2. Broad-Spec   ││   urometer       ││   Clindamycin   │
│ 3. Accurate     ││    IV Antibiotic││   (≥0.5 mL/kg/h) ││   to block      │
│    Urine Output ││ 3. IV Fluids    ││ • Escalate to    ││   exotoxin      │
│    (Catheter)   ││   (500 mL/15min)││   HDU/ICU        ││   production    │
└─────────────────┘└─────────────────┘└─────────────────┘└─────────────────┘

The Three Diagnostic Actions ("Take Three")

1. Take Blood Cultures: Inoculate two sets (aerobic and anaerobic) prior to antimicrobial administration. Also obtain diagnostic swabs (high vaginal swab, wound swab, throat swab), urine for microscopy and culture, and sputum.
2. Measure Serum Lactate & Full Blood Count: Point-of-care venous or arterial blood gas allows immediate lactate measurement. A serum lactate >2.0 mmol/L indicates cellular hypoperfusion; a lactate >4.0 mmol/L signifies severe metabolic decompensation and septic shock.
3. Measure Accurate Urine Output: Insert an indwelling Foley catheter with a dedicated urometer. Monitor hourly output to assess renal perfusion (target ≥0.5 mL/kg/hr).

The Three Therapeutic Interventions ("Give Three")

1. Give High-Flow Oxygen: Administer oxygen via a non-rebreathe reservoir mask to maintain peripheral oxygen saturations between 94% and 98% (or 88%–92% in patients with hypercapnic respiratory failure).
2. Give Intravenous Broad-Spectrum Antibiotics: Administer targeted empirical IV antibiotics within 1 hour. Standard NHS regimens include IV Piperacillin-tazobactam (Tazocin) 4.5 g TDS or Co-amoxiclav + Gentamicin.

1. Give Intravenous Fluid Resuscitation: If the systolic BP is <90 mmHg, MAP is <65 mmHg, or serum lactate is ≥2.0 mmol/L, give a crystalloid bolus of 500 mL over less than 15 minutes (NICE NG255: sodium content 130–154 mmol/L, such as Hartmann's or 0.9% NaCl), then reassess and repeat if needed, watching for pulmonary oedema (especially with pre-eclampsia).

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Maternal Cardiopulmonary Resuscitation (Modified BLS/ALS)

Maternal cardiac arrest in pregnancy requires critical modifications to standard Basic Life Support (BLS) and Advanced Life Support (ALS) guidelines established by the Resuscitation Council UK.

1. Relief of Aortocaval Compression

From 20 weeks' gestation onwards, the gravid uterus exerts massive mechanical compression upon the inferior vena cava and abdominal aorta when the woman is supine. In cardiac arrest, standard external chest compressions generate only 30% of normal cardiac output; aortocaval compression reduces this to less than 10%, making successful resuscitation impossible.

• Manual Left Lateral Uterine Displacement (LUD): The single most effective manoeuvre. A designated rescuer stands on the patient's left side and uses two hands to pull the uterus upward and to the left (or stands on the right and pushes the uterus to the left).
• Why Tilting the Bed is Disfavoured: Placing the patient in a lateral tilt (15°–30°) on a tilting operating table is acceptable if secure, but frequently causes the woman to slide off the bed and significantly reduces the mechanical force and depth of chest compressions. Resuscitation Council UK strongly recommends keeping the patient flat and supine on a firm backboard while performing manual Left Lateral Uterine Displacement.

2. Ergonomics & Hand Placement

Although the enlarged uterus elevates the diaphragm, current RCUK and OAA guidance advises the standard hand position on the lower half of the sternum, at a rate of 100–120 compressions/min and a depth of 5–6 cm. Older advice to place the hands higher on the sternum is no longer recommended.

3. Early Advanced Airway Management

Pregnant women have decreased functional residual capacity (FRC), 20% higher oxygen consumption, and mucosal airway oedema. Furthermore, progesterone reduces lower oesophageal sphincter tone, and the enlarged uterus increases intragastric pressure, creating an extreme risk of gastric regurgitation and fatal pulmonary aspiration (Mendelson's syndrome).

• A skilled anaesthetist must perform early endotracheal intubation using a smaller internal diameter tube (e.g. 6.0–7.0 mm cuffed tube) with continuous cricoid pressure.

4. Defibrillation Safety

Standard adult defibrillation energy protocols (150–200 J biphasic shocks) must be delivered without modification. Defibrillation is completely safe for the fetus; current does not penetrate the uterus in significant amounts. External fetal monitoring transducers should be removed prior to shock delivery.

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Perimortem Caesarean Section (Resuscitative Hysterotomy)

Perimortem Caesarean Section (PMCS), increasingly referred to as Resuscitative Hysterotomy, is an emergency surgical delivery performed primarily to save the life of the mother, with fetal salvage serving as a secondary benefit.

                  ┌──────────────────────────────────────────┐
                  │    RESUSCITATIVE HYSTEROTOMY (PMCS)      │
                  │   "PREPARE EARLY, PERFORM AT THE SITE"   │
                  └────────────────────┬─────────────────────┘
                                       │
         ┌─────────────────────────────┴─────────────────────────────┐
         ▼                                                           ▼
┌─────────────────────────────────┐         ┌─────────────────────────────────┐
│     FROM THE START OF ARREST    │         │      IF NO PROMPT ROSC          │
│ • High-quality ALS Ongoing      │         │ • Perform Resuscitative         │
│ • Manual Left Uterine           │         │   Hysterotomy AT THE SITE OF    │
│   Displacement (LUD)            │         │   ARREST, AS SOON AS POSSIBLE   │
│ • Call Obstetric & Neonatal Team│         │ • Deliver Infant & Placenta     │
│ • Prepare Scalpel at Bedside    │         │ • Continue CPR Throughout       │
└─────────────────────────────────┘         └─────────────────────────────────┘

Physiological Rationale

Evacuating the fetus and placenta removes the mechanical compression on the inferior vena cava and aorta, improving venous return and the effectiveness of chest compressions, and dramatically enhancing maternal cerebral and coronary perfusion. In numerous documented cases, maternal spontaneous circulation (ROSC) returns soon after uterine evacuation.

Indications & Timing (RCUK 2025)

• Gestation: Considered in any woman more than 20 weeks' pregnant (fundal height at or above the umbilicus) in cardiac arrest, because aortocaval compression becomes significant from this point.
• Timing: RCUK 2025 guidance describes resuscitative hysterotomy as a time-sensitive intervention. Preparation starts early in the arrest, and the procedure should be performed as soon as possible by a skilled team if resuscitation is not promptly successful. The 2025 ILCOR review found insufficient evidence to set a specific minute for starting it.
• Older Teaching: Earlier guidelines used the "4-minute / 5-minute rule" (decide at 4 minutes, deliver by 5 minutes). This remains a useful reminder of urgency, but the current emphasis is on early preparation and performing the procedure as soon as possible, rather than waiting for a fixed time point.
• Location: Resuscitative hysterotomy is performed at the site of the arrest (delivery room, triage, emergency department or ICU). Do not transfer to an operating theatre. Transfer wastes irreplaceable minutes and compromises chest compressions.
• Surgical Simplicity: No anaesthesia or antiseptic skin preparation is needed if the mother remains pulseless. A large incision is made with a scalpel, the uterus is incised, the infant is delivered, the cord is clamped and cut, and CPR continues throughout.