Manage the critically ill obstetric patient, including shock and organ support

In one line

The critically ill obstetric patient is a young woman with a physiology built to compensate, so she looks stable until she is peri-arrest; managing her means a structured ABCDE, naming the shock state to direct treatment, supporting failing organs to the same standard as any ICU patient, and — uniquely — recognising that delivering the baby is sometimes the resuscitation, all delivered through a high-care/ICU system that in South Africa is scarce, geographically maldistributed and reached only by referral.

Mechanism & pathophysiology

A pregnant woman is, physiologically, an athlete primed for a single haemorrhagic event. Plasma volume rises by roughly 40–50% and red-cell mass by less, producing the physiological haemodilution of pregnancy; cardiac output climbs 30–50% through both a higher stroke volume and a resting tachycardia of 10–20 beats per minute; systemic vascular resistance falls and the diastolic blood pressure with it; minute ventilation rises so that arterial CO₂ sits around 4.0 kPa with a compensated respiratory alkalosis. Every one of these adaptations is a margin of safety for delivery — and every one is a mask. The same young woman who tolerates losing 1,000–1,500 mL with barely a change in blood pressure has spent her reserve doing so, and when she finally drops her pressure she is already 30–40% volume-deplete and minutes from collapse. The lesson that organises all obstetric critical care is that vital signs in a young pregnant woman are a late and binary warning system: normal until they are catastrophic. This is why structured early-warning scoring and serial trend observation, not single readings, govern recognition. The groundwork — the four shock types and their first principles — is the shock-management chapter; the consultant task here is reading the obstetric distortion of each and choosing organ support.

Three further pregnancy facts reshape resuscitation. First, aortocaval compression: from the mid-second trimester the gravid uterus compresses the inferior vena cava and aorta when the woman is supine, dropping venous return by up to 30% and capping the cardiac output any resuscitation can generate. Left lateral tilt or manual uterine displacement is therefore not a nicety but a circulatory intervention — and in cardiac arrest it is the rationale for emptying the uterus by perimortem caesarean to restore maternal venous return. Second, the physiological hypercoagulability of pregnancy (rising fibrinogen and clotting factors, falling protein S, fibrinolytic shutdown) makes venous thromboembolism a leading cause of maternal collapse and tilts the differential of sudden dyspnoea and hypoxia towards pulmonary embolism and amniotic-fluid embolism. Third, the lower functional residual capacity and higher oxygen consumption mean a pregnant woman desaturates fast on apnoea and tolerates hypoxaemia poorly — the airway and the lungs have almost no reserve.

The shock states keep their classical mechanisms but wear obstetric clothing.

• Hypovolaemic (haemorrhagic) shock is the dominant obstetric shock — major obstetric haemorrhage, the detail of which is the postpartum-haemorrhage chapter. The mechanism is loss of preload and oxygen-carrying capacity, but the obstetric twist is the masking described above plus the dilutional and consumptive coagulopathy that develops early when crystalloid is poured in: the bleeding woman becomes coagulopathic, hypothermic and acidotic — the lethal triad — faster than her blood pressure admits.
• Distributive (septic) shock — vasoplegia and capillary leak from a dysregulated host response; the obstetric sources, the camouflaging physiology and the SA HIV/TB drivers are the maternal-sepsis chapter and are not re-derived here. Anaphylaxis (often to antibiotics, oxytocics or anaesthetic agents) and high neuraxial block are the other distributive causes on the labour ward.
• Cardiogenic shock — pump failure from peripartum cardiomyopathy, decompensated rheumatic or congenital heart disease (still common in SA), arrhythmia, or myocardial infarction. The fluid that rescues hypovolaemia drowns these patients, which is why the shock state must be named before the litre is given.
• Obstructive shock — mechanical impedance to filling or ejection: massive pulmonary embolism, amniotic-fluid embolism, tension pneumothorax, cardiac tamponade, and aortocaval compression itself. The unifying clue is shock with raised, not collapsed, venous pressure.

Amniotic-fluid embolism (AFE) deserves its own mechanism because it is the obstetric catastrophe that defines maternal collapse. The old picture of fetal squames mechanically plugging the pulmonary circulation has been replaced by an anaphylactoid / immune-mediated model: amniotic fluid components entering the maternal circulation around the time of delivery trigger a humoral response resembling anaphylaxis and the systemic inflammatory response, with massive pulmonary vasoconstriction. The haemodynamic course is biphasic — a brief phase of intense pulmonary hypertension and acute right-ventricular failure (the cause of the early arrests), followed, in survivors, by left-ventricular failure and a profound consumptive coagulopathy / DIC that produces torrential haemorrhage. It is rare (UK incidence about 1.7 per 100,000 maternities), unpredictable and unpreventable; it is a clinical diagnosis of sudden cardiorespiratory collapse, hypoxia and coagulopathy in labour or immediately postpartum, after excluding the treatable mimics. There is no specific therapy — management is high-quality resuscitation, early delivery if undelivered, and aggressive correction of the coagulopathy.

Acute respiratory distress syndrome (ARDS) is the common final pathway of the lungs in the critically ill mother, whether the insult is pneumonia, aspiration, sepsis, AFE, pre-eclampsia with severe features or massive transfusion. Diffuse alveolar damage from the inflammatory insult floods alveoli with protein-rich oedema, collapses surfactant function and produces the stiff, poorly-compliant, shunting lung of hypoxaemic respiratory failure (the Berlin definition: acute onset, bilateral infiltrates, hypoxaemia not explained by cardiac failure). The pregnant lung reaches it faster and tolerates it worse, and the management principle — protect the lung from the ventilator while you treat the cause — is the same as in any adult but is delivered against a fetus that also needs oxygen.

Assessment

The first decision is structural, not diagnostic: this woman is sick enough that she is managed by simultaneous assessment and resuscitation, by a team, in an area with monitoring and senior help, with the clock running. Within that, two systems carry the recognition.

• A structured obstetric early-warning system. The Modified Early Obstetric Warning Score (MEOWS) is the standard SA and international tool — a colour-banded chart of respiratory rate, oxygen saturation, temperature, heart rate, blood pressure, conscious level and urine output, calibrated to pregnancy so that the trend, not a single number, triggers escalation (a single red or two amber triggers mandate senior review). Its entire purpose is to convert the binary, late warning of obstetric vital signs into a graded, charted trend that catches the slow drift before collapse. The single most sensitive early sign is a rising respiratory rate, and it is the observation most often left unrecorded.
• ABCDE, done obstetrically. Airway — the pregnant airway is a difficult airway (oedematous, friable mucosa, full stomach, rapid desaturation), so a low threshold for senior anaesthetic help and a plan for failed intubation are part of the primary survey. Breathing — oxygen saturation, respiratory rate, work of breathing, auscultation; high-flow oxygen first, before the cause is known. Circulation — heart rate, blood pressure, capillary refill, two large-bore cannulae, and left lateral tilt / uterine displacement in any collapsed woman beyond the mid-second trimester. Disability — conscious level (AVPU/GCS), pupils, and crucially blood glucose and the possibility of eclampsia. Exposure — temperature, rashes, the abdomen, the perineum and the lochia, looking for the bleeding or infective source.

Naming the shock state is the pivot of the assessment because it directs opposite treatments, and the bedside tool that has changed obstetric critical care is point-of-care ultrasound (POCUS) and focused echocardiography. A focused echo at the bedside distinguishes the empty, hyperdynamic, collapsing ventricle of hypovolaemia (give volume and stop the bleeding) from the dilated, poorly-contracting ventricle of cardiogenic shock (do not flood; support the pump) from the small, hyperdynamic left ventricle with a dilated, pressure-loaded right ventricle of massive PE or AFE (an obstructive picture). Lung ultrasound separates the B-line pattern of pulmonary oedema/ARDS from a pneumothorax or effusion; abdominal/pelvic ultrasound finds free fluid (haemoperitoneum) and retained products. POCUS shortens the time from "she is shocked" to "she is shocked because", which is the whole game.

Monitoring scales to severity:

• Lactate is the key biochemical marker of tissue hypoperfusion when the blood pressure still looks acceptable; a level above 2 mmol/L flags shock and serial lactate clearance tracks the response to resuscitation, in haemorrhagic and septic shock alike.
• Arterial line for beat-to-beat blood pressure and repeated blood-gas and lactate sampling in any patient on vasopressors or with respiratory failure.
• Central venous access for vasopressor delivery and central drug administration — but central venous pressure is a poor guide to fluid responsiveness, which is better judged dynamically (passive-leg-raise or stroke-volume response, the inferior-vena-cava and ventricular filling seen on echo).
• Baseline organ-failure bloods — full blood count, U&E and creatinine, liver function, coagulation profile and fibrinogen (critical in haemorrhage and AFE), arterial blood gas, group-and-save/crossmatch, and an HIV test in every patient, because immune status shapes the differential and the reserve in the SA mother.

The output of the assessment is a problem list and a level-of-care decision: can she be safely managed on a labour ward with one-to-one observation, does she need obstetric high-care/HDU (single-organ support, vasopressor by peripheral or central line, close monitoring), or does she need ICU (mechanical ventilation, renal replacement, multi-organ support)? That decision, made early and acted on before deterioration, is itself an intervention.

Management

The plan runs immediate → ongoing → long-term, and the immediate priority is always to restore oxygen delivery to the tissues while the cause is found and controlled — resuscitation and diagnosis proceed together.

Immediate — resuscitate while you diagnose. High-flow oxygen, two large-bore cannulae, bloods sent (including crossmatch and coagulation), left lateral tilt, and a senior multidisciplinary call (obstetrics, anaesthesia/critical care, and — by source — haematology, surgery, microbiology). The single most important immediate manoeuvre is to name the shock state and treat that rather than reflexively giving fluid:

• For haemorrhagic shock, the resuscitation is stopping the bleeding and replacing blood, not crystalloid. Give a measured crystalloid bolus to buy time but move quickly to blood products and activate the massive transfusion protocol; the cause-specific surgical and uterotonic management is the postpartum-haemorrhage chapter.
• For septic / distributive shock, balanced-crystalloid resuscitation titrated to response, early broad-spectrum antibiotics, source control, and noradrenaline for fluid-refractory hypotension — the detail is the maternal-sepsis chapter.
• For cardiogenic shock, fluid is the enemy: support the failing pump (inotropy, rate/rhythm control, treat the ischaemia or the cardiomyopathy), sit the patient up, and involve cardiology/critical care early.
• For obstructive shock, relieve the obstruction: thrombolysis or embolectomy for massive PE, needle/finger decompression for tension pneumothorax, and uterine displacement for aortocaval compression.

Organ support — to the same standard as any ICU patient. The critically ill mother is owed full organ support; pregnancy modifies how, never whether.

Delivery as resuscitation — the decision unique to obstetric critical care. When the pregnancy itself is driving the maternal physiology, emptying the uterus can be the intervention that allows the mother to be resuscitated, and the reasoning is mechanical and metabolic: the gravid uterus compresses the great vessels, consumes a large share of cardiac output, and (in sepsis or abruption) may be the source. The clearest case is maternal cardiac arrest beyond ~20 weeks, where perimortem caesarean (resuscitative hysterotomy), begun within 4 minutes of arrest aiming for delivery by 5 minutes, relieves aortocaval compression, improves the quality of maternal CPR and may save both — and is performed for the mother, at the bedside, without moving her. Short of arrest, expediting delivery is considered when a deteriorating maternal condition (refractory sepsis with an intrauterine source, pre-eclampsia with severe features, worsening cardiac or respiratory failure that the pregnancy is preventing you from treating) will improve with the pregnancy ended. The counterweight is that delivery is a haemorrhagic and physiological insult of its own, so in an unstable mother whose uterus is not the problem, stabilise first; resuscitating the mother resuscitates the fetus, and a non-reassuring trace usually reflects maternal compromise to be corrected rather than an automatic call to deliver into ongoing instability.

Escalation, the team, and transfer. Critical illness in pregnancy is a multidisciplinary event — senior obstetrician, anaesthetist/intensivist, midwife, and discipline-specific input — and the timing of escalation to HDU/ICU is part of the standard of care, not an admission of failure. In the SA system this routinely means inter-facility transfer: the district hospital recognises and resuscitates, stabilises as far as it can, and refers up the district → regional → tertiary chain to where high-care or ICU and the relevant surgical and imaging services exist. Transfer is itself dangerous — the principle is stabilise before you move (secure the airway, control the bleeding, start the vasopressor, correct what you can), transfer with a trained escort and monitoring, and communicate clinician-to-clinician so the receiving unit is ready. A woman who arrests in an ambulance because she was moved before she was stable is a preventable death the confidential enquiries repeatedly describe.

The South African reality is the constraint that shapes every plan. ICU and even high-care beds are scarce and unevenly distributed; many district and regional units have no on-site ICU, intermittent access to ventilators, blood products and dialysis, and long transfer distances. The pragmatic response that SA obstetrics has built is obstetric high-care (HDU) — a designated, staffed area within or beside the labour ward delivering single-organ support and intensive monitoring short of full ICU, which catches the large group of women who need more than a ward but for whom an ICU bed is neither available nor strictly necessary. Recognising early, resuscitating well at the level you are at, and referring in time matter more in this setting than any single drug, because the commonest avoidable factor in these deaths is delay — in recognition, in resuscitation, or in transfer.

Long-term. Survivors of critical illness carry post-intensive-care syndrome — physical deconditioning, cognitive impairment and psychological sequelae (anxiety, depression, post-traumatic stress) compounded by a near-death experience around the birth and, sometimes, the loss of the baby or of future fertility (after peripartum hysterectomy). Structured follow-up, debriefing of the woman and family, documentation of the episode and its cause for future pregnancies, and linkage to district-level care so the tertiary unit is not the only safety net are part of the management, not an afterthought.

Guidelines compared

A clinical caveat the consultant should state: the major trials in this field (transfusion ratios, ventilation, vasopressors, fluid strategy) were almost all conducted in non-pregnant populations, so the guidance is largely read across to obstetrics with physiological adjustment rather than derived from obstetric trials — a point of genuine evidential humility, not a licence to withhold standard organ support.

The evidence & the controversy

The defensible position in obstetric critical care is that the principles of resuscitation and organ support are well-evidenced in general critical care and are owed to the pregnant woman in full, while the obstetric-specific evidence is thin and observational — and a candidate who can hold both halves of that statement is reasoning correctly.

Three threads of read-across evidence matter most. The transfusion-ratio debate, imported from trauma, is the clearest. Damage-control resuscitation — early, balanced, fixed-ratio blood products rather than crystalloid followed by late, unbalanced product — is the modern doctrine, but the pivotal PROPPR trial is more nuanced than the slogan: a 1:1:1 plasma:platelet:red-cell ratio did not significantly lower 24-hour or 30-day mortality versus 1:1:2, but more patients achieved haemostasis and fewer bled to death in the first 24 hours. The honest read-across to obstetric haemorrhage — where the coagulopathy is driven by early fibrinogen depletion rather than the trauma pattern — is that ratio-based packs are a sensible default until point-of-care viscoelastic testing can individualise it, and that obstetric haemorrhage may be more a fibrinogen-and-cryoprecipitate problem than a strict-ratio problem. The one genuinely obstetric haemorrhage trial, WOMAN, sits alongside: early tranexamic acid reduces death due to bleeding, with the benefit concentrated in the first three hours, which is why TXA belongs in the immediate bundle.

The fluid and vasopressor evidence reinforces restraint. The collapse of early goal-directed therapy (the pooled PRISM analysis) and the demonstration that liberal fluid offers no advantage over earlier vasopressor use (CLOVERS) together argue against the reflexive large-volume crystalloid resuscitation many were taught — an argument with extra force in a pregnant woman whose capillary leak and splinted diaphragm make her prone to pulmonary oedema. The composition question (SMART) favours balanced crystalloid over chloride-rich saline. For the pressor itself, SOAP II established noradrenaline over dopamine as the default vasopressor — equivalent overall mortality but markedly fewer arrhythmias and worse outcomes with dopamine in cardiogenic shock — and that is now the obstetric default too.

The ventilation evidence is robust and transferable. Lung-protective low-tidal-volume ventilation (the ARMA / ARDS Network trial) reduces mortality in ARDS, and prone positioning (PROSEVA) reduces mortality in severe ARDS; both are applied in pregnancy, the latter with abdominal support and attention to the fetus, and both were given fresh prominence by the COVID-19 pandemic, in which pregnant women were over-represented among the severely ill and proning of pregnant patients moved from theoretical to routine. The live controversy here is less about whether to use these techniques than about access — proning, advanced ventilation and ECMO are tertiary-only in SA, so the system question (recognise early, refer in time) often determines the outcome more than the ventilator setting.

Amniotic-fluid embolism is where the evidence is weakest and the temptation to overclaim greatest. There is no diagnostic test and no specific treatment; the diagnosis is clinical and the management is supportive resuscitation plus aggressive correction of the coagulopathy. The much-discussed "A-OK" regimen (atropine, ondansetron and ketorolac, aimed at the proposed anaphylactoid mediators) is reported in case series only and is not an evidence-based standard — presenting it as established treatment is an error. The defensible position is that AFE is managed as a maternal collapse: high-quality CPR, early delivery if undelivered, massive-transfusion-protocol correction of DIC, and consideration of mechanical circulatory support where available. The UKOSS data reframed prognosis from uniformly fatal to a case fatality around 19%, with worse outcomes when the presentation is cardiac arrest and when hysterectomy for the bleeding is delayed — which makes early, decisive haemorrhage control part of the survival story.

Landmark trials & key evidence

A worked figure makes the read-across honest: PROSEVA moved 28-day mortality in severe ARDS from 32.8% to 16.0%, an absolute risk reduction of 16.8 percentage points, so the number needed to treat ≈ 1/0.168 ≈ 6 patients proned to prevent one death — a large effect from a free, low-technology manoeuvre, which is exactly why prone positioning belongs in the obstetric ARDS toolkit even where ventilators are scarce.

Exam traps & red flags

• Reading reassuring vital signs as stability. A young pregnant woman compensates until she is peri-arrest; normal observations in a woman who looks unwell are a late, binary warning, not reassurance. Score her (MEOWS), watch the trend, and act on the rising respiratory rate.
• Giving fluid before naming the shock state. Crystalloid rescues hypovolaemia and drowns cardiogenic shock. Use focused echo/POCUS to distinguish the empty hyperdynamic ventricle from the failing pump from the obstructed right ventricle, and treat that.
• Forgetting aortocaval compression. Resuscitating a collapsed pregnant woman supine caps her cardiac output; left lateral tilt / manual uterine displacement is a circulatory intervention, and in arrest it is the rationale for resuscitative hysterotomy.
• Delaying perimortem caesarean in maternal arrest beyond ~20 weeks. It is done for the mother, at the bedside, started within 4 minutes — not deferred for transfer to theatre or for a fetal heart check.
• Crystalloid resuscitation of major obstetric haemorrhage. The resuscitation is blood products and stopping the bleeding; large-volume crystalloid worsens the dilutional coagulopathy and the lethal triad.
• Treating amniotic-fluid embolism as if a specific drug existed. There is no diagnostic test and no proven specific therapy; the "A-OK" regimen is case-series only. Manage it as a maternal collapse — CPR, deliver if undelivered, aggressively correct the DIC.
• Under-supporting organs because she is pregnant. Dialysis, lung-protective ventilation, proning, vasopressors and ICU care are all owed to the pregnant woman; pregnancy changes how, not whether.
• Moving an unstable woman. Stabilise before transfer (airway, bleeding, vasopressor) and transfer with a monitored, trained escort; an arrest in the ambulance is a preventable death.
• Withholding or delaying escalation and referral. The commonest avoidable factor in SA maternal critical-care deaths is delay in recognition, resuscitation or referral — escalate to high-care/ICU and refer up the chain early, not after deterioration.
• Quoting trials as obstetric-specific when they are not. PROPPR, SOAP II, ARMA, PROSEVA and the fluid trials are largely non-pregnant data read across to obstetrics with judgement; claiming obstetric-specific evidence where there is none reads as uncritical.

Evidence anchors

• PROPPR — Holcomb et al., transfusion of plasma, platelets and red blood cells in a 1:1:1 vs 1:1:2 ratio in severe trauma, JAMA 2015;313(5):471–482
• WOMAN trial — effect of early tranexamic acid on mortality in postpartum haemorrhage, Lancet 2017;389(10084):2105–2116
• CRASH-2 — effects of tranexamic acid on death, vascular occlusive events and blood transfusion in trauma patients with significant haemorrhage, Lancet 2010;376(9734):23–32
• SOAP II — De Backer et al., comparison of dopamine and norepinephrine in the treatment of shock, N Engl J Med 2010;362(9):779–789
• ARMA / ARDS Network — ventilation with lower tidal volumes for acute lung injury and ARDS, N Engl J Med 2000;342(18):1301–1308
• PROSEVA — Guérin et al., prone positioning in severe acute respiratory distress syndrome, N Engl J Med 2013;368(23):2159–2168
• CLOVERS — early restrictive or liberal fluid management for sepsis-induced hypotension, N Engl J Med 2023;388(6):499–510
• SMART — Semler et al., balanced crystalloids versus saline in critically ill adults, N Engl J Med 2018;378(9):829–839
• Amniotic-fluid embolism — Fitzpatrick, Tuffnell, Kurinczuk & Knight, population-based UKOSS cohort and nested case-control, BJOG 2015;123(1):100–109
• Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2026 — Prescott/Evans et al., Crit Care Med 2026
• Care of the Critically Ill Woman in Childbirth; Enhanced Maternal Care (2018) — joint guidance of the Royal College of Anaesthetists, RCOG, Royal College of Midwives, Intensive Care Society, Faculty of Intensive Care Medicine and the Obstetric Anaesthetists' Association; defines the levels of maternal/critical care and escalation.
• South Africa NDoH / NCCEMD Saving Mothers (Eighth Comprehensive Triennial Report, 2020–2022, and subsequent annual reports) — obstetric haemorrhage among the leading direct causes; non-pregnancy-related infection (mainly AIDS) the leading overall cause; delay in recognition, resuscitation and referral, and scarce critical-care capacity, named as avoidable factors.
• WHO — maternal near-miss / maternal organ-dysfunction framing and the case for critical-care capacity in low- and middle-income settings.