MOSS pre-course preparation

Obstetrics Critical Incidents E-learning module

The aim of this module is to prepare you to identify and deal with common critical incidents encountered in obstetrics. This also doubles up as a pre-course study material and test before the MOSS (Multidisciplinary Obstetric Scenario Simulation). You are required to read the material and attempt the MCQ before the course so as to aid your understanding and performance.

As critical incidents always require teamwork, this module is geared towards all healthcare professionals involved in the care of obstetric patients.

The module is presented in sections, each depicting a different critical incident. At the end of the module, a series of multiple choice questions will test your skills and knowledge on the subject.  

By the end of the module, you should be able to:

  1. Identify the critical incident
  2. Understand clearly your role and your responsibilities
  3. Deal with the scenario together as a team 

Total or Complete Spinal

Total/Complete Spinal

Cause: Cervical spread of intrathecal local anaesthetic

Risk Factors:

  1. Unrecognised dural tap following epidural
  2. Epidural catheter migration
  3. Large epidural top up dose
  4. Large spinal anaesthetic dose


  1. Rapid and unexpected rise in sensory blockade (numbness and weakness)
  2. Shortness of breath
  3. Bradycardia
  4. Hypotension (Rapid onset)
  5. Nausea and vomiting
  6. Loss of consciousness
  7. Apnoea
  8. Cardiac arrest

Differential Diagnosis:

  1. Vasovagal
  2. Haemorrhage
  3. Local anaesthetic toxicity
  4. IVC compression
  5. Embolus


Call for assistance early, communicate with urgency and delegate

A: Intubate early (RSI, Pregnant women are prone to reflux)

B: Ventilate with 100% 02 - Until block has worn off (usually about 2 hours) 

C: HR= Bradycardia (Atropine; Ephedrine) + Hypotension ( Minimise aortocaval compression, Raise legs, IV fluids, Vasopressors) + Cardiac arrest (CPR – follow ALS guidelines)

D: Appropriate sedation until block has worn off (e.g. Propofol)

Delivery of fetus after 4 mins if there is no response 

Massive Obstetric Haemorrhage

Massive Obstetric Haemorrhage (MOH)


  1. Blood loss >1500mls and ongoing
  2. Decrease Hb >4g/dL (CEACCP article 2005)
  3. Acute transfusion > 4 units (CEACCP article 2005)
  4. Signs of shock



  1. Early Pregnancy (Incomplete abortion, Ruptured ectopic)
  2. Antepartum (Placenta previa, Placental abruption, Uterine rupture, Trauma)
  3. Postpartum (Tone, Tissue, Trauma, Thrombin)


Immediate management:

Call for help: 2222 for obstetric crash call

MOH protocol in hospital to be followed

Commuicate: Senior anaesthetist, obstetrician and midwife, paediatrician, blood bank and haematologist

A: Maintain own or Intubate with RSI for surgical control if required

B: 100% O2 to patient & ventilate if required


  • x2 large bore (14g) cannule for access
  • IV fluids (warm crystalloids of up to 2L, before blood arrives)
  • Blood products (guided by clinical circumstances & coagulation tests)
    • Red cells (X-match if available; type specific if urgent)
    • FFP (4 units for every 6 units RBC)
    • Other blood products if required (e.g. cryoprecipitate, platelets)
  • Vasopressors for vital organ perfusion if required
  • Rub up uterus or bimanual compression
  • Active patient warming

D: Drugs Haemostatic


Definitive management: Specific to the cause.

  1. Surgical delivery
  2. Surgical removal retained products
  3. Surgical repair genital tract trauma
  4. Uterotonic drugs
  5. Bimanual compression of uterus
  6. Uterine haemostatic sutures
  7. Selective arterial occlusion or embolization by interventional radiology
  8. Hysterectomy

Local Anaesthetic Toxicity

Local Anaesthetic (LA) Toxicity


  1. Tinnitus
  2. Metallic taste
  3. Circumoral numbness



  1. Sudden change in mental status
  2. Severe agitation
  3. Loss of consciousness
  4. Tonic-clonic convulsions
  5. Arrhythmias: Bradycardia, conduction blocks, ventricular tachyarrhythmias
  6. Cardiac arrest


Immediate Management:

  1. Stop injecting the LA
  2. Call for help


A: Maintain airway, and intubate if required

B: 100% 02, ventilate if required (hyperventilation may help by increasing plasma pH in presence of metabolic acidosis)

C: IV access + Assessment of cardiovascular status (Management see below)

D: Seizure control (Benzodiazepine, Thiopental or Propofol – Small incremental doses)


Cardiovascular (CVS) status:

CVS arrest

  1. CPR using ALS guidelines (CPR may last >1 hour)
  2. IV Lipid Emulsion
  3. CPR to continue throughout lipid emulsion treatment

Without CVS arrest

  1. Conventional treatments for hypotension, bradycardia and tachyarrhymias


Lipid Emulsion:

Immediate IV bolus 20% Lipid Emulsion @ dose of 1.5mls/kg over 1 minute +

Infusion of 20% Lipid Emulsion @ dose of 15mls/kg/hr


After 5 minutes, if CVS stability not restored or adequate circulation deteriorates

  1. Maximum of 2 repeat boluses (same dose) @ 5 minute intervals  +
  2. Double rate of infusion to 30 mls/kg/hr


Infusion to continue until patient is stable and adequate circulation restored or maximum dose of lipid emulsion given (Max dose: 12mls/kg)


Follow up:

  1. Safe transfer to clinical area with appropriate equipment and staff until sustained recovery achieved
  2. Exclude pancreatitis by regular clinical review (include daily amylase or lipase essay for 2 days)
  3. Report cases to NSPA and International registry (