Obstetric Shock: Causes, Treatment and Prevention

Shock is among obstetric emergencies that occur when there is sudden fall or collapse of a patient during pregnancy, labour or shortly after delivery. In this condition, the body does not work normally and organs such as the heart, brain, lungs and kidneys are adversely affected due to hypoxia (lack of oxygen).

What is obstetric shock?

Whenever the circulatory system is unable to maintain adequate perfusion of vital organs or inability of the circulatory system to provide the tissues demands of oxygen and nutrients and to remove metabolic wastes, then shock is said to have occurred. 

Obstetric shock is a condition of collapse due to failure of the maternal circulatory system to meet the body’s need for oxygen, nutrients and removal of waste substances. The causes of shock can be either haemorrhagic or non-haemorrhagic.

The prompt action of the midwife, her competency and skills are required to reduce the risk of maternal morbidity and mortality related to obstetric shock.

Obstetric shock

 Signs and symptoms of obstetric shock

  • Restlessness
  • Anuria or oliguria (less than 30ml per hour) i.e. decreased urinary output
  • Air hunger and unconsciousness
  • Dimness of vision
  • Pallor in the inner eyelids, palms and around mouth
  • Dry mouth
  • Cold and clammy skin (greyish blue or pale skin, shivering, increased perspiration)
  • Skin may be flushed.
  • Confusion and anxiety
  • Fast and weak thready pulse (110 per minute or more); i.e. rapid, weak pulse, slow bounding pulse.
  • Hypotension (low blood pressure, systolic pressure less than 90mmHg); i.e. Blood pressure is normal in the beginning but after about 40% volume loss, blood pressure is unrecordable.
  •  Rapid breathing (30 breaths per minute or more), but as the mother’s condition worsens breathing becomes deeper and slower. Finally mother may become unconscious.
  • There may be pyrexia or sub-normal temperature

What are early signs of shock?

Early stage of shock is characterized by:

  • Anxious, restless
  • Rapid heart rate at 110 beats per minute or more
  • Fast and shallow respiration (30 or more breaths per minute).
  • Pale conjunctiva, palms, mouth, tips of fingers
  • Low blood pressure (systolic less than 90mmHg)
  • Haemoglobin of 8/100ml or greater
  • Clear lungs
  • Cold clammy skin, though patient be sweating.
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What are late signs of shock?

Late stage of shock is characterized by:

  • Confused or unconsciousness
  • Very fast, weak pulse
  • Very fast, shallow breathing
  • Pale and cold extremities
  • Very low blood pressure
  • Pulmonary oedema
  • Haemoglobin less than 8g/100ml or haemocrit less than 26%
  • Oliguria (less than 30ml/hour).

What are causes of obstetric shock?

  • Haemorrhage: Haemorrhagic shock may occur at any stage of pregnancy, labour or puerperium, leading to hypovolemia, non-haemorrhagic shock may be due to;
  • Trauma
  • Prolonged labour/psychological distress
  • Fluid loss
  • Septicemia
  • Pulmonary embolism
  • Following normal labour

Diagnosis of obstetric shock

The midwife should always be well-skilled and prepared. He or she should suspect or anticipate shock in the following cases such as:

  • Bleeding in early pregnancy (e.g. abortion, ectopic pregnancy, or other cervical lesions)
  • Bleeding in late pregnancy or labour (e.g. abruptio placenta, Vasa praevia or placenta praevia)
  • Infection (e.g. septic abortion)
  • Trauma to either cervix or uterus or vagina
  • Bleeding in postpartum haemorrhage (e.g. uterine atony or rupture of uterus)

Physiology of obstetric shock

There are four stages of shock in which if nothing is done to arrest the condition, the patient would die.

Stage I: Initial phase:

Here, there is reduction in blood or fluid which lowers the venous to the heart.  This makes the ventricles of the heart to be poorly filled, resulting in a decline in stroke volume and cardiac output. The falling of cardiac output and venous return also result in decline in blood pressure, which adversely affect oxygen supply to tissues and cell function is impaired.

Stage II: Compensatory or non-progressive phase:

In this phase, the body puts up its effort to maintain adequate blood supply due to reduced cardiac output. This is achieved by sympathetic nervous system stimulating the receptors in the aorta and carotid arteries, causing blood to be redirected to the essential organs with constriction of some vessels in the gastrointestinal tract, kidneys, lungs and skin.

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This is often characterized by the skin becoming pale and cool, slow-down of peristalsis, reduced urinary output, and impaired gaseous exchange due to reduction in blood flow to the lungs; rapid heart rate in attempt to improve cardiac output and blood pressure; dilation of eye pupils; sweating, moist and clammy skin.

Adrenaline (epinephrine) produced by the adrenal medulla, aldosterone produced by the adrenal cortex and anti-diuretic hormone (ADH) produced by the posterior lobe of the pituitary –all unite together to cause vasoconstriction, increase cardiac output and reduce urinary output, thereby making venous return to the heart to improve. However, if nothing is done to replace the lost fluid, the patient’s condition would deteriorate further.

Stage III: Decompensatory or progressive phase: When the compensatory effort in phase II      is not maintained by fluid replacement, multisystem organ failures occur as the vital organs no long receive adequate perfusion. There would be more declines in blood pressure and cardiac output with resultant weak or absent pulse.

Stage IV: Irreversible/ phase of inevitable death: This phase is characterized by multisystem organ failure and cell destruction and finally death occurs.

Types of obstetric shock

Haemorrhagic/hypovolemic shock:

This is a shock occurring due to excessive blood loss and may be caused by:

  1. Causes of bleeding in early gestation{e.g. abortion, miscarriage, ectopic pregnancy, or other cervical lesions (e.g. cervical erosions)}
  2. Causes of antepartum haemorrhage (e.g. abruption placenta or placenta praevia)
  3. Causes of postpartum haemorrhage (e.g. atony of the uterus, cervical lacerations, or retained placenta)

Anaphylactic shock:

This may be caused by sensitivity to drugs (allergic reactions), anaesthestic complications (e.g. Mendelson’s syndrome) or embolism (e.g. amniotic fluid, air or thrombus)

Endotoxic shock:

This is a shock due to release of toxins (e.g. from septicemia) into the bloodstream thereby disrupting the circulatory system. The toxins released causes generalized vascular disturbance.

Cardiogenic shock:

This is a form of obstetric shock resulting in inefficient or ineffective contraction of the cardiac muscles, which may be caused by heart failure or myocardial infarction.

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Neurologic shock:

This shock occurs due to painful conditions such as:

  • Ruptured uterus
  • Acute inversion of the uterus
  • Rough internal version( antenatal management of breech)
  • Ruptured ectopic pregnancy
  • Concealed accidental haemorrhage (e.g. abruptio placenta)
  • Rapid evacuation of the uterine contents(e.g. precipitate labour, or rupture of membranes in polyhydramnios)
  • Breech or forceps extraction prior to full cervical dilatation

How to manage obstetric shock

  1. Call for help: Delay is dangerous!  Since shock is a progressive condition, getting adequate help on time would save the maternal life and vice versa.
  2. Maintain airways: Turn the woman on her side, clear any mucus occluding her airways with any available device (e.g. suction machine). Start resuscitative measures immediately. Provide artificial respiration and give oxygen at a rate of 4—6litres per minute if available. Loosen tight clothing and protect the woman from any further injury.
  3. Replace lost fluids: Secure intravenous line promptly with two wide-bore intravenous carnulae.  Collect blood sample  for estimation of haemoglobin and cross-marching prior to administration of drugs(e.g. hydrocortisone or adrenaline) and intravenous fluid(e.g. Normal saline, Ringer’s lactate)
  4. Arrest haemorrhage: Try to identify the source of bleeding and stop it immediately.
  5. Provide warmth: Avoid over-heating the patient. Record intake and output

What are the roles of midwives in managing obstetric shock

  • Detect early signs of shock and put the mother in a comfortable position.
  • Check and record mother’s vital signs and FHS every 15 minutes.
  • Raise foot end
  • Maintain airway, administer oxygen
  • Try to make up fluid loss by  intravenous infusion
  • Call for medical assistance
  • In community, start resuscitation and arrange to transport the mother to a hospital and accompany her.
  • Oxygenate her on way to hospital in case oxygen is available in ambulance
  • Sometimes, shock is due to psychological stress; provide good support encouragement and emotional security.
  • Reassure the husband and family members
  • Maintain proper record and documentation.

What are complications of obstetric shock?

Poorly managed shock is associated with these complications: