Obstetric emergencies

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46

Obstetric emergencies

Introduction

Worldwide, one woman dies every minute of every day from a complication of pregnancy. In developed countries, maternal death is uncommon, but evidence from the UK Confidential Enquiry into Maternal Deaths found substandard care in around two-thirds of cases. This is partly due to the fact that most obstetric emergencies are rare and often unfold with such rapidity that junior medical staff can find themselves facing potentially catastrophic conditions that they may never have seen before, let alone have ever managed.

This chapter will examine the obstetric emergencies listed below:

icon01.gif unexpected collapse

icon01.gif amniotic fluid embolism

icon01.gif prolapsed umbilical cord

icon01.gif retained placenta

icon01.gif shoulder dystocia

icon01.gif uterine inversion

icon01.gif uterine rupture.

See also haemorrhage (Chapter 34), eclampsia (Chapter 36) and pulmonary embolism (p. 254):

Principles of management

Anticipation and preparation are essential – and they may lead to prevention. For example, if the mother has a history of postpartum haemorrhage, anticipation with i.v. access and blood sent for group and save in early labour may make an important difference to the outcome should the problem recur. If there are risk factors for shoulder dystocia, such as a presumed large fetus in a mother with diabetes and a long first stage of labour, it is important to ensure that an experienced midwife is allocated to care for her and that senior medical staff are present on the labour ward at the time of delivery.

In addition, as life-threatening emergencies are relatively rare, it is important that there should be regular ‘fire drills’ of obstetric emergencies to ensure that all staff are fully prepared, that equipment is fully functional and that supporting systems (portering, laboratory, etc.) are prepared. It should also be remembered that emergencies can arise anywhere in the unit, not just in the labour ward. There is now clear evidence of the benefits of formal team-training and use of simulation in rare obstetric emergencies. This applies to both technical aspects of delivery and non-technical (team working) aspects of care.

The principles outlined in Box 46.1 can be adapted for initial resuscitation in all obstetric emergencies which involve maternal compromise. Remember that there are often two lives at stake and in most emergencies, minutes or even seconds count. Remember too, however, that panicking is never helpful. A good principle to remember is that the fetus rarely needs to be resuscitated directly – ‘resuscitate the mother and you will resuscitate the fetus’. It should be noted that an obstetric emergency can cause profound lifelong psychological problems for both the mother and her partner. This can manifest itself as postnatal depression, post-traumatic stress syndrome and a real fear of becoming pregnant again. Counselling and debriefing after such experiences should be encouraged both while the woman is in hospital and some weeks later.

Box 46.1

On identification of an emergency

1. Call for help. Emergency bleep the obstetrical emergency team. This should include a senior obstetrician and anaesthetist, the theatre team, a person skilled in neonatal resuscitation, the midwifery sister, a porter and the junior medical staff

2. Ensure you have checked the environment is safe for you and apply ABC if appropriate:

icon01.gif Airway: Place patient head down, maintain airway patency, give O2 (15 L/min) via facemask, attach pulse oximeter

icon01.gif Breathing: Assess, monitor respiratory rate, ventilate if indicated

icon01.gif Circulation: Insert two grey/brown i.v. cannulae, take full set of bloods (FBC, coagulation, cross-match 6 units, urea and electrolytes, and liver function tests). In all cases of severe haemorrhage, give 1 litre 0.9% saline or Hartmann’s solution stat

3. Check maternal observations as appropriate, e.g. pulse, blood pressure, O2 saturation monitoring and bladder catheter for urinary output measurement
At this point, see the appropriate management guidelines for the particular emergency (e.g. 4 Hs and 4 Ts, Box 46.2) as well as:

4. Considering an ECG, blood glucose measurements, central venous monitoring and an arterial line

5. Using a compression cuff and warmer to give fluids if rapid administration is indicated

6. Remembering to document fully in the notes all observations, procedures and actions with date, timings, a signature and a printed name

7. Remembering the mother’s partner. Although some partners might wish to wait outside, others may prefer to stay in the room.

Resuscitation

Resuscitation should have a strong focus on the ABC of basic life support as noted in Box 46.1. The aim is to resuscitate the mother and then (and only then) to consider the welfare of the baby. Resuscitation in pregnancy has some differences from that in a non-pregnant person, as outlined below, but it is still essential to approach the problem by using ABC, and then consider possible causes. The 4 Hs and 4 Ts listed in Box 46.2 are helpful.

Box 46.2

Causes of collapse

4 Hs

icon01.gif Hypoxia

icon01.gif Hypovolaemia

icon01.gif Hypo/hyperkalaemia

icon01.gif Hypothermia

4 Ts

icon01.gif Thromboembolism

icon01.gif Toxic (including local anaesthesia)

icon01.gif Tamponade

icon01.gif Tension pneumothorax

Also consider:

icon01.gif Eclampsia (including magnesium toxicity)

icon01.gif Amniotic fluid embolus

The key resuscitation differences are that:

icon01.gif the aorta and vena cava are compressed by the gravid uterus, impeding venous return and reducing cardiac output

icon01.gif there is an increased risk of aspiration of stomach contents due to relaxation of the oesophageal–gastric junction (progesterone effect) and the pressure of the uterus

icon01.gif difficult intubation is more common in the pregnant than in the non-pregnant patient (1:300 vs 1:3000) – short neck and laryngeal oedema

icon01.gif chemical pneumonitis is more likely than in the non-pregnant state, owing to the decreased pH of the stomach contents and the increased chance of inhaling the contents because of the changes outlined above.

It is therefore important, in the early stages of resuscitation, to:

icon01.gif tilt the patient to the left by 15–30° (reduces aortocaval compression and increases potential cardiac output by 25%)

icon01.gif apply cricoid pressure and intubate early, to avoid aspiration of gastric contents and to facilitate oxygenation

icon01.gif involve a senior obstetrician and anaesthetist immediately or as early as possible (to facilitate intubation and early caesarean section where and when appropriate).

In cases of cardiorespiratory arrest, the revised Resuscitation UK guidelines (2010) should be followed. These have moved the emphasis for basic life support towards a single compression-ventilation (CV) ratio of 30:2. If the mother is not delivered, left lateral tilt can be achieved using firm support under the right hip (an assistant can be asked to kneel and use their knees to support the patient in left lateral tilt).

After about 20–22 weeks, it is essential to perform a caesarean section early if resuscitation is unsuccessful (at this gestation, the fundus of the uterus will be at or above the level of the umbilicus). The decision for perimortem caesarean section should be made by 4 min if there is no response to active resuscitation, and the delivery by 5 min (the ‘4-minute rule’). An anaesthetic is not required in order to proceed. This is primarily to save the life of the mother and forms part of the resuscitation technique. It makes CPR more efficient by:

icon01.gif increasing venous return

icon01.gif improving ease of ventilation

icon01.gif allowing CPR to be carried out in the supine position

icon01.gif reducing oxygen requirement after delivery.

Amniotic fluid embolism

Epidemiology

This is one of the most catastrophic conditions that can occur in pregnancy. It is rare, with an incidence somewhere between 1:10 000 and 1:30 000. As a precise diagnosis can be difficult, it is also difficult to establish an accurate mortality rate, but it is probably around 20–40%.

Aetiology

The exact pathophysiology remains unclear. It was believed that some breakdown occurred in the physiological barrier separating the mother and fetus, allowing a bolus of amniotic fluid to enter the maternal circulation. This bolus moved to the pulmonary circulation and produced massive perfusion failure, bronchospasm and shock. More recently, it has been suggested that the underlying mechanism may be an anaphylactoid reaction to fetal antigens entering the maternal circulation and individual variations in sensitivity to these antigens are reflected by the severity of the resulting clinical picture.

Risk factors

Amniotic fluid embolism can occur at any time in pregnancy but it most commonly occurs in labour (70%), after vaginal delivery (11%) and following caesarean section (19%). The following risk factors have been identified:

icon01.gif multiparity

icon01.gif placental abruption

icon01.gif intrauterine death

icon01.gif precipitate labour

icon01.gif suction termination of pregnancy

icon01.gif medical termination of pregnancy

icon01.gif abdominal trauma

icon01.gif external cephalic version

icon01.gif amniocentesis.

Clinical features

The clinical picture usually develops almost instantaneously and the diagnosis must be considered in all collapsed obstetric patients. The mother may demonstrate some or all of the signs and symptoms listed in Box 46.3 but classically a woman in late stages of labour or immediately postpartum starts to gasp for air, starts fitting and may have a cardiac arrest. There is often a profound disseminated intravascular coagulopathy (DIC) with massive haemorrhage, coma and death. There are inevitably signs of fetal compromise.

Box 46.3

Symptoms and signs of amniotic fluid embolus

Symptoms

icon01.gif Chills

icon01.gif Shivering

icon01.gif Sweating

icon01.gif Anxiety

icon01.gif Coughing

Signs

icon01.gif Cyanosis

icon01.gif Hypotension

icon01.gif Bronchospasm

icon01.gif Tachypnoea

icon01.gif Tachycardia

icon01.gif Arrhythmias

icon01.gif Myocardial infarction

icon01.gif Seizures

icon01.gif Disseminated intravascular coagulopathy

Diagnosis

The definitive diagnosis is usually at autopsy and is made by confirming the presence of fetal squames in the pulmonary vasculature. It is also possible to confirm the diagnosis in a surviving patient, again by finding fetal squames in washings from the bronchus or in a sample of blood from the right ventricle. In the acute situation, as there is no single clinical or laboratory finding which can diagnose or exclude amniotic fluid embolism, the diagnosis is made clinically by exclusion.

Management

This is primarily supportive and should be aggressive. There is, however, no evidence that any specific type of intervention significantly improves maternal prognosis. Initial therapy is aimed at supporting cardiac output and management of DIC. If the woman is undelivered, an immediate caesarean section may be appropriate, providing the mother can be stabilized.

A chest X-ray will often show pulmonary oedema, and an increase in right atrial and right ventricular size. The ECG demonstrates right ventricular strain and there is a metabolic acidosis (reduction of pO2 and pCO2).

In addition to the initial management of an obstetric emergency (Box 46.1), therapy may include:

icon01.gif aggressive fluid replacement

icon01.gif maintenance of cardiac output with a dopamine infusion

icon01.gif treatment of anaphylaxis with adrenaline (epinephrine), salbutamol, aminophylline and hydrocortisone

icon01.gif treatment of DIC with fresh frozen plasma and cryoprecipitate

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