Obesity In A Pregnant Patient

Question 1

A 34-year-old primiparous female is being assessed in the obstetric anaesthetic clinic. She has a body mass index of 46 kg/m2.

How is body mass index classified?

Answer 1

WHO classification:
Underweight - <18.5 kg/m2
Normal/Healthy weight - 18.5-24.9
Overweight - 25-29.9
Obese I - 30-34.9
Obese II - 35-39.9
Obese III - 40+

Question 2

What are the risks associated with obesity in pregnancy?

Answer 2

Obstetric risks:

• Increased risk of pre-eclampsia.
• Increased incidence of gestational diabetes.
• Increased risk of caesarean birth.
• Higher likelihood of postpartum haemorrhage.
• Overall increase in morbidity and mortality.
• Increased risk of venous thromboembolism.

Neonatal risks:

• Assessment of foetal size and presentation more difficult.
• Increased risk of congenital abnormalities.
• Higher chance of stillbirth, premature birth and miscarriage.

Anaesthetic risks:

• Difficult intravenous access.
• Increased risk of difficult or failed intubation.
• Increased risk of a dural puncture during epidural insertion.
• Increased risk of failure of neuraxial blockade.
• Increased risk of high or total spinal with both epidural top-up and spinal anaesthesia for operative procedures.
• Excessive sedation if sleep apnoea present.

Question 3

What are the risk factors associated with the development of venous thromboembolism in pregnancy?

Answer 3

Pre-existing risk factors:
* History of VTE.
* Known thrombophilia.
* Increasing age (>35 years).
* Raised BMI.
* Smoker.

Obstetric risk factors:
* Pre-eclampsia.
* Multiple pregnancy.
* Prolonged labour or caesarean section.
* Major obstetric haemorrhage.
* Preterm or stillbirth.

Transient risk factors:
* Non-obstetric surgical procedure.
* Dehydration.
* Immobility.

Question 4

How should the above patient be managed in terms of her risk of VTE?

Answer 4

• The risk of venous thromboembolism should be assessed at her booking appointment.
• Depending on the risk, this patient may need thromboprophylaxis during the antenatal period.
• Low molecular weight heparins are the first-line agent in these patients.

Question 5

The patient has been booked for induction of labour due to gestational diabetes mellitus.

What are the important aspects in her management when she is admitted?

Answer 5

Staffing and equipment:

• A senior obstetric, midwifery and anaesthetic team should be available and alerted when the patient is admitted.
• Extra equipment may be required e.g. bed, chair and retractors.

Question 6

The patient has been booked for induction of labour due to gestational diabetes mellitus. What are the important aspects in her management when she is admitted?

Answer 6

Specific anaesthetic management:

• Both the anaesthetist and patient should be aware that procedures might be more challenging, including neuraxial blockade, cannula insertion and intubation. The patient should be made aware of the risks associated with this and help should be facilitated early to mitigate these.
• Te benefits of an early epidural should be clearly explained to the patient, including avoidance of a general anaesthetic should a caesarean section be indicated; allowing adequate time for insertion and loading; and facilitating easier insertion during the earlier stage of labour.
• If the patient is on thromboprophylactic agents, these need to be omitted appropriately in order to facilitate neuraxial blockade.
• Regular antacid prophylaxis should be given in labour, and the patient should be limited to clear fluid only during labour to decrease the risk of aspiration should a general anaesthetic be required.
• Recovery after a general anaesthetic is a high-risk time for both aspiration and hypoventilation, and the patient should be monitored closely should this be required.