Peripartum Hyponatraemia TOG 2022

Question 1

What level of hypoNa poses significant risk to mother and newborn

Answer 1

125mmol/L

Question 2

When should Na+ levels be monitored in labour

Answer 2

Oxytocin infusion
Dextrose and variable rate Insulin infusion
Positive fluid balance of > 1500 ml
Na+ less than/ equal to 130mmol/L

Question 3

What is the next step of management if Na+ levels drop to 125-130 mmol/L

Answer 3

1.Fluid restriction to 80 ml/hr
2. Repeat Na in 4 hours

Question 4

What’s the next step if Na levels drop to less than or equal to 125 with or without symptoms

Answer 4

Restrict fluid to 30ml/hr
Repeat Na levels in 2 hours
STOP oxytocin
mDT

Question 5

What is the next step of management after MDT review in persisting/worsening severe hyponatraemia

Answer 5

CCU involvement
200mls of 2.7% saline in 30 minutes
20 mg furosemide if fluid overload

Question 6

How is moderate hyponatraemia (125-130) managed postpartum?

Answer 6

No fluid restriction necessary

Repeat Na in 8hrs if persistent risk factors present

Question 7

What’s the positive fluid balance by third trimester of pregnancy ?

Answer 7

6.5-8.0 litres of fluid

Question 8

What’s the level of change of plasma osmolality in pregnancy?

Answer 8

It falls by 10 mOsm/kg to 280 mOsm/Kg from 10 weeks to 1-2 weeks postpartum

Question 9

What component of Renin Adlosterone Angiotensin system is not affected by pregnancy adaption?

Answer 9

Angiotensin converting enzyme

Question 10

What is the physiologic levels of sodium in pregnancy?

Answer 10

900-1000 mmol(mEq) of Na is retained
Normal levels is therefore 130-145 mmol/L ( 135-145 outside pregnancy)

Question 11

Is oliguria always pathologic in labour?

Answer 11

False
Physiologic oliguria can occur

Question 12

What sites of stimuli leads to oxytocin release ?

Answer 12

Cervix, vagina and breast

Question 13

Why is the risk of PPH increased with prolonged spontaneous or induced labor?

Answer 13

Oxytocin receptors become desensitised with prolonged binding to oxytocin.

Question 14

Prolonged labour with continuous stimulation of ADH receptors by oxytocin becomes increased or decreased?

Answer 14

Increased.
Not affected by Down regulation of uterine receptors by stress hormones.

Question 15

What is the risk of dilution hyponatraemia in those receiving IV fluid in labour

Answer 15

Less than 1% for 1 liter
26% if received more than 2.5 litres

Question 16

What % of sheehans syndrome present with postpartum hyponatraemia

Answer 16

50% which is secondary to adrenal insufficiency