Hyperemesis Gravidarum

Question 1

Hyperemesis Gravidarum

Answer 1

Hyperemesis gravidarum

Hyperemesis gravidarum describes excessive vomiting during pregnancy. It occurs in around 1% of pregnancies and is thought to be related to raised beta hCG levels. Hyperemesis gravidarum is most common between 8 and 12 weeks but may persist up to 20 weeks*.

Associations
multiple pregnancies
trophoblastic disease
hyperthyroidism
nulliparity
obesity

Smoking is associated with a decreased incidence of hyperemesis

Management
antihistamines should be used first-line (BNF suggests promethazine as first-line)
ginger and P6 (wrist) acupressure: NICE Clinical Knowledge Summaries suggest these can be tried but there is little evidence of benefit
admission may be needed for IV hydration

Complications
Wernicke's encephalopathy
Mallory-Weiss tear
central pontine myelinolysis
acute tubular necrosis
fetal: small for gestational age, pre-term birth

*and in very rare cases beyond 20 weeks

Question 2

Hyperemesis Gravidarum Mx: Example Question

Answer 2

A 28-year-old woman presents with daily intractable vomiting. She is 10 weeks pregnant with 3+ ketones in her urine. Initially, she tried cyclizine from her general practitioner with little success. You suspect hyperemesis gravidarum. Apart from rehydration and anti-emetics, what also should be prescribed?

	> Thiamine
	Carbohydrate replacement with 5% dextrose
	Niacin
	Vitamin B12
	Folate

Nausea and vomiting are both common in pregnancy, affecting 50-80% of pregnant women. Hyperemesis gravidarum occurs in 0.3-3% of pregnancies. It is a diagnosis of exclusion and other causes of vomiting should be considered: urinary tract infection, endocrine causes (thyrotoxicosis, diabetic ketoacidosis etc), surgical causes and drugs such as iron supplements.

The Royal College of Obstetrics and Gynaecology (RCOG) guidelines state:
Thiamine supplementation (either oral or intravenous) should be given to all women admitted with prolonged vomiting, especially before administration of dextrose or parenteral nutrition. (https:www.rcog.org.uk/globalassets/documents/guidelines/green-top-guidelines/gtg69-hyperemesis.pdf) 

A 5% dextrose intravenous infusion may precipitate Wernicke’s encephalopathy. In addition, patients are frequently hyponatraemic and therefore sodium chloride 0.9% is most appropriate (+/- potassium replacement).

Folic acid (400 micrograms) daily is recommended for all women prior to conception and up to the 13th week of pregnancy. Women who are deemed higher risk of spina bifida are advised to take 5mg daily. This is to prevent neural tube defects but has no role in hyperemesis gravidarum.

Vitamin B12 deficiency is not of clinical concern in this scenario.

Niacin deficiency leads to pellagra. Hyperemesis gravidarum is a self-limiting condition associated with pregnancy and therefore niacin deficiency is not of clinical concern here.