Tutorial 3: Hyperemesis gravidarum Flashcards
What is Hyperemesis Gravidarum?
A condition where persistent vomiting occurs and subsequently interferes with fluid intake and nutrition status resulting in malnutrition and/or weight loss, fluid/electrolyte and acid-base imbalance.
Although there are varying definitions, hyperemesis gravidarum is characterised by persistent vomiting, volume depletion, ketosis, electrolyte disturbances, and weight loss (>5%).
Why is severe Hyperemesis Gravidarum of concern?
With severe hyperemesis, the effects of electrolyte imbalances, vitamin deficiencies and inadequate nutrition can cause maternal and fetal morbidity.
What causes Hyperemesis Gravidarum?
There are several theories about hyperemesis is pregnancy and these are multifactorial, including biological, psychological and sociocultural factors. Some theories point to increased oestrogens and ß-hCG that occur during pregnancy to be involved.
- Increased oestrogens causes: a) decreased gastric motility and b) delayed gastric emptying.
This results in 1) an altered pH and 2) increased H. pylori colonisation
- Increased BhCG causes: a) stimulation of secretory processes in the upper gastrointestinal tract, by the ß sub-unit of ß-hCG. b) stimulation of TSH receptors, due to the structural similarity to thyroid stimulating hormone (TSH).
How does “normal morning sickness” compare to HG?
Nausea and vomiting in pregnancy (NVP) is a very common symptom (70-85% of pregnancies). It is typically mild and self-limiting, often occurring in the morning. NVP can be grouped into 3 categories:
- NVP w/o volume depletion: ‘normal morning sickness’
- NVP w. volume depletion and electrolyte imbalance: Increasing severity
- NVP with persistent vomiting, volume depletion and electrolyte imbalance, ketosis and >5% weight loss = Hyperemesis gravidarum (0.5-2.0% of pregnancies). Most severe form of NVP
What would you include in your Hx and Ex of a patient with NVP?
Symptoms:
- Severe nausea with vomiting >3 times per day
- smelly breath
- unable to tolerate oral food/fluid
- lethargy
- oliguria
- dry mouth, thirst
Signs:
- Dehydration: tachycardia, reduced skin turgor, dry mucosa, low JVP.
- Malnutrition: weight loss >5%, anaemia. Reduced level of consciousness
What are important differentials for Hyperemesis Gravidarum/NVP?
Pregnancy Causes of N&V:
- Hyatidiform mole (Molar pregnancy)
- Multi-gestational pregnancy
- Hyponatraemia
Non-pregnancy causes of vomiting:
- hepatitis,
- pyelonephritis,
- appendicitis,
- pancreatitis,
- cholecystitis,
- bowel obstruction,
- raised intracranial pressure,
- hyperthyroidism,
- gestational trophoblastic disease
What are complications of HG which can cause serious morbidity?
- Wernicke’s encephalopathy (thiamine deficiency): Confusion, ocular abnormalities and ataxia
- Vitamins B12 and B6 deficiencies: Anaemia and peripheral neuropathies
- Depression
- Mallory-Weiss tears
- Thrombosis
- Hyponatraemia: Central pontine myelinolysis – occurs when Na replacement is too fast
What investigations would you perform for Hyperemesis Gravidarum?
- Full blood count: Anaemia, infection
- Urea and electrolytes: K, Na, Mg imbalances
- _Liver function test_s: Exclude alternative aetiologies
- Urinalysis: Ketonuria/rule out UTI or pyelonephritis
- Fetal ultrasound: Presence of multiple gestation/other fetal abnormalities
Overall, what is the treatment outline for HG?
- Electrolyte imbalance and dehydration
- Prophylaxis against complications
- Relief of symptoms
- Support and reassurance
- Diet and lifestyle modification: small dry meals, eating when nausea least severe, avoiding aggravating foods/smells
- Oral ginger (atleast 1 g daily)
- Corticosteroids (only in severe HG)
How do you treat electrolyte imbalance and dehydration in HG?
- Replacement fluid: IV 0.9% normal saline + Potassium (+Mg, P depending on what electrolyte levels are)
- Avoid using dextrose infusions as they increase the risk of the rare but serious complication of thiamine deficiency, Wernicke’s encephalopathy.
What prophylaxis against complications would you use for HG?
- Folic Acid 5mg PO dialy (in first trimester)
- Thiamine (Vit B1) 50mg PO/100mgIV daily
- Pyridoxine (Vit B6) 50mg PO daily
What medications would you give for relief of symptoms in HG?
- Metaclopramide (A): 5-10mg, IV/IM/PO q6hrly
- a) Cyclizine (A): 25-50mg IV/PO q8hrly. b) Prochlorperazine (C): 25mg PR q12hrly, or 5-10mg PO q6-8hrly
- Ondansetron (B): 4-8mg IV/PO q8-12hrly
What are the drug categories during pregnancy and what do they mean?
- Cat. A: large number of pregnant woman, without any increase
- Cat B1: limited number of pregnant woman, without any increase
- Cat B2: limited number of pregnant woman, without any increase, includes some animal or inadequate studies.
- Cat B3: limited number of pregnant woman, without any increase. Animal studies have shown evidence of fetal damage, which is of uncertain significance in humans.
- Cat C: maybe suspected of causing harmful effects, which may be reversible. No malformations.
- Cat D: expected to cause malformations or irreversible damage. +/- adverse pharmacological effects.
- Cat X: high risk of causing serious damage to the fetus and should not be used in pregnancy.
What are the Drug Categories for the medications given in HG?
- Antihistamine: Cyclizine (A), Promethazine (C)
- Phenothiazine: Prochlorperazine (C)
- Dopamine Agonist: Metochlopramide (A), Domperidone (B2)
- Serotonin Antagonist: Ondansetron (B1)
Cat A: Cyclizine, Metochlopramide
Cat B1: Ondansetron. B2: Domperidone
Cat C: Promethazine, Prochlorperazine
