PATHOLOGY - Vomiting Flashcards
Which four regions input information into the vomiting centre of the brain to trigger the vomiting reflex?
Chemoreceptor trigger zone
Gastrointestinal tract
Cerebral cortex
Vestibular system
What is the chemoreceptor trigger zone?
The chemoreceptor trigger zone detects emetic agents within the blood and relays this information to the vomiting centre to trigger emesis
Give three examples of emetic agents that are detected by the chemoreceptor trigger zone
Uraemic toxins
Ketones
Drugs (e.g. apomorphine, chemotherapy)
How does the gastrointestinal system relay information to the vomiting centre of the brain?
The gastrointestinal system relays information to the vomiting centre via the vagus nerve (CN X)
Give three examples of gastrointestinal changes that are relayed to the vomiting centre of the brain
Chemicals/irritants
Inflammation
Excessive stretch of the gastrointestinal tract
How does the vestibular system relay information to the vomiting centre of the brain?
The vestibular system relays information to the vomiting centre via the vestinbulocochlear nerve (CN VIII)
What is the difference between vomiting and regurgitation?
Regurgitation is the passive evacuation of food and/or fluid from the oesophagus due to oesophageal disease, whereas vomiting is the forceful evacuation of the stomach and/or duodenal contents
How do you differentiate between regurgitation and vomiting?
- Vomiting will usually be preceded by signs of nausea such as lip smacking and drooling
- Vomiting presents with retching/abdominal effort whereas regurgitation does not
- Vomiting may occur minutes to hours after eating whereas regurgitation is more likely to occur not long after eating
- Vomit is partially digested food or liquid and often contains bile, whereas regurgitation is typically undigested food
What are the differential diagnoses for acute vomiting?
Dietary indiscretion
Acute gastritis
Acute enteritis
Gastrointestinal foreign body
Mesenteric torsion
Intussusception (often presended by diarrhoea and hypermotility)
Gastric dilatation volvulus (GDV)
Acute pancreatitis
Acute hepatobiliary disease
Acute renal disease
Peritonitis
Pyometra
Hypoadrenocorticism
Acute neurological insult
Toxin ingestion
Remember GDV is unproductive vomiting
Remember dietary indiscretion, foreign body (unless perforated) and intusussception usually don’t present as clinical unwell beyond maybe dehydration
How do you approach investigation of acute vomiting?
- Assess history, signalement and clinical signs
- Clinical examination
- Symptomatic management if mild clinical signs
- Symptomatic management and further investigation if severe vomiting and/or signs of systemic disease
Which differential diagnoses for acute vomiting would require surgical intervention?
Gastrointestinal foreign body
Mesenteric torsion
Intussusception
Gastric dilatation volvulus (GDV)
Peritonitis
Pyometra
Which history questions are useful to ask when investigating acute vomiting?
- Has there been any recent dietary changes?
- Is the patient a scavenger?
- How frequently is the patient vomiting?
- Is the vomiting productive or unproductive?
- Is the vomit undigested food, digested food, or partially digested food?
- Is there blood or ‘coffee grounds’ in the vomit?
- Has there been any recent weight loss?
- Are there any concurrent gastrointestinal signs?
- Is the patient on any medication?
- Is the patient systemically unwell?
- Appetite?
What are the two main aims of the clinical examination when investigating acute vomiting?
Determine if there are any clinical signs that can help discriminate the cause of the acute vomiting and determine the clinical status of the patient
What should you assess in detail during the clinical examination when investigating acute vomiting?
Signs of systemic disease
Pyrexia - indicates inflammation
Signs of hepatobiliary disease (jaundice)
Signs of kidney disease
Assess if the abdomen is painful
Palpate for any abdominal masses
Ascites
Assess for dehydration
Assess for hypovolaemia
Which diagnostic tests can be used when investigating acute vomiting?
Haematology
Biochemistry
Urinalysis
Diagnostic imaging
What are the aims of haematology and biochemistry when investigating acute vomiting?
Haematology and biochemistry can be used to identify primary disease as well as gather more information on the patient’s clinical status
Which systemic disease processes can be identified using haematology and biochemistry?
Acute pancreatitis
Acute hepatobiliary disease
Acute kidney disease
Hypoadrenocorticism
What is a distinctive feature of hypoadrenocorticism (Addison’s disease) on biochemistry?
Hyperkalaemia and Hyponatraemia
Which additional test can be done to diagnose acute vomiting secondary to hypoadrenocorticism (Addison’s disease)?
ACTH stimulation test
Which factors should you assess to determine patient status based on haematology and biochemistry results?
Is the patient dehydrated?
Are there any electrolyte disturbances
Is there metabolic acidosis
Are there changes that are compatible with sepsis (neutropenia)?
Which imaging techniques can be used to investigate acute vomiting?
Radiography
Ultrasound
Which questions should you consider when assessing a radiograph when investigating acute vomiting?
Is there evidence of a gastric dilatation volvulus (GDV)?
Is there evidence of a gastrointestinal foreign body?
Is there evidence of gastrointestinal obstruction?
Is there evidence of a gastrointestinal perforation?
Is there evidence of peritonitis?
What are the key signs of a gastrointestinal perforation on radiography?
Loss of serosal detail due to free fluid
Gas bubbles in the abdomen
Bunching of the intestines
What are the benefits of using abdominal ultrasound when investigating acute vomiting?
Abdominal ultrasound allows for the assessment of the gastrointestinal tract, liver, pancreas and reproductive tract, as well as allows for ultrasound guided aspiration of free abdominal fluid