Hello, I m Eric Strong from Strong Medicine, and today in this ongoing video series on
an approach to symptoms, I ll be discussing an approach to acute nausea and vomiting.
For this video, I ll be focusing on those conditions in which it s common for nausea
and vomiting to be a primary symptom rather than those conditions in which nausea and
vomiting are just minor manifestations of a much broader symptom complex.
To understand the diagnostic framework, it s helpful to know just a little bit of the
relevant physiology.
The part of the brain responsible for integrating signals throughout the body and converting
them into the sensation of nausea and initiating the vomiting reflex is predictably called
the vomiting center or the emetic center.
The vomiting center, along with the chemoreceptor trigger zone from which it receives signals,
is located within the medulla.
The most obvious sources of pro-nausea input are the GI tract via the vagus nerve, and
the vestibular system of the inner ear, but there are several others.
For example, nausea and vomiting can be triggered by sensory receptors within the pharynx, as
well as those from the heart most classically observed in myocardial ischemia.
Metabolic deranagements and some medications directly stimulate the chemoreceptor trigger
zone.
Meanwhile, the cerebral cortex where conscious thought occurs both delivers signals to and
receives signals from the vomiting center.
The limbic system of the brain, which is normally involved in emotion and memory, can also play
a role in triggering or modulating the subjective sensation of nausea.
Once stimulated by one or a combination of multiple triggers, the vomiting center initiates
a number of physiologic changes.
It relaxes the smooth muscle of the stomach, it increases pyloric tone, decreases lower
esophageal sphincter tone, closes the glottis and vocal cords to prevent aspiration.
The soft palate rises.
And last, the abdominal wall and diaphragm contract in order to expel gastric contents.
So when we are considering the possible sources of nausea and vomiting, that is, their etiologies,
we can use some of these same categories.
Starting with GI, which is the most obvious and most common overall category, etiologies
can be further subdivided into infectious versus non-infectious.
One infectious etiology is food poisoning, though this isn t really an infection strictly
speaking.
Food poisoning is caused by the ingestion of toxins that were produced by bacteria in
the food prior to consumption most classically caused by Staph aureus in food left at room
temperature for long periods of time, like one might find at a picnic, potluck, or poorly
maintained buffet.
Infectious etiologies also include both viral and bacterial gastroenteritis,.
Non-infectious GI etiologies include almost every itis in the system, meaning: esophagitis,
gastritis, pancreatitis, cholecystitis or inflammation of the gallbladder, acute hepatitis
or inflammation of the liver, and appendicitis.
The only major itis in the GI system which does not usually cause prominent nausea and
vomiting is colitis which is inflammation of the large intestine thought nausea and
vomiting can still in a minority of these patients.
Other non-infectious causes are small bowel obstruction, for example from intraabdominal
scars from prior surgery called adhesions.
And peptic ulcer disease.
Moving to the vestibular system, there are 4 major causes here all of which are associated
with vertigo, in addition to nausea and vomiting.
Vestibular neuritis is self-limited inflammation of the inner ear, believed to be viral in
origin.
If hearing is affected in addition to vestibular function, the condition is referred to as
labyrinthitis.
Benign paraoxysmal positional vertigo is caused by free floating debris within the semcircular
canals, resulting in a characteristic abrupt worsening of symptoms with particular head
movements.
Otitis media is an infection of the middle ear.
And last in the category motion sickness.
Next category is the central nervous system.
Concussions from head trauma can cause nausea and vomiting, as can any cause of increased
intracranial pressure such as tumors and hemorrhage.
Metabolic causes include diabetic ketoacidosis, uremia from kidney failure, hyponatremia,
hypercalcemia, and adrenal insufficiency.
There are a large number of medications and drugs associated with nausea and vomiting.
Although these could all be redistributed to one of the other categories in this diagnostic
framework, I think it s useful to keep a separate category for them.
Most notable here is chemotherapy.
Literally any drug that is conventionally thought of as a chemotherapeutic could be
listed here.
Among commonly used chemotherapy, those with the highest risk of nausea are cisplatin and
carboplatin, cyclophosphamide, doxorubicin, and ifosfamide.
About one third of patients who undergo general anesthesia will experience nausea and/or vomiting
in the 24 hours following the procedure.
Other drugs with particularly high rates of nausea include opiates, and all antibiotics.
The substance of abuse most likely to cause nausea is alcohol.
Our last category is miscellaneous.
In this category, we have pregnancy.
The overwhelming majority of pregnant individuals will experience nausea and/or vomiting at
some point during their pregnancy, with an onset in the first trimester.
Usually the nausea from pregnancy is frustrating and uncomfortable, but doesn t require treatment
beyond oral anti-emetics.
However, when the nausea and vomiting is intractable, and is associated with hypovolemia and weight
loss sometimes requiring hospitalization, the condition is termed hyperemesis gravidarum.
As mentioned earlier, myocardial ischemia can lead to nausea, which is an example of
what is known as an anginal equivalent, meaning that it s unexplained presence in an older
patient or in one with cardiovascular risk factors should be approached the same way
that chest tightness is, with an ECG and at least one, if not multiple troponins.
A hypersensitive gag reflex can result in nausea and vomiting.
Last, are a variety of psychiatric conditions, including panic attacks, and conversion disorder.
Although I ve been unable to locate data on this, in my personal experience, among all
of these potential etiologies, the ones that are particularly common to cause presentations
characterized by prominent nausea and vomiting are food poisoning, viral gastroenteritis,
pancreatitis, appendicitis, small bowel obstruction, a concussion, any of the medications or alcohol,
and pregnancy.
How do we evaluate a patient with nausea and vomiting?
The duration and pattern are important.
For example, episodes that are worse in the early morning are characteristic of pregnancy
and increased intracranial pressure.
And if the nausea and vomiting have been lasting for more than several weeks, or are a manifestation
of recurrent episodes with asymptomatic periods in between, switching to a framework for chronic
nausea and vomiting is more appropriate.
What s the character of the vomit?
Bloody vomit is called hematemesis, and suggests upper GI pathology such as esophagitis, gastritis,
or peptic ulcer disease.
However, some of these patients will have a Mallory Weiss tear in which repeated vomiting
causes a tear in the inner lining of the esophagus, which is then responsible for the bleeding.
In other words, the cause of nausea and vomiting and the cause of bleeding are not necessarily
the same.
Vomit that contains material resembling coffee grounds is suggestive of the expulsion of
partially digested, older blood.
Feculent vomit that is vomit that looks or smells like feces is strongly suggestive of
distal intestinal obstruction.
There is sometimes a distinction made between bilious vomiting meaning green bile is mixed
with the vomit vs. non-bilious vomiting.
However, I have not found that distinction to be diagnostically helpful in adults.
Even if the patient has esophageal or gastric pathology, the vomiting reflex can propel
contents of the small intestines backwards too.
While it s true that the vomit observed in a gastric outlet obstruction is classically
non-bilious in nature, appearing to give some value to this characteristic, gastric outlet
obstruction is simply not a common pathology outside of pediatrics.
Are there any associated symptoms that might point to a specific etiology?
Both abdominal distention, as well as abdominal pain that improves after vomiting are specifically
suggestive of small bowel obstruction.
Headache suggests primary CNS pathology.
As mentioned earlier, vertigo or hearing loss suggests pathology in the vestibular system.
Concurrent chest, arm, or jaw pain, dyspnea, and diaphoresis all suggest myocardial ischemia.
Has the patient been around others who have had similar symptoms, such as multiple attendees
at a social function, which would suggest a food borne illness like food poisoning.
Obviously ask about their past medical and surgical histories.
What meds are they currently on, focusing on changes in the days to weeks preceding
the onset of symptoms.
And ask about substance use particularly alcohol.
The focused exam in acute nausea and vomiting should include vitals,
Obviously, a thorough abdominal exam A retinal exam to look for papilledema which
is swelling and blurring of the optic disc secondary to increased intracranial pressure,
keeping in mind it may take a day or even longer for papilledema to develop after the
onset of increased ICP.
A screening neuro exam, which is a subset of the complete neuro exam which can identify
the majority of occult neuro findings, and with practice, can be performed in 5 minutes.
One thing to pay particularly close attention to during the neuro exam is nystagmus, which
suggests vestibular pathology.
And cardiac and pulmonary exams, particularly if the patient is older and/or has cardiovascular
risk factors, or has concurrent cardiopulmonary symptoms such as shortness of breath.
Relevant tests that can be ordered include a complete metabolic panel, which can identify
electrolyte abnormalities, kidney failure, liver failure, and biliary system pathology.
An elevation of lipase to more than three times the upper limit of normal is specific
for pancreatitis, though lesser degrees of elevation can be seen in a variety of gastrointestinal
pathology.
A pregnancy test in women of reproductive age
A stool test called the GI PCR panel that can identify the presence of a large variety
of pathogens Imaging is frequently ordered.
A very common question in the initial evaluation of these patients is exactly which imaging
test should be ordered?
A CT scan or an ultrasound?
If the patient s condition warrants imaging, as a very general rule, if you are more concerned
about liver or biliary pathology, or if the patient is pregnant, start with ultrasound.
Otherwise, start with a CT.
Upper endoscopy is sometimes performed, particularly when the patient has bloody vomit, or when
there is associated epigastric pain but with an unremarkable CT scan.
If there is any concern about the possibility of cardiac ischemia, obviously get an ECG
and troponin.
And if there is concern about intracranial pathology, brain imaging is obtained.
MRI can identify much more pathology than a CT scan, but a CT scan is much faster and
more widely available.
How can we put all these questions and tests together into a diagnostic algorithm?
Every adult presenting with prominent acute nausea and vomiting needs a history, a physical
exam, a complete metabolic panel, and lipase.
In addition, if the patient is female of reproductive age, get a pregnancy test.
And if the patient has cardiovascular risk factors including advanced age, concurrent
chest pain or dyspnea, or low blood pressure, get an ECG and troponin.
Sometimes, after this initial evaluation, a specific diagnosis will already be strongly
suggested, in which case, continue a focused evaluation as appropriate for that suggested
diagnosis.
For everyone else, the next step in the work-up will depend on features of their presentation.
So, for example, if the patient has any combination of fever, feculent vomit, or significant abdominal
pain, tenderness, and/or distention, the next step is a CT scan.
The one exception to this might be the relatively young, healthy patient who presents with acute
nausea and vomiting, and either generalized or epigastric abdominal pain but the abdominal
pain is relatively modest, and the patient is with an otherwise normal exam including
vitals, and normal or near normal labs.
This patient probably just has food poisoning, and abdominal imaging is not necessary.
If the patient has hematemesis or so-called coffee ground emesis, they need an EGD the
urgency of which depends on their hemodynamic stability, and the apparent speed and volume
of blood loss.
In years past, this question was often answered with nasogastric lavage, but this bedside
procedure has fallen out of favor on account of physical discomfort, a non-trivial complication
rate, and the impression that information gain from it didn t actually impact the timing
of EGD in practice.
If diarrhea is also present, it suggests viral or bacterial gastroenteritis, in which case
you should collect a stool sample for a GI PCR panel.
If the patient has specifically right upper quadrant pain, jaundice, and/or abnormal liver
function tests, obtain a right upper quadrant ultrasound, and a hepatitis panel, which refers
to a non-standardized collection of 4-6 tests looking for antigens of and antibodies for
Hepatis A, B, and sometimes C.
If the symptoms are worse with movement, the patient has vertigo, and nystagmus is present
on exam, perform the Dix-Hallpike test to evaluate for BPPV, and perform a quick specialized
exam called the HINTS exam, which stands for head impulse, nystagmus, and test of skew.
These exam maneuvers are discussed in my video on an approach to vertigo.
And if the patient has a headache, recent history of head trauma, papilledema on retinal
exam, or focal neuro findings, they need brain imaging.
While every case is different, I d say that in general, if a patient s presentation has
features that span more than one grouping here, they should receive all of the indicated
tests in those multiple groups, unless a diagnosis is made beforehand.
For example, if a patient had not only a fever and abdominal tenderness, but also diarrhea,
they should probably get both a CT scan and a GI PCR panel.
Two last big caveats:
First, just because a person is pregnant, does not mean that their nausea and vomiting
can t be from something else.
So the work-up should not automatically end after a positive pregnancy test.
And second, when working up acute nausea and vomiting, one should also consider the possibility
that this is an initial presentation of a cause of chronic nausea and vomiting, which
is the subject of another video in this series.
The key takeaway points of this video:
Nausea and vomiting can be caused by pathology of the GI system, vestibular system, brain,
heart, metabolic derangements, medication side effect, or psychiatric illness.
Common causes of acute nausea and vomiting include food poisoning, viral gastroenteritis,
pancreatitis, appendicitis, small bowel obstruction, a concussion, chemotherapy, anesthesia, and
pregnancy.
In addition to the history and exam, the most important initial tests that patients should
receive when being worked up for acute nausea and vomiting include a complete metabolic
panel, lipase, a pregnancy test if the patient is a woman of reproductive age, and an ECG
with troponin for patients with cardiovascular risk factors or other symptoms consistent
with cardiac ischemia.
That s it for this video on an approach to acute nausea and vomiting.
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