All right. Welcome to the world of Irritable Bowel Syndrome.
This is IBS. This should be not confused
with inflammatory bowel disease which is IBD.
IBS or irritable bowel syndrome is a functional bowel disease.
There's really not identifiable pathologic changes that we can recognize.
And it's characterized by chronic abdominal pain and altered bowel motility.
And there's no identifiable organic cause.
Doesn't mean it doesn't exist
and it doesn't mean it's only in your head.
This is a real entity and you will have patients
who will suffer from this. Let's look at the epidemiology.
So, the onset is typically younger individuals who will tend to have this -
it may or may not be related to the stressors of young adult life.
We'll talk more about stress in a minute.
Overall, the most common patient is going to be a woman.
So, somewhere between two-thirds and three-quarters
of patients with irritable bowel syndrome are female.
In North America, there's a relatively high prevalence
of about 10% to 15% of the population total.
And in most of the developed nations
of the world, there is a similar prevalence.
In the developing parts of the world,
we don't have a firm handle on prevalence.
And in fact, infectious causes of bowel symptoms
are much, much, much more common.
The pathophysiology. We don't have an organic cause
but we do know that there is abnormal bowel motility.
So, what is being shown on the little column on the left
is food moving along the tubular bowel in a nice,
uniform top to bottom fashion and there's a relatively common speed
by which things transit throughout the bowel.
In irritable bowel syndrome, you may either have faster or slower,
or even waves of peristalsis that go backwards.
So, it's an abnormal frequency and irregularity of contractions.
There is also an increased sensitivity to cholecystokinin.
So, these are - this is a polypeptide hormone
that is secreted at the time of food entering the stomach.
And that will drive the normal peristaltic wave.
It will be part of the mechanism by which peristalsis is allowed to proceed.
We do know that in irritable bowel syndrome, the tubular gut
is much more sensitive to the cholecystokinin.
Because of the abnormal bowel motility, frequently with a higher frequency
and faster transit time, there's typically diarrhea.
But in some cases, you may have irritable bowel syndrome
with constipation, so called IBS-C
Intestinal inflammation may underline this.
In fact, I'm going to show you some possibilities.
These are heavily debated.
We don't know why this happens.
But you may have in some individuals slightly more lymphocytes
within their lamina propria and/or mast cells
and these would release mediators
that will increase the bowel motility.
This may happen after infections and we may have increased
serotonin levels which also modulate bowel motility.
What we have are patients who have increased sensitivity
to pain which may be associated with increased receptor stimulation
but they also, well, pound for pound
or cubic centimeter per cubic centimeter of gas,
these patients will feel distension of the bowel much more
acutely than those without irritable bowel syndrome.
There is clearly a psychosocial element of IBS.
Greater than 50% of patients have depression and/or anxiety.
Now, it's not clear whether the depression and anxiety are causing
IBS or patients have this because they have IBS
and sorting that out may be very difficult.
But in the setting of IBS,
any increased stress may drive increased corticotrophin-releasing
factor activity giving rise to increased glucocorticoids
which may stimulate increased sensitivity to abdominal pain
and may alter bowel motility.
The clinical presentation. So, depending on whether
you just have irritable bowel syndrome
or if you have it with constipation, you may or may not have diarrhea
but you will always have abdominal pain
and you will have an increased sensitivity to bowel distension.
With diarrhea, you'll have lose and watery stools.
There should not be blood in those stools
because you're not causing any epithelial damage.
With the diarrhea, clearly increased bowel movements.
And there may be real urgency that occasionally may lead to incontinence.
The IBS with constipation may give rise
to very hard stools, infrequent bowel movements
because we're not moving with the same transit time through the GI tract
and may require straining with defecation.
Making the diagnosis, it's a clinical history. It's pain that occurs classically
a day per week for the previous three months.
So, that's the clinical definition.
And so, all you have to do is ask a patient,
how often are you having pain, maybe what other symptoms
you're having with it, and for how long have you had that?
If they gave you a day per week for three months,
that is the clinical criteria.
The physical exam is not very helpful.
There may be a little bit of abdominal distension,
some tenderness but it's very hard
to find anything on a physical exam
and notably, there's not going to be borborygmi.
You will have normal bowel sounds.
The laboratory tests are really more exclusionary.
We want to rule out other causes of the diarrhea or the constipation.
So, people with irritable bowel syndrome should not have an anemia
because there was no bleeding and they have normal absorption.
So, the CBC should be fine.
Calprotectin is actually a biomarker
that allows us to see whether there is inflammation
we detect it in the stool.
And if that is elevated, then, we would implicate things like
inflammatory bowel disease, not irritable bowel syndrome.
We want to make sure that there's no infection.
We'll do stool cultures, ovas and parasites
and we will certainly want to look to make sure
that there is no elevated thyroid hormone activity
because clearly, thyrotoxicosis or hyperthyroidism
can cause increased abdominal or bowel transit.
Abdominal radiograph, usually, not all that helpful.
You may see focal areas of spasm
but you may or may not capture that at any particular
time that a patient comes in.
And the colonoscopy with biopsy,
it's just to rule out other things.
There's nothing to be seen by the pathologist
in the setting of irritable bowel syndrome.
How do we manage it? So, you can do some
dietary modifications and many cases,
it's felt that this is more of a psychological benefit
rather than a true change in how the bowel is behaving.
But eating more fiber for example,
is felt to give a better sort of bowel transit.
And certainly with increased fiber, you, for a patient
who has constipation, that may improve their symptoms.
Pharmacologic agents may be helpful. So antidiarrheal agents,
things that will cause increased fluid retention within the bowel.
Things that cause or will help with spasm.
You may try probiotics just to see if the bowel microflora
is somehow responsible and helping the patient
with their psychological issues,
helping them to develop a more Zen-like
approach to life may be helpful.
With that, irritable bowel syndrome
and how to look at it.