IRRITABLE BOWEL SYNDROME Flashcards
Pertinent Anatomy of a patient with Irritable Bowel Syndrome.
(1) Small Intestines
(2) Large Intestines
(3) Anus
(4) Rectum
What substances are involved in the perception autonomic response to
visceral stimulation
(IBS)
. 5-HT (Serotonin), Substance P,
Norepinephrine and nitric oxide
What time frame needs to be met to deemed IBS
Chronic (more than 3 months) abdominal pain or discomfort that occurs in association
with altered bowel habits.
Specific cause is yet to be determined, but some causes are:
IBS
(a) Ovum and parasite
(b) Food poisoning via:
1) Campylobacter
2) Shigella
3) Salmonella
4) E. Coli
5) C. difficile
(c) Stress
(d) GI tract stimulants
(e) Lifestyle
S/S of IBS
(1) Symptoms usually begin in the late teens to twenties
(a) abnormal stool frequency;
(b) abnormal stool form (lumpy or hard; loose or watery);
(c) abnormal stool passage (straining, urgency, or feeling of incomplete evacuation);
(d) passage of mucus;
(e) bloating or a feeling of abdominal distention.
S/S of IBS
Patients may have other somatic or psychological complaints such as
(a) dyspepsia,
(b) heartburn,
(c) chest pain,
(d) headaches,
(e) fatigue,
(f) myalgias,
(g) urologic dysfunction,
(h) gynecologic symptoms,
(i) anxiety,
(j) depression.
are These symptoms continuous or intermittent
both
crampy, and in the lower abdominal region.
Diagnosis of IBS requires
Abdominal discomfort or pain with at least two of the
following three features:
(a) Relieved with defecation
(b) Onset associated with a change in frequency of stool (It does not usually occur at
night or interfere with sleep.)
(c) Onset associated with a change in form (appearance) of stool.
`
Patients with irritable bowel syndrome may be classified into one of three categories
based on the predominant bowel habit:
(a) IBS with diarrhea
(b) IBS with constipation or infrequent bowel movements (less than three per week)
(c) IBS with mixed constipation and diarrhea
Alarm symptoms (suggest a diagnosis other than irritable bowel syndrome)
(a) Patients who have a family history of cancer, inflammatory bowel disease, or celiac
disease should undergo additional evaluation.
(b) Acute onset of symptoms, especially in patients aged > 40-50 years.
(c) Nocturnal diarrhea
(d) Severe constipation
(e) Hematochezia
(f) Weight loss
(g) Fever
Physical examination
(a) Usually normal.
(b) Abdominal tenderness, especially in the lower abdomen, is common but not
pronounced.
Differential Diagnosis
(1) Colonic neoplasia
(2) Inflammatory bowel disease (ulcerative colitis, Crohn disease)
(3) Hyperthyroidism or hypothyroidism
(4) Parasites or other infectious causes
(5) Malabsorption (especially celiac disease, bacterial overgrowth, lactase deficiency)
(6) Psychiatric disorders such as depression, panic disorder, and anxiety must be considered
as well.
Lab
(1) For patients who fulfill the diagnostic criteria for IBS and have no other alarm
symptoms, routine blood tests are typically unnecessary.
(2) Consider complete blood count, chemistry panel, serum albumin, thyroid function tests,
erythrocyte sedimentation rate if an alternative diagnosis is suspected.
RADS
(1) Routine sigmoidoscopy or colonoscopy also are not recommended in young patients
with symptoms of IBS without alarming symptoms, but should be considered in patients
who do not improve with conservative management.
(2) In all patients age 50 years or older who have not had a previous evaluation, colonoscopy
should be obtained to exclude malignancy.
Treatment
(1) Diet
(a) Fatty foods and caffeine exacerbate bloating, flatulence, and diarrhea.
(b) Food sensitivities often vary from person to person but trigger foods should be
avoided.
(c) Note: high-fiber diet and fiber supplemens appears to be of little value.
(2) Symptomatic treatment:
(a) Antidiarrheal agents
1) Loperamide (Imodium) 2 mg orally three or four times daily
(b) Anticonstipation agents
1) Treatment with osmotic laxatives (milk of magnesia or polyethylene glycol) may
increase stool frequency, improve stool consistency, and reduce straining.
(3) Antispasmodic agents (anticholinergics):
(a) Hyoscyamine (Levsin)
1) Dose: 0.125 mg orally (or sublingually as needed) or sustained- release, 0.037 mg
or 0.75 mg orally twice daily
2) MOA: antagonizes acetylcholine receptors
3) Adverse Reactions: heat stroke, hallucinations, dry eyes, xerostomia, impaired
memory, nervousness
4) Contraindications: GI obstruction or ileus, BPH, severe Ulcerative Colitis, renal
or hepatic impairment
(b) Dicyclomine (Bentyl)
1) Dose: 10-20 mg PO qid
2) MOA: antagonizes acetylcholine at muscarinic receptors; relaxes smooth muscle,
inhibits bradykinin- and histamine- induced spasms
3) Adverse Reactions: psychosis, hallucinations, delirium, heat stroke, dizziness,
nausea, somnolence
4) Contraindications: paralytic ileus, Obstructive GI disease, GERD, renal or hepatic
impairment, psychosis
(c) Methscopolamine (Pamine)
1) Dose: 2.5-5 mg orally before meals and at bedtime
2) MOA: antagonizes acetylcholine receptors, decreasing GI motility and gastric
secretions
3) Adverse Reactions: heat stroke, tachycardia, nervousness, dizziness, blurred
vision, confusion, mydriasis, loss of taste
4) Contraindications: glaucoma, GI obstruction, paralytic ileus, renal or hepatic
impairment, hyperthyroidism
(4) Psychotropic agents(tricyclics)
(a) Tricyclic Antidepressants (TCA)
1) Examples: Amitriptyline (Elavil) or Imipramine (Tofranil)
2) Dose: 25-75 mg PO qHS,
3) MOA: Increases the synaptic concentration of serotonin and/or norepinephrine in
the central nervous system by inhibition of their reuptake by the presynaptic
neuronal membrane pump.
4) Adverse Reactions: anticholinergic effects, AV conduction delays,
5) Contraindication: concurrent use of MAOI
