IRRITABLE BOWEL SYNDROME
Auguste H. Fortin VI, M.D., M.P.H.
WEEK 15
Learning Objectives:
1. Be able to list the diagnostic criteria for irritable bowel syndrome
2. Be able to list the alarm features that suggest organic disease
3. Be able to discuss a treatment plan for a patient with mild to moderate symptoms
CASE ONE:
Mattie Muesill is a 24-year-old woman who presents with four months of
intermittent crampy lower abdominal pain, diarrhea, and bloating. The pain is
relieved somewhat with defecation. During these episodes she has four to five bowel
movements per day and experiences urgency, especially after meals.
Questions:
1. Use the table of diagnostic criteria from the UpToDate article. Does this
woman have Irritable Bowel Syndrome? Do you need to ask her anything
else to make the diagnosis?
Points to emphasize:
a. While this patient has enough symptoms to support the diagnosis of IBS, it
is important to assess for alarm features that would suggest organic
disease (note that the table listing the Rome criteria begins with, “In the
absence of structural or metabolic abnormalities to explain the
symptoms…”). Physicians need to ask about hematochezia, weight loss
>10 lbs., significant anorexia, pain that prevents sleep or awakens the
patient from sleep, recurring fever, anemia, chronic severe diarrhea and a
family history of colon cancer. Presence of these complaints should
prompt an assessment for organic disease.
b. It is important to determine what the late Alvin Feinstein termed the
“iatrotropic stimulus,”(i.e. why the patient is seeking care at this time).
Tell residents that, while IBS has a prevalence of 12%, only 15% of those
affected seek medical care. Those who come to physicians have higher
psychological distress than those who do not seek care. Common issues
include concern about serious disease, acute psychosocial stressors,
anxiety, somatization, and depression. A history of physical or sexual
abuse is about four times more common among patients with functional
gastrointestinal disorders, such as IBS, than among patients with organic
gastrointestinal disorders such as colitis or unaffected controls.1,2
CASE ONE CONTINUED:
Mattie recalls that her symptoms began after a new boyfriend became violent
towards her. He was verbally abusive and forced her to have sex once. She broke
up with him last month, but he continues to call. She does not have symptoms of
depression but, does feel anxious and “on edge.”
She had similar bowel symptoms in high school, usually around the time of final
exams and when she performed in school plays. She denies fever, weight loss or
blood in her stools. She takes an oral contraceptive pill and a multivitamin. Her
family history is negative for colon cancer, colitis, lactose intolerance, and sprue.
She has neither traveled abroad nor gone wilderness camping. Her roommate is
not ill.
Physical Exam: Temperature 98.7, BP 124/68, pulse 82. Physical examination is
normal except for somewhat hyperactive bowel sounds and tenderness in the LLQ
to deep palpation. There is no rebound tenderness or guarding. Rectal exam
reveals brown, guaiac negative stool. Pelvic exam is normal.
2. Can you make a diagnosis now?
Mattie’s presentation is classic for IBS, particularly since she is a woman (IBS is
twice as prevalent in women) and can link symptoms to stress. She has the
diarrhea-predominant type. Emphasize to residents that alternating diarrhea and
constipation and constipation-predominant are also common presentations.
A biopsychocosocial approach is particularly helpful in disorders like this, to help
avoid the urge to “rule-out” all organic diseases before settling on a non-organic
diagnosis.
Ask residents what other diagnoses they are entertaining. The lack of alarm
features makes serious illness like colon cancer, colitis, and sprue highly unlikely.
I would want to be sure that Mattie did not consume excessive amounts of sorbitol
(in breath mints, for example), caffeine, or magnesium-containing antacids, which
can cause diarrhea. I would ask about symptoms for and focus my physical
examination on signs of hyperthyroidism. (Mattie’s history and exam were not
consistent with this diagnosis.)
I would feel comfortable forgoing further diagnostic testing in this classic case,
but some “experts” (remind residents that these are often subspecialists who see
a skewed population of patients and/or who do not subscribe to the
biopsychosocial model) recommend CBC, chemistry panel, TSH and three stools
for O & P. (Please stress to residents that, in Mattie’s case, a CBC would be
unlikely to contribute useful diagnostic data, absent a fever or pale conjunctivae;
hyperthyroidism severe enough to cause diarrhea would be exceedingly rare
given her pulse rate of only 82, lack of lid lag or tremor; and stool for O & P
without a history of travel or sick contacts is rarely diagnostic). In patients with
chronic diarrhea (not Mattie) a 24-hour collection of stool for weight can help
rule out osmotic or secretory diarrhea due to malabsorption, since stool weight
>300gm is rare in IBS. Testing for celiac sprue might be considered in patients at
increased risk (family history, type 1 diabetes, northern European ancestry).
Fortunately even the experts agree that routine colonoscopy/sigmoidoscopy and
biopsy in patients with presentations consistent with IBS are not warranted.
When symptoms are not associated with stress (or if the patient refuses to
entertain such an association), a firm diagnosis can be more difficult. If Mattie’s
symptoms did not improve after 4-8 weeks of treatment, I would reassess and
pursue appropriate tests.
3. Assuming that Mattie has IBS, what is your approach to treatment?
A supportive doctor-patient relationship and education about the chronicity and
benign nature of IBS is important. Dietary modifications, such as decreasing
caffeine, fat, and sorbitol are reasonable. I would also consider a trial of lactosefree diet and the possibility of fructose-intolerance. An exercise program may
help relieve symptoms. Since she doesn’t have constipation, adding fiber to her
diet may not be useful.
Psychological therapies are recommended in this case, with the strong connection
to a stressful event. Diarrhea and pain respond better than constipation.
Loperamide will reduce diarrhea but not pain. It is safe for long-term use.
To treat pain (but not diarrhea or constipation) an antispasmodic, with or without
an anxiolytic, may be needed; Table 1 in the Mertz article lists them. The article
states that dependence or recreational use of the antispasmodic/anxiolytic
combination agents are rare because the anticholinergic component causes
unpleasant side effects at higher doses. My preference is to encourage anxious
patients to enter into psychotherapy to address the cause of anxiety.
Low-dose TCAs are very useful for pain and diarrhea, even in the absence of
depression; they can be used along with antispasmodics if needed. SSRIs are not
effective.
The serotonin-3 receptor antagonist alosetron may have modest benefit in severe
diarrhea-predominant IBS. It has only been compared to placebo (and one
antispasmodic not available in the US); whether alosetron is better than standard
therapies (antidiarrheal, antispasmodic, anticholinergic) or would provide
additional benefit when added to them is not known. It is expensive, $366$723/month at www.drugstore.com. Physicians need to participate in a training
program before prescribing it because of the risk of ischemic colitis.
Of course, addressing intimate partner violence is critical. This would include
assessing her psychosocial support, assuring that Mattie has a plan for her safety
and providing numbers for domestic violence hotlines and women’s shelters.
4. What treatments would you use if Mattie had constipation-predominant
IBS?
The non-specific treatments in question 3 would also apply here. Fiber would
play a role in this instance, as would magnesium or phosphate salts or PEGbased laxatives; chronic use is OK. Avoid stimulants cathartics such as bisacodyl
and senna. The serotonin-4 receptor antagonist tegaserod may have a modest
benefit in severe cases of constipation-predominant IBS; it is only FDA-approved
for 12-week’s use. There is no evidence that it is better than standard therapies
(fiber, antispasmodics) because it has only been tested against placebo. It is
expensive, $154.00/month at www.drugstore.com.
References:
1. Mertz, HR. Irritable bowel syndrome. New England Journal of Medicine. 2003;
349:2136-46.
2. Table 3 from: Chun AB, Desautels S, Wald A. Clinical manifestations and
diagnosis of irritable bowel syndrome. UpToDate v. 12.3
Additional References:
1. Drossman DA, et al. Sexual and physical abuse in women with functional or
organic gastrointestinal disorders. Ann Intern Med. 1990; 113:828-833.
2. Drossman DA, et al. Sexual and physical abuse and gastrointestinal illness.
Review and recommendations [see comments]. Ann Intern Med. 1995; 123:782794.