Group B: IRRITABLE BOWEL SYDROME
in a 40-year old, female with diarrhea of 1-month duration
Rivera, Laila
Rivere, Djeaune Marie Trissel
Robosa, Dean Antonio
Rodas, Francis Martin
Rodriguez, Shereen Reine
Rogelio, Ma. Graciela
Roque, Marianne
Irritable bowel syndrome (IBS), a functional bowel disorder, is characterized by abdominal pain or
discomfort and altered bowel habits without detectable structural abnormalities. Although all ages can
be affected with IBS, the onset of symptoms usually come before the age of 45 years. This disorder also
has a female sex predilection (2-3 times diagnosed as often as males). The patient in the case is a 40year old female, falling under the population most commonly affected with IBS.
The criteria for the diagnosis of IBS has been set in Rome II in 2006, stating the following:
Rome II Diagnostic Criteria for Irritable Bowel Syndromea
Recurrent abdominal pain or discomfortb at least 3 days per month in the last 3 months
associated with two or more of the following:
1. Improvement with defecation
2. Onset associated with a change in frequency of stool
3. Onset associated with a change in form (appearance) of stool
aCriteria
fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.
means an uncomfortable sensation not described as pain. In pathophysiology research and clinical trials, a
pain/discomfort frequency of at least 2 days a week during screening evaluation is required for subject eligibility.
bDiscomfort
The reported duration of the patient’s abdominal pain prior to consultation was only one month.
However, the diagnosis of IBS should not be ruled out immediately simply because she sought consult
for diarrhea before fulfilling the minimum duration of pain in the IBS diagnostic criteria. Along with
abdominal pain, the patient had a change in form and frequency of stool as demonstrated by having
loose stools described as mushy and mucoid, occurring 3-5 times a day for the past month.
IBS is not diagnosed without its key symptom of abdominal pain or discomfort. In 25% of patients
with IBS, the pain is localized in the hypogastrium, as was in our patient. IBS abdominal pain is also
described as frequent episodic and crampy, which is also present in the patient.
Alteration of bowel habits in IBS can present as IBS-diarrhea predominant (IBS-D), IBS-constipation
predominant (IBS-C) and IBS-mixed (IBS-M). In IBS-D, diarrhea usually consists of small volume of loose
stools (<200 mL), without the occurrence of nocturnal diarrhea. Stools may also be accompanied by
passage of mucus, as what occurred in the patient. The patient did not report any malabsorption or
weight loss, which is not associated with IBS. Bleeding (also not a feature of IBS) occurred, but the
presence of hemorrhoids, cannot be ruled out.
The pathophysiology of IBS-diarrhea predominant in the patient may be explained by small bowel
dysmotility manifesting as accelerated meal transit in patients prone to diarrhea. Patients exhibit
shorter intervals between migratory motor complexes which is the predominant interdigestive small
bowel motor patterns. Colonic motor abnormalities are more prominent under stimulated conditions
such as eating. IBS patients exhibit increased recto-sigmoid activity for up to 3 hours after eating. The
patient’s associated crampy hypogastric pain may be due to visceral hyperalgesia – the enhanced
perception of normal motility and visceral pain characteristic of irritable bowel syndrome. Patients who
are affected describe widened dermatomal distributions of referred pain. Sensitization of the intestinal
afferent nociceptive pathways that synapse in the dorsal horn of the spinal cord provides a unifying
mechanism. Visceral afferent dysfunction manifests as exaggerated sensory responses to visceral
stimulation which influences postprandial pain in 74% of IBS patients after the entry of food bolus to the
cecum.
The IBS-diarrhea predominant symptom in the patient may have also been due to a GI infection
she could have acquired during her 1 year stay in Bangladesh. Small bowel bacterial overgrowth has
been heralded as a unifying mechanism for the symptoms of bloating and distention common to
patients with IBS. The microbes involved are Campylobacter, Salmonella and Shigella. Those patients
with Campylobacter infections who are toxin-positive are more likely to develop postinfective IBS.
Increased rectal mucosal enteroendocrine cells, T lymphocytes and increased gut permeability could
persist and may contribute to postinfective IBS.
The diagnosis of IBS relies on recognition of positive clinical features (Rome II diagnostic criteria
plus other supportive symptoms such as defecation straining, urgency or a feeling of incomplete bowel
movement, passing mucus, bloating, lethargy, nausea, backache and bladder symptoms) and elimination
of other organic diseases. The differential diagnosis of IBS should be based on the location of the pain,
accompanying symptoms, and the primary associated bowel habit. All patients presenting with possible
IBS symptoms should be asked if they have unintentional and unexplained weight loss, rectal bleeding,
family history of bowel or ovarian cancer, change in bowel habit to looser and/or more frequent stools
persisting for more than 6 weeks in a person aged over 60 years and should be referred to secondary
care for further investigation if any are present.
In people who meet the IBS diagnostic criteria, the following tests should be undertaken to
exclude other diagnoses: complete blood count (CBC), erythrocyte sedimentation rate (ESR) or plasma
viscosity, C-reactive protein (CRP), antibody testing for coeliac disease (endomysial antibodies [EMA] or
tissue transglutaminase [TTG]) (National Institute for Health and Clinical Excellence, 2008),
sigmoidoscopic examination, stool examination for ova and parasites. The laboratory features that
argue against IBS include evidence of anemia, elevated ESR, presence of leukocytes or blood in stool,
and stool volume > 200-30 mL/d (Fauci 2007).
The patient in our case presents with diarrhea and is classified as IBS-D. Antidiarrheal agents used
for IBS-D patients include peripherally acting opiate-based agents, loperamide and bile acid binder
cholestyramine resin. Peripherally acting opiate-based agents is the initial therapy of choice for IBS-D.
Some drugs showed potential for management of IBS and are currently being studied, an example is TCA
imipramine and serotonin receptor agonist and antagonists. Tricyclic antidepressant (imipramine) slows
jejunal migrating motor complex transit propagation and delays orocecal and whole-gut transit,
indicative of a motor inhibitory effect making it a possible drug for IBS-D.
There are other drugs that could be recommended for the treatment of IBS, such as
antispasmodics and antiflatulence therapy. Antiflatulence therapy includes advising the patient to eat
slow and to not chew gum or drink carbonated beverages; dietary exclusion trial; avoiding flatogenic
foods, exercising, losing weight, taking activated charcoal; probiotics which is still in trials.
In the management of IBS, patient counseling and dietary alterations are important. The patient
must be reassured and the functional nature of the disorder must be carefully explained. Food
precipitants that aggravate the symptoms should be avoided and foodstuff that appears to produce the
symptoms eliminated from the patient’s diet. Dietary change would include a high fiber diet.
References:
De Gowin’s et.al. Diagnostic examination 2004. 8th edition. McGraw-Hill, USA
Fauci et.al. Harrison’s principles of Internal Medicine 2008 17th edition. McGraw-Hill USA
Lehrer J. Irritable Bowel Syndrome. http://emedicine. medscape. com/article/ 180389-overview; Aug
2009 [Full Text]
[No authors listed].(2008). Irritable bowel syndrome in adults: Diagnosis and management of irritable
bowel syndrome in primary care by The National Institute for Health and Clinical Excellence