Irritable bowel syndrome Diagnostic Study of Choice

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

As per the Rome IV criteria, the diagnosis of IBS is made when at least two of the following diagnostic criteria are met in association with abdominal pain for ≥1 day per week, in the previous 3 months with an onset of ≥6 months : Change in stool consistency, pain related to defecation and absence of warning signs such as unintentional loss of weight, age ≥50 years, recent change in bowel habit, hematochezia or melena i.e. evidence of overt gastrointestinal bleeding.

The definition of IBS according to Rome IV, is recurrent abdominal pain associated with a change in frequency and/or form of the stool. It considers IBS as a disorder of gut–brain interaction as opposed to being a functional disorder of the GI tract. The term “abdominal discomfort” mentioned in Rome Ⅲ, has been removed in Rome IV to counter ambiguity. In addition to this, the frequency of abdominal pain has been changed from at least 3 days a month in the preceding 3 months (Rome III) to at least one day per week in the preceding 3 months (Rome IV).  The phrase ‘improvement of abdominal pain with defecation’ in Rome III has been changed to“abdominal pain related to defecation” in Rome IV, as some IBS patients may report worsening of pain following defecation. Experts state that physicians should limit evaluation to Rome criteria fulfillment, if no alarm symptoms are present.

Diagnostic Criteria

• According to the Rome IV, the diagnosis of IBS is made when patient has pain in the abdomen (On an average, ≥1 day per week, in the previous 3 months) with an onset of ≥6 months before diagnosis. Pain in the abdomen must be associated with at least two of the following:
  • Change in stool consistency
  • Pain related to defecation

Patient must have none of the following warning signs:

• Unintentional loss of weight
• Age ≥50 years, without previous colon cancer screening
• Recent change in bowel habit
• Hematochezia or melena i.e. evidence of overt gastrointestinal bleeding
• Nocturnal pain in the abdomen or passage of stools
• History of inflammatory bowel disease or colorectal cancer in the family
• Palpable abdominal mass or presence of lymphadenopathy
• Positive fecal occult blood test
• Blood testing showing evidence of iron deficiency anemia

Evolution of the Rome IV criteria:

• In 1978, the first diagnostic criteria (Manning criteria) was published. Manning criteria has a sensitivity of 78% and specificity of 72%.
• Kruis criteria published in 1984 has a sensitivity (77%) and specificity (89%). 
• The Rome criteria were subsequently developed and have undergone three iterations. Rome Ⅰ was revised to Rome Ⅱ, Ⅲ and IV in the years 1999, 2006, 2016 respectively. Rome Ⅰ criteria and determined it had a sensitivity of 71% and specificity of 85%.The Rome Ⅲ criteria have a sensitivity of 75 %.

• Rome Ⅱ states that a patient must have pain in the abdomen or abdominal discomfort for at least 12 wk ( which may not be consecutive) during the past year. This pain or discomfort must be associated with at least two of the following: change in stool frequency, relief with defecation, change in stool form.
• Rome Ⅲ states that a patient must have recurrent pain in the abdomen or discomfort for at least 3 days a month, for the last 3 months associated with two or more of the following features: onset associated with a change in stool frequency, change in stool consistency. or improvement with defecation.
• In 2009, American College of Gastroenterology (ACG) stated that no criteria based on symptoms could have accuracy for the diagnosis of IBS. It defined IBS as pain in the abdomen or discomfort that was in association with altered bowel habits over at least 3 months.
• The American Gastroenterological Association has published a set of guidelines for tests which physicians should perform prior to diagnosing irritable bowel syndrome. The following tests are meant to exclude other causes, such as infection and colon cancer.
  1. History and physical examination
  2. Diagnostic testing
     1. CBC
     2. Chemistry panel
     3. Sedimentation rate
     4. Stool for Ova & Parasites
     5. Stool for occult blood
     6. Flexible sigmoidoscopy
     7. IF > 50, colonoscopy or barium enema and sigmoidoscopy
     8. For diarrhea predominant:
        1. Small bowel radiograph
        2. Lactose/dextrose H2 breathing test
     9. For constipation predominant:
        1. Fiber trial For pain predominant:
  3. Plain film of abdomen
• Difference between Rome III and IV criteria:
  • The definition of IBS is recurrent abdominal pain associated with a change in frequency and/or form of the stool.
  •  Rome IV defines IBS as a disorder of gut-brain interaction as opposed to being a functional disorder of the GI tract.
  • The Rome III criteria mentioned the term “abdominal discomfort”, which has been removed in Rome IV to counter ambiguity.
  •   The frequency of abdominal pain has been changed from at least 3 days a month in the preceding 3 months (Rome III) to at least one day per week in the preceding 3 months (Rome IV).
  •  The phrase ‘improvement of abdominal pain with defecation’ in Rome III has been changed to“abdominal pain related to defecation” as some IBS patients may report worsening of pain following defecation.
  • Rome IV states that some symptoms must be present for at least 6 months and that patients must meet the criteria for at least 3 months before IBS is diagnosed.
  • Experts state that physicians should limit evaluation to Rome criteria fulfillment if no alarm symptoms are present.

The comparison table for diagnostic studies of choice for IBS

	Sensitivity	Specificity
Rome Ⅲ	75%	85%
Rome IV	62%	97%

✔= The best test based on the feature

Sequence of Diagnostic Studies

• The patient presents with symptoms such as recurrent pain in the abdomen (On an average, ≥1 day per week, in the previous 3 months) with an onset of ≥6 months before diagnosis accompanied by atleast two of the following: change in stool frequency, change in stool appearance or form or Pain related to defecation. In addition, the patient must have none of the following warning signs as the first step of diagnosis.
• Physicians should limit evaluation to Rome criteria fulfillment if no alarm symptoms are present.

• All the criteria described for IBS are listed below in reverse chronological order:

Diagnostic criteria	Symptoms, signs and labs
2016: Rome IV	To establish the diagnosis, the patient must have recurrent pain in the abdomen (On an average, ≥1 day per week, in the previous 3 months) with an onset of ≥6 months before diagnosis- Pain in the abdomen must be associated with at least two of the following: Change in stool frequency Change in stool appearance or form Pain related to defecation Patient must have none of the following warning signs: Unintentional loss of weight Age ≥50 years, without previous colon cancer screening Recent change in bowel habit Hematochezia or melena i.e. evidence of overt gastrointestinal bleeding Nocturnal pain in the abdomen or passage of stools History of inflammatory bowel disease or colorectal cancer in the family Palpable abdominal mass or presence of lymphadenopathy Positive fecal occult blood test Blood testing showing evidence of iron deficiency anemia
2006: Rome Ⅲ	Recurrent pain in the abdomen or discomfort at least three days a month, for the last three months associated with two or more of the following(should be present  for at least twenty five percent of the time)   Onset of symptoms associated with a change in stool form(alternating between diarrhea and constipation)  Onset of symptoms associated with a change in stool frequency   Improvement with defecation   Absence of evidence of anatomic, inflammatory, neoplastic or metabolic causes to explain the symptoms
1999: Rome Ⅱ	Pain in the abdomen or abdominal discomfort that has two of the following three features for twelve weeks(which may not be consecutive) in the last one year: Onset associated with a change in stool form Onset associated with alterations in stool frequency Relief with defecation
1990: Rome Ⅰ	Abdominal discomfort or pain relieved with defecation or associated with change in frequency or consistency of stool in addition to two or more of the following (on at least twenty five percent of occasions/days for three months): 1.     Altered stool form 2.     Altered stool frequency 3.     Altered stool passage 4.     Passage of mucus in stool 5.     Abdominal bloating or distension
1984: Kruis	Symptoms of IBS must be present for more than two years. These symptoms include the following: 1.     Pain in the abdomen, flatulence 2.     Alternating constipation and diarrhea Signs that exclude IBS are determined by the physician. They are as follows: 1.     Abnormal physical findings and/or history suggestive of any other diagnosis 2.     ESR more than 20mm/2h 3.     Anemia(Hemoglobin < 12 for women or < 14 for men) 4.     Leukocytosis > 10000/cc 5.     Bleeding per rectum found on physical exam
1978: Manning	A threshold of at least three positive symptoms needs to be present to diagnose IBS with no duration of symptoms described under this classification. 1)     Loose stools with onset of pain 2)     Increased frequency of stools with onset of pain 3)     Mucus per rectum 4)     Visible distension of abdomen reported by the patient 5)     Pain in the abdomen relieved by defecation 6)     Sensation of incomplete evacuation