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G24 Gastroenterology
Small and Large Bowel Toronto Notes 2019
notherapeuticagentconsistentlyeffective,painmostdifficulttocontrol,nodrugchangesnatural history so the drug should be “wanted, since it is not needed”
symptom-guidedtreatment
■ painpredominant
◆ antispasmodic medication before meals (e.g. hyoscine, pinaverium, trimebutine - low level
evidence)
◆ tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRI - moderate level of
evidence) ■ IBS-D
◆ increase fibre (bran or psyllium) to increase stool consistency but may worsen abdominal gas (controversial)
◆ gluten avoidance (gluten shown to alter barrier)
◆ loperamide (Imodium®)
◆ diphenoxylate (Lomotil®)
◆ cholestyramine
◆ eluxadoline ■ IBS-C
◆ increase fibre in diet
◆ linaclotide
◆ osmotic or other laxatives (help more with the constipation than the pain)
Rifaximin Therapy for Patients with Irritable Bowel Syndrome Without Constipation NEJM2011;364:22-32
Purpose: Previous evidence suggests that gut flora may play an important role in the pathophysiology of IBS. This study evaluated rifaximin, a minimally absorbed antibiotic, in treating IBS without constipation.
Methods: Two phase 3, double-blind, placebo-controlled trials (TARGET 1 and TARGET 2). 1,260 patients who
had IBS without constipation were randomly assigned
to rifaximin (550 mg dose) or placebo, 3 times daily for 2 wk, with a follow-up of 10 wk. The primary endpoint was adequate self-reported relief of global IBS symptoms. Results: Significantly more patients in the rifaximin group had adequate self-reported relief of global IBS symptoms compared to the placebo group during the first 4 wk after treatment (40.8% vs. 31.2% respectively). Also, more patients in the rifaximin group had adequate relief of bloating compared to the placebo group (39.5% vs. 28.7% respectively).
Conclusions: Rifaximin therapy for 2 wk provided significant relief of symptoms, bloating, abdominal pain, and stool consistency associated with IBS without constipation.
• •
Causes of Constipation
DOPED
Drugs
Obstruction
Pain
Endocrine dysfunction Depression
Prognosis
• 80%improveovertime
• mosthaveintermittentepisodes • normallifeexpectancy
Constipation
Definition
• passageofinfrequentorhardstoolswithstraining(stoolwater<50mL/d);bowelfrequency<3x/wk
Epidemiology
• increasingprevalencewithage;F>M
• rareinAfricaandIndiawherestoolweightis3-4xgreaterthaninWesterncountries
Etiology
• mostcommon:idiopathicattributedtocolondysmotilitybutthisisdifficulttomeasure • organiccauses
■ medication side effects (narcotics, antidepressants) are the most common
■ intestinal obstruction, left sided colon cancer (consider in older patients), and fecal impaction ■ metabolic
◆ DM
◆ hypothyroidism
◆ hypercalcemia, hypokalemia, uremia
■ neurological
◆ intestinal pseudo-obstruction ◆ Parkinson’s disease
◆ MS
■ collagen vascular disease (e.g. scleroderma) ■ painful anal conditions (e.g. fissures)
Clinical Presentation
• overlapswithIBS
• stoolfirm,difficulttoexpel,passedwithstraining,abdominalpainrelievedbydefecation,flatulence,
overflow diarrhea, tenesmus, abdominal distension, infrequent BMs (<3/wk)
Investigations
• underlying disease rarely found if constipation is the only presenting symptom
■ only test indicated in this situation is a CBC (2013 recommendation of American Gastroenterology
Association), but also consider TSH, calcium, and glucose, X-ray of abdomen
• colonvisualizationifconcomitantsymptomssuchasrectalbleeding,weightloss,oranemia
(colonoscopy, CT colonography)
• ifrefractorytotreatment,considerclassificationbasedoncolontransittime;canmeasurecolonic
transit time with radio-opaque markers that are ingested and followed with a series of plain film
abdominal x-rays (normal: 70 h)
1. normal = misperception of normal defecation (IBS)
2. prolonged throughout = “colonic inertia” (infrequent bowel movements with gas/bloating, tends to
occur in youth)
3. outlet obstruction = inability to coordinate pelvic floor muscles to empty rectum, straining, stool in
rectum on digital exam, tends to occur in old age
• combinationof1and3common