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home - Colon - Diagnostic Pathways for Colonic Disease - Constipation Tests Written by Dr Sebastian Zeki
Knowledge
Assessment
Methods GMP
Knows the physiology of intestinal absorption, secretion and motility SCE 1
Understands the biochemical processes occurring within the gut
lumen and at mucosal level

Has awareness of the factors controlling these processes – in
particular the neuro-endocrine influences

Understands the range of mechanisms by which diarrhoea can result
from disturbances in each of these processes

Knows the causes of both acute and chronic diarrhoea
Knows the range of investigations appropriate to determining the
cause of the patient’s diarrhoea and is aware of the range of
therapeutic possibilities

Skills
Makes a detailed clinical assessment of patients that present with
either acute or chronic diarrhoea

Recognises the potential need for urgent fluid replacement CbD,
Makes appropriate use of microbiology and other relevant laboratories in reaching a diagnosis

Shows ability to interpret results, reach a diagnosis and formulate a
treatment plan

Behaviours
Reacts appropriately to the urgency of the clinical presentation
Always shows sympathy and understanding especially when the
patient is distressed

Constipation Tests

Constipation Predominant IBS- Rome II criteria:-Straining during at least 25 % of defecations.-Lumpy or hard stools in at least 25 % of defecations.-Sensation of incomplete evacuation for at least 25 % of defecations.-Sensation of anorectal obstruction/blockage for at least 25 % of defecations.-Manual maneuvers to facilitate at least 25 % of defecations (eg, digital evacuation, support of the pelvic floor) -Fewer than three defecations per week. Peripheral Causes:Hirschsprung disease.Chagas disease.Autonomic neuropathy.Intestinal pseudoobstruction.Diabetes mellitus. Metabolic Causes:Hypo/hypercalcaemia.Amyloidosis/porphyria/PB.Increased urea. DermatomyositisSS Metabolic Endoscrine Neurological Neuromuscular Drugs Pseudo-obstruction Megacolon Megarectum Strain Strain Types of chronic constipation:Normal colonic transit - These exhibit increased psychosocial distress (includes IBS).b)Slow transit constipation (=colonic inertia).c)Outlet delay (=Pelvic floor dysfunction). -History and Examination-Baseline labs/ IBS criteria-Trial of fibre and simple laxatives Motility Tests If all tests normal then Dx= IBS Abnormal CTTDx= Slow transit constipation Abnormal ARM with high resting pressureDx= Rule out anal fissure Abnormal ARM with absence of anoinhibi-tory reflex- Rule out Hirshsprung’s Disease Abnormal BET or BDDx= dyssynergic defecation, (ineffective defecation assoc. with failure to relax/ inappropriate contraction of puborectalis and external anal sphincter muscles)-narrows the anorectal angle with inc. pressures in anal canal with less effective evacuation.Relaxation of these muscles involves cortical inhibition of the spinal reflex during defecation; thus, this pattern may represent a conscious or unconscious act- probably an acquired, learned dysfunction.Diagnostic criteria for dyssynergic defecation include inappropriate contraction of the pelvic floor or less than 20 % relaxation of basal resting sphincter pressure with adequate propulsive forces during attempted defecation. Pelvic Dyssynergia Pelvic Floor Dysfunction Constipation Diagnostic Tests CTT ARM Motility studies Barium DefecographyBalloon expulsion test (BET) 1) Colonic Transit Test (CTT)This tests colonic propulsion.The patients should be on a high fibre diet (20 to 30 g per day) and stop medications that may affect bowel function.Radiopaque markers are followed moving around the colon.Right colonic transit is delayed with colonic inertia.Markers progress normally through the proximal colon but can stagnate in the rectum if there is outlet delay.Most with chronic constipation have normal transit. 2) Anorectal manometry (ARM) ARM tests pressures of the anal sphincter muscles, the sensation in the rectum, and the neural reflexes. Overview of Motility studies —Tests rectal sensation and compliance and reflexive relaxation of the internal anal sphincterManometric patterns produced upon attempted expulsion of the apparatus (pseudodefecation).3. Pressures recorded by the rectal balloon provide some indication of intraabdominal pressures generated during expulsion efforts, while pressure recordings of the anal sphincter transducers indicate relaxation or inappropriate contraction of the external anal sphincter. Normal: Increase in intrarectal pressure and decrease in external sphincter pressure during monitor expulsion.Results:1. Hirschprung excluded if internal anal sphincter relaxes following rectal distension2. In patients with dyssynergic defecation, there is an increase in external sphincter pressure during attempted expulsion of the manometer. 4) Barium Defecography (BD)This involves videoing thickened barium being passed.Assessment of the anorectal structures, including the anorectal angle, are obtained at rest and during expulsion of the barium mixture.In dyssynergic defecation, for example, the anorectal angle either does not widen or actually narrows during attempts to expel the barium, so that little or no expulsion occurs. 5) Balloon expulsion test (BET) This is a seful screening test for defaecatory dysfunction.If the balloon is expelled in <1 minute, it is unlikely that dysfunction exists (90 % sensitivity). Central Causes: Multiple sclerosis (from absent colonic responses after eating a meal).Spinal cord injury (in high cord injury, colonic reflexes intact and can trigger defaecation by stimulating anal canal.Parkinson's disease. Causes:Systemic upset.Obstruction.Dilated dysmotility.Idiopathic. (1) Must include two or more of the following: (2) Loose stools are rarely present without the use of laxatives(3) There are insufficient criteria for IBS. Written by Dr Sebastian Zeki

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