Low fiber intake, inadequate amounts of fluids, poor ambulation or immobility, or medications can contribute to constipation. Once the presence of constipation is identified based on a culmination of the symptoms described above, then the cause of constipation should be figured out. Separating non-life-threatening from serious causes may be partly based on symptoms. For example, colon cancer may be suspected if a person has a family history of colon cancer, fever, weight loss, and rectal bleeding. Other alarming signs and symptoms include family or personal history of inflammatory bowel disease, age of onset over 50, change in stool caliber, nausea, vomiting, and neurological symptoms like weakness, numbness and difficulty urinating. Examination
A physical examination should involve at least an abdominal exam and rectal exam. Abdominal exam may reveal an abdominal mass if there is significant stool burden and may reveal abdominal discomfort. Rectal examination gives an impression of the anal sphincter tone and whether the lower rectum contains any feces or not. Rectal examination also gives information on the consistency of the stool, the presence of hemorrhoids, blood and whether any perineal irregularities are present including skin tags, fissures, anal warts. Physical examination is done manually by a physician and is used to guide which diagnostic tests to order. Diagnostic tests
Functional constipation is common and does not warrant diagnostic testing. Imaging and laboratory tests are typically recommended for those with alarm signs or symptoms.The laboratory tests performed depends on the suspected underlying cause of the constipation.
Tests may include CBC (complete blood count), thyroid function tests, serum calcium, serum potassium, etc.Abdominal X-rays are generally only performed if bowel obstruction is suspected, may reveal extensive impacted fecal matter in the colon, and may confirm or rule out other causes of similar symptoms.Colonoscopy may be performed if an abnormality in the colon like a tumor is suspected. Other tests rarely ordered include anorectal manometry, anal sphincter electromyography, and defecography.Colonic propagating pressure wave sequences (PSs) are responsible for discrete movements of the bowel contents and are vital for normal defecation. Deficiencies in PS frequency, amplitude, and extent of propagation are all implicated in severe defecatory dysfunction (SDD). Mechanisms that can normalize these aberrant motor patterns may help rectify the problem. Recently the novel therapy of sacral nerve stimulation (SNS) has been utilized for the treatment of severe constipation. Criteria
The Rome III Criteria for functional constipation must include two or more of the following and present for the past three months, with symptoms starting for at least 6 months prior to diagnosis. Straining during defecation for at least 25% of bowel movements
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
Fewer than 3 defecations per week
Loose stools are rarely present without the use of laxatives
There are insufficient criteria for irritable bowel syndrome

Prevention
Constipation is usually easier to prevent than to treat.