The diagnosis of colorectal cancer can be made through a variety of diagnostic tests. Early detection is very important for colorectal cancer. If colorectal cancer is found early, the chances for curing the cancer are greatly improved. Precancerous polyps can be detected and removed before they become cancerous. When colorectal cancer is detected early the prognosis is very good; approximately 90% will survive 5 years after diagnosis. When the cancer is detected at a later stage, meaning the cancer has spread to other organs near the colon or rectum, or to the blood system it is estimated that only 60% will survive 5 years after diagnosis. If the cancer has already spread to other organs such as the liver, lungs or bone, only 8% will be expected to live 5 years after diagnosis. Unfortunately in the United States only approximately 37% of all cases of colorectal cancer are diagnosed before the cancer has spread to other organs. This emphasizes the need for early detection and screening for colorectal cancer.

Colorectal cancer can be detected by the following tests, digital rectal exam, ultrasound or CT scans, barium enema studies, and colonoscopy or flexible sigmoidscopy. Blood tests such as, liver function tests and carcinoembryonic antigen assay test (CEA), are helpful in diagnosing colorectal cancer.

Digital rectal exam
A digital rectal exam is an exam in which the doctor will insert a gloved finger into the rectum to feel for any abnormal areas. This can detect the presence of polyps or cancerous growths.

Ultrasound or CT studies
Ultrasound or CT studies can be useful to detect the presence of cancer outside the colon or rectum.

Barium enema with air contrast studies
Barium enema with air contrast studies can show the presence of colon polyps or tumors. This technique is not very useful in detecting rectal polyps or tumors. Patients undergoing barium enema with air contrast studies have barium sulfate, a substance that is detected by x-ray, instilled into their colon. The colon is then filled with air and x-rays are taken.

Colonoscopy or flexible sigmoidoscopy
Flexible sigmoidoscopy and coloscopy use similar techniques. A slender, flexible, hollow, lighted fiberoptic tube is inserted through the anus and into the colon where the doctor can view the colon and rectum. If a polyp or cancerous growth is seen it can be removed or a piece of it can be removed for biopsy. The flexible sigmoidoscopy differs from a colonoscopy in the amount of colon that can be viewed. The flexible sigmoidoscope can only view about half of the colon. The colonoscope is longer and can view the entire length of the colon. In the United States about one-third of colorectal cancers are not within the reach of the flexible sigmoidoscope.

Carcinoembryonic Antigen assay (CEA)
The carcinoembryonic antigen assay test is blood test that is usually done after colorectal cancer is diagnosed. Elevated levels of CEA in the blood can occur in the presence of colon and rectal tumors, however other non-cancerous conditions can result in an elevated blood level. Because of this, the test is not useful in the screening of colorectal cancers.

Diagnosis in TCM places importance on determining the circumstances and manifestations of a disease through inquiry and observation of symptoms. Diagnosis is based on the four traditional examination techniques:

Questioning: The TCM practitioner will establish the medical history of both the patient and his family.

Observation: Examination of the physical features of the body, such as the face, tongue, hair, nails, sputum (mucus that is coughed up), and location of pain, all offer clues to the problem. The tongue is a particularly useful indicator of the functioning of the internal organs.

Listening and Smelling: The odor of sputum and breath and listening to chest sounds offer additional clues to the patient's health.

Touching: Feeling the pulse is a cornerstone of TCM diagnosis and gives the practitioner much information about any bodily imbalance.

TCM practitioners will usually begin with a full investigation of the patient and categorize symptoms under special syndrome groups known as "disharmony patterns." Certain disharmony patterns are present at different stages of a disorder. See article on "Principles of Diagnosis" In addition to manifestations of colorectal cancer as mentioned previously, practitioners also use pulse and tongue examination to obtain a diagnosis.

1. Downward migration of damp-heat
The major diagnostic presentations are abdominal cramps, diarrhea with mucous and bloody stools, tenesmus (painful, ineffectual straining to empty the bowel and bladder), and a burning sensation in the anus. On examination, the tongue is red, and covered by yellow and greasy fur. The pulse is rolling and rapid.

2. Excessive accumulation of poisonous pathogens
The major diagnostic presentations are poor appetite, fever with dysphoria (an emotional state characterized by anxiety, depression, or unease), thirst, abdominal distention and cramping, diarrhea with mucous feces (which are copious and dark purple in color). On examination, the tongue is red, and covered by yellow or dried yellow colored fur. The pulse is surging and rapid.

3. Interior retention of blood stasis
The major diagnostic presentations are fixed and persistent abdominal pain and grayish complexion. On examination, the tongue is dark and purple in color, and covered with brusied spots. The pulse is hesitant or taut or knotted and intermittent.

4. Deficiency in qi (vital energy) and blood
The major diagnostic presentations are pale complexion, light-colored lips and nails, general weakness and shortness of breath. On examination, the tongue is pale with a thin and white coating; the pulse is deep and thready.

5. Yang deficiency in spleen and kidney
The major diagnostic presentations are pale complexion, aversion to cold temperatures, limb coldness and diarrhea in the morning. On examination, the tongue is bulky and the pulse is deep, thready, and weak.

6. Yin deficiency in liver and kidney
The major diagnostic presentations are constipation, wasting of body tissue, dizziness, ringing in the ears, and a feverish sensation in the chest, palms, and soles.
On examination, the tongue is dark red and covered by scanty fur. The pulse is thready and taut, or rapid and thready.