Medical Screening

Spring 2005 CSANews Issue 54  |  Posted date : May 17, 2007.Back to list

We are all familiar with the advice to have an annual physical examination by our doctor, including certain basic blood tests and a urinalysis. But what screening tests should we be advised to have, and how often? This is the question that even the medical community continues to debate, realizing that the early detection of certain conditions can have a profound effect on outcome and the prevention of a fatal result.

A medical screening test may be defined as a diagnostic medical procedure which can detect abnormalities before the onset of any signs or symptoms. So, in addition to your physician being able to detect the early signs of disease by means of a thorough annual examination, certain other tests are advised for specific age groups. These may differ according to sex, family history and race.

Recognizing that early detection of many diseases is the best defence, this article may encourage you to take a more proactive approach to your health.

There are many conditions that can be detected by your doctor's examination, such as high blood pressure, visual impairment, carotid artery narrowing, thyroid nodule or tumour, skin cancer, lung and heart conditions, abdominal aneurysm, and impaired peripheral circulation. In addition, the routine blood and urine examinations may detect such conditions as anemia, leukemia, diabetes, infection and kidney disease. But there are also a number of conditions that this routine annual assessment may not detect and which can only be determined by other tests.

Although the necessity and frequency of screening tests may vary according to one's specific health status and the criteria adopted by one's personal physician, the following guidelines are generally accepted by Canadian physicians.

A medical screening test may be defined as a diagnostic medical procedure which can detect abnormalities before the onset of any signs or symptoms.

Men and Women
Glaucoma: This condition, more common among seniors, can develop without one's knowledge. Glaucoma is associated with an increase in intraocular pressure. Diagnosed early, the condition is very treatable and complications and blindness can likely be reduced. The test is conducted in the office using a simple procedure called tonometry, and it is performed by the optometrist or ophthalmologist (see sidebar). Although the American Academy of Ophthalmology recommends an annual eye exam and tonometry yearly for persons over the age of 40, the Canadian Task Force on Preventive Health Care has not confirmed the value of tonometry as a screening test, other than for those with family history, previous abnormal pressure or diabetes.

Cholesterol: A simple blood test measuring your blood fat levels may lead to early detection of abnormal cholesterol or other fats. Widely accepted as one of the major risk factors for the development and progression of arteriosclerosis, elevated fat levels can predispose individuals to the risk of stroke, TIA (Little Stroke), heart attack, aneurysm and peripheral vascular disease (leg artery blockages). Dietary changes, as well as medications such as the Statin family of drugs, can bring these levels lower, thereby reducing the risk of such events.

The Heart and Stroke Foundation of Canada recommends the test for men aged 40-70, even if no risks are identified. The test should be performed every five years, as long as results are normal. If results are abnormal, more frequent testing and treatment may be suggested.

The recommendation for women is to begin the testing at the onset of menopause, testing every one to three years until the menopausal effect on fat levels has stabilized. Once stabilized, the levels can be measured every five years if they are normal, and more frequently if they are not.

Those with diabetes, obesity, hypertension, previous vascular problems and family history of arteriosclerosis should be tested earlier and more frequently.

Skin Cancer: Snowbirds, in particular, should be aware of the need for regular screening for suspicious skin lesions. Because of increased sunlight exposure for many snowbirds, the risk of skin cancers may be greater. Screening can be done by the individual or spouse and, in these days of digital photography, baseline total body records can be made to prove any suspected new or changing skin lesion.

Report any such change to your physician and be sure that your doctor's periodic health examination includes a thorough evaluation of your skin. Basal cell and squamous cell cancers can be readily treated if diagnosed early, and malignant melanoma must be detected as early as possible to reduce the more serious risk with this extremely malignant tumour.

Colorectal Cancer: Colon and rectal cancer develops in the large bowel, is the third most common cancer diagnosed in Canadians and is the major cause of cancer deaths in seniors. It is largely preventable and if diagnosed in its early stages, is most often successfully eradicated. The most common screening test used by physicians is the Fecal Occult Blood Test (FOBT). The National Committee on Colorectal Cancer Screening recommends that the test be done at least every two years for people between the ages of 50 and 74. As the test simply detects possible blood in the stool, it is non-invasive and harmless.

The more sophisticated and more accurate test for such cancers is a colonoscopy (see sidebar). With this flexible scope and with proper bowel preparation, the physician is able to visualize the large bowel and detect an early cancer or its precursor, a bowel polyp. The latter, although benign, often develops into a malignancy. These can most often be removed during the same procedure without the necessity of an abdominal operation. Because this is an invasive test, often performed with some general anesthesia or sedation, there is a measurable risk. Accordingly, the National Committee does not yet endorse the procedure as a routine screening test, but does support it in patients with symptoms, such as blood in their stool, and for those with a family history of colorectal cancer. Nevertheless, many physicians now recommend this more accurate method of diagnosing polyps or cancer for everyone in this age group, and many seniors are requesting the procedure. When polyps are found and removed, a further screening colonoscopy does not need to be repeated for three to five years.

The Canadian Cancer Society recommends that all persons over the age of 50 have a FOBT at least every two years. This organization, along with the Colorectal Cancer Association of Canada, agrees that there is convincing evidence that the death rate from colorectal cancer can be significantly reduced if this screening takes place widely among the Canadian population.

Specific Female Screening

Mammography: This is an imaging technique that uses X-rays to provide pictures of the internal structures of the breast and is used to detect early breast cancer. More than 10 per cent of Canadian women will be diagnosed with breast cancer during their lifetime. Although the incidence of breast cancer has risen in the past 25 years, it is believed that the detection of early tumours through mammography is one of the factors lowering morbidity and mortality numbers. Health Canada recommends these routine screening X-ray examinations as a supplement to self and physician breast examination. Screening should be done every two years for most women between the ages of 50 and 69. Many studies have shown that such routine screening has the potential of reducing deaths from breast cancer in this age group by up to 40 per cent. Many provinces have dedicated breast cancer screening clinics in which these examinations can be done.

There is continued disagreement regarding whether or not women under 50 and over 69 encounter the same favourable experience with mammography. Until such evidence is clear, women should decide for themselves based on their personal medical advice.

Pap Test: The Papanicolaou Smear is well known to women as a very important screening test which is usually recommended regularly from the time they are young. What is less well known is when it should cease being recommended. While cervical cancer is the 10th most common cancer among Canadian women of all ages, it is far more common in the 20-49 age group. The test, a smear of the cervix mucosa, is used to detect changes in the cervix before the cells become cancerous or when they are at the early stage, when treatment can be effective.

Although the test is recommended by most physicians during the course of a periodic health exam, and at least every three years, Health Canada recommends that women over the age of 69 who have had at least two clear Pap tests, no cervical abnormalities for nine years and no history of cancer, no longer need to have the test performed as a screening tool.

Osteoporosis Screening: Numerous studies have been conducted in Canada to determine if and when special screening X-rays called DEXA (see sidebar) should be used to detect osteoporosis, especially in women. The condition, characterized by low bone mass and deterioration of bone tissue, leads to increased bone fragility and risk of fractures, especially hip, spine and wrist. One in four women and one in eight men over the age of 50 have the disease. Your doctor will advise whether certain indications with your health status warrant this investigation. However, it has been widely adopted that persons over the age of 65 now have this test. If abnormal, treatment and closer follow-up may be recommended. If normal, a repeat test is not necessary for another five years.

Specific Male Screening

Protein Specific Antigen: The PSA test is the most commonly requested and performed cancer detection test in men. This test is recommended yearly after the age of 50, along with a digital rectal examination during the annual physical. An abnormal test result indicates the possibility of cancer of the prostate, and further investigation including biopsy may be suggested.

Prostate cancer is the second most frequent cause of cancer-related death among men. Early diagnosis leads to earlier treatment, which has a direct bearing on outcome. This test is one of the best biochemical tests for the early detection of cancer. For men over the age of 70, there is still debate whether this screening test is warranted, partly because in many cases, medical and surgical treatment may cause more morbidity than the slow-growing tumour itself.


Your physician may recommend specific testing, depending upon your family and personal medical status. Be sure that you adopt this proactive approach to your health. In case medications are added or changed, or you will be undergoing an investigative test, book your annual check-up well in advance of your winter vacation in order to avoid being "unstable," as defined by your travel health insurance policy.

And remember: "An ounce of prevention is worth a pound of cure!" Be sure that you're getting the recommended screening tests.

Tonometry is an office procedure to measure the level of pressure within the eye.

A tonometry test takes only a few minutes to perform, and it should not cause any pain. If you wear contact lenses, remove them before the test. Do not put your contacts back in for at least 2 hours after the test (better bring your eyeglasses!).

There are different types of tonometry eye tests. With the non-contact "air puff" method, a brief puff of air will be blown into your eye. For other tests, such as "applanation" and "indentation", the doctor will use drops to numb your eye before conducting an instrument-to-eye surface examination.

A colonoscopy is a procedure involving the visual inspection of the mucosal lining of the rectum and large intestine using a flexible lighted tube with a camera on the end. The lining of the intestine is visualized on a video monitor and if an abnormality is detected, the doctor can remove it or take tissue samples using tiny instruments passed through the scope.

A colonoscopy can be carried out in a hospital, clinic, or doctor's office, depending on the facility. Before a colonoscopy, you will have the "fun" job of cleaning out the contents of your bowel. You will be required to follow a liquid diet for 1 to 3 days before the procedure and you will need to take laxatives, which most often cause diarrhea. This cleansing process can be quite uncomfortable, but if your bowel is not completely empty at the time of the test, your doctor may not be able to conduct a thorough examination and the test may need to be repeated at a later date.

The procedure takes 30 to 60 minutes, but may be longer if a polyp is removed or a biopsy is taken. The sedative and pain medicine should keep you from feeling much discomfort during the exam. You will not be able to drive after the procedure (due to the sedation), so make sure that you have arranged for transportation.

The Dual-Energy X-Ray Absorptiometry or DEXA Scan measures the calcium content or bone mineral density (BMD) at the spine or hip. This low dose special X-ray is the best method of measuring BMD for diagnosing osteoporosis and monitoring the effects of osteoporosis therapy.

A DEXA scan is a simple, painless procedure that takes approximately 15-20 minutes to perform. No preparation is necessary, although you should avoid wearing clothing with metal fastenings or zippers. You will be asked to lie very still on the scan table.

A scanner arm will pass over one hip and the vertebrae of the lower spine. You will have to lie in the same position for about 5 minutes for each assessment.