Colon Screening Examination Methods

Colorectal cancer refers to any form of cancer located in the large intestine.  The colon is a muscular tube about five feet long.  It empties into the rectum, or the last six inches of the digestive track.  Colorectal cancer tends to progress slowly, making it highly preventable and treatable if caught early.

Excluding skin cancer, colorectal cancer is the third most common type of cancer in the United States. In 2010, the National Cancer Institute estimated that there could be 102,900 new cases of colon cancer and 39,670 cases of rectal cancer in the United States, with 51,370 deaths making colorectal cancer the second leading cancer-related killer in the US. More than 90% of those diagnosed with this disease are over the age of 50. In addition, research shows that up to 2.3% of people with bleeding hemorrhoids also have colorectal cancer.

Colorectal cancer has been called a “silent killer” as there are often no symptoms. Occasionally, patients may experience non-specific symptoms such as blood in the stool, a change in bowel habits, diarrhea, constipation, stools that are narrower than usual, unexplained weight loss, fatigue, bloating, cramps, gas, nausea or vomiting. 

While the cause of colorectal cancer is unknown, a number of risk factors have been identified.   Notably, the risk rises markedly after age 50, although you can develop the disease at any age.  Another prime risk factor is family history, as about 30% of those diagnosed with colorectal cancer have relatives with the disease.

Other risk factors include ulcerative colitis, Crohn’s disease, obesity, smoking, physical inactivity and a history of colorectal polyps, or growths inside the colon or rectum that can sometimes become cancerous.  In addition, Jews of Eastern European descent (Ashkenazi Jews) have been found to have a higher rate of colorectal cancer.

Our goal is to significantly reduce – if not eradicate – that statistic by screening patients annually. The early diagnosis and removal of pre-cancerous polyps can, quite literally, save your life. 

Screening Methods

There are several screening methods for colorectal cancer. Please note that not all of the screening methods listed below are offered in all of the offices on this website. Please consult with the office in which you would like to be seen prior to your appointment.

Digital Rectal Exam

A digital rectal exam is often part of a routine physical examination.  During this brief procedure, a doctor or nurse inserts a lubricated, gloved finger into the rectum to feel for any abnormal growths.  If anything unusual is found, a more specific follow-up test is ordered.  A major limitation of this method is the inability to screen for growths in the colon, the five-foot long segment of intestine located above the rectum.   

Fecal Occult Blood Test (FOBT)

The FOBT screening involves gathering a small amount of stool at home so that it can be chemically tested for the presence of blood.  In many cases, blood in the stool may be the first, or only, warning sign of colorectal cancer as precancerous growths are known to bleed. Because other conditions may be responsible for blood in the stool, however, a colonoscopy is required after a positive FOBT to diagnose the cause of rectal bleeding.

Colonoscopy

This diagnostic method involves inserting a long, flexible, lighted tube into the rectum and slowly guiding it into the colon.  Images are transmitted to a computer, and the physician looks for abnormal growths.  If any are found, the physician can surgically remove them for testing (called a biopsy).  To prepare for the 30-60 minute procedure, which is performed under sedation, patients must go on a liquid diet for one to three days and take a laxative or enema the night before. 

Sigmoidoscopy

Sigmoidoscopy is similar to colonoscopy, except that it only examines the rectum and lower third of the colon, called the sigmoid.  Thus, the test is shorter, around 10-20 minutes long, and more limited.  As with a colonoscopy, any abnormal growths that are discovered can be biopsied and sent for testing to determine if they’re cancerous.  

Double-contrast Barium Enema (DCBE)

DCBE is a series of x-rays of the lower intestine taken after the colon is filled with contrast material containing barium and inflated with air.  These measures allow for a detailed view of the lining of the colon, making the identification of growths easier.  Unlike a colonoscopy, however, abnormal growths cannot be removed during this approximately hour-long procedure, and a follow-up colonoscopy may be required.  This method also has a higher rate of missed lesions when compared to colonoscopy.

Virtual Colonoscopy

Virtual colonoscopy, also referred to as CT colonography, is a new form of x-ray used to detect polyps in which multiple dimensional images are taken to visualize the lining of the colon.  While there have been some concerns raised about the potential for problems resulting from radiation exposure, it is less invasive and less expensive than colonoscopy and requires no anesthesia.  But small polyps may not show up, and if a polyp is found, a follow-up colonoscopy is needed.  Further studies are needed to determine the role of this new technique, which may not be covered yet by some insurance companies.