A Comprehensive Guide to Colon Tests

Today’s colon tests are more sensitive and accurate than ever. They give gastroenterologists and their patients the information they need to plan treatments, lessen the risks for disease, and more. What follows here is a guide to colon tests, including the reasons why your GI specialist may order them.

Reasons For Colon Testing

One of the most important reasons for colon testing is the risk of colon cancer. The American Cancer Society reports that in the US, one out of every 23 men and one out of every 26 women are diagnosed with colon cancer over the course of their lifetime.

The risk for colon cancer increases with age, so doctors advise everyone age 45 and up be tested. A colonoscopy is a procedure that detects changes in the bowel wall called polyps. While polyps are not cancerous themselves, all colon cancer develops from these small growths, and therefore, they should be visualized, removed, and biopsied.

Besides age-related cancer risk, reasons for colon testing include:

  • Persistent large intestine symptoms, such as bloating, cramping, bleeding from the rectum, diarrhea and others
  • A personal history of cancer
  • A personal history of polyps
  • Family history of colon cancer
  • Inflammatory bowel disease, Crohn’s disease, or family history of these inflammatory GI conditions

Types of Colon Testing            

Your gastroenterologist has a number of state of the art tests to use in accurate diagnosis and treatment of disorders and diseases of the large intestine. Used in conjunction with physical examination, blood work, and review of symptoms and medical history, colon tests are easier to prepare for and recover from than ever before. They include the following.

Fecal Occult Blood Test (FOBT)

The FOBT is an at-home kit which detects trace amounts of blood hidden in the stool. There is no special preparation; the patient simply provides a fresh stool sample on a piece of toilet tissue or in the collection kit and returns it to the lab for analysis.

Home kits are reliable for people at average risk for colon cancer. They reveal DNA changes in the sample which are indicative of possible gut issues. Positive results require follow up with a colonoscopy.

Flexible Sigmoidoscopy

This imaging test requires mild sedation, and preparation is easy. Simply fast for the number of hours your healthcare provider recommends, and use laxatives and enemas as directed.

During the test, the GI doctor introduces a thin, lighted endoscope through the anus and into the rectum. It advances only to the sigmoid colon located between the pelvic brim and the lower part of the bowel (descending colon) and takes images of the bowel wall.


Considered the superior method of detecting polyps, cancerous tumors, and other conditions of the large intestine, a colonoscopy involves insertion of a long endoscope into the rectum and through the entire large intestine. With the scope, the gastroenterologist can see and remove polyps (the possible precursors to colon cancer) and also detect tumors, areas of bleeding and inflammation, and more. The doctor takes real-time still photos and video images as needed, as the scope is equipped with a small camera and other instruments which facilitate tissue removal for biopsy.

Patients do an extensive fast and bowel preparation with laxatives the day prior to their colonoscopies. The 30- to 60-minute test is done with the benefit of sedation, so patients are asleep and have no memory of their tests afterwards.

Abdominal Pelvic Ultrasound

Non-invasive with no radiation exposure, an abdominal pelvic ultrasound delivers low frequency sound waves through the abdominal wall. The sound waves reflect off solid structures within the abdomen, helping GI doctors diagnose and treat a variety of lower gastrointestinal conditions.

To facilitate visualization of the lower abdomen, the patient fasts for six to eight hours prior to the exam and drinks a prescribed quantity of water one hour before. There is no anesthesia required and no downtime afterwards.

Colon Testing at Genensis Healthcare Partners

In California, Genensis Healthcare Partners provides premiere diagnostic and treatment services for a wide range of gastrointestinal conditions. We have 20 locations throughout the state with numerous board-certified providers who deliver compassionate accurate care when you need it most.

Please contact the location nearest you to learn more about colon testing. Or, if you wish, complete our appointment request form, and a scheduler will get back to you within 48 hours. We look forward to serving you!