Colonic Inertia Testing

The initial evaluation of the patient with suspected colonic inertia includes a careful history and physical examination.

A digital rectal examination may be performed as well to examine the rectum for tenderness, masses, strictures, and stool.

Blood testing, although not normally needed, may be done to check for thyroid or other hormonal issues.

Colon transit studies- Colonic transit studies are most useful in the evaluation of patients with suspected colonic inertia.  It is indicated for patients with chronic constipation that is unresponsive to laxatives and other conservative measures to differentiate slow from normal colonic transit.

- Radiopaque (sitz) marker study — This study is commonly performed by measuring movement of radiopaque markers through the gut.

Patients are instructed to stop taking any laxatives, enemas, and medications that may affect bowel function for two to three days prior to the test.

For routine clinical purposes, a single capsule with 24 markers is administered on day 1.  After the markers are swallowed, their passage through the colon is monitored by abdominal radiographs (plain x-rays). After 12 hours, the rings are usually all present in the colon. When an x-ray is obtained after 24 hours or longer, the number of rings present in the colon can be counted. Most clinicians take an x-ray 3 and 5 days after ingestion of the capsule. Alternately, x-rays can be performed on a daily basis until all of the rings have been excreted.  Based on studies in non-constipated patients, at day 5, the presence of fewer than 20% of the ingested rings suggests normal colonic transit. If more than 20% of the rings are counted on the x-ray, delayed colonic transit is present.

- Wireless motility capsule (Smart pill) — A patient swallows a special pill and wears a receiver as they return to normal activity. The patient is instructed to press the "event" button when performing certain activities such as exercise, eating, and going to the bathroom. After 3 days, the receiver is returned to the doctor. The information collected from the receiver is transferred to a computer where the doctor analyzes the data.

Motility studies

- Anorectal manometry — During this test, a flexible tube approximately a 1/8th inch in diameter is inserted through the anus and into the rectum. Once the tube is in place, the patient is asked to perform a few simple maneuvers, such as voluntarily tightening the anal muscles. There are sensors within the tube that measure the pressures that are generated by the muscles of the anus and the rectum. These sensors can determine if the muscles of the anus and the rectum are working normally

Other Tests

- Barium Enema- a lower GI Series is a study that is done using x-rays and liquid barium. The liquid barium, which outlines the colon on x-rays, is inserted through the anus to fill the rectum and colon. On the x-rays, the barium helps to show any abnormal anatomy of the colon and the rectum. Some common abnormalities discovered through this test are tumors and strictures (narrowing of the colon).

- Defecography- this test is similar to the barium enema. In the defecography, a thick paste of barium is inserted through the anus and into the rectum. As the patient defecates the barium, x-rays are taken. Since the barium outlines the rectum and the anus, it shows the changes that take place in the muscles of the pelvic floor during defecation