The large bowel, the colon and the rectum,  is like a long hollow tube running through the belly and into the pelvis. When a cancer develops in the bowel it can sometimes block off this tube, causing what is known as a bowel obstruction. This rapidly leads to pain, constipation and vomiting.

The treatment is usually an operation to remove the cancer and the blockage at the same time. Over the last 10 years stents have been developed as one way of treating bowel obstruction due to cancer, when an operation is not possible.

A stent is a cylinder of woven metallic mesh, which may or may not have a flexible plastic covering.  The stent is about 1cm in diameter but once it is in position in the bowel the metallic mesh can be stretched by an inflatable balloon to produce a tube about 2cm across which is usually sufficient to allow the normal passage of faeces through the bowel.

Insertion of the stent involves a stay in hospital.  Mild sedation is given and the stent, which as attached to a guide wire, is passed through the back passage to the obstruction. Once it is in the right position the balloon is inflated to stretch the stent to the correct diameter. 

In bowel cancer stents have usually been used either to ease an obstruction when people are too ill to have an operation or when there is a very advanced cancer which is too big to be removed by an operation.

Sometimes they may also be used to ease a cancerous blockage for a few days before an operation. This allows time for tests to be done before surgery and for careful preparation of the bowel for the operation, which may help to increase the chances of successful surgery with fewer complications afterwards.