Small Bowel Intubation study.

The intubated small bowel study is the examination of choice if other methods fail to reveal a suspected short stricture or band or adhesion. A naso-gastric tube is passed to the stomach and, with the aid of a stiff wire, is manipulated into the 4th part of duodenum. The bowel can be opacified in several ways: The simplest is to dilute the barium suspension (formulated for small-bowel examination) with water to about one third of its original density and then run the diluted suspension into the small bowel at such a rate that distension and temporary reduction in peristalsis is achieved. 100 ml of undiluted barium is injected down the tube and then followed by a solution of dextrans chosen to have similar viscosity to the barium. The principle relies on the laminar flow where flow is maximal in the centre of the lumen.

For this technique to work, there are a few assumptions:

The patient is warned about the nausia that small bowel distension induces.

The injection is not made so fast that reflux occurs through the pylorus.

Enough undiluted barium is injected to last until the caecum.

The bowel lumen is not so dilated as to allow the wave front to break down.

Some Radiologists maintain that cooling the water slows small bowel peristalis, but it doesn't endear one to the patient.

Antispasmodic drugs are contra-indicated when overfilling of the bowel is part of the investigatory technique.

Where there are problems, less stressful alternatives include the use of antispasmodic drugs to improve mucosal detail when using compression views in a standard barium follow through examination. Colonic air insufflation is often used to get double contrast images of the terminal ileum.

A vaguely double contrast examination of the small-bowel may result from combination of a small bowel follow-through after a large amount of Barium suspension (formulated for small-bowel examination) and then a gas forming agent, as used in double-contrast stomach examination. The patient is turned on their left side to empty gas into duodenum and thence to small-bowel. Antispasmodics may be given and the timing is a bit of an art. Gas moves very quickly through normal bowel.

The further the suspected obstruction is down the bowel, the greater is the probability that the use of lots of barium and antispasmodics may make the obstruction worse. Consider single contrast enema and air insufflation. Of course, the information from the greater availability of ultrasound and computed tomography will clarify your options and choices.