(e) If a retention catheter is used, it should first be deflated and then
withdrawn immediately upon completion of radiography to enable the patient to expel
the air from the colon.
(f) Examination of the rectum is necessary during the barium enema in
both the single and double contrast studies. Figure 2-19, demonstrates the Lateral
Rectum in the single contrast study. During double contrast studies with air injected,
the lateral rectum is viewed in the decubitus position with a ventral cross-table lateral
(g) The patient is directed to a toilet and instructed to evacuate. After
evacuation, a post-evacuation radiograph is made.
a. General. Radiographic studies of the Gallbladder are rarely done. These
studies have been replaced with other modalities such as ultrasound.
(1) Radiographic visualization of the gallbladder is done by
cholecystography. Radiographic investigation of the biliary tract is by cholangiography.
For these procedures, it is necessary to convey a contrast medium to the gallbladder
along with the bile.
(2) Bile is manufactured by the polyhedral cells of the liver which extract the
necessary constituents from the circulating blood. The gallbladder's ability to
concentrate the bile makes it possible for a sufficient amount of the cholecystopaque to
collect within the gallbladder to permit radiographic visualization. After oral
administration, the contrast medium, if in pill form, disintegrates in the stomach.
(a) Most of the contrast medium is absorbed in the small bowel and
conveyed to the liver via the portal vein.
(b) As the contrast medium moves throughout the liver, it becomes
associated with the liver cells and is secreted with the bile.
(c) As the bile containing the contrast medium passes along the ducts,
some of it is discharged into the duodenum and some of it backs up into the gallbladder
where concentration occurs.
(d) The elimination of the contrast medium from the body is dependent
upon various factors such as the type of contrast medium and the nature and degree of
dysfunction related to the digestive system. Normally, some of the contrast medium is
not absorbed, but is eliminated via the colon. The kidneys eliminate the part that is not
removed from the blood as it passes through the liver.