RADIOPAQUEAGENTS Diagnostic (Local)

Description

Radiopaque agents are drugsused to help diagnose certain medical problems. They contain iodine, whichblocks x-rays. Depending on how the radiopaque agent is given, it localizesor builds up in certain areas of the body. The resulting high level of iodineallows the x-rays to make a ``picture'' of the area.

The areas of the body in which the radiopaque agent localizes will appearwhite on the x-ray film. This creates the needed distinction, or contrast,between one organ and other tissues. The contrast will help the doctor seeany special conditions that may exist in that organ or part of the body.

The local radiopaque agents are used in the diagnosis of:

• Urinary tract diseases?Diatrizoates, Iohexol, Iothalamate
• Uterus and fallopian tube diseases?Diatrizoate and Iodipamide,Diatrizoates, Iohexol, Ioxaglate

A catheter or syringe is used to put the solution of the radiopaque agentinto the bladder or ureters to help diagnose problems or diseases of the kidneysor other areas of the urinary tract. It may also be placed into the uterusand fallopian tubes to help diagnose problems or disease of those organs.After the test is done, the patient expels most of the solution by urinating(after bladder or ureter studies) or from the vagina (after uterine or fallopiantube studies).

Radiopaque agents are classified by their osmolality (a measure of concentration).There are high- and low-osmolality contrast agents. Low-osmolality agentsare newer and more expensive than the high-osmolality ones. For most patients,a high-osmolality contrast agent is a good and safe choice. However, somepatients are considered to be at a greater risk of having severe reactionsto a radiopaque agent. Patients at risk are those who have had a severe reactionto radiopaque agents in the past. Also, patients with asthma or a historyof allergies may be at a greater risk of severe reactions. For these patients,a low-osmolality contrast agent may be chosen. If you have any questions aboutthis, check with the radiologist.

The doses of radiopaque agents will be different for different patientsand depend on the type of test. The strength of the solution is determinedby how much iodine it contains. Different tests will require a different strengthand amount of solution depending on the age of the patient, the contrast needed,and the x-ray equipment used. Also, for tests of the kidneys and other areasof the urinary tract, the amount of solution to be used depends on the sizeof the bladder.

Radiopaque agents are to be used only by or under the supervision of adoctor in radiology or a radiologist.

Before Having This Test

In deciding to use a diagnostic test, any risks of the test must be weighedagainst the good it will do. This is a decision you and your doctor will make.Also, test results may be affected by other things. For radiopaque agentsthe following should be considered:

Allergies?Tell your doctor if you have ever had any unusual orallergic reaction to iodine, to products containing iodine (for example, iodine-containingfoods, such as seafoods, cabbage, kale, rape [turnip-like vegetable], turnips,or iodized salt), or to other radiopaque agents. Also tell your doctor ifyou are allergic to any other substances, such as sulfites or other preservatives.

Pregnancy?Studies on effects in pregnancy when radiopaque agentsare instilled into the bladder or ureters have not been done in women. Studiesin animals have been done only with iothalamate, which has not been shownto cause birth defects or other problems.

Diagnostic tests of the uterus and fallopian tubes using radiopaque agentsare not recommended during pregnancy or for at least 6 months after a pregnancyhas ended. The test may cause other problems, such as infection in the uterus.

Also, radiopaque agents containing iodine have, on rare occasions, causedhypothyroidism (underactive thyroid) in the baby when they were injected intothe amniotic sac late in the pregnancy. In addition, x-rays of the abdomenduring pregnancy may have harmful effects on the fetus. Make sure your doctorknows if you are pregnant or if you suspect that you may be pregnant whenyou are to receive this radiopaque agent.

Breast-feeding?Although small amounts of radiopaque agents areabsorbed into the body and may pass into the breast milk, these agents havenot been shown to cause problems in nursing babies. However, it may be necessaryfor you to stop breast-feeding temporarily after receiving a radiopaque agent.Be sure you have discussed this with your doctor.

Children?Although there is no specific information comparinguse of radiopaque agents in children with use in other age groups, these agentsare not expected to cause different side effects or problems in children thanthey do in adults when used in the bladder or ureters. There is no specificinformation about the use of radiopaque agents in children for studies ofthe uterus or fallopian tubes.

Older adults?Many medicines have not been studied specificallyin older people. Therefore, it may not be known whether they work exactlythe same way they do in younger adults. Although there is no specific informationcomparing use of radiopaque agents for instillation into the bladder or uretersor into the uterus and fallopian tubes in the elderly with use in other agegroups, these agents are not expected to cause different side effects or problemsin older people than they do in younger adults.

Other medical problems?The presence of other medical problems may affectthe use of radiopaque agents. Make sure you tell your doctor if you have anyother medical problems, especially:

• Asthma, hay fever, or other allergies (history of) or
• Reaction to a skin test for allergies or to penicillins?Ifyou have a history of these conditions, there is a greater chance of havinga reaction, such as an allergic reaction, to the radiopaque agent

• Enlarged prostate or
• Kidney disease (severe)?There may be blockage that makes itdifficult or impossible to put the solution of the radiopaque agent into thebladder or ureters

• Genital tract infection or
• Urinary tract infection?The risk of complications is greaterin patients with these conditions

• Pelvic inflammatory disease (severe)?The condition may be aggravatedby this test

Preparation for This Test

Your doctor mayhave special instructions for you in preparation for your test, such as theneed for a special diet or for a laxative, enema, or vaginal douche, dependingon the kind of test you are having done. If you have not received such instructionsor if you do not understand them, check with your doctor in advance.

For your comfort and for best test results, you may be instructed to urinatejust before the procedure.

Precautions After Having This Test

Make sure your doctor knows if you are planning to have any thyroid testsin the near future. Even after several weeks the results of the thyroid testmay be affected by the iodine in this agent.

Side Effects of This Medicine

Along with its needed effects, radiopaque agents can cause serious sideeffects such as allergic reactions. These effects may occur almost immediatelyor a few minutes after the radiopaque agent is given. Although these seriousside effects appear only rarely, your health care professional will be preparedto give you immediate medical attention if needed. If you have any questionsabout this, check with your doctor.

Check with your health care professional immediately if any of the following side effects occur:

Less common

Abdominal or stomach pain and discomfort (severe); backache

Other side effects may occur that usually do not need medicalattention. These side effects should go away as the effects of the radiopaqueagent wear off. However, check with your doctor if any of the following sideeffects continue or are bothersome:

More common

Abdominal or stomach pain and discomfort (mild)

Less common

Chills; fever; nausea and vomiting

Otherside effects not listed above may also occur in some patients. If you noticeany other effects, check with your doctor.