Radiation Risk of Medical Imaging During Pregnancy
What is radiation? Background radiation is always present in our environment. It is inescapable and provides each of us with…Read more
This InsideRadiology item deals with the large number of treatment procedures that use catheter angiography requiring the ‘direct’ injection of contrast into a diseased artery or vein. This is in contrast to diagnostic angiography (which is obtained by ‘indirect’ imaging techniques) such as CT, MRI and duplex ultrasound.
Outlined below is a sample of conditions where angiography may be used (generally by means of angioplasty, stent insertion or embolisation).
Prerequisites vary depending on the specific type of angiography carried out and the indication. Fasting before an angiogram is not required in all cases, but might be appropriate in certain circumstances. In general, patients should be well hydrated before angiography in order to minimize the risk of contrast medium-induced nephrotoxicity.
Several groups of patients should have special attention:
Patient weight that exceeds the angiography table limit (150 kg mostly). Overweight patients might prohibit the use of angiography equipment because of technical safety concerns
Angiography is an invasive procedure that might incur complications.
Angiography suites have exacting protocols that aim to limit the possibility of bleeding complications after angiography. These include instructions to patients regarding periods where they must lie flat, when they can sit up, gently mobilise etc. On occasion, a patient will develop a delayed groin haematoma or bleed after having left the angiography suite. The treatment involves lying the patient flat, compression to the puncture site and communication with the angiography suite or on-call emergency (radiology) service. Occasionally, hospital admission to limit the bleeding and to correct any associated hypotension, blood loss etc. might be required.
Referrers should watch out for worsening symptoms post-angiography e.g. worsening limb ischaemia post-angioplasty. If that happens, contact the emergency department of the local hospital, and if possible contact the radiologist who carried out the angiogram. Emergency re-intervention (e.g. percutaneous thrombectomy or thrombolysis) might be required.
Delayed onset rash can occur usually within 24 hours of the procedure. It is usually self-limiting, and requires symptomatic treatment only.
There are other forms of non-invasive imaging for the integrity of the blood vessels, which include ultrasound, CT and MRI.
The best form of imaging for your patient will depend on the indications and contraindications, and in many cases this choice is best discussed with a radiologist.
Depending on the clinical problem, other investigations might be appropriate: see Diagnostic Imaging Pathways below.
Angiography is not contraindicated by the above.
Angiography is not contraindicated by the isolated development of a rash previously.
Angiography is not contra-indicated by vomiting after prior contrast medium administration. Vomiting does not indicate an allergic reaction.
There is no good evidence to support routine fasting before angiography – the risk of vomiting leading to aspiration during angiography in a conscious, normally sentient patient is very small. In certain circumstances, fasting is desirable e.g. complex angiographic procedures might require emergency anaesthetic support/transfer to an operating theatre.
Fluids should be encouraged, because the risk of contrast medium nephrotoxicity is far greater than any risk of aspiration during a routine angiographic procedure.
Society of Interventional Radiology: www.sirweb.org/medical-professionals
Diagnostic Imaging Pathways: www.imagingpathways.health.wa.gov.au
Page last modified on 29/3/2017.
RANZCR® is not aware that any person intends to act or rely upon the opinions, advices or information contained in this publication or of the manner in which it might be possible to do so. It issues no invitation to any person to act or rely upon such opinions, advices or information or any of them and it accepts no responsibility for any of them.
RANZCR® intends by this statement to exclude liability for any such opinions, advices or information. The content of this publication is not intended as a substitute for medical advice. It is designed to support, not replace, the relationship that exists between a patient and his/her doctor. Some of the tests and procedures included in this publication may not be available at all radiology providers.
RANZCR® recommends that any specific questions regarding any procedure be discussed with a person's family doctor or medical specialist. Whilst every effort is made to ensure the accuracy of the information contained in this publication, RANZCR®, its Board, officers and employees assume no responsibility for its content, use, or interpretation. Each person should rely on their own inquires before making decisions that touch their own interests.