The National Medicines Safety Agency (ANSM) reminds healthcare professionals the precautions to be taken before an imaging examination with injection of iodized contrast products (PCI). If these skin reactions of delayed hypersensitivity (HSR), occurring a few hours to a few days after administration, are most often not very severe (itching, redness), they can be very serious in rare cases and lead to death.
In its recommendations, before prescribing a radiological examination with injection, the ANSM asks to ensure that “The examination is really necessary” et “That no other imagery technique without injection can provide the required information”. Health professionals are asked to learn to recognize the signs and symptoms of severe forms (see supervised).
A systematic allergic assessment in the event of a skin symptom
It is recommended to inform the patient of the risk of HSR, as it can occur remotely. During the examination, the allergic history is to be checked and the name of the PCI to be filled in (with the lot number) on the radiology report.
In case of non -serious allergic signs, dermocorticoids can be used. In the event of a sign of severity, rapid hospitalization may be necessary.
In the event of a skin reaction, “Whatever his severity”possibly linked to an injection of PCI, it is recommended to carry out an allergological assessment a posteriori “Relating to the different classes of PCI and not only on the administered PCI”. This assessment makes it possible both to confirm the allergic nature but also to secure subsequent radiological procedures (contraindication and alternatives) taking into account the risk of cross reactions, it is specified. The patient must be informed of the positive results and PCIs which will now be contraindicated to him, as well as those who can be administered. The patient should also know that he must, before each examination, notify the radiologist of his allergies.
The ANSM has listed the iodized contrast products concerned: Iodixanol (Visipaque), Iohexol (Omnipaque), Iomeprol (Iomeron), Iopamidol (Iopamiron), Iopromide (Ultravist), Ioveversol (Optiject, Optiray), Lobitridol (Xenetix).
Conversely, the ANSM recalls that being allergic to fish and crustaceans does not mean being allergic to products containing iodine (antiseptics or PCI). “These allergies are different and independent of each other”, indicates the health agency, even if “In very rare cases, it is possible to be allergic to several of these substances at the same time”. Be wrongly qualified as “allergic to iodine”, which “Arrives frequently”can deprive the patient of an imaging examination and “Have repercussions on its care”, warns the ANSM.
Lyell, Dress, Peag, Stevens-Johnson: how to recognize these rare but serious reactions
The ANSM describes the skin reactions of severe hypersensitivity, which, “Although very rare”can last several weeks and touch other organs than the skin. This is the case: Drug hypersensitivity syndrome with eosinophilia and systemic symptoms (Dress) which begins with an influenza syndrome (fever, fatigue) then which causes an eruption with persistent edema of the face and possible damage to the mouth, eyes and genitals; of the Acute exanthematic pustulosis (PEAG)a sudden push of small pustules on red skin associated with fever and fatigue; of Syndrome de Stevens-Johnson (SSJ)a serious reaction with detachment of the skin, fever, pain, eruptions and/or lesions in the mouth or eyes; of the Toxic epidermal necrolysis (Lyell syndrome)which is a rapid and significant destruction of the upper layer of the skin and mucous membranes, with pain and a detachment of the skin which can extend over the whole body.