Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic measures used to reduce the incidence of CIN, and the management of patients receiving metformin. Key Points • Definition, risk factors and prevention of contrast medium induced nephropathy are reviewed. • CIN risk is lower with intravenous than intra-arterial iodinated contrast medium. • eGFR of 45 ml/min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR ≥ 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally.

Topics reviewed include the history, clinical features and prevalence of nephrogenic systemic fibrosis and the current understanding of its pathophysiology. The risk factors for NSF are discussed and prophylactic measures are recommended. The stability of the different gadolinium-based contrast media and the potential long-term effects of gadolinium in the body have also been reviewed.

The Contrast Media Safety Committee of the European Society of Urogenital Radiology (ESUR) has looked at the effects of contrast media on the kidney including prevention of contrast medium induced nephropathy. This has resulted in four reports dealing with 1) contrast medium induced nephrotoxicity, 2) haemodialysis and contrast media, 3) use of gadolinium contrast media instead of iodinated contrast media and 4) contrast media injection in diabetic patients receiving metformin. The review presents an overview of these four reports and offers the current understanding of the interaction between contrast agents and the kidney.

The use of iodinated or gadolinium-based contrast media in pregnant or lactating women often causes concerns in the radiology department because of the principle of not exposing a fetus or neonate to any drugs. Because of the uncertainty about the use of contrast media during pregnancy and lactation, the Contrast Media Safety Committee of the European Society of Urogenital Radiology decided to review the literature and draw up guidelines. An extensive literature search was carried out and summarized in a report. Based on the limited information available, simple guidelines have been drawn up. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela, Spain. Mutagenic and teratogenic effects have not been described after administration of gadolinium or iodinated contrast media. Free iodide in radiographic contrast medium given to the mother has the potential to depress fetal/neonatal thyroid function. Neonatal thyroid function should be checked during the 1st week if iodinated contrast media have been given during pregnancy. No effect on the fetus has been seen after gadolinium contrast media. Only tiny amounts of iodinated or gadolinium-based contrast medium given to a lactating mother reach the milk, and only a minute proportion entering the baby's gut is absorbed. The very small potential risk associated with absorption of contrast medium may be considered insufficient to warrant stopping breast-feeding for 24 h following either iodinated or gadolinium contrast agents.

The purpose of this study was, using consensus methodology, to document current understanding of contrast media nephrotoxicity (CMN) and to identify areas where there is disagreement or confusion. To draw up guidelines for avoiding CMN based on the current understanding of the condition established by the survey. One hundred sixty-four statements were mailed to 148 members of the European Society of Urogenital Radiology (ESUR) and to 48 experts in the field of CMN. They were asked about the definition, clinical features, predisposing factors and pathophysiology of CMN and about prophylactic measures. The importance of the statements was rated on a scale from 1 to 10 (1 least important, 10 most important). Fifty-three members (38%) and 23 experts (48%) responded. Both groups considered that an increase in serum creatinine that peaks within 3-4 days and a decrease in creatinine clearance are the most important (rating > 7) features of CMN. Enzymuria was not considered important (rating < 6). Pre-existing renal insufficiency, diabetic nephropathy, dehydration, congestive heart failure, concurrent administration of nephrotoxic drugs and the dose and type of contrast media were considered to be risk factors. Reduction in renal perfusion and damage to tubular cells were considered the main factors in the pathophysiology of CMN (rating > 6). Hydration and the use of low osmolar contrast media were thought to minimize the incidence of CMN (rating > 6). The majority of the responders (84.6% of members and 95.5% of experts) believe that the incidence of CMN in patients with normal renal function is less than 5%. Of the members, 62.5%, and 35.3% of experts, believe that the incidence of CMN is 20-30% in the presence of risk factors. There was disagreement about the definition of CMN, the threshold dose of contrast media above which renal complications may develop, the safe period between repeat injections, the relevance of contrast media renal retention shown on CT and whether contrast media have long-term effects on renal function. The survey showed good understanding of CMN among those who answered the questionnaires, although areas of disagreement remain which require further research. Simple guidelines are proposed.