Teaching Case

A 56-year-old woman with an ileostomy following Hartmann sigmoid colon resection of acute diverticulitis and failed recanalisation surgery 6 months earlier was hospitalised with malnutrition state and diarrhoea from Clostridium difficile enterocolitis. Laboratory disclosed metabolic acidosis, acute kidney failure, and anaemia. Furthermore, surgical wound and urinary infection were diagnosed.

Antibiotics, hydration and parenteral nutrition allowed clinical renal function and metabolic improvement.
Days later, sudden left lower abdomen pain and tenderness were investigated with enhanced multidetector CT (MDCT). During power injection of 120 ml non-ionic iodinated contrast medium (CM) at 2.5 ml/sec flow rate followed by 40 ml saline via left femoral central venous catheter (CVC), she did not experience adverse effects. Venous-phase acquisition (Fig.1) showed absent vascular and parenchymal enhancement, and vast, strongly hyperdense collection corresponding to extravasated CM occupying the left posterior pararenal space, causing anterior ipsilateral kidney displacement. Promptly removed and found intact, the femoral CVC had its distal end apparently impacted in a presacral iliac tributary vein.
Three days later, repeat MDCT (Fig.2) showed resolution of retroperitoneal CM extravasation. Prolonged hospitalisation including supportive treatment, antibiotics, albumin and blood transfusions allowed clinical improvement, normalised renal function and stool cultures, and she was finally discharged six weeks after admission.

Enhanced MDCT studies including rapid flow CM administration are increasingly performed, particularly during multiphasic liver, CT-angiography, and perfusion imaging. Whereas peripheral cannulas are used in most cases, venous access is usually difficult or unavailable in intensive care patients, or those undergoing haemodialysis or chemotherapy. In hospitalised patients, single- or multilumen CVCs are commonly positioned to deliver parenteral nutrition, incompatible medications, fluids or blood products, and to allow for frequent blood sampling, central venous pressure monitoring, and haemodialysis [1, 2].
Therefore, radiologists increasingly consider CVCs for CM administration during MDCT. However, this practice is controversial, since complications including catheter rupture, dislocation, obstruction or malfunctioning, cardiac arrhythmias, infection, and CM extravasation, have been reported in up to 1% of cases and require line replacement [1-5].
Currently, power-injectable CVCs designed for safe use with mechanical injectors are becoming available on the market. Conversely, when a CVC without the “pressure-injectable” label is present, precautions should be taken to avoid potentially serious complications [1, 2].
As demonstrated by this exceptional occurrence in the retroperitoneum from femoral CVC, catheter rupture and extravasation may result from misplacement, vessel wall penetration, or from injection pressures exceeding the device tolerance. Notably, flow rates adopted for MDCT-angiography exceed those for drug delivery in intensive care. Although some experimental and clinical studies addressed feasibility of CVC use for rapid CM infusion, safety data are limited [1, 2, 6].
The radiology nurse should check the CVC entry site for alert signs including redness, swelling, catheter loosening. The largest bore of a multilumen CVC should be chosen for CM administration, because it has lesser risk of damage and the most distal position. With sterile manipulation, line patency should be thoroughly checked for blood return by aspiration, and flushed with saline to exclude resistance, leakage, or swelling. Correct intravascular CVC tip position should be checked on the CT scout-view acquired with elevated arms as necessary for body scanning, or on preliminary unenhanced scans. Curved course or acute angle suggest impending vessel wall perforation and contraindicate CVC use. With non-pressure-injectable CVCs, the MDCT injector pressure limit should be adjusted to remain below the maximum labelled pressure (usually 100-150 psi) allowed by the CVC, alternatively a 2.0 ml/sec flow rate is recommended. During enhanced acquisition, the patient should be monitored for signs of CM extravasation or CVC malfunction. After the study the CVC port should be assessed for damage and flushed with saline or heparinised solution [1-3].