Extravasation of iodinated contrast at the puncture site on computed tomography scan.

Displacement of the intravenous catheter or rupture of the punctured vein can cause accidental extravascular injection of the iodinated contrast medium required in most computerized tomography scans. This complication occurs in approximately 1% of contrasted computed tomographys. The contrast infusion pump stops the infusion when it detects an increase in the pressure required for the infusion. However, before this, a variable amount of contrast may be injected into the perivascular soft tissues, often the cubital fossa, wrist and dorsum of the hand.

In this case, at least 20 ml of contrast were injected into the subcutaneous tissue and into the muscular plane of the cubital fossa, palpable on physical examination. The total to be injected into this patient would be 100ml. In this situation, it is important to assess whether the amount of contrast injected was sufficient to cause compartment syndrome in the limb, which can be suspected by the intensity of local pain, possibly associated with paresthesia and reduction in temperature and arterial pulse in the extremity. In these cases, surgery may be necessary to reduce compartment pressure, through local fasciotomy, associated with manual extraction of as much contrast medium as possible. Fortunately, most cases, like this parent, do not present compartment syndrome and only present mild pain and constant temperature and pulses. The recommended approach is to elevate the affected limb to facilitate venous return. Ice packs can also be applied to relieve pain, with variable results. The most important thing is to monitor the evolution for at least 1 hour, and mainly to reassure the patient regarding the favorable resolution of symptoms. Given the viscosity of the contrast medium, it may take up to 12 hours for the contrast collection to stop being palpable.

Ultrasound showing the anechoic contrast medium permeating the subcutaneous and vascular planes, without significant collection.