Contrast media extravasation

Contrast media extravasation (CMEV) is a well-known complication of contrast-enhanced CT scanning¹. It can also occur in MRI studies, but the complications are rare given the low volume that are used.

Epidemiology

CT contrast extravasation occurs relatively infrequently, in ~0.5% (range 0.13-0.68%) of cases, but can have severe side effects associated with skin changes and possible skin necrosis. 

Risk factors

• increased incidence with automated power injection because large volumes can extravasate in a short period of time ^2,3
  • with manual injection, extravasation is thought less likely, as there is direct supervision of contrast administration
• patient-related factors
  • elderly patients
  • emaciated patients
  • oedematous patients
  • confused patients
  • female sex ³
  • inpatients ³
• the site of venous access: 
  • higher percentage of leakage in the venous access in the back of the hand, wrist, foot and ankle
  • likely related to a smaller amount of subcutaneous tissue and the fact that veins are more fragile on these regions
• the gauge of intravenous catheter: only if smaller calibre access (over 22G) is used; risk of leakage is the same for 18G and 20G ¹
• high-osmolar contrast medium ²
  • pre-warming of high-osmolar (370 mg/ml) contrast to 37°C lowers the viscosity and has been proven to lower the probability of extravasation ⁵
• additionally a recently published study "incidence of contrast medium extravasation for CT and MRI in a large academic medical centre: a report on 502,391 injections" showed that ³
  • patients undergoing CT are at higher risk of developing CMEV than MRI patients
  ³
  • females and inpatients were also more likely to develop CMEV at both CT and MRI
  • at MRI, CMEV is more likely in patients above the age of 60 years and for those receiving automated power injections
  ³

Pathology

Nonionic low-osmolar contrast media is known to reduce the risk of severe soft tissue injury, but the potential for soft tissue injury is often related to the volume of CME ¹.

Treatment and prognosis

The conduct after an episode of CMEV will vary according to the protocol of each radiology department, and might include:

• discontinue the contrast infusion and notify the radiologist immediately
• complete the acquisition of images of the CT series
• attempted aspiration of the extravasation has not been shown to be effective
• apply an ice pack to the affected area and elevate the affected extremity to reduce swelling
• keep the patient under observation for at least 2two hours
• at some institutions, the policy is to require plastic surgery consultation for all patients whose extravasations involve 100 mlmL or more of contrast medium
• make contact with the doctor requesting the examination
• it is suggested to follow up the patient in the next few days until the resolution of local oedema; this can be accomplished with a phone call to evaluate the regression of the signs and symptoms
• instruct the patient to notify staff if there is:
  • increasing swelling or pain over time
  • blistering, ulceration, induration or other skin changes
  • altered tissue perfusion and/or changes in sensation

Complications

Most CMEV results in minimal swelling or erythema and havehas no long-term sequelae ². A large study found that >97% of patients with contrast extravasation had minimal or no injury and reported that 79% of patients had localised swelling after extravasation, 24% had pain, and 8% were asymptomatic ⁴. 

Large volumes (>50 mlmL) of high-osmolar contrast media are known to induce significant tissue damage:

• skin ulceration
• soft-tissue necrosis
• compartment syndrome