It is important when diagnosing extravasation that a misdiagnosis is not made. This is because the treatment is physiologically traumatic to the body and may involve the administration of drugs which, in their own right, could cause or potentiate extravasation.
Early detection of extravasation is crucial. Common misdiagnoses are made because the observer is not differentiating discoloration reactions in the vein, venous shock, flare or phlebitis reactions of the vein wall and / or anaphylaxis. This is complicated further as some cytotoxics are highly coloured agents and if the vein in question is particularly superficial then a bright red solution injected into the vein may cause local discoloration. Furthermore, cytotoxics are often administered cool, at best at room temperature. They are then administered fairly rapidly into blood at a temperature of 37°C. The greater the thermal gradient between the drug solution and the blood the greater the stress on the vein and often contraction and / or venus spasm is observed due to the thermal shock.
It is also important to differentiate extravasation from other intravenous phenomena such as phlebitis and / or anaphylaxis. Phlebitis, (inflammation of the vein) often occurs despite correct administration due to the nature of some of the agents involved either because their formulation had an irritant component e.g. etoposide, or because the pH of the formulation is particularly acidic or alkaline e.g. doxorubicin and epirubicin. Here a transient, but well pronounced inflammation along the line of the vein will occur and this may track for some considerable distance. Anaphylaxis will have a central component of cardiovascular nature along with pulmonary complications, but often starts at the local site of injection. A less traumatic form of anaphylaxis is the hypersensitivity reaction. This was not well observed or recognised with the oncology drugs until the recent introduction of the taxains, both of these due to the nature of their formulation often cause local and / or central hypersensitivity. Once these alternative diagnoses have been considered, and excluded, the practitioner should go on to consider the diagnosis of extravasation.