Lymphedema (PDQ®): Supportive care - Health Professional Information [NCI] - Overview
If the diagnosis is not evident on the basis of clinical assessment, imaging of the lymphatic system with lymphoscintigraphy (radionuclide imaging) may be necessary. Lymphangiography is generally no longer a favored diagnostic test and may be contraindicated in patients with malignancy because of concern that it may contribute to metastatic spread of tumor. Additional imaging techniques such as magnetic resonance imaging may complement information obtained via lymphoscintigraphy by providing anatomic and nodal detail.
The wide variety of methods described in the literature for evaluating limb volume and lack of standardization makes it difficult for the clinician to assess the at-risk limb. Options include water displacement, tape measurement, infrared scanning, and bioelectrical impedance measures.
The most widely used method to diagnose upper-extremity lymphedema is circumferential upper-extremity measurement using specific anatomical landmarks. Arm circumference measures are used to estimate volume differences between the affected and unaffected arms. Sequential measurements are taken at four points on both arms: the metacarpal-phalangeal joints, the wrist, 10 cm distal to the lateral epicondyles, and 15 cm proximal to the lateral epicondyles. Differences of 2 cm or more at any point compared with the contralateral arm are considered by some experts to be clinically significant. However, measuring specific differences between arms may have limited clinical relevance because of implications, for example, of a 3-cm difference between the arm of an obese woman and the arm of a thin woman. In addition, there can be inherent anatomic variations in circumference between the dominant and nondominant limb related to differences in muscle mass and variations after breast cancer treatment that may occur with atrophy of the ipsilateral arm or hypertrophy of the contralateral arm. A small study comparing various methods of assessing upper-limb lymphedema did not show any superiority of any one method. Sequential measurements over time, including pretreatment measurements, may prove to be more clinically meaningful.
The water displacement method is another way to evaluate arm edema. A volume difference of 200 mL or more between the affected and opposite arms is typically considered to be a cutoff point to define lymphedema.