Palpation of Increased Skin and Subcutaneous Thickness, Tissue Dielectric Constant, and Water Displacement Method for Diagnosis of Early Mild Arm Lymphedema

Katarina Karlsson, RPT, MSc,1,2 Lena Nilsson-Wikmar, RPT, PhD,3,4 Christina Broga˚rdh, RPT, PhD,1 and Karin Johansson, RPT, PhD1,5. Lymphatic Research Biology 2019.


Background: Early diagnosis of mild lymphedema and treatment are important to prevent its progress. The tissue dielectric constant (TDC), measuring local tissue water in the skin and upper subcutis, has neither been related to the water displacement method (WDM) nor been used to diagnose mild arm lymphedema in patients at risk. Our aims were to evaluate TDC and WDM in combination with palpation, examine the association between TDC and WDM measurements, and compare lymphedema-related factors.

Methods and Results: Seventy-two women treated for breast cancer were diagnosed with mild arm lymphedema using skin palpation in combination with TDC from fixed measurement sites (threshold ratio for upper arm ‡1.45 and forearm ‡1.3) and/or WDM (lymphedema relative volume [LRV]: ‡5% to £8%). Results revealed that 32 (45%) women were diagnosed by TDC only, 19 (26%) by WDM only, and 21 (29%) by both TDC and WDM. TDC ratios exceeding the threshold were most frequently identified on the medial site of the arm, proximal and distal to the antecubital fossa. TDC and WDM were negatively associated; LRV (r=-0.545, p<0.001). The women diagnosed by TDC only were diagnosed earlier after surgery (p=0.003) and had a lower LRV (1.3%) than those diagnosed by WDM only (6.3%) or both TDC and WDM (6.2%; p<0.001).

Conclusions: TDC and WDM can be used together for early diagnosis of arm lymphedema, but TDC is the most valid method, determining the diagnosis earlier after surgery and at a lower arm volume than WDM.

Main findings

  • Clinical examinations included:
    • Increased subcutaneous thickness. Palpation of the skin and subcutaneous tissue was performed with the subject seated.18 The tissues were pinched between fingers and thumbs at the medial, frontal, and lateral sites of the whole arms simultaneously. An increased skin and subcutaneous thickness on the operated side compared with the non operated side indicated edema. Palpation combined with water displacement has been shown to be reliable with a negative predictive value of 95%3 and has previously been used to diagnose early arm lymphedema.
    • Local tissue water. Local lymphedema was evaluated using tissue dielectric constant (TDC) of MoistureMeterD (Delfin Technologies Ltd., Finland). Each site was measured once according to Mayrovitz et al., at six points: 5cm proximal and 5cm distal to the antecubital fossa (medial, frontal, and lateral). If lymphedema was palpated more proximally or distally in the arm, complementary measurements were made 15cm proximal or distal to the elbow. The TDC threshold ratio of the upper arm was set to 1.45 and of the forearm to 1.3.
    • Lymphedema volume (WDM). Arm volume was measured using water displacement.
    • Hand edema. The women were asked to self-rate the presence and degree of hand edema using a scale ranging from 0 (none) to 3 (very noticeable). The ratings were only used as descriptive data.
    • Body–mass index. Bodyweight and height were measured to calculate body–mass index (BMI).
    • Lymphedema-related factors Subjective experiences. The women’s self-rated experiences of heaviness, tightness, and pain in the affected arm were rated on a 100-mm horizontal visual analog scale.
    • One study-specific questionnaire included questions about age, education, and marital status. Another questionnaire included questions about heavy lifting at work, physical activity level/exercise, and housework before surgery.
  • Thirty-two women (45%) were diagnosed using TDC only (TDC group), 19 (26%) using WDM only (WDM group), and 21 (29%) using both WDM and TDC (WDM/TDC group). Totally, 53/72 women (74%) were diagnosed with mild arm lymphedema by the TDC technique and 40/72 (55%) by the WDM.
  • Among the 53 women diagnosed with TDC (32 from the TDC group and 21 from the TDC/WDM group), the highest frequencies of TDC ratios exceeding thresholds were found at the medial site close to the antecubital fossa in the upper arm and forearm, followed by the distal parts of the forearm. Only a few exceeded thresholds at the lateral and frontal sites of the forearm, and none were found at the frontal or lateral site of the upper arm.
  • A significant difference in time from surgery to onset of lymphedema (p=0.003) was found in the TDC group (on average, 4.1 months) compared with the WDM group (on average, 9.1 months) and the WDM/TDC group (on average,6.7months).
  • Both TDC and WDM can be used for early diagnosis of mild arm lymphedema, but TDC determines the diagnosis earlier after surgery and at a lower arm volume than WDM.
  • In the present study, we were unable to evaluate whether there was an association between palpation of increased thickness and TDC measurements as the two examinations were performed by the same person and thus not blinded. However, the author’s clinical experience leads them to believe that TDC might in the future replace palpation in the clinic as a more objective assessment, but this has to be investigated in further studies.
  • Lymphedema diagnosed with TDC was found mostly in the medial upper arm, medial forearm, or at both sites. These results agree with clinical experience in which one can often palpate a thickness at the medial site and in accordance with findings of Lahtinen et al.
  • In the present study, they also found that in almost all cases a positive lateral and ventral/frontal TDC ratio in the upper arm or forearm was associated with a positive medial TDC ratio, indicating that it is not necessary to measure these sites. Measuring on the frontal side also carries a risk for error from having venous vessels too close to the measuring points.
  • For practical reasons, they did not measure the women preoperatively. However, Mayrovitz et al. measured the presurgical TDC ratio and showed a very low ratio in breast cancer patients. This may indicate that no preoperative measurements are necessary other than the determination of the postoperative ratio. Future research will explore whether there is a need for preoperative TDC measurements.