Introduction
Indentation tonometry is the most reliable and objective method for determining breast firmness. Breast firmness is difficult to identify as the breast has different thicknesses and densities on the hard chest wall. Breast firmness can be measured by the resistance to indentation to various depths. An indentation tonometry is a device used for identifying the softness and firmness of the breast tissue by applying a controlled pressure over the breast tissue thereby measuring an indentation of the breast tissue. It can also be used in measuring the indentation of the breast in breast augmentation and reconstruction patients.
What Is an Indentation Tonometer?
The indentation tonometer comprises two identical blunt probes connected to a display system. Each probe contains a calibrated spring and linear differential transformer that can sense the probe tip's movement. Among the two probes, one is taken as probe A, which is of variable depth and contains a 3.0lb/ in spring, and the one-pound calibration weight creates a movement of 0.33 inch, and the other one is marked as probe B, which has a fixed depth and contains a 125lb/ in spring. The one-pound calibration weight creates a movement of 0.008 inches. Probe A measures the overlying breast tissue's firmness with its retractable tip, and probe B measures the firmness of the underlying fibrous capsule and prosthesis.
How to Measure the Intramammary Tension?
Intramammary tension can be measured by making the patient sit straight on the examining table while the examiner sits facing the patient. The display unit should be placed away from the examiner’s sight, which should be placed behind the examiner, and the readings are taken on the right breast two centimeters above the areolar margin at 12, 3, 6, and 9 o’clock. Probe A can be applied to the skin surface perpendicularly, and these steps are repeated with probe B. These processes may be repeated in the case of a squeeze capsulotomy.
How to Place the Tonometer on the Breast?
The medial side of the breast provides tension measurement easily compared to the other side. In the case of less breast tissue present, it can allow us to measure only the tension of the thoracic wall. Later, the other side can be measured. If the tonometer is placed vertically on the lower pole of the breast, it may provide a proper reading. Instead, it may provide a measurement of intramammary tension along with the weight of the breast.
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Capsule Formation and Contracture: Capsule formation refers to the formation of fibrous tissue or scar tissue around the prosthesis or a breast implant. Contracture refers to the contraction of scar tissue formed around the prosthesis leads to the hardening of the breast and changing the shape of the breast. These can occur in most breast implant patients.
What Are the Benefits of an Indentation Tonometer?
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This device helps to provide consistent measurements without any change in measurements due to any other factors.
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This device helps measure the softness and firmness of the female breasts.
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It can also help in measuring the capsule formation and contracture around the prosthesis after augmentation or reconstruction of the breast.
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It is a non-invasive procedure and can be measured easily without any surgeries.
What Are the Limitations Associated With an Indentation Tonometer?
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This device does not provide information about the size and shape of the breast.
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This can provide readings only for a small area of the breast.
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This does not provide measurements regarding the depth of the breast tissue.
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The readings might differ among the patients based on the following variables: skin elasticity, patient’s posture, consistency of the subcutaneous tissue and breast tissue, prosthesis, capsule formation around the prosthesis, and the underlying muscle.
Conclusion
Indentation tonometry is a non-invasive, objective, and reproducible method of measuring the softness or firmness of human female breasts. Capsule formation and contracture around the prosthesis after breast augmentation or reconstruction can be accurately measured using indentation tonometry. The device provides objective measurements that are consistently reproducible without any change in the measurements due to other factors. Although it has some restrictions, the possibilities of indentation tonometry are immense and are useful for measuring the softness or firmness of human female breasts.
