Palpation of a child's abdomen
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Palpation is used as part of a physical examination in which an object is felt (usually with the hands of a healthcare practitioner) to determine its size, shape, firmness, or location. Palpation should not be confused with palpitation, which is an awareness of the beating of the heart.
Palpation is used by various therapists such as medical doctors, practitioners of chiropractic, osteopathic medicine, physical therapists, occupational therapists, and massage therapists, to assess the texture of a patient's tissue (such as swelling or muscle tone), to locate the spatial coordinates of particular anatomical landmarks (e.g., to assess range and quality of joint motion), and assess tenderness through tissue deformation (e.g. provoking pain with pressure or stretching). In summary, palpation might be used either to determine painful areas and to qualify pain felt by patients, or to locate three-dimensional coordinates of anatomical landmarks to quantify some aspects of the palpated subject.
Palpation is typically used for thoracic and abdominal examinations, but can also be used to diagnose edema and to measure the pulse. It is used by veterinarians to check animals for pregnancy, and by midwives to determine the position of a fetus.
Quantitative palpation of anatomical landmarks for measurements must occur according to strict protocols if one wishes to achieve reproducible measurements. Palpation protocols are usually based on well-described definitions for the location of anatomical, usually skeletal, landmarks.
Locating anatomical landmarks 
Locating anatomical landmarks can be performed using two palpation protocols: 1) manual palpation that allows spatial location of landmarks using hands combined or not with three-dimensional (3D) digitizing, and 2) virtual palpation on 3D computer models obtained, for example, from medical imaging.
Manual palpation of skeletal landmarks (illustrated here on a patient's shoulder, see left image). The gauntlet on the palpating ha (left) allows to locate the spatial coordinates of the palpated landmarks with a satisfactory accuracy (below 1 cm). Reflective markers are part of the scientific protocol and allow further quantified motion analysis for joint disorders follow-up.
Virtual palpation of skeletal landmarks located on a 3D bone models (illustrated here on a patient's knee model obtained from medical imaging, see right image). Coloured spheres on bones indicate palpated skeletal landmarks. This method combined with quantified manual palpation allows subject-specific visualisation of joint behavior during particular motion tasks (e.g., walking, stair climbing, etc.).
The above protocols can be used independently. Manual palpation is used in clinical activities for various aims: - identification of painful areas; - positioning of particular pieces of equipment (electromyography electrodes, auscultation, external landmarks used in clinical motion analysis or body surface scanning); or - measurements of morphological parameters (e.g., limb length). Virtual palpation alone is useful to quantify individual morphological parameters from medical imaging: - limb length; - limb orientation; - joint angle; or - distance between various skeletal locations.
Combining data from both manual and virtual palpation protocols allows achieving supplementary analysis: - registration protocols aiming at building reference frames for motion representation according reproducible clinical conventions; - to modelize joint kinematics accurately during musculoskeletal analysis; - to align precisely orthopaedic tools according to the individual anatomy of a patient; or - to wrap and to scale surface textures to motion data when creating animation characters.
Use of standardized definitions for the above activities allows better result comparison and exchange; this is a key element for patient follow-up, or the elaboration of quality clinical and research databases. Such definitions also allow acceptable repeatability by individuals with different backgrounds (physiotherapists, medical doctors, nurses, engineers, etc.). If applied strictly, these definitions allow better data exchange and result comparison thanks to standardization of the procedure. Without anatomical landmark standardization, palpation is prone to error and poorly reproducible.
See also 
- Physical examination
- Inspection (medicine)
- Percussion (medicine)
- Motion analysis
- Medical imaging
- Van Sint Jan S, Della Croce U 2005 Identifying the location of human skeletal landmarks: why standardized definitions are necessary – a proposal. Clinical Biomechanics 20:659-660.