Exploración abdominal II: Percusión
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Overview
Fuente: Alexander Goldfarb, MD, profesor de medicina, centro médico Beth Israel Deaconess, MA
Percusión médica se basa en la diferencia de tono entre los sonidos sacados por los golpecitos en la pared del cuerpo. La respuesta auditiva a tocar depende de la facilidad con que vibra la pared del cuerpo y está influenciada por los órganos subyacentes, fuerza de la carrera y el estado de la pared del cuerpo. Hay tres sonidos de percusión médica principal: resonancia (escuchado en los pulmones), tympany (oído sobre las asas intestinales llenas de aire) y matidez (oído sobre órganos sólidos o líquidos). El contraste entre la tardanza vs tympany o resonancia permite la determinación del tamaño y márgenes de órganos y masas, así como la identificación de la acumulación de líquido y áreas de consolidación. Percusión es una parte intrincada de la diagnosis física ya que fue introducido hace más de 200 años y es especialmente útil en el examen de los pulmones y el abdomen.
Como parte de un examen abdominal, percusión sigue auscultación e inspección visual. El examinador debe percuss primero sobre cada una de las nueve regiones abdominales (región epigástrica, región derecha hipocondríaco, región izquierda hypochondriac, región umbilical, región lumbar derecha, región lumbar izquierda, hypogastric de la región, región inguinal derecha y región inguinal izquierda). Ternura provocada por percusión es anormal, y se debe sospechar inflamación peritoneal. Como las asas intestinales llenas de aire se colocan en la proximidad más cercana a la pared abdominal, la percusión sobre la mayor parte de la cavidad abdominal produce un sonido timpánico predominante. La presencia de grandes áreas de matidez debe incitar la evaluación de organomegalia, masas intrabdominales o líquido.
Además de evaluar la cantidad y distribución de gas abdominal, un examen abdominal debe incluir una estimación del tamaño del bazo y hígado por percusión. Como el hígado y el bazo están cubiertos por la caja torácica, el examinador debe percuss sobre el pecho anterior inferior también. Normalmente, uno espera escuchar sonido mate a la percusión del tórax anterior derecho sobre el hígado y sonido timpánico a la percusión del pecho izquierdo anterior sobre la burbuja de aire gástrica y el ángulo esplénico del colon (figura 1).
Figura 1. Notas de percusión normal sobre la región abdominal. Con la excepción de un área de matidez sobre el hígado en el tórax anterior inferior derecho, tympany es el sonido predominante oído sobre la región.
Procedure
Applications and Summary
Despite rapid advances in imaging techniques, abdominal percussion remains an essential part of a physical examination. Correct percussion technique is critical for this method to be effective. The percussion strike should be kept the same over the entire abdomen. All the information obtained during the patient’s interview and full physical examination, and a good knowledge of differential diagnoses of each pathological sign is essential for proper interpretation of any findings. For example, a false increase of liver span on percussion can result from right lung consolidation and/or a pleural effusion. One should also be aware of the limitation of the method and the sensitivity of each diagnostic maneuver. While percussion is only moderately accurate in detecting hepato-and splenomegaly, abnormal findings should prompt further clinical evaluation.
Transcript
Percussion is a critical part of the abdominal examination; therefore, learning the correct technique is essential for any physician aiming to make quick, yet accurate diagnosis of gastrointestinal pathologies. As you might know, medical percussion is based on the difference in pitch between the sounds elicited by tapping on the body wall. The sounds produced during abdominal percussion can help detect pathologies like organomegaly, intra-abdominal masses, and fluid accumulation. This video will illustrate the major anatomical areas to be percussed during an abdominal exam, and the steps and findings of this procedure.
First, let’s talk about the expected abdominal percussion sounds and their interpretations. As the air-filled bowel loops are positioned in the closest proximity to the abdominal wall, percussion over most parts of the abdominal cavity elicits a predominantly tympanic sound… Notice that this sound is relatively long, high pitched, and loud.
Percussion over dense organ tissues, like the spleen or the liver, produces a dull sound… Therefore, the contrast between dullness versus tympany allows for determination of the margins of these organs and thus help in detection of conditions like hepatomegaly or splenomegaly. Dull sounds are also produced on percussing areas filled with fluid and feces. Therefore, by percussing one can predict the cause of protuberant abdomen, which helps in diagnosis of conditions like ascites.
With this background in mind, let’s review a detailed step-wise procedure for abdominal percussion. Explain the procedure to the patient and obtain their consent before starting with the exam. Drape the patient appropriately to expose the torso area and perform light percussion over each of the nine abdominal regions.
Listen to the intensity, pitch, and duration of the percussion note. Normally, tympanic sound produced by air in the bowel loops will be heard… As you percuss, watch the patient’s face for any signs of discomfort. Ask the patient if they are experiencing any tenderness. Tenderness on percussion is abnormal and can indicate peritoneal inflammation.
After abdominal area, percuss the lower anterior chest, above the costal margins. Dull sound on the right, over the liver is expected… On the left, one should hear tympany over the gastric air bubble and the splenic flexure of the colon… Following that, move to the area of pubic symphysis. Again, this should yield a tympanic sound…dullness indicates enlarged uterus or distended bladder.
Next step is to determine the liver span. Start by locating the right midclavicular line. Starting in the area of tympany below the umbilicus, lightly percuss in the right midclavicular line moving upwards… Make a mark where the tympany changes to dullness with a skin pencil. This is the lower border of the liver. Then, starting at the nipple line, again percuss in the right midclavicular line moving downwards. Note the point where the resonant sound changes to dullness…and mark it with a skin pencil. This is the upper border of the liver. Measure the distance between upper and lower border in centimeters. The liver span is normally 6-12 cm.
Following the liver span measurement, percuss to detect splenomegaly. The two maneuvers for this include Percussion of the Traube’s space and the Castell’s method. For percussion of the Traube’s space, make sure that the patient’s left arm is slightly abducted, and percuss from the medial to lateral border of this area. Overall dullness on percussion, or reduction of the area of tympany can indicate spleen enlargement. For the Castell’s method, percuss in the anterior axillary line in the lower intercostal space. Ask the patient to take a deep breath and percuss again. Normally, the percussion tone is tympanic on both inspiration and expiration. If the percussion note is dull, or becomes dull on inspiration, splenomegaly should be suspected.
Lastly, percussion is helpful to detect the cause of a protuberant abdomen. If the patient has a protuberant abdomen, percuss from the umbilicus in a lateral direction and with the skin pencil make a mark of the point where the tympanic sound changes to dullness. Then, ask the patient to roll on their side and repeat the percussion starting from the top and make a second mark when the tympanic sound changes to dull. If abdominal fluid were present, the level of dullness on the side would shift upwards toward the umbilicus, compared to the level of dullness in supine position.
You’ve just watched JoVE’s video on percussion to be performed during an abdominal exam. You should now know the important abdominal percussion steps and understand differential diagnoses that can be performed by proper interpretation of percussion findings. As always, thanks for watching!