From the Guidelines
Shifting dullness is the most reliable percussion finding in ascites, with 83% sensitivity and 56% specificity, as noted in the study published in Hepatology in 2009 1. To detect shifting dullness, the patient should lie supine while the examiner percusses from the midline outward toward the flanks, marking where the sound changes from tympanic to dull. Then, the patient rolls onto their side, and percussion is repeated. In ascites, the dullness will shift to the dependent side as the free fluid moves with gravity, while the tympanic area expands on the upper side. Some key points to consider when evaluating ascites include:
- Approximately 1500 mL of fluid must be present before flank dullness is detected 1
- If no flank dullness is present, the patient has less than a 10% chance of having ascites 1
- The fluid wave and puddle sign are cumbersome and perform less well when compared to shifting dullness 1
- Abdominal ultrasound may be required to determine with certainty if fluid is present, especially in obese patients 1 The presence of shifting dullness is a key diagnostic finding in ascites, and its absence makes the diagnosis unlikely 1.
From the Research
Percussion Finding in Ascites
- The percussion finding in ascites is typically a dull sound, which can be detected through various methods such as shifting dullness, fluid wave, and auscultatory percussion 2.
- Auscultatory percussion has been shown to have a greater sensitivity (65.7%) compared to the puddle sign (45%) in detecting ascites, although it has a lower specificity (48.4% vs 67.7%) 2.
- The use of ultrasonography as a gold standard for detecting ascites has been established, but in areas where it is not available, auscultatory percussion can be a useful alternative 2.
- The treatment of ascites typically involves sodium restriction, diuretics, and therapeutic paracentesis, with the goal of eliminating the ascitic fluid and preventing its reaccumulation 3, 4, 5.
- Percussion findings can aid in the diagnosis and monitoring of ascites, but the treatment approach should be individualized based on the patient's underlying condition and response to therapy 3, 4, 5.