Ascites: shifting dullness and fluid wave !

Maneuver

Maneuvers to tell whether a swollen abdomen holds free fluid: the dull note moves with position, and a tap on one side is felt on the other.

Updated 2026-11-01

See it in 3D: Peritoneum · Liver · Portal vein

What it is

Ascites is free fluid in the peritoneal cavity; its most common cause is cirrhosis with portal hypertension. The fluid settles in the lowest parts, so with the patient supine the flanks are dull and the area around the umbilicus is tympanic. Shifting dullness and the fluid wave confirm that the fluid is free. The exam misses small ascites (below about one and a half liters), which ultrasound shows.

The anatomy it tests

The peritoneal cavity is a potential space; free fluid collects first in the lowest areas (flanks and pelvis) while gas-filled loops float to the top.
In cirrhosis, portal hypertension and low albumin increase fluid leak from splanchnic and hepatic capillaries into the peritoneum.
The fluid wave travels through fluid; without blocking the midline, subcutaneous fat also carries it and gives false positives.

How to do it

Patient supine; inspect for bulging flanks and the umbilicus.
Percuss from the umbilicus out to each flank and mark where tympany turns to dullness.
Shifting dullness: ask the patient to roll toward the side opposite the one being examined and wait about 30 seconds for the fluid to move.
Percuss again: if the area that was dull is now tympanic (the border moved toward the lower side), the test is positive.
Fluid wave: ask the patient or a helper to press the ulnar edge of a hand firmly along the midline of the abdomen.
Rest one hand on one flank and tap the opposite flank with the fingertips.
Positive if a clear impulse reaches the receiving hand; the hand edge in the midline blocks transmission through fat.
Measure abdominal girth at the umbilicus and daily weight to follow progress (a nursing task).

What a positive result means

Positive: shifting dullness or a fluid wave in a distended abdomen.
Causes: cirrhosis with portal hypertension (the most common), heart failure, peritoneal carcinomatosis, nephrotic syndrome, pancreatitis, peritoneal tuberculosis.
If the flanks are not dull, clinical ascites is unlikely.
A negative exam does not rule out small ascites; in obesity false positives and negatives are common.

Usefulness and limits

In words: flank dullness and shifting dullness are the most sensitive; the fluid wave is the most specific but is lost in moderate ascites.
Ultrasound is the test of choice to confirm it and to guide paracentesis.

Test yourself

Think of the answer, then tap the question to see it.

How is shifting dullness tested?

Mark the tympany-dullness border in the flank with the patient supine, roll the patient to the other side, wait and percuss again; if the border moves, it is positive.

Why is a hand pressed along the midline when testing for a fluid wave?

To block transmission of the impulse through the fat of the abdominal wall and avoid a false positive.

What is the most common cause of ascites?

Cirrhosis with portal hypertension.

What should fever or abdominal pain suggest in a patient with cirrhosis and ascites?

Spontaneous bacterial peritonitis, confirmed by diagnostic paracentesis.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Evaluation of the Patient With a Liver Disorder - Merck Manual Professional Edition (Merck & Co., Inc., 2025); Ascites: MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine, 2025); Shifting dullness (Wikipedia, 2026).

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Representative model, for educational purposes only.