Hepatic hydatid cyst - ultrasound water lily sign

Case contributed by Dr Sameer Peer


Referred to the Emergency Department for a FAST scan after sustaining blunt abdominal trauma. Otherwise asymptomatic.

Patient Data

Age: 14 years
Gender: Female


A well-defined cystic lesion measuring 8.0 cm x 6.5 cm x 7.4 cm in the right lobe of the liver (segment VII/VIII) with low-level internal echoes. The cyst shows a detached, irregular laminated membrane inside it which appears to float within the contents of the cyst.

Rest of the study is unremarkable.

Case Discussion

The findings are suggestive of a hepatic hydatid cyst with ultrasound "water lily sign". According to the WHO classification of hepatic hydatid cysts, the water-lily sign is seen in stage CE3a, which represents a transitional stage between active and inactive disease. The mechanism of detachment of membrane is related to decreased intra-cystic pressure, degeneration, host response, trauma or following therapy. 

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Case information

rID: 38039
Published: 1st Jul 2015
Last edited: 30th Dec 2019
Inclusion in quiz mode: Included
Institution: Sher-i-kashmir institute of medical sciences

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