Pseudo gallbladder sign in biliary atresia--an imaging pitfall

Abstract

Background: Ultrasound (US) is used to identify causes of neonatal cholestasis. We describe a potential sonographic pitfall, the "pseudo gallbladder," in biliary atresia (BA).

Objective: To describe the Pseudo Gallbladder sign (PsGB sign).

Materials and methods: Sonograms/clinical records of 20 confirmed BA infants and 20 non-BA cases were reviewed retrospectively. For the BA group, preoperative sonography and surgical and pathological findings were examined. For the non-BA group, sonographic features and pathological findings were examined. The PsGB sign is defined as a fluid-filled structure, located in the expected region of the gallbladder, measuring ≤ 15 mm in length but without a well-defined or normal-appearing gallbladder wall.

Results: A recognizable gallbladder and normal gallbladder wall were present in all non-BA infants. However, none of the BA infants had a sonographically normal gallbladder. Seventy-three percent of BA patients had a PsGB, and in 27% no gallbladder or gallbladder-like structure was detected.

Conclusion: A gallbladder-like structure in BA is common and can be misinterpreted as a normal gallbladder, delaying diagnosis and therapy. Recognition of this imaging pitfall, described here as the pseudo gallbladder sign, will help avoid this error.

Fig. 1

Normal gallbladder wall. Normal sonographic appearance of the gallbladder in a 2-day-old neonate with no known hepatobiliary disease demonstrates a well-defined measurable normal gallbladder wall. Note the central echogenic mucosal interface (arrow) and peripheral thin fibromuscular layer (arrowhead)

Fig. 2

The pseudo gallbladder sign (PsGB sign). Different appearances (arrows) of the PsGB sign, which is defined as a fluid-filled structure <15 mm in length in the region of the interlobar fissure without a normal gallbladder wall (see Fig. 1 for a normal-appearing wall). a Notice the smooth contour of this PsGB compared with another PsGB (b) with an irregular margin. c Irregular contour in another PsGB. d PsGB appears as a very small, focal, nonspecific fluid collection. Note that a normal gallbladder wall is not seen in any of these cases

Fig. 3

Two cases of PsGB with length >15 mm but with absence of a definable wall. a PsGB has a length of 21 mm but with wavy contour and no definable wall. b PsGB has a length of 17 mm but with irregular margins and no measurable wall

Fig. 4

The triangular cord sign (TC sign) in a BA patient. a The TC sign (arrowhead) measured 4.8 mm in this case of BA. b The PsGB sign in this case (arrow) is seen as a fluid-filled structure demonstrating an irregular contour but without a normal gallbladder wall