The porta hepatis microcyst: an additional sonographic sign for the diagnosis of biliary atresia.

OBJECTIVES

To describe and evaluate an additional sonographic sign in the diagnosis of biliary atresia (BA), the microcyst of the porta hepatis, in comparison with previously described signs.

METHODS

Ultrasound performed in 321 infants (mean age 55 days) with cholestasis were retrospectively analyzed. BA was surgically confirmed in 193 patients and excluded in 128. US evaluated gallbladder type (1: normal; 2: consistent with BA; 3: suspicious), triangular cord sign (TCS), microcyst and macrocyst, polysplenia syndrome, portal hypertension, and bile duct dilatation. T test and Pearson χ2 test were used to compare US signs between the two groups, followed by univariate regression analysis.

RESULTS

The highest specificity and sensitivity for BA (p < 0.001) were respectively obtained with non-visible gallbladder (100 %-13 %), macrocyst (99 %-10 %), polysplenia (99 %-11 %), microcyst (98 %-20 %), type 2 gallbladder (98 %-34 %), and TCS (97 %-30 %). Combination of signs (macro or microcyst; cyst and no bile duct dilatation; microcyst and/or TCS; type 2 gallbladder and/or cyst) provided better sensitivities (25-49 %) with similar specificities (95-98 %) (p < 0.001). On univariate analysis, the single US signs most strongly associated with BA were polysplenia (odds ratio, OR 16.3), macrocyst (OR 14.7), TCS (OR 13.4) and microcyst (OR 8).

CONCLUSIONS

Porta hepatis microcyst is a reliable US sign for BA diagnosis.

KEY POINTS: • The porta hepatis microcyst is a specific sign of biliary atresia. • It was found in 31 (16.1 %) of 193 patients with biliary atresia. • Its specificity was 98 % (p < 0.001). • High frequency transducer and color Doppler can show the porta hepatis microcyst.