Text Box: THE DIFFERENTIAL DIAGNOSIS BETWEEN BILIARY ATRESIA (TYPE ⅠCYST) AND CHOLEDOCHAL CYST IN NEONATES FENG Jiexiong, LI Minju, TANG Hongfeng, et al. Department of General Surgery, Children’s Hospital, Medical College of Zhejiang University, Hangzhou, China Objective: To investigate the difference between type Ⅰcyst of biliary atresia(BA) and choledochal cyst(CC) in neonates. Methods: Symptoms, signs, hepatic function, B Ultrasound, CT, intraoperative cholangiograhy and pathologic features were all analysed in 4 neonates with BA and 17 neonates with CC. Results: Both malformations occured more commonly in girls, and the obstructive jaundice was the main manifestion in this two groups. All of the indexes of hepatic function are similar between patients with BA and CC. No significant difference is also seen in the pathologic features either in microscopy or in transmission electron microscopy. The length and the width of the cyst and the gallbladder in neonates with BA were all shorter than that in CC found by B ultrasound and CT (p<0.05). The deformation of biliary tree within liver and the stricture of the portal bile were the predominant features in BA, while the bile within liver was normal or dilated in neonates with CC. Conclusion: By the means of B ultrasound, CT, and intraoperative cholangiography, the precise and effective differential diagnosis between BA and CC could be gained. [Key words] Biliary atresia; Choledochal cyst; neonate 1703