Clinical characteristics and risk factors of congenital choledochal cysts

Abstract

Objective To investigate the clinical characteristics and risk factors of congenital choledochal cysts (CCC). Methods This retrospective study recruited 52 cases who were antenatally diagnosed with CCC and underwent surgical treatment after birth in Guangdong Women and Children Hospital from January 2013 to August 2018, with complete clinical data. According to the enlargement of cysts during pregnancy, they were divided into two groups: progressive group (≥15 mm, 22) and stable group (<15 mm, 30). Antenatal and postpartum ultrasound and MRI features of the two groups were analyzed. Clinical manifestations and biochemical examination results before and after operation were compared between the two groups. Other data, including amylase level in cyst fluid during operation, cholangiography findings, liver biopsy results, and post-operation follow-up, were also analyzed. Chi-square test, t (t') test, and Pearson correlations tests were performed for data analysis. Results (1) The average age of the 52 patients at operation was 46(7-822) d. The cysts of all cases were first detected during 19-21 weeks of gestation. The maximum diameter of the cyst in the progressive group was larger than that in the stable group after 34 weeks of pregnancy [31-34 weeks: (31.1±8.4) vs (23.1±6.6) mm, t=3.911; >34 weeks: (36.1±6.8) vs (27.1±7.3) mm, t=4.557; pre-operation: (51.8±18.0) vs (34.0±15.6) mm, t=3.809; all P<0.01]. (2) In the progressive group, the cysts were irregular in shape and enlarged after birth. The common hepatic duct and intrahepatic bile duct were dilated and gradually distended after birth, while the distal end of the common bile duct was narrowed, thus to form a cone-like duct. Deposits could be seen inside the cysts after delivery. Irregular cysts were also presented in the stable group, and five of them had dilatation of common hepatic duct and intrahepatic bile duct after birth. However, no cone-like formation was seen, the distal end of the common bile duct was visible, and deposits in cysts were occasionally found. (3) Twenty-five patients underwent laparotomy, and seven of them showed increased amylase level in cyst fluid including four with 2-5 times above the upper limit of normal value (one in the progressive group and three in the stable group). The other three cases were all in the stable group and their amylase levels in cyst fluid were more than ten times of the upper limit. The level of direct bilirubin in the progressive group was higher than that in the stable group before the operation [18.40(2.50-113.30) vs 8.70(0.00-16.80) μmol/L, u=2.400, P<0.05]. (4) Among the 52 cases, patients with type Ⅰ, Ⅳ and Ⅴ cyst accounted for 71.1% (37/52), 26.9% (14/52) and 2.0% (1/52), respectively. All cases were followed up regularly six months to one year after the operation. Liver function and bilirubin became normal and the growth and development of the babies were similar to those of the same age. (5) Different degrees of liver fibrosis and inflammation were shown in 46(88.5%) cases and more severe in older babies among those who underwent surgery in the progressive group. The time at operation was not associated with the severity of liver fibrosis and inflammation in the stable group. Hepatic fibrosis and inflammation were more serious in the progressive group than in the stable group (fibrosis grading: χ2=14.260, P=0.006; inflammatory activity grading: χ2=9.904, P=0.019). Conclusions Larger diameter (≥30 mm) in the initial prenatal examination or a significant increase in cystic diameter (≥15 mm) during pregnancy are risk factors for early stenosis or occlusion in the distal end of common bile duct requiring close follow-up after birth. When jaundice or abnormal liver function occur and stool color becomes light, early surgical treatment (one to two months after birth, generally within three months) for CCC is recommended to rule out the anomalous union of the pancreaticobiliary duct and hepatic disorders, as well as the cystic biliary atresia. Key words: Choledochal cyst; Ultrasonography, prenatal; Risk factors