the diagnosis of extrahepatic biliary atresia ( ehba ) was always delayed and done by exclusion , peroperative cholangiogram , and histopathology .
recent advances in imaging have led to increased antenatal prediction of ehba , particularly on high - resolution maternal ultrasonography .
prenatal mr studies enhance fetal diagnosis , with many reports of antenatal diagnosis of choledochal cysts ( cdcs ) on ultrasound ( usg ) and magnetic resonance imaging ( mri ) studies published . amongst these , to the best of our knowledge , biliary atresia ( ba ) has not been reported .
we report a case of ehba with terminal cystic dilatation of cbd predicted on antenatal and postnatal imaging with operative and histopathologic confirmation .
a 25-year - old primigravida presented to our hospital at 22 week of gestation for target scan targetted imaging for fetal anomalies ( tiffa ) .
anatomical survey revealed a longitudinally oval , avascular anechoic cyst measuring 14  9 mm in the right upper abdomen , separate from duodenum , showing continuity with hepatic hilum superiorly without identifiable gall bladder ( gb ) .
fetal mri was performed 2 weeks later on 1.5 t essenza ( siemens , erlangen , germany ) to investigate the correct anatomical location of the cyst and its relationship with adjacent organs to assist with prognostication and treatment planning for the perinatal period .
t2-weighted half - fourier acquisition single - shot turbo spin - echo ( haste , tr / te 900/86 ms , 4-mm slice thickness ) sequences were obtained in the axial , coronal , and sagittal planes with respect to the fetus .
sequences were monitored in real time and manipulated to determine optimal imaging planes during the scan , as fetal orientation is unpredictable and often changes during acquisitions .
in addition to the standard orthogonal planes , oblique planes were acquired for demonstrating the relationship to surrounding structures .
mri showed a 14  9 mm ellipsoid [ figure 1a ] homogenous cystic lesion at liver hilum hyperintense on t2w images .
the cyst was longitudinally oval , coursing posteroinferiorly from hepatic hilum appreciated on sagittal images [ figure 1c ] .
coronal images revealed hyperintense cord - like structure above the cyst , showing communication with it [ figure 1d ]
. the normal morphology of fetal gb was not visualized in the inferior surface of liver in right upper quadrant .
( a ) usg : cystic lesion ( 14  9 mm ) at porta hepatis ( arrow ) separate from duodenum without identifiable gall bladder .
( b - d ) mri : axial images reveal the cyst ( arrow ) posterior to the duodenum ( asterisk ) ( b ) . on sagittal images , the cyst is coursing posterior to the midabdomen ( c ) .
on coronal images , hilar structures were replaced by hyperintense cord - like structure above the cyst ( arrow ) ( d ) the imaging characteristics on usg and mri are presented in table 1 .
prenatal imaging features follow - up using serial usg scans in pregnancy revealed static size of the cyst with persistent ghost gb .
postnatal usg , on day 3 after a 4-h fast , revealed liver extending beyond subcostal margin ; echotexture was homogenous with normal surface contour .
there was an echogenic area anterior to the portal vein at porta and measured 3.2 mm [ figure 2a ] . a well - defined , longitudinally oval anechoic cyst was present at the hilum ~14  9 mm .
the cyst size , echogenicity , and morphology were the same as seen in prenatal imaging [ figure 2b ] .
maximum width and length of gb was 11  2 mm , with irregular , compressed lumen s / o ghost gb [ figure 2c ] .
hepatic artery was prominent , running parallel to the right portal vein , and measured 1.7 mm .
main portal vein ( mpv ) diameter was obtained at the same level , which measured 3 mm .
the ratio of ha / mpv diameter was > 0.5 ( > 0.45 increase ) [ figure 2d ] .
( a ) echogenic area anterior to the portal vein at porta ( arrow):triangular cord sign .
( b ) a well - defined , longitudinally oval anechoic cyst present at the hilum ~14  9 mm .
maximum length and width of gb was 11  2 mm with irregular compressed lumen ( arrow ) ( s / o ghost gb ) .
( d ) prominent hepatic artery ( arrow ) seen running parallel to the right portal vein and measured 1.7 mm .
the ratio of ha / mpv diameter was > 0.5 ( > 0.45 increased ) the imaging characteristics at porta are presented in table 2 .
postnatal usg features liver function tests ( lft ) revealed increased -glutamyl transferase ( 831 u / l ) , elevated alkaline phosphatase ( 698 u / l ) , conjugated hyperbilirubinemia ( 2.8 mg / dl ) , and normal serum glutamate pyruvate transaminase ( sgpt ) 10
u / l , serum glutamate oxaloacetate transaminase ( sgot ) 29 u / l , albumin , and international normalised ratio [ ( inr ) .
hepatobiliary scintigraphy was performed on day 24 which showed prompt and good uptake by the liver and absent tracer excretion into the intestines in 24-h delayed images .
hepatobiliary scintigraphy showed prompt and good uptake by the liver and absent tracer excretion into the intestines in 24-h delayed images .
gallbladder and extrahepatic ducts were not visualized a diagnosis of extrahepatic cystic biliary atresia ( cba ) was made based on imaging .
operative findings included firm brownish liver , fibrotic porta inclusive of non - visualized right / left hepatic duct , common hepatic duct , and proximal cbd [ figure 4a ] .
corresponding schematic representation is shown in figure 4b and was classified as type 3 ba according to japanese classification system .
( a ) operative findings included firm brownish liver ( l ) , fibrotic porta inclusive of non - visualized right / left hepatic duct , common hepatic duct , and proximal cbd ( arrow ) .
cystic structure was seen at the site of terminal part of cbd ( c ) , going behind the duodenum ( d ) , and ending blindly .
( b ) corresponding schematic representation showing japanese classification system with our case classified as type 3 atresia of entire ductal system ( arrow ) with terminal dilatation of cbd ( c ) , ending blindly and being engulfed by pancreatic tissue ( p ) excision of fibrotic hilar structures including cyst en masse with a kasai 's portoenterostomy was performed with ~30 cm of roux - en - y jejunal loop .
cba is an uncommon variant of ba in which prognosis may be relatively favorable but liable to misdiagnosis as cdc .
it is classified into three types according to the japanese classification system based on the atretic segment of bile duct into type 1 ( distal atresia ) , type 2 ( proximal atresia ) , and type 3 ( complete atresia ) .
the cyst can occur anywhere along the atretic segment and is proximal to atresia in types 1 and 2 and distal to it in type 3 .
a thorough literature search revealed less than 100 cases of ehba associated with cdcs reported till date of which majority were type 1-ehba ( 76% ) and only 21% were type 3-ehba as in our case , classified according to japanese pathological classification system .
the mainstay of confirmatory diagnosis in most of the published reports was surgical exploration and intraoperative cholangiogram .
zhou et al . have demonstrated the accuracy of usg diagnosis to be 98 - 100% and evaluated objective differential characteristics of cba and cdcs .
the collaborative signs include gb signs , hilar signs , hepatic artery signs , and miscellaneous signs ( increased hepatic subcapsular flow ) on usg .
ghost gb is an indirect sign of unfilled atretic gb in ehba described by zhou et al . as gb length < 19 mm , lack of a smooth mucosal lining with an indistinct wall , and irregular or lobular contour .
hilar cyst in ba represents fibrotic remnant of the cbd , explaining the constant size and echogenicity .
prominent hepatic artery has been a well - known association with ba , making it a possible collaborative imaging sign .
the present case showed triangular cord and all the collaborative signs described on postnatal usg as presented in table 2 .
, fetal gb presents as a right - sided pear - shaped structure on the inferior surface of liver and is consistently demonstrated from 18 weeks of gestational age onward . before 27 weeks , the signal intensity of fetal bile is exclusively hyperintense on t2w , corresponding to t1w hypointensity .
non - visualization of fetal gb with cyst at porta is diagnostic of cba on prenatal imaging . in our case
, the normal shape of gb was not visualized in its expected location , thus confirming ghost
thus , prenatal mri can improve the pick - up rate of ehba and also differentiate between cba and cdc .
to the best of our knowledge , this is the first report of prenatal mr predicted cba .
non - visualization of gb and cyst specific to biliary tract on prenatal mri are suggestive of ba .
bhatnagar et al . have reported cdc with ba , but the present case differs in that the ba existed both proximally and distally .
abnormal pancreas was evident in this case peroperatively where the terminal cystic structure was engulfed by pancreas .
kasai 's portoenterostomy has been the universally accepted initial surgical modality to establish biliary drainage .
the present case also underwent kasai 's portoenterostomy after the excision of fibrotic extrahepatic biliary ducts .
early surgery , as evident in this case that was operated < 8 weeks of life , has yielded satisfactory initial biliary excretion leading to normal serum bilirubin levels .
imaging helps in the prediction of ehba and also helps in early postnatal surgical referral , improving the results of kasai 's portoenterostomy .
 extrahepatic biliary atresia ( ehba ) is an uncommon cause of neonatal jaundice . 
 antenatal magnetic resonance imaging ( mri ) diagnosis of ehba has not been published to the best of our knowledge till date . 
 ehba with cystic component is likely to be mistaken for choledochal cyst . 
 a case that was antenatally predicted and postnatally confirmed by surgery and histopathology is being reported . 
 all imaging signs are analyzed herewith . 
 imaging helps in the prediction of ehba and also helps in early postnatal surgical referral which in turn improves the results of kasai 's portoenterostomy . 
Introduction
Case Report
Discussion