Congenital extrahepatic portosystemic shunts
- First Online:
- Cite this article as:
- Murray, C.P., Yoo, S. & Babyn, P.S. Pediatr Radiol (2003) 33: 614. doi:10.1007/s00247-003-1002-x
- 572 Views
A congenital extrahepatic portosystemic shunt (CEPS) is uncommon. A type 1 CEPS exists where there is absence of intrahepatic portal venous supply and a type 2 CEPS where this supply is preserved. The diagnosis of congenital portosystemic shunt is important because it may cause hepatic encephalopathy.
To describe the clinical and imaging features of three children with CEPS and to review the cases in the published literature.
Materials and methods
The diagnostic imaging and medical records for three children with CEPS were retrieved and evaluated. An extensive literature search was performed.
Including our cases, there are 61 reported cases of CEPS, 39 type 1 and 22 type 2. Type 1 occurs predominantly in females, while type 2 shows no significant sexual preponderance. The age at diagnosis ranges from 31 weeks of intrauterine life to 76 years. Both types of CEPS have a number of associations, the most common being nodular lesions of the liver (n=25), cardiac anomalies (n=19), portosystemic encephalopathy (n=10), polysplenia (n=9), biliary atresia (n=7), skeletal anomalies (n=5), and renal tract anomalies (n=4).
MRI is recommended as an important means of diagnosing and classifying cases of CEPS and examining the associated cardiovascular and hepatic abnormalities. Screening for CEPS in patients born with polysplenia is suggested.
KeywordsCongenital extrahepatic portosystemic shuntMagnetic resonance imagingHepatic nodular hyperplasiaPolyspleniaLeft isomerism
Classification of congenital extrahepatic portosystemic shunts (after )
Type 1. With absence of intrahepatic portal veins
1a. Superior mesenteric and splenic veins do not join to form extrahepatic portal vein
1b. Superior mesenteric and splenic veins join to form a short extrahepatic portal vein
Type 2. With patent intrahepatic portal veins
Materials and methods
Summary of patient data
3 month old/female
18 month old/female
4 year old/male
Acute respiratory distress requiring ICU admission
Rectal bleeding and peripheral edema
Follow up post biliary diversion in infancy
Type of shunt
Route of shunt
Visceral situs and splenic status
Heterotaxy with polysplenia and interruption of inferior vena cava
Solitus with normal spleen and normal inferior vena cava
Heterotaxy with polysplenia and interruption of inferior vena cava
Three nodular lesions
A focal nodular lesion
Focal nodular hyperplasia, hepatoblastoma
Liver function tests
Hepatic function normal
Hepatic function normal
Serum ammonia normal
Serum ammonia normal
Serum ammonia elevated
Juvenile polyposis defect
Ventricular septal defect
Atrial septal defect
Right heart failure
Persistent rectal bleeding and anemia
Liver transplant performed
There have been 61 cases of CEPS reported in the literature to date (including our cases), 39 type 1 and 22 type 2 [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38]. Type 1, and in particular type 1a, CEPS occurs predominantly in females (74% and 89%, respectively). The incidence of type 2 CEPS is essentially split between the sexes with 12 female and 10 male patients. The range of age at diagnosis for type 1 CEPS is 31 weeks of intrauterine life to 76 years, with a median age of 10 years. For type 2, the age varies from 28 weeks of intrauterine life to 69 years, with a median age of 18 months.
Associations of CEPS
Type 1 (n=39)
Type 2 (n=22)
Congenital heart disease
Focal nodular hyperplasia
Other nodular liver lesionsa
IVC interruption/azygos cont
Renal tract anomalies
The clinical presentations of CEPS vary widely. Most often, shunts have been detected incidentally in the investigation of cardiac anomalies or liver dysfunction. Occasionally, shunts are detected as the cause of psychiatric disturbance or mental retardation secondary to chronic hyperammonemia. In CEPS there are typically no secondary signs of portal venous hypertension such as ascites, varices, or splenomegaly. A report in 1997 of a 5-month-old girl with type 1b CEPS has not been considered in the present literature review because of the presence of splenomegaly, possibly indicating portal hypertension .
Development of the portal venous system occurs between the fourth and tenth weeks of embryonic life by selective apoptosis of portions of the left and right vitelline veins before they enter the septum transversum . The development of the portal vein and inferior vena cava is a complex, coinciding process, which probably explains the potential for congenital portosystemic anastomoses. Shunting of mesenteric venous return to the inferior vena cava presumably leads to a marked diminution in flow within the normally developed portal venous system and therefore eventually to portal venous hypoplasia or atresia. Alternatively, hypoplasia or aplasia secondary to excessive involution of the vitelline venous system may be the initializing event [1, 2].
CEPS is most common to the inferior vena cava and less common to the renal veins, the iliac veins, the azygos vein, or the right atrium. Morgan and Superina  have classified CEPS into two types according to the presence or absence of the intrahepatic portal vein and further subclassified the first type into two groups depending on the status of the extrahepatic portal vein (Table 1).
CEPSs have been described in a variety of animals and are relatively common in dogs [41, 42]. CEPS may not be as rare in humans as is generally believed. In the reported cases, there was a significant female preponderance (74%) in type 1 CEPS, while female preponderance was not significant (54%) in type 2 [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38]. Given the likelihood that some cases of type 2 CEPS have been misclassified as type 1, the true sex incidence for each type cannot be established. The younger median age for type 2 CEPS (2 years versus 10 years) contradicts the previously held belief that type 2 shunts are typically diagnosed in older children and adults .
To date, cases of congenital absence of the portal vein have generally been reported as a distinct entity. In congenital complete absence of the portal vein, a systemic shunt must be present and this therefore represents a type 1a CEPS. Strictly speaking, congenital absence of the portal vein is characterized by the lack of a junction between the superior mesenteric and splenic veins and independent outflow of these veins into the systemic circulation , as well as complete absence of venules within the portal triads at liver biopsy . It is noteworthy that histological confirmation of the absence of hepatic portal venules has been made in only 8 of the 39 reported cases of type1 CEPS [5, 10, 20, 21, 23, 26, 37]. Of interest, Bellah et al.  described a patient in whom portal venous structures were not identified on ultrasound but later confirmed on liver biopsy. Yonemitsu et al.  reported a patient in whom portal venous structures were not identified on computed tomography, ultrasound, and liver biopsy, but were found on retrograde portography and computed tomography angioportography performed under balloon occlusion of the portocaval shunt. In patient 1 of the present series, a tiny portal vein was identified on magnetic resonance imaging. In patient 3, portal venules were only identified on histological examination of the explanted liver. On this basis, we propose that some of the previously described cases of type 1 CEPS may have actually been type 2, particularly those in which magnetic resonance imaging or X-ray angiography were not performed. In other words, intrahepatic portal venous flow may have been present but beyond the limits of resolution of the imaging available.
The importance of determining the type of shunt is heightened when considering candidacy for surgical ablation. Type 1 shunts should not be occluded as they represent the only drainage pathway for mesenteric venous return. However, work-up of the shunt should entail X-ray or magnetic resonance angiography so as not to exclude patients with diminutive intrahepatic portal systems from definitive treatment. Accurate preoperative depiction of the intra- and extrahepatic vascular anatomy will undoubtedly guide management decisions and the surgical or angiographic approach, to which end magnetic resonance imaging with contrast-enhanced angiography is recommended.
CEPSs are uncommon and under-recognized and as such no standard treatment is available. Children have generally been treated conservatively because of the associated abnormalities such as complex congenital heart disease or hepatobiliary dysfunction. Poor development of the intrahepatic portal veins is not considered a contraindication for definitive repair of the shunt [12, 14, 22]. Shinkai et al.  recently found that most patients with type 2 shunts can be treated with ligation or banding of the shunt vessel. In one case, Ikeda et al.  noted a return to almost normal size of the hypoplastic intrahepatic portal veins after coil embolization of a shunt. For patients with CEPS, early diagnosis and correction are needed to avoid the deleterious effects of hyperammonemia on the central nervous system .
CEPSs are often associated with nodular lesions of the liver, biliary atresia, skeletal anomalies, and renal tract anomalies (Table 3). The various associations of CEPS are consistently more common in type 1 with the exception of renal tract anomalies, which are evenly represented. Nevertheless, the coincidence of associations in both types suggests that the two variants are closely related.
Polysplenia with interruption of the inferior vena cava and azygos venous continuation was identified in patients 1 and 3 of our series representing a significant addition to the seven prior recorded cases of polysplenia and three recorded cases of interrupted inferior vena cava. There were possibly other cases of polysplenia and anomalous systemic venous drainage that were not specifically identified in the literature. The authors recommend screening for CEPS in patients diagnosed with polysplenia or anomalies of the abdominal systemic venous circulation.
Cardiac anomalies are a particularly common association with CEPS, having been recognized in patient 2 of the current article and nearly a third of cases overall. The most common lesion is an atrial septal defect. Coincidence of cardiac defects suggests either a prenatal insult during the simultaneous development of the heart and abdominal venous system, or an adaptive response to the hyperdynamic effect of CEPS [7, 11].
Nodular liver lesions are a fundamental response to almost any significant liver injury . Nearly half of the recorded cases of CEPS describe associated nodular liver lesions. Focal nodular hyperplasia and other regenerative nodular lesions are associated with hepatic ischemia, and a compensatory increase in hepatic arterial flow is a possible stimulus . Growth factors and hormones may also be important etiological factors . Shinkai et al.  identified an association between small liver volumes and congenital absence of the portal vein, although this was not so in the present series. In focal nodular hyperplasia, the surrounding liver is histologically normal so that the stimulus to development of the nodule is probably not a decrease in functional liver mass . Importantly, there is an association between CEPS and liver malignancy with case reports of hepatocellular carcinoma, hepatoblastoma, and sarcoma.
Biliary atresia is a disorder of unknown etiology that manifests as an inflammatory process involving the extrahepatic bile ducts in the late intrauterine or early neonatal period. Extrahepatic bile ducts appear from the intestinal bud at 5 weeks of embryonic life, therefore the association of biliary atresia with portal venous anomalies may indicate a shared insult in early development [32, 45]. Of 61 cases, seven (11%) were associated with biliary atresia and all but one of these was type 1. Of the seven cases associated with biliary atresia, five (71%) also had polysplenia, reiterating the known association of biliary atresia and the polysplenia syndrome and again suggesting a common insult in early fetal life .
Toxic compounds produced in the digestion process are normally metabolized in the liver. CEPSs cause some or all of the mesenteric circulation to bypass the liver, delaying the metabolism of galactose and ammonia, amongst other potentially dangerous metabolites. Newborn screening for high blood galactose levels has recently been found to be useful for the detection of congenital portosystemic shunts. Portosystemic encephalopathy was previously considered a rare association of CEPS, although careful review of the literature indicates that 16% of cases showed encephalopathy [2, 3, 10,15]. It is generally believed that portosystemic encephalopathy may manifest later in life as the younger brains are less sensitive to toxic materials; however, seven of the ten reported cases were children .
CEPS is a rare though increasingly reported anomaly that is important to diagnose given the potentially dire clinical consequences. CEPSs have several associations that the radiologist should be aware of, in particular the association with polysplenia, nodular lesions of the liver including malignancy, congenital heart disease, and hepatic encephalopathy. It is important to identify the presence or absence of hepatic portal venous supply as this may influence treatment options. Magnetic resonance imaging is recommended as a noninvasive imaging technique for the identification and classification of CEPS with the aim of guiding management and improving outcomes.