In the fetal circulation the umbilical vein enters the left branch of the portal vein at the umbilical recess, lying in the free border of the falciform ligament from the umbilicus to the liver (Fig. 5.1). The left portal vein connects with the hepatic vein via the ductus venosus, and the blood then flows into the right atrium of the heart. The ductus venosus effectively forms a large venous shunt and bypasses the liver, allowing most of the blood from the placenta to pass directly to the heart. This fetal anatomy is important, as umbilical venous catheters should follow this route. If they enter the right portal vein then there is the potential for portal vein thrombosis to occur. After birth the umbilical vein obliterates and goes on to form the ligamentum teres in the falciform ligament. The ductus venosus also obliterates and goes on to form the ligamentum venosum. Within a few hours of birth and in very early neonatal life these structures can be readily identified with careful sonography. In the older child the ligamentum teres can be seen as an echogenic structure arising from the left branch of the portal vein (Fig. 5.2). When the pressure in the liver rises, as in cirrhosis, this channel re-canalizes and opens so that portal venous blood can flow away from the liver towards the umbilicus. This is how umbilical varices develop.

Figure 5.1 Fetal hepatic blood system. The diagram shows the relationship of the umbilical vein to the portal and hepatic venous systems in the fetus. The ductus venosus connects the left portal vein to the hepatic vein/ right atrial region. The ductus venosus goes on to become the ligamentum venosum. The umbilical vein goes on to form the ligamentum teres of the liver, which is found on the lower margin of the falciform ligament. It is easy to understand how, if a catheter from the umbilical vein is misplaced, the portal vein can occlude with thrombus.

Figure 5.2 Ligamentum teres of the liver. Longitudinal sonogram in an older child showing the echogenic line of the obliterated ligamentum teres. This is occasionally seen in children, most commonly in a newborn, where it sometimes takes hours or days to close. It can be identified arising from the left portal vein.

The inferior vena cava has a complex developmental anatomy, but anomalies are surprisingly infrequent. The most common anomaly is a persistent left-sided IVC which drains into the right atrium through the enlarged orifice of the coronary sinus.

In the abdomen the commonest anomaly is an interrupted IVC with failure of development of the hepatic segment. As a result the blood from the lower body drains via the azygous and hemiazygous system of veins. The hepatic veins drain separately into the right atrium. There may also be a double IVC, which usually occurs below the renal veins, with the left IVC being smaller than the right.

THE NORMAL PEDIATRIC HEPATOBILIARY SYSTEM

Ultrasound is the first-line investigation in any suspected abdominal pathology in children. Liver disease may be suspected clinically, in which case the findings of ultrasound will guide further imaging. However, lesions in the liver are often detected incidentally. Hence, abdominal examinations, regardless of the clinical history, should include a full examination of the major abdominal organs and their vasculature. This is particularly true in children, where many conditions are congenital. The liver has a very large functional reserve and may need to suffer extensive disease before dysfunction becomes clinically apparent. Also, there are many conditions, for example, renal, which are associated with liver disease, which will not be detected unless they are specifically sought.

A thorough basic knowledge of the normal anatomy of the liver is essential but, in addition in children, knowledge of the congenital anomalies that may simulate disease is also required. Perhaps nowhere else in the abdomen is the use of Doppler so important both to characterize focal lesions and evaluate the portal and hepatic vasculature.

Hepatic vasculature

Figure 5.3 shows Doppler waveforms of the hepatic vessels.

Figure 5.3 Doppler waveforms of hepatic vessels. (A) Hepatic vein waveform. This is triphasic. (B) Portal vein. The waveform is undulating and continuous. It is very important that sonographers learn to carry out Doppler examination of this vessel in the pediatric abdomen.

Hepatic veins

The hepatic veins drain blood from the liver into the IVC and right atrium of the heart. The normal waveform is triphasic, toward the liver in diastole and a brief reversal in systole.

The hepatic vein waveform is affected by:

• compliance, that is the flexibility of the liver, so that conditions affecting the liver parenchyma and ‘stiffening’ the liver will dampen the waveform

• cardiac status—there is normally reversal of flow in atrial systole but, if the heart is failing, the veins may massively dilate. In addition the IVC also dilates. There is loss of the normal fluctuation in the size of the lumen of the IVC and hepatic veins with respiration

• extrahepatic conditions such as ascites, which may compress the veins and change the normal waveform.

Portal vein

The portal vein brings blood to the liver from the spleen and bowel. The portal vein enters the liver in the porta hepatis and divides into the right and left branch. In the liver its branches have echogenic walls and are the most prominent vessels.

Normal diameter under 10 years of age should be in the region of 8 mm; over 10 years, it is 10 mm. Diameter is highly variable and varies with deep inspiration, food and posture. Normal waveform is monophasic with modulations due to respiration and cardiac activity.^2,³

Congenital variations of the portal vein include a pre-duodenal portal vein which is frequently associated with situs inversus, duodenal stenosis, annular pancreas, malrotation of the bowel and other congenital malformations. Double portal vein and agenesis of the portal vein also occur.

Hepatic artery

The hepatic artery carries oxygenated blood to the liver from the aorta. It is pulsatile with forward flow throughout the cardiac cycle.

Inferior vena cava

The IVC drains the venous blood from the lower body. It should always be carefully examined, in particular for its normal course and anatomy, size and any intraluminal obstruction or pathology.

Normal appearances of the gallbladder and biliary tree

The gallbladder and biliary tree in a child are best examined after a fast. In infants, time the examination for the next feed if they are fed 4-hourly; in older children, a minimum of 6 hours’ fast is needed. Alternatively, give older children appointments for the first examination of the morning so that they can have an overnight fast. After an adequate fast, the normal gallbladder will be well distended with bile. The shape and size of the gallbladder are very variable (Table 5.1). In children, as in adults, folding of the gallbladder may be mistaken for a septum and, when this occurs, patients should be examined in the decubitus position, or even erect.

Table 5.1 Normal ranges (−2 SD to +2 SD) for the anteroposterior and coronal diameter as well as length of the gallbladder and diameter of the right portal vein

Congenital anomalies of the gallbladder are also quite rare, and intrahepatic gallbladder and duplication are probably the anomalies one is likeliest to see. Provided the infant or child is adequately prepared the sonographer should always expect to see the gallbladder in pediatric practice.^4,⁵

Gallbladder wall thickness and common hepatic duct diameter show no significant change with age:^6,⁷

• gallbladder wall thickness 1–3 mm

• common hepatic duct diameter 1–4 mm.

ABNORMALITIES OF THE NEONATAL LIVER

Pathological conditions encountered in the neonate and in childhood differ, so this and subsequent sections divide liver abnormalities into neonatal and childhood conditions. There will be some overlap, but the intention is to provide a better understanding and help narrow the diagnosis for the sonographer.

Hepatomegaly

One of the commonest clinical indications for examining the neonatal abdomen is hepatomegaly. Box 5.1 lists the differential diagnoses.

BOX 5.1 Causes of hepatomegaly in the neonate

Diffuse

• 4S Neuroblastoma

• Cardiac failure

• Fatty infiltration, metabolic liver disorders

• Hepatitis

• Leukemia

Focal

• Angiomatous lesions

• Metastases from stage IV neuroblastoma

• Hepatoblastoma

Congestive cardiac failure

The liver may appear enlarged and echogenic. The most striking feature is dilation of the hepatic veins and the inferior vena cava. The infant will usually have a clinical history of heart failure. Ascites may also be present.

Hemangioma and hemangioendothelioma

A hemangioma is a primary, benign, frequently symptomatic, vascular neoplasm. Infantile vascular hemangioendothelioma is the most common hepatic mass in the neonate, and over 80% present within the first 6 months of life.

Infants typically present with hepatomegaly or are thought to have an abdominal mass. Other clinical presentations include high-output heart failure (25%) caused by intratumoral, high-flow, arteriovenous shunts. Disseminated intravascular coagulation occurs as the platelets are damaged and trapped as they pass through the AV shunt, and so thrombocytopenia results and the potential to bleed is high (Kasabach–Meritt syndrome). If rupture of the hemangioma has occurred during delivery, they may even present with a hemoperitoneum. Occasionally these infants may be asymptomatic and are referred, from dermatologists, with skin hemangiomas. The reported incidence of associated hepatic hemangiomas varies in the literature, because of selection of patients, but generally about half of those with multiple skin hemangiomas will have them in the liver as well. There is also an association with hemangiomas in the lung, trachea, thymus, spleen, lymph nodes and meninges.

Diagnosis may be made in utero, and fetal hydrops may occur as a result of the AV shunting of blood.

Ultrasound appearance

There are two different types of hemangiomas: Type I has proliferation of small vascular channels and cavernous areas, and Type 2 has an irregular structure and tendency to fibrosis. Hemangioendotheliomas may be solitary, multiple or diffuse, ranging in diameter from a few millimeters to several centimeters, and reflect the capillary nature of the hemangioma. Asymptomatic and sometimes even symptomatic tumors can undergo complete involution by 2 years.

There is a wide spectrum of ultrasound appearances, from a single small hyper- or hypoechoic nodule to multiple similar nodules throughout the liver parenchyma (Fig. 5.4). Lesions may be present in the spleen as well. Calcification occurs in approximately 15%. They are highly vascular on Doppler examination but settings must be optimal for slow flow. Spectral traces should always be obtained from the hemangioma, which will demonstrate the AV shunting. Ultrasound is particularly useful to look at vessels both feeding and draining the hemangiomatous mass, so the aorta, celiac, superior mesenteric feeding vessels, and hepatic veins draining the mass need to be examined carefully. In addition this will also help in the differential diagnosis—if a mass is found in the liver in a neonate, with large feeding arteries and large draining veins, the diagnosis is most likely to be a hemangioma. In massive intratumoral AV shunting the patient may be in severe congestive heart failure. Ultrasonically the multiple small hemangiomas appear hypoechoic. The single hemangiomas may appear hyperechoic, as seen in adult hemangioma. An enhanced CT examination will show early peripheral enhancement with delayed progression to the center of the lesion. Occasionally the central portion of large masses will remain hypodense, and this corresponds to central fibrosis.

Figure 5.4 Hepatic hemangiomas. (A) Longitudinal sonogram of the liver showing multiple hypoechoic areas within the liver parenchyma. (B) Doppler examination of these multiple small hemangiomas demonstrating the AV shunting of blood within the hemangioma. The spectral waveform is abnormal, with spectral widening and no obvious arterial and separate venous waveform. When severe shunting occurs, the patient will go into heart failure.

Angiography will show the associated abnormalities of the hepatic artery and large tortuous draining veins with shunting.

Cavernous hemangiomas contain large cystic spaces (Fig. 5.5). The sonographer must carefully evaluate the mass and examine the aorta and major blood vessels, as shunting of blood to the liver may be large and the diversion of blood may increase the size of the hepatic artery and superior mesenteric artery. Ultrasound is an excellent modality for demonstrating this in the neonate, as other cross-sectional imaging does not generally produce images of such exquisite detail due to the small size of the infant. Blood flow in the cavernous hemangioma may be slow and difficult to detect on Doppler but with newer equipment and optimal settings for slow flow this can be overcome. Very rarely these hemangioendotheliomas may fill the whole of the liver, producing a very specific and extraordinary appearance (Fig. 5.6). These infants may be in severe heart failure and have major problems with a bleeding diathesis. Sometimes extreme measures have to be taken in order for the infant to survive, and embolization of the hepatic artery has been attempted in order to prevent the shunting of blood.

Figure 5.5 Cavernous hemangioma. (A) This newborn presented with a large palpable mass in the liver. Ultrasound examination revealed a well-defined mass containing serpiginous channels (between calipers). (B) Doppler examination revealed large draining vessels (arrow). This was a cavernous hemangioma of the liver. On Doppler very little flow or no flow is seen within these large dilated channels, because of the slow flow of blood. (C) Ultrasound examination of the mass 1 month later shows that the channels are still evident but the mass is better defined and smaller in size. (D) Longitudinal sonogram of the mass 1 month later revealed increased peripheral echogenicity, suggesting calcification, and once again the mass has regressed in size. (E) Follow-up 6 months after birth shows that the cavernous hemangioma has become much smaller, thrombosed its blood supply and become highly calcified.

Figure 5.6 Hemangioendothelioma. (A) Transverse sonogram of the liver at the level of the superior mesenteric artery. The liver is markedly enlarged and filled with multiple hypoechoic hemangiomas. This baby was extremely ill and eventually died from an uncontrollable disseminated intravascular coagulation. (B) MRI examination on the same infant showing these extensive lesions throughout the whole liver.

Interferon and steroids have been used with variable success to decrease the size of the mass. The natural history of hemangiomas is to decrease in size with time.

Carefully performed dynamic enhanced CT scanning and MRI will help show the vascular nature of the mass. Calcification is occasionally seen in the vessels.

These lesions are the most commonly seen hepatic masses in neonates and, provided the alfa-fetoprotein is normal, should be the first diagnosis excluded. It is for this reason that every effort must be made to perform a careful Doppler examination on all these patients (Fig. 5.7).

Figure 5.7 Hepatic hemangioma. (A) This female neonate was discovered prenatally to have a liver mass. This is the first scan at 1 week of age. Transverse sonogram of the liver shows a large mass occupying most of the left lobe of the liver (between calipers). It has a heterogeneous appearance and centrally some tubular structures which look like blood vessels. (B) Transverse sonogram of the mass with color flow Doppler. There are huge draining hepatic veins which indicate that this mass is highly vascular with some shunting of blood. This was diagnosed at biopsy as an infantile hemangioendothelioma.

Liver tumors in the neonate

Hepatoblastoma

Hepatoblastoma may occasionally be seen in the neonate. It is for this reason that the alfa-fetoprotein levels should be measured in any suspicious cases, as they will be elevated in the vast majority. Alfa-fetoprotein is a glycoprotein that is made by the liver, yolk sac and gut. In the fetus it may escape into the amniotic fluid via an open neural tube defect or from open ventral wall defects. This is why it is used so successfully prenatally to help detect these defects.

Ultrasound appearances

Hepatoblastomas are usually solitary, reasonably well-defined lesions. They are most common in the right lobe and may contain areas of calcification.

Hepatic tumors are very vascular and must not be mistaken for hemangiomas. One of the differentiating features to look for is the Doppler shift, which is greater in hepatoblastoma, as is vascular invasion with amputation of portal vessels (Fig. 5.8).

Figure 5.8 Neonate hepatoblastoma. (A) Longitudinal sonogram of the right lobe of the liver and right kidney in a young infant presenting with an abdominal mass. There is a well-defined solid mass within the liver (between calipers) which on biopsy was a hepatoblastoma. (B) Contrast-enhanced CT examination of the liver in this infant. This shows what appears to be predominantly a cystic mass with rim enhancement. This is an unusual enhancing lesion. The alfa-fetoprotein level was raised. (C) Longitudinal sonogram of the mass 2 months later after treatment. The mass is much smaller in size (between calipers) but now shows some dense calcification around the edge.

4S Neuroblastoma

4S NBL presents in the early neonatal period with a generalized enlargement of the liver and, on ultrasound, has a heterogeneous appearance typically described as a ‘pepper pot’ appearance. This should be the first differential diagnosis considered when a massively enlarged heterogeneous liver is found in the neonate and an active search for an adrenal primary tumor made. This is fully described in Chapter 4.

ABNORMALITIES OF THE NEONATAL BILIARY SYSTEM

Neonatal jaundice

Jaundice is a result of elevation of bilirubin in the blood. Bilirubin may be unconjugated, when it has been released from red cells which have been broken down normally or pathologically, or conjugated, when the released bilirubin is converted by liver cells to a water-soluble form excreted in the bile ducts. The conjugated form normally aids fat digestion and turns stools dark.

Most newborn infants become clinically jaundiced. If the jaundice persists for more than 2 weeks it is called persistent or prolonged. This is usually an unconjugated hyperbilirubinemia which resolves.

Persistent jaundice caused by liver disease is conjugated hyperbilirubinemia. Clinical evaluation gives very few clues to the etiology, but typically the infants have pale stools, dark urine, hepatomegaly, bleeding disorders (as the liver is unable to synthesize prothrombin) and failure to thrive. Diagnosis of the cause of the jaundice is urgently required, as early intervention improves the ultimate prognosis.

Clinically the infants present in the first month of life with jaundice. The initial steps are:

• Confirm elevated bilirubin, of which more than 20% will be conjugated.

• Identify a potentially treatable cause such as sepsis or hypothyroidism or a metabolic condition (Box 5.2).

• Differentiate neonatal hepatitis from biliary atresia or a potentially surgically treatable condition such as a choledochal cyst. Ultrasound is an excellent modality to screen neonates with jaundice.

BOX 5.2 Causes of persistent neonatal jaundice

Unconjugated

• Breast milk jaundice

• Infection, particularly urinary tract

• Hemolytic anemia, e.g. G6PD deficiency

• Hypothyroidism

• High gastrointestinal obstruction

Conjugated > 20% total bilirubin

• Bile duct obstruction, such as:

Biliary atresia, choledochal cysts

• Neonatal hepatitis, such as:

Congenital infection

• Inborn errors of metabolism, such as:

Alfa-1 antitrypsin deficiency

Tyrosinemia, galactosemia

• Cholestasis, such as:

Intrahepatic biliary hypoplasia

Alagille syndrome

Inspissated bile plug syndrome

Choledocholithiasis

Cystic fibrosis

Total parenteral nutrition (TPN)

Biliary atresia

This occurs in 1 in 10–14 000 live births. It is a progressive disease in which there is destruction of the extrahepatic biliary tree and intrahepatic bile ducts.

Current thinking is that it is an acquired inflammatory disease of the bile ducts with resulting damage to segments of the biliary tree, giving abnormal intrahepatic ducts and an interruption of the extrahepatic bile duct. There are many types and they vary according to the extent of the sclerotic and fibrotic process in the biliary tree. All or part of the extrahepatic biliary tree may become atretic and absent. The gallbladder may be preserved, isolated or associated with a choledochocele or patent common bile duct. A choledochocele is an isolated segment of bile duct which fills with fluid. Those who have a patent extrahepatic bile duct and gallbladder have a better prognosis.

These babies have a normal birth weight but rapidly fail to thrive. They have cholestatic jaundice, with pale stools and dark urine. Hepatomegaly is present, and splenomegaly will develop secondary to portal hypertension.

Ultrasound findings

Ultrasound examinations must be carefully performed with the highest resolution transducers available. Generally the findings in neonatal jaundice are non-specific, but there are a few features that need to be specifically commented on.

• Common bile duct. It is important to try to identify the common bile duct, which will be non-dilated in neonatal hepatitis and biliary atresia. In infants the normal common bile duct may be difficult to detect, and Doppler should always be used to confirm the position of the hepatic artery. The major differential is a choledochal cyst, so identification of a dilated common bile duct is crucial.

• Gallbladder. The infant must be adequately fasted. In biliary atresia the gallbladder is not always absent as previously thought but may be small and abnormal. Failure to find the gallbladder after an adequate fast is highly suggestive of biliary atresia.

• Intrahepatic bile ducts. These are not dilated in neonatal hepatitis or biliary atresia. They may be dilated in a choledochal cyst and in cholelithiasis or where sludge fills the biliary tree. Bile plug syndrome is a condition where pigment stones fill the biliary tree; some of the causes are total parenteral nutrition (TPN), furosemide treatment, dehydration, infection and prematurity. Sludge may be seen in the gallbladder.

• Portal cyst. A separate cyst may be seen in the porta hepatis in approximately 10% of patients. This is a remnant of the extrahepatic bile duct. It must not be confused with a choledochal cyst; if any suspicion exists, further imaging should be undertaken to determine the nature of the cystic structure. ‘Cysts’ may also be intrahepatic in location.

Other abnormalities to look for include polysplenia, pre-duodenal portal vein and an interrupted inferior vena cava which does not join the inferior aspect of the right atrium. Situs inversus is also associated.

The ultimate diagnosis of biliary atresia is made by a combination of tests. Radioisotope studies show failure of excretion of the IDA compounds by the liver with no filling of the bowel on delayed images. Percutaneous liver biopsy makes the diagnosis by demonstrating portal fibrosis.

Biliary atresia leads to chronic liver failure and death within 2 years unless surgical intervention is performed. Surgery consists of bypassing the fibrotic ducts by performing a portoenterostomy (Kasai procedure) in which the jejunum is anastomosed to the patent ducts on the cut surface of the porta hepatis. If surgery is performed before the infant is 60 days old, 80% achieve bile drainage. The success decreases with age—hence the urgency for diagnosis. If this surgery is not successful then liver transplantation is the only alternative.

Possible future complications include cholangitis and a 2% risk of malignancy in the biliary tree. Follow-up after portoenterostomy is to monitor for the development of cirrhosis.

Neonatal hepatitis

In neonatal hepatitis there is hepatic inflammation. The causes are mainly congenital neonatal infections such as cytomegalovirus, toxoplasmosis, rubella and congenital syphilis but some are idiopathic in origin. In contrast to biliary atresia, these infants may have intrauterine growth retardation and hepatosplenomegaly at birth.

Intrahepatic biliary hypoplasia (Alagille syndrome)

This is an autosomal dominant condition. Infants have characteristic triangular facies, skeletal abnormalities, peripheral pulmonary stenosis, renal tubular disorders, defects in the eye and intrahepatic biliary hypoplasia with severe itching and failure to thrive. Half survive into adult life without transplantation.

Inspissated bile plug syndrome

This is a rare condition where thick, inspissated bile obstructs the biliary tree usually in the lower common bile duct. It is associated with conditions which cause the bile to become thick and viscid, such as cystic fibrosis, which also causes meconium ileus in the neonate, or total parenteral nutrition in the older infant. Excessive hemolysis is also associated. Ultrasound will demonstrate a dilated common bile duct often with sludge in the gallbladder.

Spontaneous perforation of the bile duct

This is a very rare condition presenting in the early neonatal period. Infants present with jaundice and ascites resulting from the leakage of bile around the liver from the perforated duct. The biliary tree is not dilated on ultrasound.

Role of ultrasound

The major role of ultrasound in neonatal jaundice is the following.

• Identify a cause of the obstructive jaundice that may be amenable to treatment such as dilation of the biliary tree—for example, a choledochal cyst or obstruction by inspissated bile or biliary calculi.

• Once these conditions have been excluded, the role of ultrasound is to try to differentiate biliary atresia from neonatal hepatitis. It must, however, be emphasized that there is no single biochemical test or imaging procedure that is entirely satisfactory to differentiate the two (Table 5.2).

Table 5.2 Differentiation of idiopathic neonatal hepatitis from biliary atresia

	Neonatal hepatitis	Biliary atresia
Familial incidence	20%	None
Size	Premature or small for gestational age	Normal
Stool		Usually persistently pale (acholic)
Nasogastric aspirate		No bile
Liver parenchyma	Normal or increased echogenicity	Normal or increased echogenicity
Bile ducts	Not dilated	Not dilated
Gallbladder	Normal Contracts after a feed	Contracted and abnormal 15% absent 10% normal
Associated anomalies		Polysplenia, pre-duodenal portal vein, diaphragmatic hernia, situs inversus
HIDA scan	Poor uptake, but excretion into bowel	Good uptake, with no liver excretion into bowel
Other		Intra- or extrahepatic ‘cysts’; choledochocele
Liver biopsy	Non-specific	Portal fibrosis
Diagnosis	ERCP or operative cholangiography outlines normal biliary tree	ERCP or operative cholangiography fails to outline normal biliary tree
Treatment	Treatment of the underlying cause if found	Early: hepatoportoenterostomy (surgical bypass of fibrotic ducts) Kasai procedure Late: liver transplantation

ERCP, Endoscopic retrograde cholangiopancreatography; HIDA, hepatobiliary iminodiacetic acid.

CYSTIC DILATION OF THE BILIARY SYSTEM

Congenital hepatic fibrosis

Congenital hepatic fibrosis is a condition that is most commonly associated with autosomal recessive polycystic kidney disease (ARPKD) in the infant. Older children may present to a physician with signs and symptoms of liver disease. Hepatic fibrosis is essential to the diagnosis of autosomal recessive polycystic kidney disease.

The ultrasound diagnosis of congenital hepatic fibrosis is a spectrum of appearances. The liver may appear normal, particularly in the young infant. Later, the liver may enlarge, often predominantly the left lobe. The periportal fibrosis appears as an increase in the echogenicity around the portal veins although the changes can often be very subtle and difficult to appreciate. The most diagnostic appearances are those of cystic dilations in the liver parenchyma, which are saccular dilations of the biliary tree. It is essential to carefully examine the liver in all infants suspected of having ARPKD.

Congenital hepatic fibrosis may also be associated with Jeune syndrome, Meckel syndrome, chondrodysplasia syndromes and Zellweger syndrome (see Ch. 3, section on cystic kidneys).

Caroli disease

In the 1950s Caroli et al described a disease characterized by non-obstructive dilation of the intrahepatic bile ducts. These cystic dilations of the bile ducts were prone to developing biliary calculi, and the patients were at risk of developing cholangitis. The disorder may be associated with congenital hepatic fibrosis and medullary cystic disease of the kidneys and a choledochal cyst (Fig. 5.9). Any infant or child with large echogenic kidneys and suspected of having ARPKD should have a careful evaluation of the liver. Polycystic disease of the liver is seen in autosomal dominant polycystic kidney disease and differs in that the cysts do not communicate with the bile ducts. It rarely occurs in children.

Figure 5.9 Caroli disease. (A) This boy presented with a longstanding history of liver disease. He was diagnosed as an infant with congenital hepatic fibrosis and Caroli disease. CT examination shows multiple cystic areas related to the bile ducts. (B) Ultrasound examination of the right lobe of the liver 5 years later shows the multiple cystic areas within the liver, which have enlarged. These were cystic dilations of the biliary tree and not hepatic cysts. (C) He had recently had a hematemesis, and longitudinal ultrasound examination of the liver revealed a dilated tortuous vessel around the porta hepatis. (D) Doppler examination in the same projection revealed that this vessel was venous and was feeding the gastric vessels. (E) Transverse examination of the liver at the level of the pancreas revealed the multiple abnormal vessels within the porta hepatis and on the undersurface of the liver leading to the gastric fundus (arrow). In addition he had a grossly abnormal hepatic echo texture consistent with his congenital hepatic fibrosis.

Choledochal cysts

These are cystic dilations of the extrahepatic biliary system.⁸^–¹² About 25% present in the neonatal period with cholestasis (Fig. 5.10). Some are detected by prenatal scanning. Choledochal cysts appear most commonly as cystic or fusiform dilation of the common bile duct. They are thought to be related to an anomalous connection between the common bile duct and pancreatic duct which results in chronic reflux of pancreatic juices and dilation of the common bile duct. Ultrasound is the initial imaging modality of choice and will generally give an excellent demonstration of the dilation of the intra- and extrahepatic biliary tree. ERCP (endoscopic retrograde cholangiopancreatography) will further delineate the anatomy of the biliary tree (Fig. 5.11). Intraoperative (i.e. during surgery) cholangiography is also sometimes performed.