The 2001 World Health Organization (WHO) classification of hepatic hydatid cysts is used to assess the stage of hepatic hydatid cyst on ultrasound and is useful for deciding on its appropriate management, depending on the stage of the cyst. This classification was proposed by the WHO in 2001 and...
The 5-F rule refers to risk factors for the development of cholelithiasis in an event of upper abdominal pain:
fair: more prevalent in Caucasian population 1
fat: BMI >30
fertile: one or more children
forty: age ≥40
cholelithiasis can occur in young patients with a positive f...
The American Association for the Surgery of Trauma (AAST) injury scoring scales are the most widely accepted and used system of classifying and categorising traumatic injuries. Injury grade reflects severity, guides management, and aids in prognosis. At the time of writing (mid 2016), 32 differe...
The 1994 revision of the AAST (American Association for the Surgery of Trauma) liver injury scale is the most widely used liver injury grading system at the time of writing (late 2016).
haematoma: subcapsular, <10% surface area
laceration: capsular tear, <1 cm parenc...
Abdominal radiology curriculum for medical students is broadly split into content that refers to imaging (the test and findings) and conditions that are considered key for this stage of training.
Some non-abdominal conditions are included in this portion of the curriculum, including breast dise...
Abdominal radiology presentations are a relatively distinct group of presentations that precipitate assessment medical and surgical teams.
The abdomen, when looking from in front, is divided into nine regions by imaginary planes (two vertical and two horizontal) forming abdominal surface anatomy. The nine regions are of clinical importance when examining and describing pathologies related to the abdomen. The horizontal planes are o...
Abernethy malformations are rare vascular anomalies of the splanchnic venous system. They consist of congenital portosystemic shunts and result from persistence of the embryonic vessels.
Type I malformations are thought to occur only in females, while type II have a male predomin...
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core comprised of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessels...
Accessory gallbladders are a rare anatomical variant occurring in 0.03% of cases (approximately 1 in 3000 people). They can arise from either the left or right hepatic ducts or both. Accessory gallbladders arise from a bifid diverticulum of the hepatic duct in the 5th or 6th week of development ...
An accessory right inferior hepatic vein is the most common variation of the hepatic veins. It is present in up to 48% of the population and drains the posterior part of the right lobe (mainly segments 6 and 7) directly into the inferior vena cava.
Variations in hepatic vascular anatomy are pa...
Acquired hepatocerebral degeneration is an uncommon irreversible extrapyramidal neurodegenerative condition encountered in patients with cirrhotic chronic liver disease, resulting in widespread cerebral, basal ganglia and cerebellar damage.
Acquired hepatocerebral degeneration is ...
Acute acalculous cholecystitis refers to the development of cholecystitis in a gallbladder either without gallstones or with gallstones where they are not the contributory factor. It is thought to occur most often due to biliary stasis and/or gallbladder ischaemia.
Acute cholangitis, or ascending cholangitis, is a form of cholangitis and refers to the acute bacterial infection of the biliary tree. It is a condition with high mortality that necessitates emergent biliary decompression.
The classical presentation is the Charcot triad ...
Acute cholecystitis refers to the acute inflammation of the gallbladder. It is the primary complication of cholelithiasis and the most common cause of acute pain in the right upper quadrant (RUQ).
Constant right upper quadrant pain that can radiate to the right shoulder. ...
Acute cholecystitis refers to the acute inflammation of the gallbladder. It is the primary complication of cholelithiasis and the most common cause of acute pain in the right upper quadrant (RUQ).
This is a summary article; read more in our article on acute cholecystitis.
Acute fatty liver of pregnancy (AFLP) is a rare pregnancy-associated condition that tends to manifest in the 3rd trimester of pregnancy or early postpartum period.
The estimated incidence is at around 1:7000-20,000 births.
Patients may present with nausea,...
Acute hepatitis occurs when the liver suffers an injury with a resulting inflammatory reaction. The cause of the injury can occur in multiple different ways, and imaging findings are often non-specific. Ultrasound and MRI may be useful imaging modalities to suggest the diagnosis, but often the d...
Acute liver failure (ALF), or fulminant hepatic failure (FHF), refers to sudden severe liver dysfunction from injury without underlying chronic liver disease (CLD), although sometimes ALF presents as decompensation of an unknown CLD.
ALF is rare, with < 1 case per 100,000 in the ...
Acute necrotic collections (ANCs) are an early, local complication of necrotising pancreatitis.
The following are the latest terms according to the updated Atlanta classification to describe fluid collections associated with acute pancreatitis 1,2:
fluid collections in interstitia...
Acute pancreatitis is an acute inflammation of the pancreas and is a potentially life-threatening condition.
The diagnosis of acute pancreatitis is made by fulfilling two of the following three criteria 8:
acute onset of persistent, severe epigastric pain (i.e. pain consistent with acute pancr...
Acute pancreatitis refers to acute inflammation of the pancreas and is a potentially life-threatening condition.
This is a summary article; read more in our article on acute pancreatitis.
epidemiology is dependent on the cause of pancreatitis
Acute peripancreatic fluid collections (APFC) are an early complication of acute pancreatitis that usually develop in the first four weeks. After four weeks, the term pseudocysts is used. The absence of necrosis differentiates APFCs from acute necrotic collections (ANC), that is, APFCs occur in ...
Human alpha fetoprotein (AFP) elevation may occur in a vast number of conditions:
liver tumours (hepatocellular carcinoma, hepatoblastoma)
<10 ng/ml is within normal limits
>20 ng/ml is above normal limits but has low specificity for tumor since it may occur in a setting of diffuse liver inju...
Agenesis of the left hepatic lobe is a rare variation in liver anatomy. It is clinically asymptomatic and discovered during imaging or surgery.
absence of the left hepatic lobe (left of the falciform ligament, Couinaud segments II and III)
absence of left hepatic artery,...
Agenesis of the right hepatic lobe is a rare variation in liver anatomy.
absence of the right hepatic lobe
absence of right hepatic artery, right portal vein, and right hepatic biliary system
compensatory hypertrophy of the left hepatic lobe and caudate lobe
AIDS cholangiopathy refers to an acalculous, secondary opportunistic cholangitis that occurs in AIDS patients as a result of immunosuppression.
Characterised by multiple irregular strictures essentially indistinguishable from primary sclerosing cholangitis (PSC). There are four path...
Alpha-1 antitrypsin (A1AT) deficiency is a hereditary metabolic disorder and is the most common genetic cause of emphysema and metabolic liver disease in children. It results in the unopposed action of neutrophil elastase and subsequent severe basal pan lobular emphysema and respiratory symptoms...
Amiodarone hepatotoxicity is one of the complications that can occur with amiodarone therapy.
In the majority of patients, it is discovered incidentally during routine testing of liver biochemistry and rarely do the hepatic effects develop into symptomatic liver injury o...
Amoebic hepatic abscesses are a form of hepatic abscess resulting from Entamoeba histolytica infection.
Patients may experience general malaise or present with frank sepsis and right upper quadrant pain. Although the causative pathogen is found worldwide, it is endemic to...
The ampulla of Vater is a conical structure at the confluence of the common bile duct (CBD) and the main pancreatic duct that protrudes at the major duodenal papilla into the medial aspect of the descending duodenum. The entire structure is encased by smooth muscle fibers that compose the sphinc...
The term ampullary tumour generally refers to either benign or malignant neoplasms that arise from the glandular epithelium of the ampulla of Vater, including 1:
ampullary adenoma (adenoma of ampulla of Vater)
ampullary carcinoma (carcinoma of ampulla of Vater)
According to some authors, ampu...
The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge.
Head and neck anatomy
Abdominal and pelvic anatomy
Lower limb anatomy
Upper limb anato...
Aneurysms of the portal vein are extremely rare and represent only 3% of all aneurysms of the venous system 1.
Most patients are asymptomatic but may present with nonspecific abdominal pain as a major symptom 2-4.
Both congenital and acquired causes have been ...
An anomalous pancreaticobiliary junction describes the abnormal junction of the pancreatic duct and common bile duct that occurs outside the duodenal wall to form a long common channel (> 15 mm).
The anomalous junction is often associated with a choledochal cyst or a biliary tract carcinoma and...
The ansa pancreatica is a rare type of anatomical variation of the pancreatic duct. It is a communication between the main pancreatic duct (of Wirsung) and the accessory pancreatic duct (of Santorini). Recently, the ansa pancreatica has been considered as a predisposing factor in patients with i...
Ascites is defined as an abnormal amount of intraperitoneal fluid.
Patients with large volume of ascites can present with abdominal distension (which may be painful), nausea, vomiting, dyspnoea and peripheral oedema 7, 9.
Ascitic fluid is traditionally charact...
The atoll sign in radiology can refer to:
reverse halo sign (atoll in thoracic CT)
atoll sign in liver MRI: suggestive of an inflammatory hepatic adenoma
The atoll sign in hepatic imaging has been described when a liver lesion shows a peripheral rim of high T2 signal intensity with the center of the lesion appearing isointense to the background of non-cirrhotic liver on T2WI mimicking an atoll. It is considered a characteristic sign of an inflamm...
Autoimmune hepatitis is a rare type of chronic hepatitis, currently classified as "type 1" or "type 2". It may eventually lead to cirrhosis. The role of imaging is primarily to exclude other diagnoses and evaluate for complications.
It may occur in children or adults, but most pat...
There are several sets of diagnostic criteria for autoimmune pancreatitis (AIP), with some overlap and contradictions.
At the time of writing (July 2016), these are the most widely used sets of diagnostic criteria.
Asian 2008 AIP diagnostic criteria
both criteria I to be fulfilled
Autosplenectomy denotes spontaneous infarction of the spleen with resulting hyposplenism.
Autosplenectomy is most frequently encountered in patients with homozygous sickle cell disease, although it has also been reported in pneumococcal septicaemia 1, and SLE 2. The demographics t...
Bacillary angiomatosis is an infective complication in those with the acquired immunodeficiency syndrome (AIDS) 3. Amongst other widespread multi-organ manifestations, the infection causes skin lesions which can be similar to those of Kaposi sarcoma.
Characterised by a non-neoplastic...
The Balthazar score is a subscore within the CT severity index (CTSI) for grading of acute pancreatitis.
The CTSI sums two scores:
Balthazar score: grading of pancreatitis (A-E)
grading the extent of pancreatic necrosis
The Balthazar score was originally used alone, but the addition of a sc...
Beaver tail liver, also known as a sliver of liver, is a variant of hepatic morphology where an elongated left liver lobe extends laterally to contact and often surround the spleen. It is more common in females. The parenchyma is normal and thereby has the same risks of hepatic pathology as the ...
Paediatric benign liver tumours are a relatively rare, but important group of conditions. Importantly, the commonest cause of a benign liver tumour is specific to the paediatric population. The list in descending order of frequency is:
mesenchymal hamartoma of t...
The gallbladder and extrahepatic bile ducts play host to a surprisingly large number of benign tumours and tumour-like lesions which may be visible on imaging. In the gallbladder, most of them are detected incidentally, whereas in the bile ducts they are usually found in symptomatic patients (ob...
In most instances predicting histology of a gallbladder polyp based purely on imaging is not possible. A number of features are however helpful in helping to decide management of a polypoid lesion of the gallbladder.
polyps that are less than 5 mm in size are almost alway...
Beta catenin mutated hepatic adenomas are a genetic and pathologic subtype of hepatic adenoma. Their appearance and prognosis are different than other subtypes.
They are the least common subtype of hepatic adenoma (10-15%). They occur more frequently in men and are associated with...
Bile duct dilatation can be due to several aetiologies.
Variable, depending on underlying cause, but usually:
right upper quadrant pain
Harmonic imaging is useful when assessing the biliary system, as it improves the clarity ...
Bile duct strictures are problematic in terms of management and distinction between benign and malignant.
There are numerous causes of biliary duct strictures, including 1,2 :
involvement by pancreatic head adenocarcinoma
involvement by am...
Bile duct wall thickening can occur from a number of etiologies.
bile duct wall thickening
bile duct walls are typically not visible when normal
possible narrowing of the ducts with obstruction
possible secondary signs of cholangitis, including debris in th...
The bile sump syndrome refers to a complication occurring in ~1% of patients following a side-to-side choledochoduodenostomy, a procedure where communication is formed between the mid common bile duct and duodenum to prevent recurrent choledocholithiasis or biliary obstruction. The syndrome occ...
Ascariasis is the commonest helminthic infection world wide and estimated to affect nearly 1 billion people (25% of population). The disease is transmitted by Ascaris lumbricoides which belongs to the nematode family (roundworms).
Infection occurs by ingestion of contaminated food (...
Biliary atresia (BA) is a congenital biliary disorder, which is characterised by an absence or severe deficiency of the extrahepatic biliary tree. It is one of the most common causes of neonatal cholestasis, often causing cirrhosis immediately and leading to death and accounts for over half of c...
Biliary cystadenocarcinomas are rare cystic hepatic neoplasms. They can be thought of as a malignant counterpart of biliary cystadenomas.
There is recognised increased female predilection. Its incidence peak is around 60 years of age.
The clinical symptoms ...
Biliary cystadenomas are uncommon benign cystic neoplasms of the liver.
Biliary cystadenomas occur predominantly in middle-aged patients and are more common in women 1.
The clinical presentation of biliary cystadenomas is variable, depending on the size and...
Biliary papillomatosis (BP) is rare type of papillomatosis that involves the biliary ducts.
It is often observed in middle-aged and elderly patients and is more common in men (male-to-female ratio 2:1).
Biliary papillomatosis is usually at an advanced stage...
Various channels that collect bile from the hepatic parenchyma and transport it to the duodenum constitute the biliary tree.
By convention the biliary tree is divided into intra- and extra-hepatic bile ducts 1. There is significant variation in the biliary tree with the classical...
Bilomas refer to extrabiliary collections of bile. They can be either intra- or extrahepatic.
There is a slight discrepency in the reported literature in the use of the term "biloma". Many authors have used it exclusively to refer to intrahepatic bile collections or other bilious ...
The Bismuth-Corlette classification is a classification system for perihilar cholangiocarcinomas, which is based on the extent of ductal infiltration.
limited to the common hepatic duct, below the level of the confluence of the right and left hepatic ducts
The bright dot sign refers to the presence of a bright dot within a lesion which remains hyperattenuating on arterial and portal venous phase CT, corresponding to early nodular enhancement seen on dynamic MRI of liver haemangioma.
This can be used as an indicator that the lesion in question is...
Budd-Chiari syndrome refers to the clinical picture that occurs when there is partial or complete hepatic venous outflow obstruction.
Budd-Chiari syndrome is rare. A Japanese study estimated the prevalence to be in the region of 2.4 cases/million 4. In Western populations, the mo...
Major duodenal papilla is a conic or cylindric protuberance at the medial aspect of the descending or horizontal duodenum at the site of the sphincter of Oddi. It is finding on small bowel follow-though (and endoscopy) and has a relatively long differential.
On cross sectional imaging, the unde...
Bunch-of-grapes sign refers to the ultrasound appearance of multiple cystic spaces or lesions and it has been described in a number of settings:
within the uterus as a result of hydropic swelling of trophoblastic villi within a hydatidiform mole
in bronchiectasis, where on plain radiograph, th...
CA 19-9 is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepato-pancreatico-biliary origin. It is nonspecific, however, and can rise in both malignant and nonmalignant conditions.
Elevation of serum CA 19-9 has been...
Serum CA-125 is well recognised as an ovarian cancer-associated marker and is an antigen determinant on a high-molecular-weight glycoprotein. The normal range of CA-125 is 0-35 U/mL.
Serum CA-125 levels can also be used to monitor the response to treatment as well as a prognostic indicator as t...
Calot triangle is a small (potential) triangular space at the porta hepatis of surgical importance as it is dissected during cholecystectomy. Its contents, the cystic artery and cystic duct must be identified before ligation and division to avoid damaging them during the operation.
The caput medusae sign, refers to developmental venous anomalies of the brain, where a number of veins drain centrally towards a single drain vein. The appearance is reminiscent of Medusa, a gorgon of Greek mythology, who was encountered and defeated by Perseus.
The sign is seen on both CT and ...
The caput medusae sign is seen in patients with severe portal hypertension. It describes the appearance of distended and engorged paraumbilical veins, which are seen radiating from the umbilicus across the abdomen to join the systemic veins.
History and etymology
The appearance is reminiscent...
Serum carcinoembryonic antigen (CEA) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumour markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue.
Normal range of CEA is...
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionising radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
Cardiac sclerosis, or "cardiac cirrhosis" is the end-point of passive hepatic congestion from heart failure.
Causes of cardiac cirrhosis include 1:
ischaemic heart disease: ~30%
valvular heart disease: ~25%
restrictive lung disease: ~15%
Caroli disease is a congenital disorder comprising of multifocal cystic dilatation of segmental intrahepatic bile ducts. However, some series show that extrahepatic duct involvement may exist 2. It is also classified as a type V choledochal cyst, according to the Todani classification.
Caudate-right lobe ratio (C/RL) is used in the assessment of livers, usually in the setting of cirrhosis, in which there is atrophy of the right lobe with hypertrophy of the caudate lobe.
Method for measuring
image: axial slice immediately below the bifurcation of the main portal vein
Cavernous transformation of the portal vein (CTPV) is a sequela of portal vein thrombosis and is the replacement of the normal single channel portal vein with numerous tortuous venous channels.
For a discussion of demographics and presentation, please refer to the article on portal vein thrombo...
Chemotherapy induced cholangitis is caused when intra-arterial chemotherapy is introduced to treat liver metastases. This causes strictures of the common hepatic duct and main ducts, but spares distal and proximal (i.e. common bile duct and intrahepatic ducts).
The Child-Pugh score is a scoring system to measure the severity of chronic liver disease inclusive of cirrhosis. The intention is to provide a system with which clinicians can objectively communicate about liver function.
The score is composed from several categories:
total bilirubin, μmol/l ...
Cholangiocarcinoma is a malignant tumour arising from cholangiocytes in the biliary tree. It tends to have a poor prognosis and high morbidity. It is the second most common primary hepatic tumour, with intrahepatic cholangiocarcinomas (ICCs) accounting for 10-20% of primary liver tumours.
Cholangiocarcinoma staging is dependant on whether the tumour is primarily intrahepatic (ICC), hilar/perihilar (Klatskin), or extrahepatic.
Tumour resection is currently the most optimal treatment and the ability of the tumour to infiltrate longitudinally and radially along the biliary tree nec...
Cholangitis is a relatively broad descriptive term term referring to inflammation of the bile ducts.
It has many forms and can arise from a number of situations:
primary sclerosing cholangitis
chemotherapy induced cholangitis
eosinophilic cholangitis 5
Cholecystectomies are one of the most common surgical procedures performed. Evidence of a cholecystectomy are often seen on imaging procedures with surgical clips in the gallbladder fossa and radiologists should be aware of possible complications.
Cholecystitis refers to any form of inflammation involving the gallbladder and has many forms including:
acute calculous cholecystitis
acute acalculous cholecystitis
Choledochal cysts represent congenital cystic dilatations of the biliary tree. Diagnosis relies on the exclusion of other conditions (e.g. tumour, gallstone, inflammation) as a cause of biliary duct dilatation.
Choledochal cysts are rare, with an incidence of 1:100,000-150,000. Al...
Choledochocoeles refer to a specific type of choledochal cyst (type III under the Todani classification system). In this type, there is dilatation of the intramural portion of the distal common bile duct within the duodenal wall. Its precise aetiology is not clear 3. Patients are usually adolesc...
Choledocholithiasis denotes the presence of gallstones within the bile ducts (common hepatic duct / common bile duct).
Choledocholithiasis is relatively common, seen in in 6-12% of patients who undergo cholecystectomy 2.
Stones within the bile duct are ofte...
Cholescintigraphy is the use of radiotracers to assess the anatomy and function of the biliary system (and the liver indirectly). Currently this is most commonly performed with Tc99m-IDA analogues, and "h"epatic "IDA" imaging gave rise to the more common term "HIDA scan."
After intravenous inje...
Chronic cholecystitis refers to prolonged inflammatory condition that affects the gallbladder. It is almost always seen in the setting of cholelithiasis (95%), caused by intermittent obstruction of the cystic duct or infundibulum or dysmotility.
Patients may have a histor...
Chronic pancreatitis represents the end result of a continuous, prolonged, inflammatory and fibrosing process that affects the pancreas. This results in irreversible morphologic changes and permanent endocrine and exocrine pancreatic dysfunction.
The most common cause of chronic p...
Ciliated hepatic foregut cyst is a very rare type of hepatic cyst, with nonspecific radiological features. Less than a hundred of cases have been reported yet 1. They are usually benign, but rare cases of malignant degeneration (in squamous cell carcinoma) have also been reported 1-4.
Cirrhosis is the common endpoint of a wide variety of chronic liver disease processes which cause hepatocellular necrosis. Cirrhosis can be diagnosed with ultrasound, CT, and MRI, and these imaging modalities can also be used to evaluate for possible complications of cirrhosis, such as portal hy...
Clonorchiasis is a trematodiasis caused by chronic infestation by Clonorchis sinensis, and can lead to recurrent pyogenic cholangitis, biliary strictures and cholangiocarcinoma.
Infection with Clonorchis sinensis occurs in endemic areas, mainly east China. Over 85 million people ...
Coarsened hepatic echotexture is a sonographic descriptor where there uniform smooth hepatic echotexture of the liver is lost. This can occur due to number of reasons which include:
conditions that cause hepatic fibrosis 1
various types of hepatitis 3