4D syndrome is a term given to syndromic glucagonomas, a type of pancreatic endocrine tumour.
D: dermatitis (necrolytic migratory erythema, often involving the groin)
D: deep vein thrombosis
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 American Association for the Surgery of Trauma (AAST) splenic injury scale is the most widely used grading system for splenic trauma at the time of writing (late 2016).
subcapsular haematoma <10% of surface area
capsular laceration <1 cm depth...
AP supine radiograph can be performed as a standalone projection or as part of an acute abdominal series, depending on the clinical question posed, local protocol and the availability of other imaging modalities.
the patient is supine, lying on their back, either on the X-ray ...
The lateral decubitus abdominal radiograph is used to identify free intraperitoneal gas (pneumoperitoneum). It can be performed when the patient is unable to be transferred to, or other imaging modalities (e.g. CT) are not available. The most useful position for detecting free intraperitoneal ai...
The PA erect abdominal radiograph is often obtained in conjunction with the AP supine abdominal view in the acute abdominal series of radiographs. When used together it is a valuable projection in assessing air fluid levels, and free air in the abdominal cavity.
The erect abdominal radiograph h...
Abdominal adhesions are bands of scar tissue (ﬁbrous or ﬁbrous fatty), most often occurring as a complication of previous abdominal surgery.
Adhesions often occur with
multiple abdominal operations or previous postoperative intra-abdominal complications
history of intra-abdominal i...
The abdominal cavity is divided into two major compartments, the peritoneum and retroperitoneum, early in fetal development.
The parietal peritoneum is reflected over the peritoneal organs to form a series of supporting peritoneal ligaments, mesenteries and omenta. The peritoneal reflections ca...
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
The lateral view abdominal radiograph is a useful problem-solving view that can complement frontal views of the abdomen, often utilised in the context of forging dies or to better visualise lines such as a shunt. It is different than the lateral decubitus view of the abdomen and looks more like ...
An opacity projecting over the abdomen has a broad differential. Possibilities to consider include:
ingested, e.g. coins, batteries, bones, etc
artifacts, e.g. object attached to the cloth of the patient like a safety pin or button
iatrogenic, e.g. haemostatic clips, gastric b...
This mnemonic helps to remember the relative echogenicity of abdominal organs on ultrasound:
Darling Parents So Love Kids
From most to least echogenic:
K: kidneys (cortex)
Abdominal paracentesis, more commonly referred to as an ascitic tap, is a procedure that can be performed to collect peritoneal fluid for analysis or as a therapeutic intervention.
diagnostic: especially for newly diagnosed ascites
determine aetiology of ascites
assess for bacter...
AP supine radiograph for neonates is a mobile examination performed on the neonatal unit. It can be taken as a standalone projection or as part of a series including a left lateral decubitus x-ray in cases of suspected perforation.
the patient is supine, lying on their back i...
Abdominal radiography can be useful in many settings. Before the advent of computed tomography (CT) imaging, it was a primary means of investigating gastrointestinal pathology and often allowed indirect evaluation of other abdominal viscera.
Although abdominal radiography has lower...
Abdominal radiology conditions are a broad group of heterogeneous conditions that are split into:
true pathology (e.g. colonic carcinoma)
the underlying process (e.g. large bowel obstruction)
It is important to have an overview of these conditions and understand what imaging is useful in thei...
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...
Imaging in general surgery is vital to ensure timely and accurate diagnosis for patients.
You need to know the gamut of tests that are available when to use the correct test, some important findings that commonly occur and (for some investigations) how to approach looking at the images that ar...
Abdominal radiology interpretation is a key component of how to make the most of diagnostic imaging. You need to know how to look at the commonly performed radiology tests and how to make common diagnoses.
Abdominal radiology key findings are a group of imaging findings that are really important in imaging of the abdomen. They point to disease processes and help to narrow the differential diagnosis. It is important to know these and recognise them on imaging.
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...
Abdominal trauma is usually divided into blunt and penetrating trauma.
Findings of abdominal trauma
splenic trauma: most common
gastrointestinal tract (bowel) trauma:
proximal jejunum is most commonly affected by blunt trauma,...
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review:
A: air - where it should and shouldn't be
B: bowel - position, size and wall thickness
D: dense st...
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where A refers to the assessment of the presence and location of air.
This is a s...
Abdominal radiographs can be challenging examinations to look at. It is always best to approach radiographs in a systematic way.
Bowel gas pattern
Gas within the bowel forms a natural contrast with surrounding tissues since it has a very low density. Bowel can only be seen if it contains air/g...
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where X refers to the assessment of external objects and artifacts.
This is a sum...
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where B refers to the assessment of the bowel loops.
This is a summary article; w...
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where D refers to the assessment of dense structures such as the bones and areas of calcification.
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where O refers to the assessment of the intra-abdominal organs and soft tissues.
Abdominal radiographs can be a useful examination, but you need to think about the question you are asking before getting the test. Before the advent of computerised tomography (CT) imaging, it was a primary means of investigating gastrointestinal pathology (and often allowed indirect evaluation...
Abnormal bowel wall attenuation patterns on CT scan can be grouped under five categories:
water halo sign
fat halo sign
The first three patterns are seen on contrast studies.
It is defined as uniform enhancement of th...
A mnemonic used for abnormal collection of barium anywhere in the body :
Abnormal intra-abdominal gas is an important radiologic finding with many potential causes. It may be seen on a chest radiograph, abdominal radiograph, CT or MRI.
abnormally located bowel, e.g. Chilaiditi syndrome (bowel interpose...
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
The accessory appendicular artery (or artery of Seshachalam) is a branch of the posterior caecal artery, which in turn arises from the ileocolic artery, and runs in the mesoappendix.
The exact prevalence of this accessory artery and its impact upon the risk of appendicitis varies among studies....
The accordion sign is seen on CT examinations of the abdomen and refers to the similarity between the thickened oedematous wall of pseudomembranous colitis and the folds of an accordion. This appearance is the result of oral contrast being trapped between oedematous haustral folds and pseudomemb...
Achalasia (primary achalasia) refers to a failure of organised oesophageal peristalsis with an impaired relaxation of the lower oesophageal sphincter (LOS), resulting in often marked dilatation of the oesophagus and food stasis. Obstruction of the distal oesophagus (often due to tumour) has been...
The acute abdominal series is a common set of abdominal radiographs obtained to evaluate bowel gas.
The acute series is used for a variety of indications including:
determine the amount of bowel gas, with possible bowel distention
assess air-fluid levels
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 gastritis is a broad term that encompasses a myriad of causes of gastric mucosal inflammation.
Depends on the aetiology (see below).
nausea and vomiting
loss of appetite
infection: H. ...
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 pa...
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 ...
Acute superior mesenteric artery occlusion, which can then result in an acute mesenteric ischaemia, can be a life-threatening event related to the artery supplying the majority of the small bowel and right side of the colon.
An acute occlusion is an uncommon event that typically...
Acute superior mesenteric vein thrombosis is one of the less common causes of intestinal ischaemia.
For a general discussion refer to intestinal ischaemia.
Compared to acute superior mesenteric artery occlusion or ischaemia secondary to small bowel obstruction, acute superior me...
Adenocarcinoma of the appendix, also referred to as nonmucinous adenocarcinoma of the appendix, is an uncommon type of appendiceal epithelial neoplasm. Different from the appendiceal mucinous neoplasms, these tumours share similar epidemiology and pathology with colorectal adenocarcinoma.
Duodenal adenocarcinoma is the most common primary malignancy of the duodenum.
Adenocarcinoma is the most common primary malignant neoplasm of the duodenum. It represents 0.3% of all gastrointestinal malignancies and accounts for 50-70% of small bowel adenocarcinomas occurring ei...
Primary adenocarcinoma of the small bowel is about 50 times less common than colonic carcinoma.
Almost 50% of small bowel adenocarcinomas are found in the duodenum, especially near the ampulla. In the remaining cases, the jejunum is more commonly involved than the ileum1.
Adenomyomatosis of the gallbladder is a hyperplastic cholecystosis of the gallbladder wall. It is a relatively common and benign cause of diffuse or focal gallbladder wall thickening. It is most easily seen on ultrasound and MRI.
Adenomyomatosis is relatively common, found in ~9%...
Adrenal metastases are the most common malignant lesions involving the adrenal gland. Metastases are usually bilateral but may also be unilateral. Unilateral involvement is more prevalent on the left side (ratio of 1.5:1).
They are present at autopsy in up to 27% of patients with ...
Adrenal washout can be calculated using the density value of an adrenal mass on non-enhanced, portal venous phase and 15 minutes delayed CT-scans (density measured in Hounsfield units (HU)). It is primarily used to diagnose adrenal adenoma.
[(HUportal venous phase) - (HUdelaye...
Adynamic ileus is the failure of passage of enteric contents through the small bowel and colon that are not mechanically obstructed. Essentially it represents the paralysis of intestinal motility.
Patients may be asymptomatic or present with symptoms similar to a mechanic...
Afferent loop syndrome is an intermittent partial or complete mechanical obstruction of the afferent limb of a gastrojejunostomy.
The syndrome classically refers to obstruction of the upstream limb of a side-to-side gastrojejunostomy, but has also been used to refer to the biliopancreatic limb ...
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...
AIDS defining illnesses are conditions that in the setting of a HIV infection confirm the diagnosis of AIDS, and do not commonly occur in immunocompetent individuals 2. According to the CDC surveillance case definition 1, they are:
bacterial infections: multiple or recurrent
Allgrove syndrome (also known as triple A syndrome) is an autosomal recessive condition that consists of three main findings:
The Alvarado score is a clinical decision rule and predictor of the likelihood of acute appendicitis:
right lower quadrant tenderness (+2)
elevated temperature (37.3°C or 99.1°F) (+1)
rebound tenderness (+1)
migration of pain to the right lower quadrant (+1)
nausea or vomitin...
Amoebic colitis is a type of infectious colitis, more common in tropical and subtropical areas. The causative agent is the trophozoite form of the protozoan Entamoeba histolytica. In most cases of transmission, the cyst form lives in the colon as commensal and remains asymptomatic.
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 Amsterdam criteria are used in the diagnosis hereditary non polyposis colorectal cancer (HNPCC).
Amsterdam Criteria I
Initial description in 1991:
> or equal to 3 relatives with colorectal cancer (CRC)
> or equal to 1 case in a first degree relative
> or equal to 2 successive generation...
Amyand hernia is a rare form of inguinal hernia in which the vermiform appendix is located within the hernial sac. It is seen in less than 1% of inguinal hernia.
It should not be confused with an appendix-containing femoral hernia, known as De Garengeot hernia.
Anal atresia, or imperforate anus, refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.
The estimated incidence is 1 in 5000 live births.
Clinically there is no anal opening. Subtypes can be classified in...
The anal canal is the terminal part of the gastrointestinal tract. Anatomically, the anal canal is referred to as the terminal alimentary tract between the dentate line and anal verge. However, histologically it extends more proximally and includes the columns of Morgagni and anal sinuses. Surgi...
Anal canal cancer is relativity rare, however, there are several protocols that exist for assessment of various pelvic pathology. One method adopted for optimum assessment for anal cancer is (Auckland-New Zealand)
Overview: whole pelvis
T1 +/- T2FS
Fine 3 mm slices through region of concern (...
MR of the pelvis can demonstrate hidden areas of pelvic infection and secondary extensions which are important to detect prior to the sugary to minimize high rate of recurrence post intervention. Also pelvic MRI assists to delineate the anatomic relationships of the fistula to sphincters which c...
Anal cancer is a relatively uncommon malignancy. It accounts for less than 2% of large bowel malignancies and 1-6% of anorectal tumours (~1.5% of all gastrointestinal tract malignancies in the United States 14).
There may be a slight male predilection where its incidence has been...
The accepted TNM staging of anal cancer is as follows 1:
Primary tumour (T)
TX: primary tumour cannot be assessed
T0: no evidence of primary tumour
Tis: carcinoma in situ
T1: tumour 2 cm or less in greatest dimension
T2: tumour >2 cm but <5 cm in greatest dimension
T3: tumour >5 cm in gre...
Anal margin or perianal skin is arbitrarily defined as a skin tissue with a radius of 5 cm from the anal verge, consisting of keratinizing squamous epithelial tissue containing hair follicles.
anal margin neoplasms
The anal sphincter is divided into an internal and external anal sphincter. It surrounds the anal canal.
Internal anal sphincter
continuation of inner rectal muscle
thickened, circular muscle fibres, up to 5 mm thick
composed of visceral muscle
External anal sphincter
The anal verge is part of the anal region and consists of a band of squamous epithelial tissue which lacks hair follicles and extends from the inter-sphincteric groove to the perianal skin.
The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists.
Head and neck anatomy
Abdominal and pelvic anatomy
An angiosarcoma of the spleen is a rare malignant splenic neoplasm. The term is usually given to describe a primary angiosarcoma of the spleen although angiosarcoma elsewhere can also rarely metastasise to the spleen. Despite its absolute rarity, a splenic angiosarcoma is considered the most co...
Annular pancreas is a morphological anomaly which can cause duodenal obstruction. This condition is important to recognise, as radiologists are frequently the first to make the diagnosis.
The incidence is probably 1 in 250, however incidence is not accurately reported 1. It is as ...
Anorectal disease is a group of conditions that affect the anus and rectum. The most common conditions in this group include haemorrhoids, anal fissures, anorectal abscess and anal fistula.
This is a summary article; we do not have a more in-depth reference article.
The anterior pararenal space is the portion of the retroperitoneum that lies between the posterior surface of the parietal peritoneum and the anterior reflection of the perirenal fascia.
It contains the duodenum, pancreas and retroperitoneal segments of the ascending and descendi...
Antibiotic-associated diarrhoea can be broadly divided into two groups:
Clostridium difficile colitis
The former is a life-threatening condition, requiring prompt diagnosis and treatment whereas the later is milder and self-limiting.
Both result from changes in the bo...
The antral nipple sign refers to redundant pyloric mucosa protruding into the gastric antrum and is seen in pyloric stenosis.
cervix sign of pyloric stenosis
target sign of pyloric stenosis
shoulder sign of pyloric stenosis
The antral pad sign is a feature seen on a spot radiograph of the upper gastrointestinal tract obtained with orally-administered contrast material. It refers to the extrinsic impression or indentation on the posteroinferior aspect of the antrum. The impression is generally arcuate and smooth, an...
The aortic hiatus is one the three major apertures through the diaphragm and lies at the level of T12. Strictly speaking, it is not a real aperture in the diaphragm, but an osseoaponeurotic opening between it and the vertebral column.
The hiatus is situated slightly to the left of the midline ...
Aortoenteric fistula is an uncommon catastrophic cause of gastrointestinal haemorrhage. Aortic fistulas can be primary (associated with complicated abdominal aortic aneurysm) or secondary (associated with graft repair).
The annual incidence of primary aortoenteric fistulas is thou...
Aphthoid ulcers are shallow ulcers of the gastrointestinal mucosa.
infective inflammatory conditions
noninfective inflammatory conditions
idiopathic granulomatous gastritis
Appendiceal carcinoids are rare overall but represent the most common tumour of the appendix. The appendix is also one of the most common (but not the most common) locations for gastrointestinal carcinoid tumours.
Appendiceal carcinoids can present as the obstructive cau...
Appendiceal intussusception happens when appendix segment is pulled into itself or into the cecum. This condition can mimic various chronic and acute abdominal conditions. It is an important entity to recognise since it could be mistaken for a caecal mass.
Appendiceal mucocoeles occur when there is an abnormal accumulation of mucin causing abnormal distention of the appendix. They are due to either a non-neoplastic process, such as luminal obstruction, or mucin-secreting epithelial tumours.
The reported prevalence at appendectomy is...
Appendicitis occurs when there is inflammation of the vermiform appendix. It is a very common condition and is a major cause of abdominal surgery in young patients. CT is the most sensitive modality to detect appendicitis although its use should be limited because of the radiation dose required ...
An appendicolith is a calcified deposit within the appendix. They are present in a large number of children with acute appendicitis and may be an incidental finding on an abdominal radiograph or CT. Incidence may be increased among patients with a retrocaecal appendix. Overall they are seen in 1...
Appendicular abscess is considered the most common complication of acute appendicitis, in particular after a perforated appendix.
Appendicular abscesses can arise either in the peritoneal cavity or the retroperitoneal space.
Ultrasound is the first investiga...
The appendicular artery is a branch of the ileal or posterior caecal branch of the ileocolic artery, which is from the superior mesenteric artery.
It courses posteriorly to the terminal ileum in the free wall of the mesoappendix to supply the appendix.
The appendix or vermiform appendix is a blind muscular tube that arises from the caecum, which is the first part of the large bowel.
The appendix arises from the posteromedial surface of the caecum, approximately 2-3 cm inferiorly to the ileocaecal valve, where the taeniae coli c...
The Appleby procedure is a type of pancreatic cancer resection.
For some patients with pancreatic cancer involving the body and tail of the pancreas, involvement of the coeliac axis is a classic contraindication to pancreaticoduodenectomy (Whipple procedure).
With the Appleby procedure, ther...