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...
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,...
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...
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...
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. ...
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
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...
Aphthoid ulcers are shallow ulcers of the gastrointestinal mucosa.
infective inflammatory conditions
noninfective inflammatory conditions
idiopathic granulomatous gastritis
Areae gastricae are a normal finding on double contrast images of the stomach.
fine reticular network of barium-coated grooves between 1-5 mm islands/areas of gastric mucosa
may be seen in ~70-80% of patients if there is adequate high-density barium coating of the stomac...
Asbestos related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibres. They can be divided into benign and malignant changes 1-3.
Benign pleural and parenchymal lung disease
asbestos related benign pleural d...
Barium peritonitis is a rare complication of gastrointestinal fluoroscopy, and occurs when there is gastrointestinal tract perforation and spillage of barium into the peritoneal cavity.
Barium in the peritoneal cavity is treated as a foreign body with resultant immune response that ...
Benign oesophageal lesions are less symptomatic than malignant oesophageal lesions, making up for only 1% of clinically apparent oesophageal lesions.
oesophageal leiomyoma (>50%)
oesophageal fibrovascular polyp (~12.5%)
may contain fat
oesophageal duplication cyst (10...
Body packing refers to the internal concealment of drugs within the gastrointestinal tract or other orifices. People who do this may be called body packers, (drug) mules, stuffers, couriers or swallowers. Drugs may be concealed within condoms, foil, latex or cellophane.
There is ...
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...
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...
Cantlie's line is a vertical plane that divides the liver into left and right lobes creating the principal plane used for hepatectomy. It extends from the inferior vena cava posteriorly to the middle of the gallbladder fossa anteriorly.
It contains the middle hepatic vein which divides the live...
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...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Colonic strictures can be long (>10 cm) or short.
scirrhous colorectal carcinoma (apple core sign)
post surgical (anastamotic stricture)
scirrhous colorectal carcinoma
inflammatory bowel disease (IDB)
There are many complications that can occur following gastric banding. It is helpful to divide these into early and late post-surgical complications.
Although the exact mode of presentation can vary depending on the underlying complication common modes of presentation tha...
Complications post optical colonoscopy are most commonly assessed by CT if patients present with abdominal symptoms post colonoscopy. Complications include:
bowel perforation (most common)
lower gastrointestinal haemorrh...
Cricopharyngeal bar refers to the radiographic appearance of a prominent cricopharyngeus muscle contour on barium swallow.
The terms cricopharnygeal bar and cricopharyngeal muscle spasm/achalasia are often used synonymously but this is incorrect because studies have demonstrated th...
CT peritoneography is an examination used to assess difficulties with peritoneal dialysis.
Recurrent peritonitis with difficulty with fluid exchange abdominal wall or genital soft-tissue oedema, localized bulging of the abdomen, and poor ultrafiltration.
Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions:
squamous cell carcinoma metastases
plasmacytoid T-cell leukemia
acute myeloid leukemia
herpes simplex lymphadenit...
The differential for cystic lesions of the pancreas includes:
intraductal papillary mucinous neoplasms (IPMN)
serous cystadenoma uncommonly uni/macrolocular
pancreatic cysts occur in association with
von Hippel Lindau syndrome
autosomal dominant polycysti...
A cystic retroperitoneal lesion can carry a relatively broad differenital which includes:
retroperitoneal cystic lymphangioma
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
Diffuse colonic nodularity on barium enema or CT colonography has a range of possible etiologies:
lymphoid hyperplasia (tend to be small and discrete)
lymphoma (tend to be larger nodules and confluent)
urticaria (closely spaced polygonal lesions, history is often helpful)
Diffuse small bowel disease may be caused by a number of conditions may be generalised multisystem disorders or conditions that effect the bowel in a global fashion:
Discrete colonic ulcerations are nonspecific findings, and can be due to:
The double bubble sign is seen in infants and represents dilatation of the proximal duodenum and stomach. It is seen in both radiographs and ultrasound, and can be identified antenatally 2.
Causes include 1,2:
Dysphagia refers to subjective awareness of difficulty or obstruction during swallowing. It is a relatively common and increasingly prevalent clinical problem.
Fluoroscopy is the mainstay of imaging assessment but manometry can help evaluate the esophageal motor pattern and lower esophageal sp...
Enteritis refers to inflammation of the small bowel. When associated with inflammation of the stomach, the term gastroenteritis is used which is usually caused by infection.
inflammatory bowel disease
An epigastric hernia occurs ventrally through a defect in linea alba superior the umbilicus. It is also known as a fatty hernia of linea alba.
Shows a midline defect which is usually small with or without herniation of omenta...
Foregut duplication cysts are type congenital duplication cyst. They are sometimes classified under broncho-pulmonary foregut malformations.
Entities that fall under forgut duplication cysts include:
other enteric cysts
oesophageal duplication cysts
A specific cause of the gasless abdomen can usually be made when the patient's history is known. Common causes include:
small bowel obstruction
large abdominal mass - due to displacement
A gastric band is a surgically placed device, used to assist in weight loss. It is now the most popular form of bariatric surgery, largely replacing gastric bypass procedures 1.
Performed laparoscopically, a silicone band device is placed around the stomach to reduce its volume. The band is adj...
Gastric band erosion or penetration is a potentially serious complication following laparoscopic gastric band surgery for obesity.
Gastric band erosion is a delayed complication observed in between 0.3-14% of patients 1-2.
Patients often present non-specif...
Gastric band malposition is an early complication from laparoscopic gastric band procedures which are performed for obesity. It can occur as in isolation or with other gastric band complications.
As surgical experience of lap gastric banding has accumulated, it has become a relatively rare comp...
Gastric diverticula are sac-like projections that usually originate from the gastric fundus, most commonly on the posterior surface. They are the least common gastrointestinal diverticulum.
Gastric diverticula are rare and commonly detected incidentally. The incidence varies from...
Gastric emphysema, referring to the presence of gas in the wall of the stomach is a relatively rare imaging finding 1. The stomach is the least common location for intramural gas in the gastrointestinal tract.
There is a wide range of causes, ranging from life-threateni...
Gastric outlet obstruction is a syndrome resulting from mechanical obstruction of stomach emptying.
Gastric outlet obstruction can be due to malignant or benign causes.
adenocarcinoma (second most common 4)
lymphoma (less commonly than other malignancies...
The gastrinoma triangle is an anatomical area in the abdomen, from where the majority (90%) of gastrinomas are thought to arise.
The triangle is formed by joining the following three points:
superiorly: confluence of the cystic and common bile ducts
A giant colonic diverticulum is a rare form of presentation of colonic diverticulosis and is characterised by a large diverticular mass, usually filled with stool and gas, that communicates with the colonic lumen.
The most common presentation is abdominal pain. Other pr...
Granular mucosal pattern of the oesophagus represents very fine nodularity of the oesophageal mucosal surface. This finding is nonspecific and may represent:
reflux oesophagitis (most common)
superficial spreading oesophageal car...
Abdominal complications of haematopoietic stem cell transplantation can occur early (0-100 days) or late (>100 days) post transplant.
bacterial infections, e.g. pseudomembranous colitis
fungal infections, often affecting the oesophagus or as hepatic/splenic microabscesse...
Haemoperitoneum is the presence of blood within the peritoneal cavity.
penetrating or non-penetrating abdominal trauma (often with associated organ injury) 1
ruptured ectopic pregnancy
ovarian cyst rupture
aneurysm or pseudoaneurysm rupture
Haustral markings are the radiological appearance of the haustral folds within the colon. Disappearance of the haustral folds results in the lead pipe appearance of ulcerative colitis.
HIV-associated neoplasms are numerous and can be broadly divided into two groups:
associated but not AIDS defining malignancies
The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4:
Gastrointestinal manifestations of AIDS are protean and can be broadly divided into opportunistic infections and tumours:
herpes simplex virus (HSV)
primary infection with HIV
IgG4-related disease (IgG4-RD) is a systemic disease that is characterised by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs.
This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
Ingested bones that become lodged in the throat or gastrointestinal tract are a common presentation to the emergency department. Recognition is important because these cases can be potentially fatal.
Patients may present with a 'foreign body' feeling in the throat after eating fish ...
Ingested foreign bodies in children are common as the world is a curious place to young children, who will put anything and everything into their mouth, and will often inadvertently swallow.
The usual practice is for plain films of the chest/abdomen to identify a foreign body.
Internal hernias are protrusions of the viscera through the peritoneum or mesentery but remaining within the abdominal cavity.
Internal hernias have a low incidence of <1% and represent a relatively small amount of presentations, of ~5% 1.
The most common p...
Internal hernias due to gastric bypass surgery are more common after laparoscopic gastric bypass than after an open procedure.
It is a particularly sinister complication with variable, nonspecific clinical presentations. Most patients report a combination of postprandial...
Intestinal failure is when a patient's native bowel is unable to digest and absorb the food, electrolytes and fluids needed for normal growth and development.
This often includes intractable diarrhoea, weight loss, dehydration, electrolyte imbalance, and malnutrition.
Intestinal nonrotation is a congenital anomaly of the intestines that results in the small bowel occupying the right side of the peritoneal cavity and the colon predominantly on the left.
It is sometimes thought of as a subtype of intestinal malrotation.
Nonrotation is estimated ...
Intestinal transplantation is a surgical treatment for intestinal failure. It is one of the most rarely performed transplant procedures performed, exclusively involving the transplantation of donor small bowel to a recipient, with an ileostomy formation.
Due to the high risk of complications w...
Intra-abdominal calcification in a neonate can be caused by a number of pathologies that cause calcification within the peritoneal space or within organs.
The commonest cause is meconium peritonitis which is the result of aseptic peritonitis secondary...
Ivor Lewis procedure (also known as a gastric pull-up) is a type of oesophagectomy, an upper gastrointestinal tract operation performed for mid and distal oesophageal pathology, usually oesophageal cancer.
Due to the necessity of removing a significant length of the oesophagus, the stomach is "...
Linitis plastica is a descriptive term usually referring to the appearance of the stomach, although the rectum can also be described this way (see: linitis plastica of the rectum). The appearance is said to be reminiscent of an old leather water-bottle.
The underlying cause is usuall...
Littre hernia is a hernia containing a Meckel's diverticulum. Also known as a persistent omphalomesenteric duct hernia. It is most frequently encountered in the inguinal region.
blind ending tubular structure arising from antimesentric border of small bowel and extend...
Causes of calcifications in the lower abdomen and pelvis include:
seminal vesicle and ductus deferens calcification
dropped stones following chol...
Lower gastrointestinal bleeding usually occurs distal to the ligament of Treitz.
Presents with melaena, haematochezia or, if subclinical slow bleeding, chronic anaemia.
Lumbar hernias are a rare form of posterior abdominal hernia.
Most common in patients aged between 50 and 70 years with a male predominance 1.
Patients with lumbar hernias can present with a variety of symptoms, including a posterolateral mass, back pain,...
Malignant oesophageal neoplasms are much more common than benign oesophageal neoplasms, especially if the patient is symptomatic.
oesophageal carcinoma (90%)
oesophageal squamous cell carcinoma (SCC)
oesophageal spindle cell carcinoma
Barium meal has been frequently used to differentiate malignant and benign gastric ulcers:
Features suggesting benign gastric ulcer
outpouching of ulcer crater beyond the gastric contour (exoluminal)
smooth rounded and deep ulcer crater
smooth ulcer mound
smooth gastric folds that reach the...
Maydl hernias are defined as the presence of two small bowel loops within a single hernial sac, that is, there are two efferent and two afferent loops of bowel, forming a "W" shape.
This type of hernia is more prone to strangulation and necrosis. The intervening intra-abdominal loop is also at ...
McBurney's point is defined as a point that lies one-third of distance laterally on a line drawn from the umbilicus to the right anterior superior iliac spine. Classically, it corresponds to the location of the base of the appendix 1.
Clinically, McBurney's point is relevant for the elicitation...
Medical devices in the abdomen and pelvis are important to be recognised, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Mega oesophagus or diffuse oesophageal dilatation can be caused by a variety of conditions.
Some of the more common causes are given below 1-3:
malignant stricture, e.g. oesophageal canc...
Mucinous cystic neoplasms of the pancreas are the most common cystic neoplasm of the pancreas and include:
mucinous cystadenoma of pancreas
mucinous cystadenocarcinoma of pancreas
intraductal papillary neoplasms (IPMN) of the pancreas: sometimes classified separately
There are a number of neoplasms that can involve the appendix, some of which are peculiar to this site.
Tumours involving the appendix have been found in only about 1% of all appendectomy 9. Epithelial neoplasms and neuroendocrine tumours represent the gross majority of the tumour...
Nodular filling defects due to mucosal lesions in the duodenum are due to a number of processes. For a differential list which includes non-mucosal lesions see duodenal filling defects.
The differential diagnosis for mucosal lesions includes:
heterotopic gastric mucosa
Non-neoplastic solid lesions of the pancreas (NNSLP) are conditions which may mimic pancreatic neoplasms on imaging. They include:
intrapancreatic accessory spleen
congenital anomalies, such as prominent pancreatic lobulations and bifid pancr...
Oesophageal dysmotility refers to the pathological disruption of the normal sequential and coordinated muscle motion of the oesophagus to transport food from the oropharynx to the stomach. It is an umbrella term used to refer to the common pathophysiological endpoint of dysmotility that can be c...
Omental cake refers to infiltration of the omental fat by material of soft-tissue density. The appearances refer to the contiguous omental mass simulating the top of a cake. Masses on the peritoneal surfaces and malignant ascites may also be present.
The most common cause is metasta...
Omphalomesenteric fistula occurs as aresult of failure of obliteration of the omphalomeseneric duct. It is one of the congenital fistulas of gastrointestinal tract .
Treatment of choice is often a partial trans umbilical resection with umbilical restitution.
Pancreatic atrophy is non-specific and is common in elderly patients, although in younger patients it can be a hallmark of pathology. Most commonly it is associated with aging, obesity and end-stage chronic pancreatitis.
It occurs principally with fatty replacement of the pancreas (pancreatic ...
Pancreatic calcifications can arise form many aetiologies.
Punctate intraductal calcifications
acute alcoholic pancreatitis (20-40%)
intraductal, numerous, small, irregular
preponderant cause of diffuse pancreatic intraductal calcification
idiopathic: no underlying ca...
There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.
Classification based on function
exocrine: ~99% of all primary pancreatic neoplasms
pancreatic ductal adenocarcinoma ~90-95%
intraductal papillary muc...
Pancreatitis refers to inflammation involving the pancreas.
It has various forms which can be classified in many many ways according to time of onset, aetiological agent or associated pathology.
interstitial oedematous pancreatitis
A pantaloon hernia (dual hernia or Romberg's hernia or saddle bag hernia) is defined as ipsilateral, concurrent direct and indirect inguinal hernias. Hernial sacs are present on both sides of the inferior epigastric vessels, and separated by the posterior wall of the inguinal canal brought down ...
Periampullary tumours are those that arise within two cm of the ampulla of Vater in the duodenum.
Tumours that fall under this group includes four main types of tumours 1,4
pancreatic head / uncinate process tumours: includes pancreatic ductal adenocarcinoma involving head and uncinate process...
Peritoneal calcification is seen in a limited number of conditions that result in calcification of peritoneal structures. Therefore, the differential diagnosis is small:
psammoma bodies in malignancy (most frequently cystadenocarcinoma of the ovary): fine sand like calcification
PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). F-18 is an unstable radioisotope and has a half-life of approx...
Pneumatosis coli is a descriptive sign presenting radiographically as intramural gas limited to the colonic wall.
There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoides intestinalis. Pneumatosis in...
Pneumoretroperitoneum is by definition presence of gas within the retroperitoneal space. It is always abnormal and has a relatively small differential:
perforated retroperitoneal hollow viscus
peptic ulcer disease
blunt or penetrating abdominal trauma
endoscopy +/- biopsy (rare) 3...
Portal venous gas is the accumulation of gas in the portal vein and its branches. It needs to be distinguished from pneumobilia, although this is usually not too problematic, when associated findings are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, cent...
Primary peritoneal neoplasms comprise of an uncommon group of heterogenous entities.
The list includes
primary (malignant) peritoneal mesothelioma
primary perioneal multicystic mesothelioma
primary peritoneal well differentiated papillary mesothelioma
Primary pneumatosis intestinalis (PPI) is a benign idiopathic condition in which multiple gas-filled cystic lesions are seen in the gastrointestinal tract wall. The changes are usually seen initially on radiography or CT with CT being the more sensitive test.
Primary pneumatosis i...
Pseudopneumoperitoneum describes any gas within the abdominal cavity that masquerades as free intraperitoneal gas or pneumoperitoneum when it is in fact contained within an organ. Correctly identifying pneumoperitoneum is important, but making the diagnosis in error may lead to further unnecessa...
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...