Anal sphincter injury (ASI) is a form of perineal injury that can involve internal or external anal sphincters and may extend to the anorectal mucosa in severe cases.
This article is focusing on the most common type of ASI that is associated with vaginal delivery and represents third and fourth...
Small bowel diaphragm disease is a rare clinical entity involving diaphragm-like septa causing small bowel lumen narrowing.
Small bowel diaphragm disease is a relatively rare disease, with limited reported literature on its incidence and prevalence 1.
The following ...
Dyspepsia is a group of upper abdominal gastrointestinal symptoms often described as a burning sensation, discomfort, nausea and bloating, especially after meals.
Dyspepsia is a common condition affecting up to 25% of the population in the United States.
Helicobacter pylori (H. pylori) is a gram-negative spiral flagellate microaerophilic bacterium found in the human gastric mucosa 1. It is classified as a Group I carcinogen and is considered necessary but insufficient alone to cause gastric adenocarcinoma. More often than not, it results in chro...
The pancreaticoduodenal arcade refers to an arterial network that links the blood flow of the celiac artery and superior mesenteric artery via the superior and inferior pancreaticoduodenal arteries.
The pancreaticoduodenal arcades originate from the superior pancreaticodu...
A CT gastro-intestinal bleed protocol utilizes a multiphasic technique to detect active gastrointestinal bleeding (as well as other potential non-bleeding bowel disease 1.
Note: This article is a general guideline for evaluating CT gastrointestinal bleeds. Protocol factors are variable as they...
The inner tube sign on ultrasonography refers to two echogenic lines that run along the center of the roundworm Ascaris lumbricoides, paralleling its two outer echogenic walls, depicting its alimentary system. As a result, the longitudinal section of the worm on the ultrasound creates the distin...
A pancreatic duct stone (or calculus) is a stone embedded within the pancreatic duct. They typically arise in the setting of chronic pancreatitis.
The exact incidence of pancreatic duct stones remains to be fully evaluated. The current literature estimates that up to 50% of patien...
Duodenal ulcer is defined as injury to the duodenal mucosa, most commonly due to either medication or infection. These ulcers are a subtype of peptic ulcer disease.
The incidence of duodenal ulcers ranges between 5-10% in developed countries. There is, however, evidence of decreas...
Intra-abdominal hypertension is defined as an elevation in intra-abdominal pressure that is greater than or equal to 12 mmHg. Although it can be asymptomatic, medical management of this condition is essential to avoid progression to abdominal compartment syndrome. Radiology plays a role in facil...
Gastroenteritis is a common illness affecting people of all ages. It is typically characterized by diarrhea, nausea, and vomiting.
Gastroenteritis is a common entity, with it being one of the leading causes of mortality among children in developing countries 1. Gastroenteritis aff...
The hiatal surface area (HSA) is a measurement that has been proposed to define the size of the hiatal defect in the preoperative assessment of a hiatus hernia. It allows to determine the two-dimensional expanse of the hiatal orifice and then adapts the crural closure to the exact dimension of t...
Splenic ultrasound is a non-invasive diagnostic imaging method that uses high-frequency sound waves to visualize and assess the size, shape, structure, and potential abnormalities of the spleen.
trauma: splenic injuries resulting from accidents, sports injuries, or any other form of...
Esophageal foreign bodies are frequently encountered in clinical practice, representing the most common site for ingested foreign bodies or food impaction within the gastrointestinal tract.
This article discusses esophageal foreign bodies; a general view of the theme is available in the main a...
Microgastria is a rare congenital condition involving an abnormally small stomach. It is typically associated with other congenital conditions such as asplenia, congenital heart disease, skeletal anomalies or tracheoesophageal anomalies.
Microgastria is an extremely rare anomaly, ...
Gastro-oesophagal reflux grading is based on the vertical height that contrast-media reaches during fluoroscopy 1:
grade I: reflux in the distal esophagus
grade II: reflux up to or just above the carina
grade III: reflux into cervical esophagus
grade IV: reflux in the cervical esophagus with...
A gastrosplenic fistula is a very rare type of gut fistulation that can occur as a complication with either a gastric or splenic lesion.
Recognized causes include
lymphoma (considered commonest cause)
most commonly diffuse large B-cell lymphoma (DLBCL)
usually in context...
The anal columns, also known as columns of Morgagni are a number of longitudinal folds of the anal mucosa.
The columns unite inferiorly to form crescentic shaped anal valves. Shallow clefts of mucosa are formed in between the columns and valves, termed the anal sinuses. The anal valves form a c...
The pancreaticoduodenal space (PDS) or groove (PDG) is a small anatomical potential space between the pancreatic head and duodenum 1.
medial: pancreatic head
lateral: 2nd portion of duodenum
superior: duodenal bulb
inferior 3rd portion of duodenum
Perianal genital warts, also known as condyloma acuminata (singular: condyloma acuminatum), are a complication of human papillomavirus (HPV) infection. They are diagnosed clinically and are usually painless and benign, but can rarely undergo malignant transformation into squamous cell carcinoma....
The Eckhardt score is a clinical scoring system commonly used to characterize the severity of achalasia.
It is a 12-point score which is as follows:
recent weight loss (kg)
none = 0
<5 kg = 1
5-10 kg = 2
>10 kg = 3
none = 0
occasional = 1
daily = 2
each meal = 3
Tertiary esophageal contractions are a type of contractions of the esophagus often described as as the irregular contraction or indentations of the distal esophageal wall. Isolated tertiary esophageal waves of the non-repetitive type are thought to occur in normal subjects. Swallowing induced re...
Disseminated histoplasmosis, also known as progressive disseminated histoplasmosis, is a severe form of histoplasmosis infection typically seen in immunosuppressed patients, especially in the setting of HIV infection. It results from hematogenous dissemination of the infection, involving multipl...
Esophageal MRI, or gastro-esophageal junction (GEJ) MRI, is a targeted mediastinal imaging protocol performed to stage and aid treatment decisions in esophageal and GEJ carcinoma. It is not yet included in major treatment guidelines, but recent literature have pointed promising accuracy compared...
The median arcuate ligament is a fibrous arch connecting the left and right diaphragmatic crura at the aortic hiatus 1,2.
A low-lying median arcuate ligament can compress the celiac axis to cause celiac artery compression syndrome which is also known as median arcuate ligament syndrome (MALS) 2.
Pseudosacculations (also known as pseudodiverticulae) are outpouchings of normal bowel wall along the antimesenteric border. Inflammation and fibrosis along the mesenteric border of the bowel loop causes asymmetric shortening of the mesenteric wall, and subsequent pseudosacculations of the norma...
Cholecystocutaneous fistulas are abnormal fistulous connection between the gallbladder and the skin. It is a rare form of gastrointestinal fistulation and may result from a complication of cholecystitis, gallbladder carcinoma, or percutaneous procedures 1,2.
The peak incidence is ...
The omphalomesenteric duct, also called the vitelline or vitellointestinal duct, is a communicating tract between the embryonic yolk sac and the primitive midgut.
This duct is obliterated at around the 5th to 8th week of gestation. Approximately 2% of people have a failure of involution.
The component separation index is a value used to quantify the degree of diastasis of the rectus abdominis muscles in the context of anterior abdominal wall hernias.
The mode of repair of midline abdominal wall hernias (often incisional hernias through laparotomy wounds) depends on the d...
The Paris Classification of inflammatory bowel disease is used to classify the severity of ulcerative colitis and Crohn disease in the pediatric population. Primary differences between the adult and pediatric phenotype include the location, behavior, propensity for disease extension as well as i...
The white line of Toldt is a line formed at the junction of the lateral reflection of the posterior parietal peritoneum and the visceral peritoneum of the colon in the paracolic gutter. After the 270-degree counter-clockwise rotation of the intestinal tract during embryologic development, the tr...
The Montreal Classification of inflammatory bowel disease is used primarily to classify the severity of ulcerative colitis and Crohn disease based on specific categories.
This can then be used to guide treatment, discern risk of complications as well as facilitate epidemiological studies 1. The...
Centrifugal (inside-out) enhancement of liver hemangioma are a type of atypical hepatic hemangioma, which due to its imaging features, often raises the concern of a malignant process rather than a benign one.
Centrifugal (inside-out) enhancement of liver hemangiomas are a relativ...
Gastric neuroendocrine tumors (GNETs), previously known as gastric carcinoids, are rare primary neoplasms that arise from enterochromaffin-like cells of the gastric mucosa.
GNETs account for less than 2% of all gastric neoplasms and up to 10% of all gastrointestinal neuroendocrine...
Inflammatory fibroid polyps (IFP's) are rare, benign lesions of the gastrointestinal tract, most commonly affecting the gastric antrum, followed by small bowel, and large bowel 1. Rarely it occurs in rectum, esophagus or gall bladder 1.
The tumor is most commonly found in in patie...
Adenosquamous carcinoma of the pancreas is a rare, highly aggressive malignancy, clinically indistinguishable from the more common pancreatic ductal adenocarcinoma. Their defining pathological and imaging characteristics are the frequent presence of central necrosis and vascular invasion.
The thoracic splanchnic nerves are three paired autonomic nerves that provide sympathetic innervation of the abdominopelvic viscera and vessels. They contain efferent and afferent fibers.
Three pairs of thoracic splanchnic nerves arise from the T5 to T12 sympathetic ganglia.
The hepatic plexus (plural: plexuses) is an autonomic nerve plexus and ganglia located in the upper abdomen. Most descriptions are of a periarterial extension of the celiac plexus along the common hepatic artery and portal vein.
location: the plexus and ganglia extends to the right fr...
The celiac plexus (plural: plexuses) is an autonomic nerve plexus and ganglia in the upper abdomen. It is the largest major autonomic plexus.
location: the ganglion and plexus lie close to the celiac trunk
preganglionic sympathetic fibers via the greater and les...
The ganglion impar, also know as the ganglion of Walther, is the midline autonomic ganglion located in the lower pelvis. It is the most distal convergence of the pelvic sympathetic chain which is usually located anterior to the coccyx. It can be found anywhere between the sacrococcygeal joint a...
The squeeze sign is a pathognomonic feature of a colonic lipoma, where the lesion is seen to change in size and shape upon compression. This can be demonstrated with a barium enema examination where a well-circumscribed, spherical filling defect will be seen to elongate during peristalsis 1,2. T...
The superior mesenteric plexus is an autonomic nerve plexus and ganglia located in the retroperitoneum.
location: the plexus and ganglia lie in the retroperitoneum at the origin of the superior mesenteric artery within the small bowel mesentery
origin: formed from branches from ...
The inferior mesenteric plexus is an autonomic nerve plexus and ganglia located in the retroperitoneum.
location: the plexus and ganglia lie in the retroperitoneum at the origin of the inferior mesenteric artery
formed mainly from branches from the aorticorenal plexus
The autonomic ganglia and plexuses are a collection of ganglia where autonomic preganglionic neurons arising from the CNS synapse with postganglionic neurons outside the CNS, i.e. in the peripheral nervous system. Many of the ganglia contain nerves of the sympathetic and parasympathetic nervous ...
This article lists examples of normal imaging divided by body region and system.
head and neck
Traditional serrated adenomas are a type of premalignant serrated colonic polyp.
They are thought to account for <1% of all colonic polyps and 1-7% of all serrated lesions. They tend to occur in older patients (usually over 50 years) with no significant gender predilection.
Acute esophageal necrosis, sometimes known as Black esophagus or esophageal stroke, is a rare entity characterized by patchy or diffuse circumferential black pigmentation of the esophageal mucosa from ischemic necrosis.
It is classically characterized by a striking endoscopic image of diffuse, ...
A splenectomy is the surgical removal of the spleen. This can be partial or total, however a partial splenectomy is rarely performed due to an increased risk of complications compared to a total splenectomy 1.
Indications for a splenectomy can be divided into absolute and relative ...
Decreased duodenal folds may be seen on imaging modalities, particularly MR enterography, and differential diagnoses include:
scleroderma - usually with duodenal dilatation
celiac disease - particularly involves the distal duodenum and jejunum
Nontoxic megacolon refers to colonic dilatation of more than 6 cm in an adult without mural abnormality. This is in contrast to toxic megacolon, an acute complication accompanied by mural abnormalities such as thickening, loss of haustral folds, pneumatosis or free gas.
The differential diagnos...
Bowel wall fat deposition refers to the infiltration of the submucosa with fat and usually occurs in chronic processes such as inflammatory bowel disease, causing characteristic fat halo sign on CT images.
Other differential diagnoses include:
normal variant - particularly in obese patients w...
Bowel wall calcification is not common and can occur secondary to various mechanisms due to benign, premalignant, or malignant lesions.
The differential diagnoses include:
gastrointestinal stromal tumor (GIST)
metastatic calcification - due to renal failure
An esophageal balloon tamponade device is a form of balloon catheter designed to exert direct pressure on bleeding gastro-esophageal varices in order to obtain hemostasis. It is considered a temporizing measure in hemodynamically unstable patients in whom endoscopic (or angiographic) interventio...
Feces, also known as stool, is the solid component of human waste. Almost half of its dry mass is bacterial biomass, with the remainder comprised of undigested dietary matter, exfoliated cells of the gut, intestinal secretions, small metabolites and mucus.
Fecal matter is semisoli...
A gastrocolic fistula (plural: fistulas/fistulae), also known as cologastric fistula, is a rare form of gut fistulisation between the stomach and the colon.
Gastrocolic fistula, is much more common in the literature than its synonym cologastric fistula, which is in line with the co...
The pseudokidney sign is a non-specific sonographic sign that describes the reniform shape of a mass with a hypoechoic region (representing bowel wall thickening) surrounding a central hyperechoic portion or echogenic stripe (which represents the apposition of the mucosal surfaces) 1,2.
A gastropancreatic fistula is a rare form of gut fistulation where there is a fistulous communication between the stomach and the pancreas.
It has been described in association with
chronic pancreatitis 1 / severe pancreatitis
intraductal papillary mucinous neoplasm (IPMN) 4
peptic ulcers 2
Hypoglycemia describes an abnormally low blood glucose level (<4 mmol/L). It is a common clinical problem in diabetics overtreated with glucose lowering agents.
Signs of hypoglycemia include:
tremors, palpitations and anxiety
The evocative appearance of the coat of a zebra has been used for several distinctive signs in radiology:
zebra sign: cerebellar hemorrhage 1
zebra sign: amyotrophic lateral sclerosis 2
zebra spleen: arterial phase appearance of normal spleen 4,5
zebra stripe sign: treated osteogenesis imper...
Radiation therapy has the potential to cause complications in many organ systems, many of which, especially in the thorax, are important for radiologists to be aware of.
acute radiation syndrome
complications of cranial radiation therapy
radiation-induced cerebral vasculopathy
Gastrointestinal (GI) stents are increasingly used to treat obstruction of the GI tract, most commonly due to malignancy.
Types of stent
History and etymology
Somewhat surprisingly the word 'stent' is actually a...
The Glasgow-Blatchford score (GBS) is a widely-used and well-validated scoring system for upper GI bleeding and the need for intervention.
The scoring system relies upon knowing the patient's urea, hemoglobin, systolic blood pressure, and several other criteria. Each criterion is scored,...
The 7th edition of the TNM classification of colorectal carcinomas was proposed in 2010, and has now been updated and replaced by the 8th edition, published in 2016.
Primary tumor staging (T)
Tx: primary tumor cannot be assessed
T0: no evidence of primary tumor
Tis: carcinoma in situ
A traction esophageal diverticulum is a true esophageal diverticulum (i.e. includes all layers of the esophageal wall) which occurs secondary to external pulling/traction forces on the esophageal wall.
pulmonary/mediastinal scarring or fibrosis
inflammatory processes in th...
Scaphoid abdomen is the term given to an inward concavity of the anterior abdominal wall. It is used both for the clinical appearance and its radiological equivalent.
In children it maybe a sign of congenital diaphragmatic hernia. In both adult and pediatric patients, it raises the possibility...
N-butyl-2-cyanoacrylate pulmonary embolism is a potentially life-threatening complication that can arise following the use of the tissue glue, butyl-cyanoacrylate, for endoscopic sclerotherapy to treat variceal bleeding.
Sclerosis with biological glue (butyl cyanoacrylate) is curr...
A water-soluble contrast challenge (more widely known as a Gastrografin challenge) is a combined diagnostic study and therapeutic intervention utilized in the evaluation and management of small bowel obstruction. It is used when clinical or imaging features determine there to be small bowel obst...
Pica refers to a psychiatric disorder in which patients report a craving for and compulsive consumption of substances that are not food. Substances consumed include earth, clay, plaster, paint chips, string, hair, animal feces and stones 1.
Although the condition can present in a...
Congenital pouch colons are an anomaly in which there is cystic dilation of a shortened colon. They can either partially or totally replace the colon.
Congenital pouch colons can be associated with vaginal or vestibular fistulas and less frequently with other genitourin...
A sliding hiatus hernia or type 1 hiatus hernia is considered the most common type of hiatus hernia. They can be present to varying degrees and can also co-exist with other types (inclusive of a rolling hiatus hernia).
Many patients may have gastro-esophageal reflux. Some...
The timed barium esophagogram (TBO) is a simple physiologic assessment and objective method for assessing the esophageal emptying used in patients with suspected achalasia and to evaluate and follow up patients who have been treated with myotomy or pneumatic dilatation1,3.
Mackler's triad consists of the clinical symptoms of vomiting, followed by severe pain in the chest, usually retrosternal, lower thoracic, and upper abdominal, associated with subcutaneous emphysema detected on physical examination, which is suggestive of esophageal rupture (Boerhaave syndrome) ...
The Anderson triad consists of the clinical findings of tachypnea and abdominal rigidity with lower thoracic or epigastric pain, associated with subcutaneous emphysema, which is usually related to esophageal rupture.
Subhepatic appendicitis refers to inflammation of the appendix in which the appendix and cecum have failed to descend inferiorly during normal development; resulting in a "subhepatic" position.
Presentation of an inflamed subhepatic appendix is exceedingly uncommon, representing o...
The double beak sign refers to the sudden tapering that two adjacent intestinal loops show in the internal hernia at the transition point of the closed loop obstruction.
The marked reduction in caliber results in distension of the afferent and efferent intestinal loops.
History and etymology
The characteristic shape of the crescent has been given to many radiological signs over the years:
air crescent sign (aspergillosis)
crescent in a doughnut sign (intussusception)
crescent sign (arterial dissection)
crescent sign (intravenous pyelogram)
crescent sign (lung hydatid)
This is a basic article for medical students and other non-radiologists
Intussusception occurs when a loop of bowel is pulled into the lumen of a distal bowel loop, and is an important cause of acute abdominal pain, particularly in young children.
This is a summary article; ...
A corkscrew esophagus, also known as a rosary bead esophagus, is a classic appearance of distal esophageal spasm on a barium swallow. It is actually quite a rare appearance which is seen in <5% cases of distal esophageal spasm. The finding is caused by multiple tertiary (non-propulsive) contract...
The superficial epigastric vein (TA: vena epigastrica superficialis) is an important tributary of the great saphenous vein that drains the anterior abdominal wall inferior to the level of the umbilicus.
The superficial epigastric vein drains into the great saphenous vein at the saphenous openin...
Diverticula of the anal canal are very rare with only a few cases reported in the global literature.
Patients have presented with anorectal bleeding and/or pain.
The few cases have either not been characterized on imaging or only imaged on barium s...
Intramural pseudocysts are a rare form of pancreatic pseudocysts that occur within the wall of the upper gastrointestinal tract. They may result in gastric outlet obstruction.
They can considerably vary in size with one study reporting a range of 8 mm to 8 cm 1.
The bowler hat sign refers to an appearance on a GI contrast study, which may be seen with both polyps and diverticula of the bowel. The filling defect produced by the pathology mimics the outline of a bowler hat. It was originally described for colonic lesions, but can be seen with lesions thro...
Cameron lesions refer to linear ulcers or erosions that occur on the mucosal folds at the diaphragmatic impression of a hiatus hernia. They are usually radiographically occult and diagnosed endoscopically (although still useful for a radiologist to know).
Their prevalence has been...
The superior hypogastric plexus is an autonomic nerve plexus and ganglia located in the lower abdomen.
location: the plexus and ganglia lie anterior to the aortic bifurcation extending inferiorly between the common iliac arteries and along the left common iliac vein and median sacral v...
The Clermont or DWI-MaRIA scoring system is used to assess ileocolonic Crohn disease activity on noncontrast MRI enterography. It is based on the earlier Magnetic Resonance Index of Activity (MaRIA) index, however, it does not require intravenous gadolinium by substituting relative contrast enha...
Cholecystocolonic fistulas are most commonly a rare late complication of gallstone disease, resulting from an abnormal communication between the gallbladder and the colon. It is the second most common cholecystoenteric fistula after cholecystoduodenal fistulas 1.
The Magnetic Resonance Index of Activity (MaRIA) scoring system is used to assess ileocolonic Crohn disease activity on contrast-enhanced MRI enterography. The segmental index represents disease severity in one bowel segment, whilst assessing six defined anatomic regions these can be combined in...
Rectal MRI is a key imaging investigation in the diagnosis, staging and follow up of rectal cancer. An increase in the utility of rectal MRI as been driven by the recognition of the mesorectum as a distinct anatomic compartment containing and limiting the margins of the rectum, and forming a sur...
Dolichocolon refers to an abnormally elongated redundant colon. It is considered a developmental variant.
The main symptoms and signs of dolichocolon are:
However, dolichocolon is a contentious entity, and so...
The interstitial cells of Cajal are mesenchymal cells closely apposed to neural and smooth muscle cells of the gut. They form a heterogeneous group with differing ultrastructure and functions.
One cell type has an ancillary neural function as a gastrointestinal pacemaker, generating electrical ...
Odynophagia is the term given for painful swallowing.
It can arise from a number of causes which include
esophageal inflammation - esophagitis
dysphagia: difficulty swallowing.
An incompetent ileocecal valve is a situation where there can be reflux of backward flow of food content from the large bowel (cecum) through to the small bowel (terminal ileum) and through the ileocecal valve. A low degree of incompetence is not an uncommon finding 3. In some states, patients m...
A sphincter (TA: musculus sphincter) is a term used in anatomy to refer a ring of muscle which narrows a tube or closes off a bodily orifice 1.
external anal sphincter
internal anal sphincter
lower esophageal sphincter