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...
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...
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 apple core sign, also known as a napkin ring sign (bowel), is most frequently associated with constriction of the lumen of the colon by a stenosing annular colorectal carcinoma.
The appearance of the apple-core lesion of the colon also can be caused by other diseases...
Apple-peel intestinal atresia, also known as type IIIb or Christmas tree intestinal atresia, is a rare form of small bowel atresia in which the duodenum or proximal jejunum ends in a blind pouch and the distal small bowel wraps around its vascular supply in a spiral resembling an apple peel. Oft...
The arrowhead sign refers to the focal caecal thickening centred on the appendiceal orifice, seen as a secondary sign in acute appendicitis. The contrast material in the caecal lumen assumes an arrowhead configuration, pointing at the appendix.
The arrowhead sign is applicable only when enter...
Backwash ileitis is seen in patients with ulcerative colitis (UC), where the entire colon is involved. In such cases the terminal ileum is oedematous.
Backwash ileitis extends contiguously backward from the caecum without skip regions. One source estimates it to occur in 6% of patients with UC,...
The ball of wool sign, also referred to as the yarn sign or congealed water lily sign, is an ultrasound appearance, representing degeneration of hydatid cysts (WHO class CE 4). The inner side of the cyst detaches from the cyst wall and folds on itself, causing a change from anechoic (fluid) to a...
Beak sign in pyloric stenosis is one of the fluoroscopic (barium meal) findings which is useful in the diagnosis of congenital hypertrophic pyloric stenosis.
A beak-like tapering projection of barium is seen entering into the narrowed and compressed pyloric ...
Bilateral adrenal gland hyperenhancement or intense adrenal enhancement may be a feature of hypotension and forms part of the CT hypoperfusion complex.
Adrenal gland hyperenhancement has been described in paediatric and small adult series or individual cases of haemorrhagic shock, pancreatitis,...
The bird's beak sign of the oesophagus is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the rat-tail sign.
The appearance, although classically occurring in primary achalasia, ca...
The bird beak sign of the right colon is tapering obstruction of the inferior part of right colon seen on contrast enema or CT scan with rectal contrast indicating caecal volvulus.
This sign can help to differentiate caecal volvulus from caecal bascule, in particular on a contrast/barium enema ...
Bird's beak sign of the sigmoid is one of the signs of sigmoid volvulus. It represents gradual narrowing/tapering of sigmoid colon up to the level of obstruction during contrast/barium insertion to the rectum or on CT.
When located in the sigmoid colon, it suggests the diagnosis of sigmoid volv...
The caecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled caecum.
The Carman meniscus sign describes the lenticular shape of barium in cases of large and flat gastric ulcers, in which the inner margin is convex toward the lumen. It usually indicates a malignant ulcerated neoplasm; in cases of benign gastric ulcers, the inner margin is usually concave toward th...
The centipede sign is seen as engorged mesenteric vessels in cases of acute sigmoid diverticulitis which gives an appearance similar to a centipede 1.
The cervix sign of pyloric stenosis describes indentation of the pylorus into the fluid-filled antrum, seen in pyloric stenosis.
antral nipple sign
target sign of pyloric stenosis
shoulder sign of pyloric stenosis
Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn disease.
Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones.
The coffee-bean sign (also known as the kidney bean sign or bent inner tube sign 4) is a sign on an abdominal plain radiograph of a sigmoid volvulus although some authors have also used the term to refer to closed loop small bowel obstructions. Caecal volvulus may be mistaken with sigmoid volvul...
Colon cut-off sign describes gaseous distension seen in proximal colon associated with narrowing of the splenic flexure in cases of acute pancreatitis. Though originally described in abdominal radiographs, this sign has also been demonstrated in contrast enemas and computed tomography 1.
The comb sign refers to the hypervascular appearance of the mesentery in active Crohn disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel...
A cone-shaped caecum refers to a loss of the normal rounded appearance of the caecum, which instead becomes narrow and cone-shaped with the apex pointing towards the base of the appendix. It is encountered in a number of conditions including:
The corkscrew sign describes the spiral appearance of the distal duodenum and proximal jejunum seen in midgut volvulus. It has been identified as a diagnostic indicator of midgut volvulus 1.
In patients with malrotation and volvulus, the distal duodenum and proximal jejunum do not cross the mid...
The crescent in a doughnut sign refers to the transverse ultrasound appearance of intestinal intussusception, and is a variation of the target sign (which is also known as the doughnut sign)
The doughnut is formed by concentric alternating echogenic and hypoechogenic bands. The echogenic bands ...
The cupola sign is seen on a supine chest/abdominal radiograph in the presence of pneumoperitoneum.
It refers to non-dependent gas that rises within the abdominal cavity of the supine patient to accumulate underneath the central tendon of the diaphragm in the midline. It is seen as lucency ove...
The dependent viscera sign is one of the signs of diaphragmatic rupture on axial CT or MR images, where herniated viscera lie against the posterior thoracic wall in a dependent position, as they are no longer supported by the diaphragm.
collar sign (or hourglass sign)
The doge cap sign is a radiographic sign of pneumoperitoneum. It presents as a triangular-shaped gas lucency in the right upper quadrant on abdominal radiographs due to air in the Morison pouch, which resembles the medieval caps worn by Italian doges.
Double barrel sign is an imaging appearance of two lumens adjacent to each other.
It can be seen in:
dilated bile duct adjacent to portal vein
double barrel aorta: aortic dissection
double barrel oesophagus: oesophageal dissection
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:
The double duct sign refers to the presence of simultaneous dilatation of the common bile and pancreatic ducts. Being an anatomical sign it can be seen on all modalities that can visualise the region, including: MRI, CT, ultrasound and endoscopic retrograde cholangiopancreatography (ERCP).
The double track sign is a radiological sign described in pyloric stenosis on various imaging modalities.
Double streaks of barium passing through the narrow pylorus 1.
On fluid aided real-time examination, the pyloric fluid is compressed into smaller tracks as it is...
The double wall sign is another name for the Rigler sign. It is a sign of pneumoperitoneum with gas outlining both sides of the bowel wall. It is seen when large amounts of free gas, >1000 mL, are present.
It should be distinguished from the false double wall sign which refers to two dilated lo...
The duct penetrating sign is a radiographic sign which can be useful in differentiating between focal pancreatitis (inflammatory pancreatic mass) from pancreatic carcinoma.
A positive sign is when a mass is penetrated by an unobstructed pancreatic duct; this makes focal pancreatitis the most li...
The falciform ligament sign (also called the Silver sign) is a sign seen with a pneumoperitoneum.
It is almost never seen in isolation. If there is enough free gas to outline the falciform ligament, there is usually enough gas to also provide at least a Rigler sign.
The falciform ligament con...
The fascial tail sign is the linear extension along the fascia/muscular aponeurosis from a deeper tumour.
It appears as a tail and is best appreciated on MRI, classically seen in desmoid tumours as T2 hypointense bands that progressively enhance particularly on delayed ph...
The fat halo sign refers to a feature seen on CT examination of the abdomen, and represents infiltration of the submucosa with fat, between the muscularis propria and the mucosa. It is characterised by an inner (mucosa) and outer (muscularis propria and serosa) ring of enhancing bowel wall along...
The fat ring sign (also known as a fat halo sign) describes preservation of fat around the mesenteric vessels and around soft tissue nodules on a background of diffuse fat stranding in patients with mesenteric panniculitis or mesenteric lipomas.
This finding may help distinguish mesenteric pan...
Fat stranding is a common sign on CT seen anywhere fat can be found but is most commonly seen in the abdomen/pelvis, but also in the retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localising both acute and chronic pathology.
Fat stranding can a...
Fat stranding is a sign that is seen on CT. It describes the change in attenuation of fat around an inflamed structure and is a very helpful signpost for intra-abdominal pathology.
This is a summary article; read more in our article on fat stranding on CT.
The Fleischner sign refers to a widely gaping, thickened, patulous ileocaecal valve and a narrowed, ulcerated terminal ileum associated with tuberculous involvement of the ileocaecum.
Fleischner sign (enlarged pulmonary artery)
The floating aorta sign refers to displacement of the abdominal aorta away from the vertebral column.
It is a radiographic/CT sign of retroperitoneal masses.
On lateral lumbar spine radiographs, the expected location of the posterior aortic wall is expected to be ≤10 mm ...
Foamy oesophagus is an appearance seen on a single contrast barium study in Candida oesophagitis with associated scleroderma/achalasia (stasis).
Pathophysiologic basis of the foamy oesophagus is uncertain. Stasis is a predisposing factor. Foam is produced directly by the fungal organ...
The football sign is seen in cases of massive pneumoperitoneum, where the abdominal cavity is outlined by gas from a perforated viscus. The median umbilical ligament and falciform ligament are sometimes included in the description of this sign, as representing the sutures.
Which football is use...
The Frimann-Dahl sign is a diagnostic sign demonstrated when three dense lines, representing the sigmoid walls, are seen converging to the site of obstruction in sigmoid volvulus and associated with empty rectal gas 1.
History and etymology
Johan Frimann-Dahl (1902-82) was a Norwegian Professo...
Frostberg inverted 3 sign is a radiological sign seen on a barium examination where there is effacement and distortion of the mucosal pattern on the medial wall of the second part of the duodenum due to focal mass and local oedema. It is most commonly associated with carcinoma of the head of the...
The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall.
Bowel has 5 layers, comprised of alternating hyperechoic and hypoechoic layers. Anatomically these layers are as follows (innermost to outermost) 1,2:
The Hampton line is a thin millimetric radiolucent line seen at the neck of a gastric ulcer in barium studies (profile view), indicating its benign nature. It is caused by a thin line of mucosa overhanging the ulcer's crater.
The hidebound bowel sign refers to an appearance on a barium study of the small bowel in patients with scleroderma. The sign describes the narrow separation between the valvulae conniventes which are of normal thickness despite dilatation of the bowel lumen.
Although the term hidebound is use...
The hyperattenuating ring sign is a sign that has been described with epiploic appendagitis and refers to a hyperattenuating ring of visceral peritoneum surrounding a inflammed epiploic appendix 1. On CT it can be seen as a ring of soft tissue surrounding a region of fat attenuation adjacent to ...
Hypercontracting (nutcracker) oesophagus is a motility disorder of the oesophagus. This condition is primarily diagnosed with manometry with high intra-oesophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.
Hypercontracting oesophagus ("nutcracker oesopha...
The ice pick sign is a smooth tapered narrowing of the upstream pancreatic duct distal to the pancreatic lesion seen frequently in benign pancreatic lesions such as a focal autoimmune pancreatitis, this is due to the extrinsic narrowing of the duct secondary to periductal fibrosis and inflammati...
Intramural bowel gas, also known as pneumatosis intestinalis, refers to the clinical or radiologically finding of gas within the wall of the bowel.
There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cysto...
The inverted "V" sign, also known as lateral umbilical ligament sign, is a sign of pneumoperitoneum manifested by visualization inverted "V" shape in the pelvis on supine view of abdominal radiographs. It represent free air outlining the lateral umbilical ligaments. In infants, the lateral umbi...
Jejunoileal fold pattern reversal (a.k.a. jejunisation of the ileum) is one of the signs of coeliac disease, and is seen on small bowel follow-through studies as well as CT. The pattern is one of increased number of ileal folds and reduced number of jejunal folds 1,2, and is considered positive ...
The Kirklin complex is a combination of the Carman meniscus sign associated with a radiolucent semi-circular zone surrounding the elevated ridge of the ulcer. This complex is seen in cases of gastric adenocarcinoma on barium studies.
Carman meniscus sign
The Kirklin sign refers to a deformity of the normal gastric air bubble on an upright chest radiograph due to a mass lesion of the gastric cardia or fundus.
The differential for a Kirklin sign includes
gastrointestinal stromal tumour (G...
Lateral crescent sign is a useful diagnostic sign of a direct inguinal hernia on CT scan, the hernia causing compression and lateral displacement of the inguinal canal contents (ductus deferens, testicular vessels, fat, etc) to form a semicircle of tissue that resembles a moon crescent seen late...
Lead pipe appearance of colon is the classical barium enema finding in chronic ulcerative colitis. There is complete loss of haustral markings in the diseased section of colon, and the organ appears smooth walled and cylindrical.
The light bulb sign of an adrenal pheochromocytoma is MRI feature of this tumour. This refers to marked hyperintensity seen on T2 weighted sequences however this finding is neither sensitive nor specific and pheochromocytomas are more often heterogeneous with intermediate or high T2 signal inten...
Low attenuation lymphadenopathy suggests underlying necrosis and can be seen in:
metastatic carcinoma (or lymphoma)
infections (tuberculous or fungal)
low attenuation lymphadenopathy
high attenuation lymphadenoapthy
The lucent liver sign is represented by a reduction of hepatic radiodensity on supine radiograph when there is a collection of free intraperitoneal air located anterior to the liver.
Mallory Weiss tears occur due to violent projection of gastric contents against the lower oesophagus, which results in mucosal and submucosal tear with involvement of the venous plexus.
Patients present with massive painless haematemesis.
Tears most commonly ...
In the gallbladder, the Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2.
Fissures, usually fluid-filled, are present in close to 50% of gallstones. Less than half of these fissured gallstones contain some amo...
The moulage sign is related to sprue, in particular coeliac disease. It occurs where there is a dilated jejunal loop with complete loss of jejunal folds 1. It is said to appear like a tube into which wax has been poured.
History and etymology
Moulage (French: casting/moulding) is the art of ap...
Mushroom cap sign is one of the important signs of deep rectosigmoid endometriosis seen on T2 weighted MRI sequence. It indicates the submucosal involvement in rectosigmoid region.
Hypertrophic muscularis propria appears as heterogeneous low signal intensity surrou...
The mushroom sign (also called umbrella sign) is a radiological sign described in pyloric stenosis on barium examination.
This sign refers to the impression made by the hypertrophic pylorus on the duodenal cap.
cervix sign of pyloric stenosis
target sign of pyloric st...
Neuhauser sign refers to a soap bubble appearance seen in the distal ileum in cases of meconium ileus, related to the air mixed with meconium. It may be seen with barium enema if contrast passes beyond the ileocaecal valve or with small-bowel follow-through.
Although classically described with ...
The northern exposure sign has been described as a high specificity sign in sigmoid volvulus. On a supine abdominal radiograph, the apex of the sigmoid volvulus is seen above (cranial to) the transverse colon.
The periportal free gas sign has been described as being strongly suggestive for upper gastrointestinal hollow viscus perforation.
bowel perforation (summary)
The polo mint sign is a description given to a venous thrombosis on contrast enhanced CT imaging. When viewed in the axial plane, a thin rim of contrast persists around a central filling defect due to thrombus. This gives an appearance like that of the popular mint sweet, the polo, also referre...
The pseudo vein sign can occur with active gastrointestinal bleeding where contrast extravasation during angiography may have a curvilinear appearance as it pools in the gastric rugae or mucosal folds of bowel, mimicking the appearance of a vein. However, contrast in the “pseudo-vein” persists b...
Radiological signs are described across the disciplines of imaging, including the gastrointestinal tract. Fruit-inspired, nature-related, and more feature in the list of signs described for a wide array of pathology. How fascinating are the minds of radiologists work in describing pathology?
The rat-tail sign is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the bird beak sign (oesophagus).
The reverse figure 3 sign (also known as the E sign) is seen on barium swallows in patients with a coarctation of the aorta and is the medial equivalent of the figure 3 sign seen on CXR. It is formed by prestenotic dilatation of the ascending aorta, indentation of the coarctation site (or "tuck"...
The Rigler sign, also known as the double wall sign, is seen on a radiograph of the abdomen when the air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall.
Pneumoperitoneum may be a result of perforation or, from recent i...
Ring shadows are radiographic signs seen on either chest x-rays or on upper gastrointestinal fluoroscopy:
ring shadow (chest)
ring shadow (abdomen)
Rose-thorn ulcers or rose-thorn appearance refers to deep penetrating linear ulcers or fissuring typically seen within stenosed terminal ileum with a thickened wall. They appear as thorn-like extraluminal projections on barium studies and this appearance is one the f typical signs of Crohn disea...
A sandwich sign, sometimes known as a hamburger sign, refers to a mesenteric nodal mass, either para-aortic or not, giving an appearance of a hamburger. Confluent lymphadenopathy on both sides of the mesenteric vessels gives rise to an appearance described as the sandwich sign 2.
The sign is sp...
The seatbelt sign is both a clinical and radiological sign. It is simply the presence of bruising/abrasions in the distribution of a seatbelt (i.e. horizontal and/or diagonal) across the abdomen, chest and sometimes neck.
A positive seatbelt sign, in combination with abdominal pain or tenderne...
A sentinel loop is a focal area of adynamic ileus close to an intra-abdominal inflammatory process.
The sentinel loop sign may aid in localising the source of inflammation. For example, a sentinel loop in the upper abdomen may indicate pancreatitis, while one in the right lower quadrant may be ...
Seurat spleen is an angiographic appearance seen following blunt trauma to the spleen. Multiple small punctate regions of intraparenchymal contrast extravasation lead to a spotted appearance.
History and etymology
The term refers to a likeness between the angiographic appearance and the artwor...
Shading sign is an MRI finding typically seen in an endometrioma. It may also be seen with some endometrioid tumours (e.g endometrioid carcinoma of the ovary)
It helps to distinguish endometriomas from other blood containing lesions (e.g. haemorrhagic corpus luteum cysts), with a sensitivity of...
The small bowel faeces sign can be observed on abdominal CT scans. The sign has been described as a finding indicative of small bowel obstruction or another severe small bowel abnormality (e.g. metabolic or infectious disease). While the reported prevalence of the sign in small bowel obstruction...
Stepladder sign may refer to:
intra-capsular breast implant rupture (ultrasound)
air-fluid levels in obstructed small bowel (erect abdominal radiograph)
Stepladder sign represents the appearance of air-fluid distended small bowel loops that appear to be stacked on top of each other, typically observed on erect abdominal radiographs in the setting of small bowel obstruction.
On breast imaging, the stepladder sign is used to describe intracapsul...
The Stierlin sign refers to repeated emptying of the caecum, seen radiographically as barium remaining in the terminal part of the ileum and in the transverse colon. This occurs due to irritation of the caecum caused by M. tuberculosis.
The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses ...
String of pearls sign can refer to:
string of pearls sign on an abdominal radiograph of fluid-filled dilated small-bowel loops
string of pearls sign on ultrasound in polycystic ovarian syndrome
string of pearls sign for angiographic appearances in fibromuscular dysplasia
The string of pearls (or beads) sign can be seen on upright or decubitus abdominal radiographs as well as on CT in patients with small bowel obstruction, increased intraluminal fluid, and slow resorption of intraluminal gas.
It consists of an obliquely or horizontally oriented row of small gas ...
The gastrointestinal string sign (also known as string sign of Kantour) refers to the string-like appearance of a contrast-filled bowel loop caused by severe narrowing of a bowel loop.
Originally used to describe the reversible narrowing caused by spasms in Crohn disease, it is now used for any...
The string sign may refer to:
angiographic string sign
gastrointestinal string sign
string sign of parosteal osteosarcoma
The target sign of intestinal intussusception, also known as the doughnut sign or bull's eye sign.
The appearance is generated by concentric alternating echogenic and hypoechogenic bands. The echogenic bands are formed by mucosa and muscularis whereas the submucosa is responsible fo the hypoec...