Dr. Baldwin is a Radiologist at South Shore Hospital, Weymouth, MA; Dr. Genant is an Associate Professor of Radiology at San Francisco Medical Center, San Francisco, CA; Dr. Braver is
the Director of Gastrointestinal Radiology at Brigham & Women’s
Hospital and an Assistant Professor at Harvard Medical School, Boston,
MA; and Dr. Mortele is the Director of the Division of Clinical
MRI at Beth Israel Deaconess Medical Center, Boston, MA, and the
Associate Professor of Radiology at Harvard Medical School, Boston, MA.
the years, radiologists have established many classic imaging signs
that represent visual manifestations of myriad underlying
pathophysiologic processes. Though many of these signs were initially
described on plain films, they are still used daily by radiologists
reviewing images from cross-sectional modalities. For example, classic
plain-film signs, such as the “accordion sign,” are also commonly cited
today when seen on multidetector CT (MDCT) images.
The names of
many classic radiologic signs derive from analogues to objects commonly
encountered in everyday life; eg, the “comb” sign. The use of familiar
objects to describe visual findings enables radiologists both to arrive
at a correct diagnosis and to effectively convey such diagnostic
findings to clinicians.
The goal of this article is to review an
array of classic signs associated with gastrointestinal tract
pathologies whose imaging manifestations resemble everyday objects. The
“football” and “cobblestone” signs, for instance, are especially well
known to the authors in Boston.Signs that do not conjure a resemblance
to familiar objects, such as the “moulage” and the “colon cut-off”
signs, are not covered. This article organizes the gastrointestinal
signs from proximal to distal within the gastrointestinal tract. The
hepatobiliary and pneumoperitoneum signs are then reviewed.
Bird’s beak sign
“bird’s beak” sign is a classic finding on esophagrams; it describes a
dilated proximal esophagus with a smooth-tapered, distal esophagus at
the level of the esophageal hiatus in the setting of achalasia.1 The
smooth tapering of the distal esophagus resembles the beak of a bird
(Figure 1). On imaging and manometry, achalasia is further characterized
by esophageal aperistalsis and failure of the lower esophageal
sphincter to relax.
There are both primary and secondary forms of
achalasia. Primary achalasia, the more common etiology, is idiopathic.
The lack of lower esophageal sphincter relaxation is likely due to a
loss of inhibitory neurons in the esophageal myenteric plexus. Proposed
causes include neuronal degeneration, viral infection, genetic
inheritance, and autoimmune disease.2 Secondary achalasia
affects patients much less commonly and can be caused by entities such
as esophageal carcinoma and Chagas disease.
“corkscrew” sign is the visual manifestation of lumen-obliterating,
simultaneous, nonperistaltic contractions within the esophagus.
These abnormal contractions of varying amplitude occur in diffuse esophageal spasm, a rare esophageal motility disorder.3 Diffuse
esophageal spasm is characterized on manometry by periods of normal
peristalsis followed by simultaneous, repetitive, ineffective
contractions. These abnormal contractions segment the normal esophageal
lumen, mimicking a corkscrew on barium studies of the esophagus (Figure
“double-barrel esophagus” classically refers to the radiographic
appearance of a dissection between the esophageal mucosa and submucosa
without perforation. This rare condition was first described by Marks
and Keet in 1968.5 The double-barrel radiographic appearance
(Figure 3) of the esophagus is due to the visualization of a
barium-filled, intramural dissecting channel separated from the true
esophageal lumen by a lucent line, the mucosal stripe.6
esophageal dissection is most commonly seen in middle-aged or elderly
women. This entity can occur in the setting of a coagulopathy,
emetogenic injury, trauma, instrumentation, ingestion of foreign bodies
and, rarely, spontaneously.7 The double-barrel esophagus
appearance can also be seen with intramural esophageal abscess,
intraluminal diverticulum, or esophageal duplication.6
Bull’s eye lesions
within the stomach forming central collections of oral contrast within
ulcerated intramural masses can produce a target or bull’s eye
appearance (Figure 4) on upper gastrointestinal barium examinations.
This bull’s eye appearance has been described with many disease
processes.This differential diagnosis is broad and includes gastric
metastatic lesions from melanoma and lymphoma.8 Kaposi’s sarcoma and carcinoid tumors have also been documented to produce a gastric bull’s eye appearance.8,9 Rarely, gastric lipomas may also ulcerate and produce a bull’s eye appearance.10
Crohn’s disease affects the stomach and duodenum in 0.5% to 4.0% of patients.11
The antrum is the gastric region most frequently involved. Crohn’s
disease of the stomach leads to gastric deformity, causing a tubular
shape, conical narrowing, and limited distensibility of the stomach.12
These changes may give the stomach an unusual shape resembling the horn
of a ram (Figure 5). The presence of this gastric appearance in a young
patient without an established diagnosis of Crohn’s disease should lead
to a thorough workup to confirm or exclude the diagnosis.11
Leather bottle stomach
scirrhous adenocarcinoma of the stomach spreads predominantly in the
submucosa and muscularis propria. This type of tumor spread leads to a
marked desmoplastic reaction and a thickened, stiff gastric wall and a
narrow lumen.13 Scirrhous tumors constitute 5% to 15% of all gastric carcinomas.14 The stiff, nondistensible wall gives the stomach a leather bottle appearance,also known as linitis plastica (Figure 6).
Scirrhous adenocarcinoma is thought to arise near the pylorus and spread proximally.15
These tumors can eventually demonstrate diffuse involvement of the
entire stomach. Other patients occasionally demonstrate localized tumors
confined to the distal antrum.16
diagnoses for the appearance of a leather bottle stomach include
scirrhous metastases from lung, breast, colon, and pancreatic
carcinomas; lymphoma; or inflammatory conditions, such as Crohn’s
disease, sarcoidosis, and syphilis.
duodenal diverticulum is a rare congenital cause of duodenal
obstruction. Nelson first described the entity in 1947.17
These intraluminal diverticula are believed to arise from an improper
luminal recanalization of the foregut in the 7th week of embryogenesis. A
residual tissue diaphragm may span the entire circumference of the
duodenum and only allow passage of enteric contents through
The presence of these rare
diverticula can be seen on upper gastrointestinal series and MDCT scans
demonstrating the pathognomonic“windsock” sign. This windsock appearance
is most commonly located in the second portion of the duodenum and
consists of the barium-filled diverticulum that lies entirely within the
duodenum (Figure 7). The windsock appearance is formed by passive
elongation of the intraluminal diverticulum due to continual peristalsis
of the duodenum.18,19
Double bubble sign
“double bubble” sign represents the appearance of 2 gas-filled
structures in the upper abdomen of newborns and infants on plain filmsof
the abdomen (Figure 8). The left-sided, proximal bubble is the
distended gas and fluid-filled stomach. The second, right-sided, more
distal bubble is the distended duodenum.20,21
double bubble sign indicates the presence of duodenal obstruction that
can be caused by a number of intrinsic or extrinsic etiologies.The
intrinsic causes include duodenal webs, duodenal atresia, and duodenal
stenosis. The extrinsic etiologies include a preduodenal portal vein,
malrotation of the gut with a midgut volvulus or by Ladd bands, or an
Duodenal atresia is the causative
entity most commonly linked with a double bubble sign. Duodenal atresia
is found in 1 in 10,000 newborns and is typically associated with other
congenital anomalies; 30% of children with duodenal atresia have Down’s
“whirlpool” sign is found on both cross-sectional imaging as well as
abdominal ultrasound in the presence of midgut volvulus. The whirlpool
appearance represents the swirling pattern of the gut and the superior
mesenteric vein as they wrap around the superior mesenteric artery (SMA)
in a clockwise rotation (Figure 9).24
midgut undergoes a 270-degree, counterclockwise rotation during
embryologic development. Malrotation of the midgut represents a spectrum
of developmental anomalies that result in either an insufficient or
total lack of counterclockwise rotation of the midgut around the axis of
the SMA. These anomalies all lead to a shortened mesenteric base.25
The shortened mesentery predisposes to volvulus that may result in
bowel obstruction. Midgut volvulus is the most common complication of
malrotation of the small bowel in adults. It is the clockwise rotation
of the bowel loops that result in the whirlpool sign on cross-sectional
String of pearls
of pearls” sign indicates the presence of a small-bowel obstruction.
This sign is also commonly referred to as the “string of beads” sign. It
represents a row of small gas bubbles oriented in a relatively linear
fashion within the abdomen on plain films (Figure 10).26
observed rows of gas bubbles represent gas trapped between the valvulae
conniventes of the nondependent wall of small bowel. These loops of
small bowel are dilated and filled with fluid in the setting of a
small-bowel obstruction, thus the meniscal effect of the surrounding
fluid gives these pockets of gas a rounded or ovoid appearance. The
string of pearls sign can be seen in both upright and decubitus plain
radiographs in the setting of a small-bowel obstruction.27
Stack of coins
“stack of coins” sign typically indicates the presence of a small-bowel
hematoma. This sign is seen on plain films or MDCT images and
represents adjacent, thickened folds with sharp demarcation and crowding
of the valvulae conniventes (Figure 11).28
hematomas are being seen with increasing frequency due to the
prevalence of anticoagulation therapy. Over-anticoagulation with
warfarin is the most common cause of spontaneous intramural small-bowel
hematoma. Other causes that may lead to the stack of coins sign include
idiopathic thrombocytopenic purpura, leukemia, pancreatitis, pancreatic
cancer, hemophilia, lymphoma, myeloma, chemotherapy, and vasculidites.29
the setting of Crohn’s disease, the terminal ileum often becomes
markedly stenotic secondary to bowel-wall inflammation and fibrosis.This
results in the lumen of this portion of the small bowel resembling a
piece of string on plain radiographs after ingestion of high-density
oral contrast material (Figure 12).30
The string sign
represents the marked narrowing of the terminal ileum lumen secondary to
symmetric, transmural granulomatous inflammation and subsequent
fibrotic thickening of the bowel wall.31 Bowel-wall thickening is the most common manifestation of Crohn’s disease on MDCT scans, occurring in up to 82% of patients.32
lymphoid cells damage host tissues in graft-versus-host disease (GVHD).
The organs most commonly affected by GVHD include the gastrointestinal
tract, liver, and skin. Marked bowel-wall thickening can occur both in
the small and large bowel.33
performed with high-density oral contrast material in patients with
GVHD of the GI tract may demonstrate marked fold thickening, luminal
narrowing, separation of folds, and ultimately complete effacement of
the valvulae conniventes. The latter causes the so-called “ribbon sign”
(Figure 13).34,35 Colonic findings in GVHD include luminal
narrowing, wall thickening, and loss of haustration. Evaluation with
MDCT may demonstrate diffuse wall thickening and luminal narrowing of
both the small and large bowel.33
The ribbon bowel
appearance can also occur with multiple other clinical settings, such as
infection, irradiation, allergy, ischemia, ingestion of corrosives or
medications, amyloid, mastocytosis, lymphoma, Crohn disease, and celiac
- Sabharwal T, Cowling M, Dussek J, et al. Balloon dilatation for achalasia of the cardia: Experience in 76 patients. Radiology. 2002;224:719-724.
- Park W, Vaezi MF. Etiology and pathogenesis of achalasia: The current understanding. Am J Gastroenterol. 2005;100:1404-1414.
- Richter JE, Castell DO. Diffuse esophageal spasm: A reappraisal. Ann Intern Med. 1984;100:242-245.
- Chen YM, Ott DJ, Hewson EG, et al. Diffuse esophageal spasm: Radiographic and manometric correlation. Radiology.1989;170:807-810.
- Marks IN, Keet AD. Intramural rupture of the oesophagus. Br Med J. 1968;3:536-537.
- Eisenberg RL. Gastrointestinal radiology: A pattern approach. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2002:138-145.
- Chiu HH, Lee SY. Intramural dissection of the esophagus: Endoscopic findings. J Intern Med Taiwan. 2006;17:302-305.
- Dunnick NR, Harell GS, Parker BR. Multiple “bull’s-eye” lesions in gastric lymphoma. Am J Gastroenterol. 1976;126:965-969.
- Richey LE, Cooley RN. Kaposi’s sarcoma: The radiographic manifestations of involvement of the stomach. Gastroenterology.1963;44:195-198.
- Park SH, Han JK, Kim TK, et al. Unusual gastric tumors: Radiologic-pathologic correlation. Radiographics. 1999;19:1435-1446.
- Fielding JF, Toye DM, Beton DC, Cooke WT. Crohn’s disease of the stomach and duodenum. Gut. 1970;11:1001-1006.
- Farman J, Faegenburg D, Dallemand S, Chen CK. Crohn’s disease of the stomach: The “ram’s horn” sign. Am J Gastroenterol.1975;1:242-251.
- Levine MS, Kong V, Rubesin SE, et al. Scirrhous carcinoma of the stomach: Radiologic and endoscopic diagnosis. Radiology. 1990;175: 151-154.
- Moore JR. Gastric carcinoma: 30 year review. Can J Surg. 1986;29:25-28.
- Raskin MM. Some specific radiological findings and consideration of linitis plastica of the gastrointestinal tract. CRC Crit Rev Clin Radiol Nucl Med. 1976;8:87-105.
- Balthazar EJ, Rosenberg H, Davidian MM. Scirrhous carcinoma of the pyloric channel and distal antrum. AJR Am J Roentgenol.1980;134:669-673.
- Nelson WI. Congenital diaphragm of the duodenum: Case report with preoperative x-ray studies. Minn Med. 1947;30:745-752.
Johnston P, Desser TS, Bastidas JA, Harvin H. MDCT of intraluminal
“windsock” duodenal diverticulum with surgical correlation and
multiplanar reconstruction. Am J Gastroenterol. 2004;183:249-250.
F, Mortele KJ, Hesse U, et al. Giant intraluminal duodenal
diverticulum: Conventional barium study and computed tomography
findings. JBR-BTR. 2000;83:71-72.
- Traubici J. The double bubble sign. Radiology. 2001;220:463-464.
- De Backer AI, Mortele KJ, Ponomarenko N, De Keulenaer B. Images in clinical radiology. Double bubble sign in the newborn. JBR-BTR. 2003;86:306.
- Leonidas JC, Berdon W. The neonate and young infant: The gastrointestinal tract. In: Silverman FN, Kuhn JP, eds. Caffey’s Pediatric X-Ray Diagnosis. 9th ed. St Louis, Mo: Mosby; 1993:2048-2055.
- In: Rudolph AM, Hoffman JIE, Rudolph C. Rudolph’s Pediatrics. 20th ed. Stamford, CT: Appleton and Lange; 1996:1069.
- Epelman M. The whirlpool sign. Radiology. 2006;240:910-911.
- Bernstein SM, Russ PD. Midgut volvulus: A rare cause of acute abdomen in an adult patient. Am J Gastroenterol. 1998;171:639-641.
DD, Reyes BL, Harmon BH, et al. Reliability and role of plain film
radiography and CT in the diagnosis of small-bowel obstruction. Am J Gastroenterol. 1996;167:14511455.
- Nevitt PC. The string of pearls sign. Radiology. 2000;214:157-158.
- Lane MJ, Katz DS, Mindelzun RE, Jeffrey RB Jr. Spontaneous intramural small bowel haemorrhage: Importance of non-contrast CT. Clin Radiol. 1997;52:378-380.
- Abbas MA, Collins JM, Olden KW. Spontaneous intramural small-bowel hematoma: Imaging findings and outcome. Am J Gastroenterol.2002;179:1389-1394.
SW. Some interesting and unusual manifestations of Crohn’s disease
(“regional enteritis”) of the stomach, duodenum, and small intestine. Am J Roentgenol Radium Ther Nucl Med. 1969;107:86-101.
- Cotran RS, Kumar V, Robbins SL. Diseases of Immunity. In Schoen, FJ, ed. Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, Pa:W.B. Saunders; 1994:801-804.
- Goldberg HI, Gore RM, Margulis AR, et al. Computed tomography in the evaluation of Crohn disease. Am J Gastroenterol. 1983;140:277-282.
B, Kramer SS, Sara R, et al. Gastrointestinal inflammation after bone
marrow transplantation: Graft-versus-host disease or opportunistic
infection? Am J Gastroenterol. 1988;150:277-281.
- Jones B, Wall S. Gastrointestinal disease in the immunocompromised host. Radiol Clin North Am. 1992;30:555-577.
Kalantari BN, Mortele KJ, Cantisani V, et al. CT features with
pathologic correlation of acute gastrointestinal graft-versus-host
disease after bone marrow transplantation in adults. Am J Gastroenterol. 2003;181:1621-1625.
- Gramm HF, Vincent ME, Braver JM. Differential diagnosis of tubular small bowel. Curr Imaging.1990;2:62.