String sign, or gastrointestinal string sign (also called string sign of Kantour), is a medical term for a radiographic finding on an
upper GI series
An upper gastrointestinal series, also called a barium swallow, barium study, or barium meal, is a series of radiographs used to examine the gastrointestinal tract for abnormalities. A contrast medium, usually a radiocontrast agent such as bari ...
, in which the patient is given a
radio-opaque
Radiodensity (or radiopacity) is opacity to the radio wave and X-ray portion of the electromagnetic spectrum: that is, the relative inability of those kinds of electromagnetic radiation to pass through a particular material. Radiolucency or hypod ...
material, such as barium, to drink.
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s are then taken of the patient's stomach and intestines.
The gastrointestinal string sign represents a severe narrowing of loop of bowel, in which a thin stripe of contrast within the lumen looks like a string.
It may be seen in
Crohn's disease
Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension ...
,
hypertrophic pyloric stenosis,
carcinoid tumor and
colon cancer
Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel mo ...
. In people with Crohn's Disease, the string sign is caused by incomplete filling of the intestinal lumen, which results from irritability and spasm associated with severe ulceration. In such cases, the string sign is most frequently seen at the terminal ileum.
In infants with hypertrophic pyloric stenosis, the pylorus is narrowed and the radio-opaque material will take on the appearance of a thin string as it passes through this narrowed channel. Often, there are several of these strings seen (called the "railroad track sign"). The use of the upper GI series for the diagnosis of HPS, which was the primary diagnostic tool for this condition in the 1980s and 1990s, has been largely replaced by the use of
ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, which is less invasive and can visualize the thickened pylorus, giving actual measurements of this thickening.
References
*"Nelson's Textbook of Pediatrics," Twelfth Edition. Richard Behrman, M.D. and Victor Vaughan, III, M.D. Editors, p. 904.
*Radiology 2007; 242:632– 633, 10.1148/radiol.2422041244
External links
radiopaedia. org
Gastroenterology