The comb sign is a radiological sign seen on computed tomography or magnetic resonance imaging scans, primarily used to identify inflammation in the mesentery. [1] It refers to the appearance of engorged mesenteric vessels resembling the teeth of a comb, which is a key feature seen in several abdominal conditions, particularly those associated with inflammatory bowel diseases, such as Crohn's disease. [2] This sign was first described by Dr. Morton Mayers. [3]
The comb sign is characterized by the appearance of dilated, prominent vessels in the mesentery of the abdomen, which appears similar to the teeth of a comb. These engorged vessels result from inflammation and increased blood flow in the mesenteric vessels, which is a common response to acute or chronic inflammatory conditions in the gastrointestinal tract. [2]
This sign is most often seen in patients with Crohn's disease but can also be associated with other conditions that cause mesenteric inflammation. [4]
The mesentery may appear thickened, and the mesenteric vessels (which supply blood to the intestines) become dilated and appear to resemble a comb. This sign is best seen in the small intestine or colon and can be associated with peripheral fat stranding or mesenteric fat changes indicative of active inflammation. This sign is helpful in determining the acutiy of the inflammatory process. [3]
Crohn's disease is a chronic inflammatory bowel disease characterized by recurrent episodes of intestinal inflammation, primarily manifesting as diarrhea and abdominal pain. Unlike ulcerative colitis, inflammation can occur anywhere in the gastrointestinal tract, though it most frequently affects the ileum and colon, involving all layers of the intestinal wall. Symptoms may be non-specific and progress gradually, often delaying diagnosis. About one-third of patients have colonic disease, another third have ileocolic disease, and the remaining third have isolated ileal disease. Systemic symptoms such as chronic fatigue, weight loss, and low-grade fevers are common. Organs such as the skin and joints can also be affected. Complications can include bowel obstructions, fistulas, nutrition problems, and an increased risk of intestinal cancers.
Ulcerative colitis (UC) is one of the two types of inflammatory bowel disease (IBD), with the other type being Crohn's disease. It is a long-term condition that results in inflammation and ulcers of the colon and rectum. The primary symptoms of active disease are abdominal pain and diarrhea mixed with blood (hematochezia). Weight loss, fever, and anemia may also occur. Often, symptoms come on slowly and can range from mild to severe. Symptoms typically occur intermittently with periods of no symptoms between flares. Complications may include abnormal dilation of the colon (megacolon), inflammation of the eye, joints, or liver, and colon cancer.
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion. The small intestine is about 5.5 metres long and folds many times to fit in the abdomen. Although it is longer than the large intestine, it is called the small intestine because it is narrower in diameter.
The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approximately 75% of total liver blood flow is through the portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins.
Bowel obstruction, also known as intestinal obstruction, is a mechanical or functional obstruction of the intestines which prevents the normal movement of the products of digestion. Either the small bowel or large bowel may be affected. Signs and symptoms include abdominal pain, vomiting, bloating and not passing gas. Mechanical obstruction is the cause of about 5 to 15% of cases of severe abdominal pain of sudden onset requiring admission to hospital.
Enteritis is inflammation of the small intestine. It is most commonly caused by food or drink contaminated with pathogenic microbes, such as Serratia, but may have other causes such as NSAIDs, radiation therapy as well as autoimmune conditions like coeliac disease. Symptoms include abdominal pain, cramping, diarrhoea, dehydration, and fever. Related diseases of the gastrointestinal system involve inflammation of the stomach and large intestine.
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 barium sulfate mixed with water, is ingested or instilled into the gastrointestinal tract, and X-rays are used to create radiographs of the regions of interest. The barium enhances the visibility of the relevant parts of the gastrointestinal tract by coating the inside wall of the tract and appearing white on the film. This in combination with other plain radiographs allows for the imaging of parts of the upper gastrointestinal tract such as the pharynx, larynx, esophagus, stomach, and small intestine such that the inside wall lining, size, shape, contour, and patency are visible to the examiner. With fluoroscopy, it is also possible to visualize the functional movement of examined organs such as swallowing, peristalsis, or sphincter closure. Depending on the organs to be examined, barium radiographs can be classified into "barium swallow", "barium meal", "barium follow-through", and "enteroclysis". To further enhance the quality of images, air or gas is sometimes introduced into the gastrointestinal tract in addition to barium, and this procedure is called double-contrast imaging. In this case the gas is referred to as the negative contrast medium. Traditionally the images produced with barium contrast are made with plain-film radiography, but computed tomography is also used in combination with barium contrast, in which case the procedure is called "CT enterography".
Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Since the abdomen contains most of the body's vital organs, it can be an indicator of a wide variety of diseases. Given that, approaching the examination of a person and planning of a differential diagnosis is extremely important.
In human anatomy, the mesentery, an organ that attaches the intestines to the posterior abdominal wall, comprises the double fold of the peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines.
Gastrointestinal diseases refer to diseases involving the gastrointestinal tract, namely the esophagus, stomach, small intestine, large intestine and rectum; and the accessory organs of digestion, the liver, gallbladder, and pancreas.
Toxic megacolon is an acute form of colonic distension. It is characterized by a very dilated colon (megacolon), accompanied by abdominal distension (bloating), and sometimes fever, abdominal pain, or shock.
A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction. Symptoms include abdominal pain, abdominal bloating, vomiting, constipation, and bloody stool. Onset of symptoms may be rapid or more gradual. The mesentery may become so tightly twisted that blood flow to part of the intestine is cut off, resulting in ischemic bowel. In this situation there may be fever or significant pain when the abdomen is touched.
Intestinal malrotation is a congenital anomaly of rotation of the midgut. It occurs during the first trimester as the fetal gut undergoes a complex series of growth and development. Malrotation can lead to a dangerous complication called volvulus, in which cases emergency surgery is indicated. Malrotation can refer to a spectrum of abnormal intestinal positioning, often including:
Lymphangiectasia, also known as "lymphangiectasis", is a pathologic dilation of lymph vessels. When it occurs in the intestines it is known as intestinal lymphangiectasia, colloquially recognized as Waldmann's disease in cases where there is no secondary cause. The primary defect lies in the inability of the lymphatic system to adequately drain lymph, resulting in its subsequent accumulation and leakage into the intestinal lumen. This condition, first described by Waldmann in 1961, is typically diagnosed in infancy or early childhood. However, it can also manifest in adults, exhibiting a broad spectrum of clinical symptoms.
Ischemic colitis is a medical condition in which inflammation and injury of the large intestine result from inadequate blood supply (ischemia). Although uncommon in the general population, ischemic colitis occurs with greater frequency in the elderly, and is the most common form of bowel ischemia. Causes of the reduced blood flow can include changes in the systemic circulation or local factors such as constriction of blood vessels or a blood clot. In most cases, no specific cause can be identified.
In the anatomy of humans and homologous primates, the descending colon is the part of the colon extending from the left colic flexure to the level of the iliac crest. The function of the descending colon in the digestive system is to store the remains of digested food that will be emptied into the rectum.
Bowel infarction or gangrenous bowel represents an irreversible injury to the intestine resulting from insufficient blood flow. It is considered a medical emergency because it can quickly result in life-threatening infection and death. Any cause of bowel ischemia, the earlier reversible form of injury, may ultimately lead to infarction if uncorrected. The causes of bowel ischemia or infarction include primary vascular causes and other causes of bowel obstruction.
Idiopathic sclerosing mesenteritis (ISM) is a rare disease of the small intestine, characterized by chronic inflammation and eventual fibrosis of the mesentery. It has also been called mesenteric lipodystrophy, or retractile mesenteritis.
Computed tomography enterography is a medical imaging technique which uses computed tomography scanner and contrast media to examine the small bowel. It was first introduced by Raptopoulos et al. in 1997. CT Enterography can be used to assess a variety of problems involving the small bowel, however it is mainly used to diagnose and assess severity of Crohn's disease.
The colon cut-off sign is a radiographic finding seen on abdominal radiographs and computed tomography scans. It is characterized by a marked dilatation of the transverse colon, with an abrupt transition to collapsed distal colon, particularly the splenic flexure. This sign is indicative of underlying pathology, most commonly acute pancreatitis.