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Author: Shaina McQuilkie, D.C.
Abstract: Imaging techniques are commonly used to diagnose pathologies of the gastrointestinal (GI) system. Frequently used methodologies include X-rays, computed tomography (CT), barium contrast studies, magnetic resonance imaging (MRI) and ultrasonography (US). As technological advances are constantly being made, continual study regarding the proper utilization of such technologies is imperative. This article provides a continuing education activity for registered technologists (R.T.) with emphasis being placed on radiographic pathology of the gastrointestinal system including gastroesophageal reflux disease (GERD), hiatal hernia, gastroenteritis, small bowel obstruction (SBO), Crohn’s disease, appendicitis, diverticulitis, volvulus and intussusception.
This article was designed as a continuing education (CE) activity with focus being placed on the topic of radiographic pathology of the GI system. The participants will be able to describe imaging modalities and techniques that are frequently used for the diagnosis of different pathologies of the GI system. Participants will also be able to define several common GI system pathologies (GERD, hiatal hernia, gastroenteritis, SBO, Crohn’s disease, appendicitis, diverticulitis, volvulus and intussusception) that are typically diagnosed through radiographic techniques. Further, they will be able to identify typical signs and symptoms that are associated with each pathology. A technologist may benefit from an improved understanding of their main features and signs. This may help to decide on the choice of equipment, positioning, doses and technical settings that may optimize the visualisation of these diseases.
The digestive system is comprised of the gastrointestinal (GI) tract, liver, pancreas and gallbladder and runs from the mouth to the anus . The digestive tract is a series of hollow organs that are joined along a twisting tube from the mouth to the anus. The hollow organs that make up the GI tract include the mouth, esophagus, stomach, small intestine, large intestine and the anus; while the solid organs of the digestive system include the liver, pancreas and gall bladder . The digestive system helps to digest the food that an individual eats and is important for the breakdown of food into nutrients, which the body uses for energy, growth and cell repair .
Digestive disorders, including GERD, hiatal hernia, gastroenteritis, SBO, Crohn’s disease, appendicitis, diverticulitis, volvulus and intussusception affect the normal functioning of the GI tract. Digestive disorders affect millions of people around the world, which places a high burden on the healthcare and economic systems .
The role of imaging in the diagnosis of digestive diseases will become increasing popular with technological advancements. Various conventional imaging studies, including barium swallow, have been used to successfully characterize gastrointestinal pathology. However, newer technologies, including CT enteroclysis and MR enteroclysis have been recently introduced and are gaining popularity . CT enteroclysis is a hybrid technique that combines fluoroscopic intubation-infusion small-bowel examinations with that of abdominal CT . MR enteroclysis uses MRI to assess the small bowel after it has been distended with fluid that has been infused via a small catheter through the nose . Successful imaging strategy is dependent on using the most appropriate radiology technique to answer the right clinical questions . Various imaging techniques are available to help confirm diagnosis, localize lesions and masses their severity and inflammatory activity of digestive disorders as well as to identify the presence of complications and other entities that may require surgical intervention; these imaging techniques and how they relate to various GI disorders will be discussed in this article .
Gastroesophageal Reflux Disease (GERD)
GERD is a common chronic disorder of the upper gastrointestinal tract that is prevalent in many countries; in Western countries 10% to 20% of the population experiences weekly symptoms [4,5]. The number of GERD patients is increasing around the world [4,5]. Apart from the economic burden of the disease and its associated impact on a patient’s quality of life, GERD is the most common predisposing factor for adenocarcinoma of the esophagus . Adenocarcinoma represents the last of a sequence that starts with the development of GERD and progresses to metaplasia (Barrett’s esophagus), low-grade dysplasia, high-grade dysplasia and finally, adenocarcinoma .
GERD has been defined in the Montreal Consensus Report as a chronic condition that develops when the reflux of gastric contents into the esophagus in significant quantities causes troublesome symptoms, with or without mucosal erosion and/or relevant complications [6,7]. There are two pathophysiological states of GERD, which are categorized, based on endoscopy results: reflux esophagitis (RE) and non-erosive reflux disease (NERD)[4,5]. NERD patients are further sub-classified into three types based on the results of a 24-hour pH evaluation:
Type 1: patients with a demonstrated abnormal acid exposure time in a manner similar to patients with ER 
Type 2: patients with a demonstrated normal acid exposure time, but with symptoms and reflux events that are strongly correlated, suggesting acid hypersensitivity (the hypersensitive esophagus) 
Type 3: patients with typical reflux symptoms, but normal pH studies and no correlation between symptoms and acid exposure 
Symptoms and Diagnosis of GERD
Typical symptoms of GERD include heartburn and/or acid regurgitation [4,6]. Heartburn is defined as a burning sensation in the retrosternal area, whereas regurgitation is defined as the perception of flow or refluxed gastric contents into the mouth or hypopharynx .
Diagnosis of GERD may be evaluated with a patient history and physical exam, combined with upper GI endoscopy, esophageal manometry (a test that measures the rhythmic contractions of the esophagus when swallowing; also measures the co-ordination and force that is exerted by the muscles of the esophagus)and 24-hour pH monitoring .
Specific Radiologic Exams for GERD
While cross-sectional imaging techniques have made great advancements, the double-contrast barium swallow examination (BSE) remains the best imaging study for the evaluation of patients presenting with GERD [8,9]. The BSE documents the presence or absence of gastroesopohageal reflux and also detects complications including erosive esophagitis, stricture (transverse and longitudinal), hiatal hernia, Barrett’s esophagus, adenocarcinoma and dysmotility .
In the majority of patients with reflux disease, reflux is initiated by the transient collapse of lower esophageal sphincter (LOS) pressure. This results in the lower end of the esophagus being covered in gastric acid for a lengthy period of time. Patients may be symptomatic and have normal endoscopy findings; further, these patients will have no detectable abnormalities on a barium swallow examination . In patients with minor reflux disease, loss of appropriate LOS function results in symptoms of reflux and globus symptoms which are affected by anatomical and physiological abnormalities, including: prolonged fundal distension, sphincter shortening and repetitive transient LOS pressure collapse . In patients with advanced reflux disease, the LOS pressure is permanently low and symptoms are generally more severe; further, evidence of disease is visualized on endoscopic and barium examinations . Abnormalities that can be visualized include: free reflux, impaired primary peristalsis and poor clearance, abnormal esophageal contractions, scarring of the esophagus, strictures, Barrett esophagus and aspiration .
While plain chest x-ray findings are not useful in diagnosing GERD, they may be helpful in assessing pulmonary status and basic anatomy . Further, chest x-rays may demonstrate a hiatal hernia, which may be contributing to a patients symptoms .
At the present time, there is no role for CT, MRI or US in the routine evaluation of patients with GERD .
A hiatal hernia is a condition that results when the upper part of the stomach bulges through a tear or weakness in the diaphragm . Hiatal hernias are more common in individuals over the age of 50 and in those that are obese [12,13]. Hiatal hernias can be caused by various conditions, including 
- Injury to the area
- Being born with a large hiatus
- Persistent and forceful pressure on the surrounding musculature (i.e. coughing, vomiting or straining during a bowel movement or with heavy lifting)
There are two major types of hiatal hernias, which may co-exist. Approximately 90% of cases are sliding hiatal hernias (Type I) and the remaining 10% are rolling (para-esophageal) hiatal hernias . Para-esophageal hernias are further subcategorized into Type II, Type III and Type IV, which are outlined below.
A sliding hiatal hernia (Type I) is a type of hernia in which part of the stomach, along with the gastroesophageal junction (GOJ) protrudes upwards through the hiatus . A para-esophageal hernia (Type II) includes a peritoneal layer that forms a true hernia sac, which distinguishes it from the sliding hiatal hernia. Type III is another type of para-esophageal hernia and is a combination of types I and II. Type III hernias contain a displaced GOJ as well as a hernia sac containing portions of the fundus of the stomach protruding through the hiatus . Type IV is the last type of para-esophageal hernia and is characterized by displacement of the stomach and other organs (spleen, pancreas, colon and small bowel) into the thorax .
Symptoms and Diagnosis of Hiatal Hernia
A hiatal hernia on its’ own rarely causes symptoms; the majority of smaller hiatal hernias cause no signs and symptoms. [11-13]. Often hiatal hernia is diagnosed as an incidental finding when imaging is used to asses unrelated symptoms . However, larger hiatal hernias can cause GERD and can lead to symptoms including chest or abdominal pain, dry cough, heartburn which worsens with bending over or lying down and difficulty swallowing [11-13].
Hiatal hernia is classically diagnosed with endoscopy or barium esophagram. However, recent research has shown that high–resolution manometry (HRM) can be highly sensitive and specific for hiatal hernia detection, with a sensitivity of 92% and a specificity of 95%, which exceeds the sensitivity of endoscopy or radiography alone (both are 73% sensitive) .
Specific Radiologic Exams for Hiatal Hernia
In a patient with a sliding hiatal hernia, the GOJ will usually be displaced by greater than 2 cm above the hiatus and the oesophageal hiatus is often widened to 3-4cm (for reference, the upper limit of normal is 1.5cm) . The gastric fundus may be displaced above the diaphragm and be visualized as a retrocardiac mass on a chest x-ray. The presence of an air-fluid level in the mass suggests a diagnosis of sliding hiatal hernia .
Sliding hiatal hernia on HRM are manometrically characterized by an esophagogastric junction (EGJ) with partial or complete separation of the lower esophageal sphincter (LES) and crural diaphragm; with complete separation being associated with a significantly lower EGJ pressure .
In a patient with a rolling hiatal hernia, the GOJ remains in its’ normal location while a portion of the stomach herniates above the diaphragm . The mixed (compound) hiatal hernia (compound) is the most common type of rolling hiatal hernia and occurs when the GOJ is displaced into the thorax with a large portion of the stomach; further, this type of hernia is often abnormally rotated .
Acute gastroenteritis is a very common disorder that causes significant mortality in developing countries and a significant economic burden in developed countries . Acute gastroenteritis is extremely common in children and infants, with the Centers for Disease Control and Prevention (CDC) reporting that acute diarrhea among children in the United States being responsible for more than 1.5 million outpatient visits, 200,000 hospitalizations and approximately 300 deaths per year . In developing nations, acute gastroenteritis is a common cause of death in children under the age of five, accounting for an estimated 2 million deaths per year .
Viruses are responsible for approximately 70% of acute gastroenteritis cases in children. There are over 20 different types of viruses that have been identified that can cause acute gastroenteritis with rotavirus being one of the most studied of these viruses as it is the most common virus that causes this disease . Bacterial and parasitic infections can also cause gastroenteritis. Bacterial and parasitic gastroenteritis are often the result of poor sanitation, the lack of safe drinking water and contaminated food . Parasitic infections that commonly cause gastroenteritis are Giardia and Cryptosporidium .
Eosinophilic gastroenteritis (EG) is another type of gastroenteritis which is an uncommon condition that is characterized by diffuse infiltration of any or all layers of the gut wall by eosinophils [19,20]. EG has a slight male predominance and while it can affect individuals of any age, it typically appears in the 3rd to 5th decades of life . The cause of EG remains unknown; however atopy-related genes as well as inflammatory cells and mediators play a role in the disease. Patients often have a history of allergy, in particular food allergy, which is found in approximately 50% of case .
Symptoms and Diagnosis of Gastroenteritis
Gastroenteritis attacks the intestines and can cause signs and symptoms including watery diarrhea, abdominal cramps and pain, nausea and vomiting, occasional headache or muscle aches and/or low-grade fever . Depending on the causative agent, viral gastroenteritis symptoms may appear within one to three days after being infected and symptom severity can range from mild to severe. Often symptoms only last a day or two, however they can persist for up to 10 days .
Gastroenteritis is usually diagnosed based on patient symptoms, a physical examination and occasionally on the presence of similar cases in the community . A rapid stool test may be ordered to determine if the infective agent is either rotavirus or norovirus; however, there are no rapid tests to detect other viruses . If symptoms persist the diagnostic evaluation may also include blood tests, a hydrogen breath test or a barium enema of the bowel. Further, a colonoscopy or sigmoidoscopy may be performed .
may have various clinical presentations depending on the area of the GI tract that is involved and the depth of bowel wall involvement. Often, the disease involves the stomach and small bowel . Patients with the mucosal form of EG may present with symptoms such as vomiting, indigestion, abdominal pain, diarrhea, bloody stool, iron deficiency anemia, malabsorption, protein-losing enteropathy and failure to thrive . Patients with the muscularis form of EG may present with symptoms such as GI obstructive symptoms, which may mimic those seen with pyloric stenosis or gastric outlet syndrome . Lastly, patients presenting with the serosal form of EG (rare) may have symptoms such as significant bloating, exudative ascites and higher peripheral eosinophil counts . If EG is suspected based on a patients clinical presentation, the diagnosis is usually confirmed by an upper endoscopy and microscopy. .
Specific Radiologic Exams for Gastroenteritis
Radiographic imaging of a patient presenting with gastroenteritis symptoms, including abdominal pain is usually done to rule out more serious pathologies .
Radiographic features of EG on fluoroscopy may include :
- Eosinophilic esophagitis may show as a series of ring like structure and/or a smooth long segmental narrowing of the esophagus
- Gastrointestinal involvement, which usually involves the gastric antrum and proximal small intestine. Shows non-specific mucosal fold thickening and nodularity. When chronic, the antrum is narrowed and has a cobblestone mucosal appearance.
EG findings on CT are non-specific and may show GI wall thickening and submuscosal oedema .
Small Bowel Obstruction (SBO)
SBO is a clinical condition that is often initially diagnosed and managed in the emergency department [24,25]. SBO occurs when there is an obstacle to the flow of luminal contents caused by an intrinsic or extrinsic encroachment on the lumen . The early and accurate diagnosis of SBO is essential, especially in cases of strangulation as this can lead to bowel ischemia, necrosis and perforation .
In neonates the most common causes of SBO are atresia, midgut volvulus and meconium ileus. In infants the most common causes of SBO are groin hernia, intussusception and Meckel’s diverticulum. In young adults and adults, the most common causes of SBO are adhesions and groin hernia .
Symptoms and Diagnosis of SBO
Signs and symptoms that may be present in patients with a SBO include nausea, vomiting (associated with more proximal SBO), diarrhea (an early finding), constipation (a late finding) fever and tachycardia (late findings that may be associated with strangulation) , abdominal pain and abdominal distension if the obstruction is not in the proximal jejunum .
Diagnosis of SBO includes a patient history, physical exam, laboratory tests and imaging tests, including plain x-ray, enteroclysis, CT and/or US [24,26].
Specific Radiologic Exams for SBO
Abdominal x-rays should include at least two views, supine and upright . Abdominal x-rays are only approximately 50% to 60% sensitive for SBO, and are diagnostically more accurate in cases of simple SBO [26,27]. In most cases of SBO, plain radiographs of the abdomen will have the following features :
- Dilated loops of small bowel proximal to the obstruction
- Central dilated loops (predominantly)
- Three dilatations over 3cm
- Vavulae conniventes are visualized
- Fluid levels in upright studies
Further, SBO may present with the following features :
- A gasless abdomen
- The string of beads sign (small pockets of gas in the fluid filled small bowel)
Enteroclysis is valuable technique in detecting a SBO and in differentiating partial from complete blockages . This technique is useful in patients that have normal results on plain imaging in the presence of clinical signs and symptoms of SBO .
CT is more sensitive and can demonstrate the cause of SBO in approximately 80% of cases . CT is the study of choice in patients presenting with fever, tachycardia, localized abdominal pain and/or leucocytosis . Positive oral contrast is not usually needed for the diagnosis of SBO . CT shows the dilation of the proximal bowel and the collapse of the distal bowel .
Crohn’s disease belongs to a group of diseases called inflammatory bowel disease; it is a chronic inflammatory disease of the GI tract [28-30]. Crohn’s disease can affect any area of the GI tract, however it most commonly affects the small intestine and the beginning of the large intestine [28-30]. Crohn’s disease is commonly diagnosed between the ages of 15 and 25, with no gender predilection . The exact cause of Crohn’s disease remains unknown, however, researchers believe that autoimmune reactions, genes and the environment may play a role in the disease .
The disease is initially limited to the mucosa, with lymphoid hyperplasia, lymphedema and shallow aphthoid ulceration. As the disease progresses, the entire bowel wall becomes involved, which leads to liner longitudinal and circumferential ulcers that extend deep into the bowel wall, predisposing the patient to fistulae . Over time, inflammation extends into the mesentery and can lead to chronic fibrotic change as well as the formation of strictures . Other areas outside of the GI tract can become involved including the skin, joints, eyes, liver and biliary system, renal tract as well as the pulmonary system .
Symptoms and Diagnosis of Crohn’s Disease
The most common signs and symptoms of Crohn’s disease include diarrhea, abdominal cramping and pain, and weight loss [30,31].
Diagnosis of Crohn’s disease may include a medical and family history, physical examination, laboratory tests, upper GI series (barium swallow), CT scan and intestinal endoscopy .
Specific Radiologic Exams for Crohn’s Disease
The characteristic features of Crohn’s disease, which can be visualized with imaging, include the presence of skip lesions (discontinuous involvement of the bowel with intervening areas of normal bowel) . The frequency with which each part of the GI tract is affected by skip lesions varies dramatically. The small bowel is affected in 70% to 80% of cases, the small and large bowel are affected in 50% of cases and the large bowel only is affected in 15% to 20% of cases .
Barium swallow may show the following characteristics :
- Mucosal ulcers
- Widely separated loops of bowel
- Thickened folds due to edema
- Pseudo diverticula formation
- String sign (string like appearance of contrast filled bowel loop caused by severe narrowing of the bowel loop)
- Partial obstruction
CT may show the following characteristics :
- Fat halo sign (infiltration of the submucosa with fat, between the muscularis and the mucosa)
- Comb sign (hypervascular appearance of the mesentery)
- Bowel wall enhancement
- Bowel wall thickening (1-2 cm)
- Strictures and fistulae
- Mesenteric/intra-abdominal abscess or phlegmon formation
MRI enterography (MRE) is a useful technique for evaluating the bowel; inflamed loops of bowel show thickening and contrast enhancement . Other characteristics, which may be visualized on MRE, include :
- Fibrofatty proliferation (equivalent of fat halo sign seen on CT)
- Vascular engorgement (comb sign)
- Stenosis and strictures
Acute appendicitis is the most common indication for emergency abdominal surgery worldwide [32,33]. Appendicitis involves inflammation of the appendix . Delayed treatment can result in complications including the development of an inflammatory mass as well as appendix abscess or rupture with generalized peritonitis . Acute appendicitis is typically a disease that is seen in children and young adults, with a peak incidence in the 2nd to 3rd decades of life .
Appendicitis is often caused by obstruction of the appendiceal lumen, which results in a build-up of fluid, secondary infection, venous congestion, ischemia and necrosis. The obstruction can be caused by various factors including lymphoid hyperplasia, appendicolith, foreign bodies, Crohn’s disease and other rare causes such as a parasite or tumor .
Symptoms and Diagnosis of Appendicitis
Classical presentation of appendicitis is referred periumbilical pain, which within a day or so localizes to McBurney’s point (the point that lies 1/3 of the distance laterally on a line that is drawn from the umbilicus to the right anterior superior iliac spine (ASIS) and is associated with fever, nausea and vomiting [32,34]. However, this presentation is only seen in a minority of cases and is not helpful in the diagnosis of children who often present with nonspecific signs and symptoms .
General signs and symptoms of appendicitis include :
- Nausea and vomiting
- Localized pain and tenderness
Diagnosis of appendicitis may involve a patient history and physical examination, blood and urine tests and imaging tests such as x-ray, ultrasound or CT .
Specific Radiologic Exams for Appendicitis
A major challenge in regards to imaging the appendix, is locating it . Once correctly identifying its’ location, determining if its normal is relatively straightforward in most patients. The location of the base of the appendix is usually located between the ileocecal valve and the apex of the cecum in most patients. However, the location of the tip of the appendix varies, especially considering that the length of the appendix ranges widely among patients (2-20cm) . The distribution of various positions of the tip of the appendix has been identified as :
- Behind the cecum (ascending retrocecal): 65%
- Inferior to the cecum (subcaecal): 31%
- Behind the cecum (transverse retrocecal): 2%
- Anterior to the ileum (ascending paracecal preileal): 1%
- Posterior to the ileum (ascending paracecal retroileal): 0.5%
Plain film is often unable to give the diagnosis of appendicitis; rather it is useful in in identifying free gas and may show an appendicolith in 7% to 15% of cases . If an inflammatory phlegmon is present, cecal gas with be displaced and mural thickening may be visualized .
Ultrasound should be the study of choice in young patients because it is performed with no ionizing radiation. Unfortunately, the identification of a normal appendix is more problematic and in many patients, appendicitis cannot be ruled out with US. The US technique that is used is called graded compression and it uses a linear probe over the site of maximal thickness, with a gradual increase in pressure exerted to displace normal overlying bowel gas . Findings that may be found on US that are suggestive of acute appendicitis include :
- Aperistaltic, non-compressible, dilated appendix (>6 mm outer diameter)
- Distinct appendiceal wall layers
- Target appearance
- Periappendiceal fluid collection
- Echogenic prominent pericecal fat
CT is highly sensitive and specific for diagnosing acute appendicitis and can also be used to diagnose alternative causes of abdominal pain and tenderness [33,34]. The use of CT has helped to reduce the number of negative appendectomies . Findings that may be found on CT include :
- Dilated appendix with distended lumen (>6mm diameter)
- Thickened and enhanced wall
- Thickening of the cecal apex
- Periappendiceal inflammation
- Extraluminal fluid
- Inflammatory phlegmon
- Abscess formation
Diverticulosis is a condition that is characterized by the presence of diverticula, which are small pouches that bulge outwards through the colon. When these diverticula become inflamed or infected, diverticulitis results . Diverticulosis is one of the most common conditions in Western countries; however, only a fraction of affected patients will experience an episode of diverticulitis . Diverticulosis occurs in 5% to 10% of individuals over the age of 45 and in approximately 80% of individuals over the age of 85 . Diverticulitis is the result of obstruction of the neck of the diverticulum, with subsequent inflammation, perforation and infection . In the early stages of the disease, the inflammation and infection are contained by inflammatory phlegmon. However, the infection may progress to abscess formation and generalized peritonitis .
Diverticulitis is categorized as either uncomplicated or complicated diverticulitis. Uncomplicated diverticulitis involves localized diverticular inflammation. Conversely, complicated diverticulitis is diverticular inflammation that is associated with an abscess, phlegmon, fistula, obstruction, bleeding or perforation . Diverticulitis is a disease that ranges from isolated, mild, acute attacks to severe, recurrent disease .
Factors associated with diverticulosis include changes in colonic wall resistance, colonic motility and dietary issues (low fibre diet). There may also be a genetic factor for the development of diverticulosis . Risk factors associated with diverticulitis include the use of aspirin and non-steroidal anti-inflammatory drugs (NSAIDs), increasing age, obesity and a sedentary lifestyle .
Symptoms and Diagnosis of Diverticulitis
Patients with acute diverticulitis often present with left lower quadrant pain, tenderness, abdominal distension and fever [35,38]. Other symptoms that may be present include anorexia, constipation, nausea, diarrhea and dysuria [35,38].
Specific Radiologic Exams for Diverticulitis
CT is the modality of choice for the diagnosis of diverticulitis. Characteristics that are visualized on CT may include :
- Pericolic stranding
- Segmental thickening of the bowel wall
- Enhancement of the colonic wall (usually present as inner and outer high-attenuation layers combined with a thick middle layer of low attenuation)
- Diverticular perforation
- Abscess formation (may contain gas, fluid or a combination of both)
- Fistula formation (may be visualized as gas in the bladder or direct visualization of fistulous tract)
Colonic volvulus is the axial twisting of the colon on its vascular pedicle, which leads to a closed loop obstruction . Volvulus stops venous return and compromises arterial supply which leads to ischemia, which can result in necrosis of the intestinal wall, acidosis and death . The most common site of volvulus is the sigmoid colon (~75% of cases), followed by the cecum (~22% of cases). Rare sites of colonic volvulus include the transverse colon, occurring in about 2% of cases, and at the splenic flexure in about 1-2% of cases . Simultaneous volvulus of the transverse and cecum is rare .
Sigmoid volvulus is a leading cause of acute colonic obstruction in South America, Eastern Europe and Asia . Conversely, it is rare in developed countries such as the United States, United Kingdom, Japan and Australia . Sigmoid volvulus occurs when the sigmoid colon twists on the sigmoid mesocolon .
There are a number of causes of sigmoid volvulus including chronic constipation and/or laxative abuse, diet rich in fibre (especially in Africa), and Chagas disease (especially in South America) . Further, sigmoid volvulus has been associated with chronic neurological conditions, including Parkinson’s disease, multiple sclerosis and pseudobulbar palsy as well as with the use of medications for chronic psychiatric conditions .
Symptoms and Diagnosis of Volvulus
Clinical presentation of colonic volvulus is progressive abdominal pain combined with nausea and vomiting, rebound tenderness and obstipation (severe constipation) . The most common signs that are found on physical examination include abdominal distension and hypoactive or diminished bowel signs .
Diagnosis of volvulus may involve a patient history and physical examination and lab tests, as well as imaging studies including abdominal x-ray and CT-scan . Imaging will help to differentiate sigmoid volvulus from large bowel obstruction resulting from other causes, caecal volvulus and colonic pseudo-obstruction . Early diagnosis of acute volvulus may result in emergency surgical intervention .
Specific Radiologic Exams for Volvulus
Sigmoid volvulus is differentiated from cecal volvulus by its ahaustral wall as well as the lower end pointing towards the pelvis .
Abdominal x-ray may show a large, dilated loop of bowel, often with a few air-fluid levels. Specific signs associated with sigmoid volvulus include :
- Coffee bean sign (area of hyperlucency that resembles the shape of a coffee bean)
- Frimann Dahl’s sign (three dense lines converging towards the site of obstruction)
- Absent rectal gas
CT findings that may be seen in patients with sigmoid volvulus include [41,42]:
- large gas-filled loop without haustral markings (this forms a closed-loop obstruction)
- Whirl sign (twisting of the mesentery and mesenteric vessels)
- Beak sign
The role of fluoroscopy in the diagnosis of volvulus has diminished and it is now rarely used for the diagnosis of this condition. However, when it is used, a water-soluble contrast enema thoroughly demonstrates sigmoid volvulus with the appearance of a beak sign .
Intussusception is the invagination of one segment of intestine within a more distal segment [43-46]. Intussusception can occur in both children and adults; however, most cases occur in children and boys are affected four times more often than girls .
Intussusception is the most common cause of intestinal obstruction in young children, usually occurring between 4 and 10 months of age . In most infants, the intussusception involves the ileum invaginating through the ileocecal valve into the cecum . If the intussusception is not relieved, the vascular supply to the intestine may be compromised which can lead to intestinal ischemia and possible bowel perforation [43,44]. If intussusception is left untreated, it may be fatal . The cause of intussusception in children remains unknown; conditions that may lead to intussusception include viral infection, nodule on the lymph nose and/or polyp or tumor.
Intussusception in adults is rare and is often secondary to an underlying malignant neoplasm . Other causes of intussusception in adults include adenomatous polyps, inflammatory bowel disease, mycobacterial infection and surgical anastomoses .
Symptoms and Diagnosis of Intussusception
The first symptom of intussusception in children is often sudden, loud crying, which is the result of abdominal pain. The pain is intermittent but it comes often; further, it will get stronger and persist for a longer period of time each time it returns . An infant suffering from severe abdominal pain will sometimes pull their knees in towards their chest while crying . Other signs and symptoms that may be present in children with intussusception include :
- Palpable abdominal mass
- Bloody, mucus-like bowel movements
- Stool mixed with mucus and blood
Many children, with intussusception, present with atypical signs and symptoms. The classic triad consisting of abdominal pain, bloody stool and a palpable mass is present in less than 40% of cases .
Diagnosis of intussusception in children usually involves a patient history, physical examination and imaging tests. US is an ideal choice for low-risk patients as it does not use ionizing radiation; however, other imaging exams may be necessary including an abdominal x-ray, barium enema or abdominal CT [45,47].
Adults with intussusception have variable signs and symptoms. Adult patients may report symptoms including :
- Crampy abdominal pain
- Rectal bleeding (occasionally)
- Diarrhea and mucus (sigmoidrectal intussusceptions)
- Palpable abdominal mass (infrequent)
Accurate diagnosis of intussusception in adults is difficult. A history, physical examination and imaging including an abdominal and pelvic CT will help to accurately diagnosis this condition .
Specific Radiologic Exams for Intussusception
A plain film x-ray may show an elongated soft tissue mass, which is typically located in the right upper quadrant in children, with a bowel obstruction visualized proximal to it .
US is a reliable screening tool for children at a low risk for intussusception, findings include :
- Target sign (concentric alternating echogenic and hypoechogenic bands)
- Pseudokidney sign (longitudinal ultrasound appearance of the intussuscepted segment of bowel)
- Crescent in a doughnut sign (doughnut is formed by concentric alternating echogenic and hypoechogenic bands and the echogenic crescent is formed by mesentery that is dragged into the intussusception)
A barium enema is the gold standard for children presenting with classic signs of intussusception. However, if there is a perforation, a contrast enema is contraindicated. Intussusception will be visualized with contrast enema as an occluding mass that is prolapsing into the lumen. This gives the coiled spring appearance (barium in lumen of the intussusception and in the intraluminal space) .
Abdominal and pelvic CT is the preferred test of choice in adults with the advantage of detection of lead points and accurate localization of the lesion in adults presenting with acute abdomen [46,47]. The findings on CT are often pathognomonic and are dependent on the imaging plane and the location along the bowel where the images are obtained; findings include [46,47]:
- Bowel-within-a-bowel appearance (layers of the bowel are duplicated forming concentric rings when imaged at right angles to the lumen, and a soft tissue mass resembling a sausage when imaged longitudinally)
- Two concentric enhancing/hyperdense rings at the proximal end of the intussusception formed by the inner bowel and the folded edge of the outer bowel
- Mesentery will form a crescent of tissue around the compressed inner most lumen which will be surrounded by the two layers of the outer bowel
- Distal to the intussusception, the lead point may be visualized (if present)
The use of various imaging techniques is commonly used for the diagnosis of pathologies of the GI tract. This article has outlined common pathologies of the GI tract, including GERD, hiatal hernia, gastroenteritis, SBO, Crohn’s disease, appendicitis, diverticulitis, volvulus and intussusception. Participants should be able to define each of these conditions and identify common signs and symptoms that are associated with each. Further, participants should be able to identify specific radiographic exams and identify characteristics that are visualized on different techniques with each condition.
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