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Abdominal X-Rays

Plain radiographs continue to play a role in imaging of patients with acute abdominal pain. Upright chest radiographs can detect as little as 1 mL of air injected into the peritoneal cavity. Lateral decubitus abdominal radiographs can also detect pneumoperitoneum effectively in patients who cannot stand. As little as 5 to 10 mL of gas may be detected with this technique.
  1. Signs of Pneumoperitoneum on supine film are:
    1. Football sign (air dome)
    2. QRigler’s double wall sign (visualization of both sides of bowel wall)
    3. Saddlebag/mustache Cupola sign (air trapped below the central tendon of diaphragm)
    4. Doge’s cap sign (triangular collection of gas in Morrison’s pouch)
    5. Lucent liver sign
    6. Inverted ‘V’ sign (medial and lateral umbilical ligament visualization)
    7. Visualization of falciform ligament
    8. Urachus sign
    9. Right upper quadrant gas (perihepatic, subhepatic, Morrison’s pouch)
    10. Gas in scrotum (in children)
    11. Tell-tale triangle sign (air seen between bowel loops) on lateral horizontal beam film

A left lateral decubitus radiograph will almost always resolve the problem by demonstrating gas between the liver and the abdominal wall and is best view to visualize minimum free gas in abdomen. Radiographic technique is also important, and the patient should remain in position for 5 to 10 minutes before the horizontal ray so as to ensure that the free gas if present has had time to rise to the highest position.

However, with the advent of CT scan, as minimum as 1 ml of free air can be easily detected on CT scan, especially when viewed under lung window.Q

Although as little as 1 ml of free gas can be demonstrated radiographically, either in chest PA or a left lateral decubitus abdominal film, CT is superior to plain radiographs in detecting minute quantities of pneumoperitoneum.
CT is most sensitive investigation for detection of free intraperitoneal gas.

  1. Abdominal calcification:
    Plain films also show abnormal calcifications. About 5% of appendicoliths, 10% of gallstones, and 90% of renal stones contain sufficient amounts of calcium to be radiopaque. Pancreatic calcifications seen in many patients with chronic pancreatitis are visible on plain films, as are the calcifications in abdominal aortic aneurysms, visceral artery aneurysm, and atherosclerosis in visceral vessels.

Abdominal USG
  1. Abdominal ultrasonography is extremely accurate in detecting gallstones and in assessing gallbladder wall thickness and the presence of fluid around the gallbladder. 
  2. It is also good at determining the diameter of the extrahepatic and intrahepatic bile ducts. Its usefulness in detecting common bile duct stones is limited. Abdominal and transvaginal ultrasonography can aid in the detection of abnormalities of the ovaries, adnexa, and uterus.
  3. Ultrasound can also detect intraperitoneal fluid. The presence of abnormal amounts of intestinal air in most patients with an acute abdomen limits the ability of ultrasonography to evaluate the pancreas or other abdominal organs. There are important limits to the value of ultrasonography in the diagnosis of diseases that present as an acute abdomen.
  4. Because CT has become more widely available and less likely to be hindered by abdominal air, it is becoming the secondary imaging modality of choice in the patient with an acute abdomen, following plain abdominal radiographs.
  • Abdominal CT
  1. A number of studies have demonstrated the accuracy and utility of CT of the abdomen and pelvis in the evaluation of acute abdominal pain. Many of the most common causes of acute abdomen are readily identified by CT scanning, as are their complications. A notable example is appendicitis. .
  2. CT is also excellent in differentiating mechanical small bowel obstruction from paralytic ileus and can usually identify the transition point in mechanical obstruction. Some of the most difficult diagnostic dilemmas, including acute intestinal ischemia, can often be identified by this method.
  1. Barium swallow study
    Despite widespread application of endoscopy, barium studies still remain the primary imaging technique in suspected esophageal disorders, especially in cases of dysphagia. 
Extra Edge

Involvement (Feeble or absent peristalsis in) of the distal two-thirds i.e. smooth-muscle portion of the esophagus occurs characteristically in scleroderma but may be found also in other connective tissue disorders, esophagitis, presbyesophagus, alcoholism, diabetes, idiopathic intestinal pseudo-obstruction, myxedema, anticholinergic medication, and variants of achalasia.



  1. Tracheoesophageal fistula
    Contrast study of esophagus (water soluble low-osmolarity nonionic iodinated contrast agent is ideal) confirms the diagnosis. If simple swallow doesn't show the fistula, modification may be required in the form of contrast injection into NG tube with patient prone and as the tube (Rubber) is withdrawn the fistula is seen.
  2. Esophageal varices
    Varices are seen as Qserpiginous (worm-like) filling defects in the regular contour of esophagus in barium studies.
    Barium studies have largely been replaced by endoscopy.
  3. Hiatus hernia
    Examination of hiatal area requires the patient to be placed in prone/oblique position on a horizontal table and given a bolus of barium to swallow so there is maximal distension of hiatal segment.
    When looking for reflux during barium studies, the usual technique is to have the patient in a supine horizontal position and then slowly to lift left side off the couch while screening continuously.
    1. Epiphrenic bulge
    2. > 4 longitudinal coarse thick gastric folds above gastroesophageal junction or in the suprahiatal pouch
    3. Distance between B ring an hital margin >2 cm
    4. Peristalsis causes above hiatus
  1. Esophageal Motility Disorders
    1. Diffuse esophageal spasm
      Compartmentalization of esophagus by numerous tertiary contractions, i.e., episodes of pronounced abnormal motility occurs without cause, causing severe chest pain. The intermittent nature of the disorders makes it difficult to diagnose by Barium studies; 24 hours. QManometry is best diagnostic test. The tertiary contractions are nonpropulsive, uncoordinated and nonperistaltic and hence seen as intermitted 'riggles' along the wall of esophagus, as multiple simultaneous contraction rings, or as a segmented Barium column producing a "corkscrew," "rosary bead," or "curling" appearance. Q
    2. Achalasia cardia
      1. It is a motility disorder of esophagus, probably due to degeneration of myenteric plexus in gastroesophageal junction region, resulting in failure of relaxation of the gastroesophageal junction.
      2. CXR may reveal absent fundic bubble, areas of aspiration pneumonitis in lung fields and mediastinal air-fluid level.
      3. Earliest change seen on Barium study is defective distal peristalsis associated with a slight narrowing at G-E junction.
  • Features:
  1. QMegaesophagus/sigmoid esophagus
  2. Q"Bird beak" deformity
  3. Absence of primary peristalsis below level of cricopharyngeus
  4. Hurst phenomenon (temporary transit through cardia when hydrostatic pressure of barium column is above  LES pressure)
  5. Vigorous achalasia (numerous tertiary contractions in nondilated distal esophagus of early achalasia)
  6. QApart from pneumatic dilatation of affected segment, Heller’s operation is surgical treatment for achalasia

  1. Carcinoma Oesophagus
    Squamous cell carcinoma accounts for 65% of the malignant lesions of the esophagus.Q
    Adenocarcinomas are far less common.The great preponderance of these (59% to 86%) appears to arise from the metaplastic columnar epithelium of the Barrett esophagus.Q

  • Radiological features:
    1. Any stricture, mass lesion, ulcer, or mucosal irregularity of the esophagus must be viewed with suspicion of cancer. The classic radiologic patterns of esophageal carcinoma are annular constrictive, polypoid, infiltrative, and ulcerative.
    2. The most frequent presentation, the annular carcinoma or "applecore lesion," has sharp overhanging edges proximally and distally.
    3. "Rat-tail" esophagus, Shouldering sign are other common features.Q
    4. Endoscopic USG overcomes limitation of CT in assessing esophageal cancer.Q​
Barium study feature of few more esophageal diseases
  1. Tertiary esophageal contractions (presbyesophagus, diffuse V esophageal spasm, neuromuscular diseases)
    1. “Yo – Yo” motion of barium.
    2. "Corkscrew" appearance (scalloped configuration of barium column)
    3. "Rosary-bead/Shish kebab"  configuration (compartmentalization of barium column)
  2. Feline esophagus (transient contraction of 10ngitudinally oriented muscularis mucosa)
    1. Normal variant
    2. Gastroesophageal reflux disease
  3. Double-barrel esophagus
    1. Dissecting intramural hematoma
    2. Mallory- Weiss tear
    3. Intramural abscess
    4. Intraluminal diverticulum
  4. Candidal esophagitis
    1. Cobble stone mucosa
    2. Shaggy/fuzzy contour of the esophagus with small diffuse superficial ulcers
    3. Plaques
    4. Thickened mucosal folds
  5. Cytomegalovirus esophagitis
    1. Giant ovoid flat ulcers (vasculitis of submucosal vessels)
    2. Gastroesophageal junction with adjacent part of stomach is commonly affected.
  6. Herpes esophagitis
    1. Discrete superficial punctate/linear serpentine/stellate/diamond shaped ulcers
  7. Scleroderma
    1. Esophageal shortening
    2. Sliding hiatus hernia
    3. Hidebound esophagus

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