Plain Abdominal Radiography GIT Lecture 1 Dr. Abdullateef Albayati MD FCABMS

PRINCIPLE

Indications Suspected intestinal obstruction Perforation of the gastrointestinal tract Follow-up of urinary tract calculi Foreign bodies due to penetrating injuries or ingestion

How to look at a plain abdominal film Analyze the intestinal gas pattern Identify any dilated portion of the gastrointestinal tract Look for gas outside the lumen of the bowel If there are any calcifications, try to locate exactly where they lie Assess the size of the liver and spleen Look for ascites and soft tissue masses in the abdomen and pelvis

Positioning Supine AP Erect AP Lateral decubitus The main purpose of horizontal beam films is to detect air-fluid levels and free intraperitoneal air

RADIOGRAPHIC ANATOMY

Intestinal gas pattern Relatively large amounts of gas are usually present in the stomach and colon. The stomach can be readily identified by it's location, gastric rugae in the supine view and by the air fluid level beneath the left hemidiaphragm in the erect view The duodenum often contains air and show a fluid level Short fluid levels in the small and large bowel are normal.

Dilatation of the bowel Causes of bowel dilatation Mechanical SB obstruction : small bowel dilation with normal or reduced caliber of colon Mechanical LB obstruction: dilated colon down to the point of obstruction. May be accompanied by small bowel dilation if the ileocecal valve becomes incompetent Generalized paralytic ileus: SB and LB dilatation, gas may be present in the rectum Localized peritonitis: dilatation of loops adjacent to inflammatory process (sentinel loops) Closed loop obstruction : e.g. cecal and sigmoid volvulus Toxic dilatation of the colon: the dilatation is maximal in transverse colon more than 6 cm The haustra are lost or grossly abnormal . Ulcerative colitis is the commonest cause 7. SB infarction : mimic obstruction of SB or LB depending on distribution of ischemia

Dilatation of the bowel   Small bowel obstruction Large bowel obstruction Valvulae conniventes Present Absent Number of loops Many Few Distribution of loops Central Peripheral Haustra Diameter 3 – 5 cm More than 5 cm Radius of curvature Small Large Fecal material

SMALL INTESTINAL OBSTRUCTION

LARGE INTESTINAL OBSTRUCTION

Dilatation of the bowel

Dilatation of the bowel

Gas in the wall of the bowel Spherical or oval bubbles of gas are seen in wall of LB in adults in pneumatosis coli Linear streaks of intramural gas usually indicate infarction of the bowel wall Gas in the wall of bowel in neonates, whatever its shape, is diagnostic of necrotizing enterocolitis

Gas in the wall of the bowel

Pneumoperitoneum Defined as free gas in the peritoneal cavity The commonest cause is perforated peptic ulcer and two-thirds of such cases are recognizable radiologically Free intraperitoneal air is a normal finding after a laparotomy or laparoscopy. In adults, the air is usually absorbed within 7 days . In children, the air absorbs much faster ,usually within 24 hours. An increase in the amount of air on successive films indicates continuing leakage of air. Pneumoperitoneum under the right hemidiaphragm is usually easy to recognize, but free gas under the left hemidiaphragm is difficult to recognize because of the overlapping gas shadows of the stomach and splenic flexure. Gas under the diaphragm is much easier to diagnose on an erect chest film than on an upright abdominal film

Pneumoperitoneum

Pseudopneumoperitoneum Chilaiditi syndrome

Gas in an abscess It may form either small bubbles or larger collections of air , both of which could be confused with gas within the bowel. Fluid levels in abscesses may be seen on a horizontal x-ray film. Subphrenic abscess cause elevation of the diaphragm, pleural effusion and pulmonary collapse/consolidation Ultrasound and CT are extensively used to evaluate abdominal abscesses  

Gas in the biliary system

Gas in the portal vein

Tissue emphysema

Abdominal calcifications 1. Pelvic vein phleboliths: very common, may be mistaken for urinary stones & fecoliths 2. Calcified mesenteric LN: caused by old TB. They are irregular, very dense and mobile 3. Vascular calcification: e.g. aortic aneurysm which best assessed on lateral film 4. Uterine fibroids: irregular shaped well-defined calcifications conforming to the spherical outline of fibroids 5. Soft tissue calcification in buttocks following injection of certain medicines 6. Ovarian masses may contain calcification. Dermoid cyst may contain teeth 7. Adrenal calcification after adrenal haemorrhage & TB, also in tumor & Addison disease

Abdominal calcifications 8. Liver calcification: occur in hepatoma, hydatid cyst, abscess and TB 9. Gall stones 10. Splenic calcifications in cysts, infarcts, old hematomas and TB 11. Pancreatic calcification: occur in chronic pancreatitis & diagnosed from it's position 12. Faecoliths seen in colonic diverticulae or in the appendix. The presence of appendicolith is a strong indicator of acute appendicitis, often with perforation. 13. Renal stones and other calcifications of the urinary tract

Abdominal calcifications

Abdominal calcifications

Abdominal calcifications

Abdominal calcifications

Abdominal calcifications

Plain films of the liver and spleen Substantial enlargement of the liver has to occur before it can be recognized on a plain abdominal film. As the liver enlarges it extended well below the costal margin displacing the hepatic flexure, transverse colon and right kidney downwards and displacing the stomach to the left .The diaphragm may also be elevated Occasionly, there is a tongue-like extension of the right lobe into the right iliac fossa, this is a normal variant known as a "Reidl's lobe" and should not be confused with generalized liver enlargement. As the spleen enlarges, the tip become visible in the left upper quadrant below the lower ribs. Eventually, it may fill the left side of the abdomen and even extend across the midline into the right lower quadrant. The splenic flexure and the left kidney are displaced downwards and medially , and the stomach is displaced to the right.

Plain films of the liver and spleen

Ascites Plain films are of very limited value in the diagnosis of ascites Small amounts of ascites cannot be detected on plain films. Larger quantities separate the loops of bowel and displace the ascending and descending colon from fat stripes. SB loops float to the center of abdomen Ascites is more readily recognized with ultrasound or CT

Quiz Q.1 Appropriate x-ray for detection free peritoneal air is: Upright abdominal x-ray Supine abdominal x-ray Erect chest x-ray. Lateral decubitus abdominal x-ray Q. 2 all are true regarding toxic mega colon except: Ulcerative colitis is one of common causes. Defined as transverse colon diameter is exceeding 6 cm Barium edema is investigation of choice Haustra lost or decreased in number Q. 3 regarding plain abdominal x-ray; one is true Very sensitive in detection of ascites. Gall stone is visualized in 50% of cases. Cysteine renal stone is radio-lucent Spherical intramural bowel wall gas usually indicate infarction. Q. 4 diagnosis