Plain abdominal radiography (plain abdominal radiography) is a radiographic examination modality also known as abdominal plain radiography (KUB). The term “plain abdominal radiography” refers to the absence of contrast medium. It is a native radiograph that can be obtained using film-slide combinations or as a digital radiograph. The abdominal voiding radiograph is used, among other things, in combination with abdominal sonography (ultrasound examination of the abdominal organs) as a diagnostic measure in acute abdomen (acute, usually life-threatening symptoms in the area of the abdomen/abdominal cavity), which is the most important indication. The findings of the abdominal voiding scan can be indicative for further diagnostics and therapy.
Indications (areas of application)
- Acute abdomen – symptom complex characterized by severe abdominal pain (abdominal pain, abdominal pain) and possible life-threatening.
- V. a. (Suspected) gastrointestinal perforation (gastrointestinal perforation).
- V. a. ileus (intestinal obstruction)
- Evidence of pathological calcifications
- V. a. a space-occupying lesion
- Localization of foreign bodies
- Before cholecystography (contrast imaging of the gallbladder and bile ducts).
- Before an i.v. pyelogram (contrast imaging of the urinary organs or urinary tract system).
- Elective (optional) before gastrointestinal examinations.
The procedure
The abdominal overview radiograph is taken while the patient is supine, standing, or in the left lateral position. The supine image is obtained with a. p. beam path (anterior posterior beam path – the X-rays penetrate the patient’s tissues from the front and are registered by the detector at their back). Various structures should be delineated on the abdominal plain radiograph:
- Musculus psoas major – This muscle presents as a sharp lateral border contour.
- Symphysis (pubic bone)
- (filled) urinary bladder
- Kidney shadow
- Liver shadow
- Spleen shadow
- Stomach bladder – This is visible in the upper left quadrant.
- Diaphragm
The abdominal overview image basically precedes any excretory urogram (i.v. pyelogram) and cholecystography (contrast imaging of the gallbladder). In addition, it is sometimes the basis for examinations of the gastrointestinal tract (gastrointestinal tract). The evaluation of the images usually takes place according to an orienting scheme that facilitates the preparation of the findings for the examining physician: A-B-D-O-M-E-N
- A – Air (free air?)
- B – Bones (texture of the skeleton?)
- D – Densities (shading? calcification? foreign bodies?)
- O – Organs (location, shape, and delineation?).
- M – Muscles and masses – (musculature and soft tissues? Displacements?)
- E – Edges (assessment of body parts not belonging to the abdomen?).
- N – Nitrogen (repetition: free air?)
When looking at the X-ray images, typical pathological phenomena can be found, which allow diagnostic conclusions:
- Calcifications (calcifications) – calcifications are found primarily as vascular calcifications (elongated, tubular form), for example, in the aorta (abdominal aorta) or as small phleboliths (calcified venous thrombi). In addition, calcifications can occur in various organs as signs of inflammation. Here are the calcifications of chronic pancreatitis (inflammation of the pancreas) and calcifications in the kidney as well as in the ureters, which indicate urolithiasis (kidney stone disease). Furthermore, gallbladder concretions or gallstones are clearly visible.
- Free air – Free air is present in perforations of the intestine, peritonitis (peritonitis), and ruptured abscesses (encapsulated collection of pus that has opened). Evidence of free air requires prompt emergency treatment of the patient. Perforation can result from an ulcer (e.g., ventriculi ulcer/stomach ulcer), perforating appendicitis (appendicitis with rupture of the intestinal wall), diverticulitis (disease of the large intestine in which inflammation forms in protrusions of the mucosa (diverticula)), or after laparascopic surgery (laparoscopy).The free air is visible as crescent-shaped brightenings below the diaphragm (diaphragm).
- Fluid levels – Fluid levels play a major role, especially in ileus diagnosis. In both the small intestine and the colon (large intestine), these indicate ileus (intestinal obstruction), which is a life-threatening situation.
- Free fluid – Free fluid indicates abscesses (pus cavities) or fistula formation.
- Gas in the intestinal wall – The causes of gas in the intestinal wall are the following: Abscesses, intestinal necrosis (dead intestinal tissue), trauma (injury), pneumatosis intestinalis (gas-containing cysts in the intestinal wall caused by gas-forming bacteria).
- Gas in the bile ducts – The most common cause of this is cholecystitis (gallbladder inflammation).
- Fuzzy psoas margin – This may indicate, for example, tumorous processes.
- Foreign body – For example, swallowed foreign bodies.