Abdominal X-ray - System and anatomy
Soft tissues

Key points

  • Abdominal X-rays provide a limited means of assessment of soft tissue structures

Although plain radiographs of the abdomen provide limited detail of the abdominal organs, occasionally a knowledge of their normal appearance will allow identification of abnormalities.

Soft tissue organs visible on abdominal X-rays include the liver, spleen, kidneys, psoas muscles, bladder (within pelvis), and lung bases (within thorax).

Liver on abdominal X-ray

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Liver on abdominal X-ray

  • The liver lies in the right upper quadrant (RUQ) and is seen as a bland area of grey on an abdominal X-ray.
  • The superior edge of the liver forms the right hemi-diaphragm contour (arrowhead).
  • In this patient the breast shadow (red line) overlies the liver, and markings of the right lung are visible behind the liver.
  • The gallbladder is only rarely visible on an abdominal X-ray. Its position is very variable. This patient has had a cholecystectomy. The clips mark the previous location of the gallbladder.

Lung bases on abdominal X-ray

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Lung bases on abdominal X-ray

  • The lung bases, which pass behind the liver and diaphragm in the posterior sulcus of the thorax, may be visible on some abdominal X-rays.
  • It is worth checking the lung bases as some patients with lung pathology present with abdominal symptoms.
  • If there is consolidation suspected from the abdominal X-ray then a review of the patient's respiratory system is necessary.
  • Costophrenic angle (asterisk)

Psoas edges on abdominal X-ray

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Psoas edges on abdominal X-ray

  • The psoas muscles (red) arise from the transverse processes of the lumbar vertebrae (arrowheads) and combine with the iliacus muscles. Together these powerful muscles form the iliopsoas tendon, which attaches to the lesser trochanter of the femur (asterisk). The iliopsoas muscles are the flexors of the hip.
  • An abdominal X-ray often demonstrates the lateral edge of the psoas muscles as a near straight line. The iliacus muscles are not visible, as they lie over the iliac bones of the pelvis.

Kidneys on abdominal X-ray

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Kidneys on abdominal X-ray

  • Natural contrast between the kidneys and the low density retroperitoneal fat that surrounds them means they are often visible on an X-ray of the abdomen.
  • They lie at the level of T12-L3 and lateral to the psoas muscles. The right kidney is usually slightly lower than the left due to the position of the liver.

Spleen on abdominal X-ray

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Spleen on abdominal X-ray

  • The spleen lies in the left upper quadrant immediately superior to the left kidney.

Bladder abdominal X-ray

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Bladder abdominal X-ray

  • The bladder has variable appearance depending on how full it is. It has the same density as other soft tissue structures, due to its water content.