SPLEEN ULTRASOUND TECHNIQUE
Category: Diagnostic Radiology
Abstract : spleen ultrasound technique : The spleen normally lies posterior to the splenic
flexure and stomach, making an anterior approach almost invariably unsuccessful
due to overlying bowel gas. The spleen should therefore be approached from the
left lateral aspect: coronal and transverse sections may be obtained with the
patient supine by using an intercostal approach. Gentle respiration
spleen ultrasound technique : The spleen normally lies posterior to the splenic
flexure and stomach, making an anterior approach almost invariably unsuccessful
due to overlying bowel gas. The spleen should therefore be approached from the
left lateral aspect: coronal and transverse sections may be obtained with the
patient supine by using an intercostal approach.
Gentle respiration is
frequently more successful than deep inspiration, as the latter brings the lung
bases downwards and may obscure a small spleen altogether. Lying the patient
decubitus, left side raised, may also be successful but sometimes has the effect
of causing the gas-filled bowel loops to rise to the left flank, once again
obscuring the spleen. A slightly posterior approach may overcome
this.
Ultrasound appearances
The normal spleen has a fine, homogeneous
texture, with smooth margins and a pointed inferior edge. It has similar
echogenicity to the liver but may be slightly hypo- or hyperechoic in some
subjects. Sound attenuation through the spleen is less than that through the
liver, requiring the operator to ‘flatten’ the time gain compensation controls
in order to maintain an even level of echoes throughout the organ. The main
splenic artery and vein and their branches may be demonstrated at the splenic
hilum.
The spleen provides an excellent acoustic window to the upper pole
of the left kidney, the left adrenal gland and the tail of the
pancreas.
Splenic variants
Spleen size and shape are both highly
variable, with a gradual age-related decrease in volume. A splenic length of
below 12 cm is generally considered normal, although this is subject to
variation in shape and the plane of measurement used. Rarely, the diaphragmatic
surface of the spleen may be lobulated, or even completely septated.
This
appearance may give rise to diagnostic uncertainty, and Doppler may be helpful
in establishing the vascular supply, and differentiating this from other masses
in the left upper quadrant (LUQ), or from scarring or infarction in the spleen.
The spleen may lie in an ectopic position, in the left flank or pelvis, or
posterior to the left kidney. The ectopic (or wandering) spleen is situated on a
long pedicle, allowing it to migrate within the abdomen.
The significance
of this rare condition is that the pedicle may twist, causing the patient to
present acutely with pain from splenic torsion. Ultrasound demonstrates the
enlarged, hypoechoic organ in the abdomen, with the absence of the spleen in its
normal position.
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