Spleen Ultrasound Indication, Technique And Some Common Errors

The spleen is the largest lymphatic organ, normal size is variable; no universal consensus. Generally, a normal adult spleen is considered 12 cm length X 4 cm thickness X 7 cm width. (Functions) spleen manufactures lymphocytes, filters blood ( removes damaged red blood cells and platelets). It acts as a blood reservoir it can expand or contract in response to changes in blood volume.

9 Major indications of the spleen (scanning)

• Splenomegaly (enlarged spleen)
• Left abdominal mass
• Blunt abdominal trauma
• Left upper abdominal pain (an erect abdominal X-ray, including both sides of the diaphragm, is also needed if perforation of the bowel is suspected)
• A suspected sub-phrenic abscess (pyrexia of unknown origin)
• Jaundice combined with anemia
• Echinococcosis (hydatid disease)
• Ascites or localized intra-abdominal fluid
• Suspected malignancy, especially lymphoma or leukemia

Normal Spleen and its echo pattern?

When the spleen is normal in size, it can be difficult to image completely. The splenic hilus is the reference point to ensure correct identification of the spleen. Identify the hilus as the entry point for the splenic vessels.

The spleen should show a uniform homogeneous echo pattern. It is slightly less echogenic than the liver.

It is important to identify the:

1. Left hemidiaphragm.
2. Splenic hilus. 
3. Splenic veins and their relationship to the pancreas.
4. Left kidney (and renal/splenic relationship).
5. The left edge of the liver.
6. Pancreas.

It is important to identify the left diaphragm and the upper edge of the spleen.

Abnormal spleen 

(a) Enlarged spleen/splenomegaly

There are no absolute criteria for the size of the spleen on ultrasound. When normal, it is a little larger than or about the same size as the left kidney. The length should not exceed 15 cm on the major axis.

A chronically enlarged spleen may often distort and displace the left kidney, narrowing in both the anterior-posterior diameter and the width.

(b) Homogeneous splenomegaly

This may be due to:

• Tropical splenomegaly, which includes idiopathic splenomegaly, malaria, trypanosomiasis, leishmaniasis, and schistosomiasis.
• Sickle cell disease (unless infarcted).
• Portal hypertension.
• Leukemia.
• Metabolic disease.
• Lymphoma (may contain hyperechogenic masses).
• Infections such as rubella and mononucleosis.

Whenever there is splenomegaly, examine the liver for size and echogenicity. Also examine the splenic and portal veins, the inferior vena cava, hepatic veins, and mesentery for thickening. The region near the hilum of the spleen should be scanned for tubular structures due to varicosities

Preparation and position of patients 

1. The patient should take nothing by mouth for 8 hours preceding the examination. If the fluid is essential to prevent dehydration, only water should be given. If the symptoms are acute, proceed with the examination.
2. Infants- clinical condition permitting- should be given nothing by mouth for 3 hours preceding the examination.

For acutely ill patients (e.g. trauma, sudden abdominal pain, postsurgical pyrexia), no preparation is needed.

Position

• The patient should be supine initially and later on the right side.
• Apply coupling agent liberally over the left lower chest, the upper abdomen, and the left flank.
• The patient should take a deep breath and hold it in when a specific area is being scanned.

Choice of transducer and scanning technique

• For adults, use a 3.5 MHz sector transducer. For children and thin adults, use a 5 MHz sector transducer. A small sector transducer is helpful, if available.
• Setting the correct gain- Start by placing the transducer centrally at the top of the abdomen (the xiphoid angle). Angle the beam to the right side of the patient to image the liver.; adjust the gain to obtain the best image. 

Scanning technique of the Spleen ultrasonography;

Scan with the patient in the supine and oblique positions. Multiple scans may be necessary.

Scan from below the costal margin, angling the beam towards the diaphragm, then in the ninth intercostal space, first with the patient supine and then with the patient lying obliquely (30 degrees) on the right side. 

Also, perform longitudinal scans from anterior to posterior axillary lines and transverse upper abdominal scans. Scan the liver also, particularly when the spleen is enlarged.

  

Video reference: 👇👇

Gulfcoast Ultrasound Institute

Common errors during spleen ultrasound

The following may be mistaken for splenic lesions:

• A kidney lesion.
• The tail of the pancreas.
• Adrenal tumors.
• The stomach.

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Identify these lesion organs before looking at the spleen.