2.1. Preparation

A full clinical  history and physical examination are mandatory prior to any ultrasound examination.   With respect to the scanning time, any time is sono-time. Specific preparation of the patient is not necessary but generally the fasting state is preferable for examination of the gall bladder.

2.2. Technique

Realtime ultrasound scanning of the abdomen (or any other regions or organs) is a dynamic procedure which requires an element of handicraft or manipulative skill and of course an element of intelligence and some - not too much - imagination related to interpretation. The latter will be described in more a detail under 4.General Considerations.

For the first element the probe must be applied to the skin with the aim of the best visualising  all abdominal organs not only according to a number of general criteria (shape, size, position, diameter of tubular structures etc), but also with respect to their inner structure: presence of calculi or masses in fluid filled organs; vascular architecture, over all reflectability and presence or absence of focal lesions in parenchymatous organs.  Cognisance must also be taken of  active (pulsatory) or passive - respiratory, palpatory - movements or pain sensations, respectively.

The organ/region of interest is visualized best in the shortest possible distance to the skin surface: the aorta and vena cava are best seen in the midline or slightly to the right (as seen from the patient), the liver under the right costal margin and so on.

Respiratory movements are helpful to obtain a better view of organs which are hidden by the ribs, and in addition, by placing the patient in left or right lateral positions, optimum visualization of e.g. the right liver lobe or the pancreatic tail region may be obtained. This positioning should be done as part of the routine  and systematic scanning of all organs and regions of the abdomen.

We recommend following a set pattern to abdominal ultrasound scanning with examination of the great vessels, the pancreas, the liver including its vascular structures at the hilum and the gallbladder, both kidneys, the spleen, and the pelvis.

The ultrasound probe with its freely variable scanning plane can produce sectional slices from any portion of the organ of interest; part of the more intellectual aspect of ultrasound examination is the addition of these freely reproducible two dimensional slices into a realtime three dimensional picture. For beginners, finding the organs and adding the slices is easy once big parts of the organ are visible on the screen. This is particularly  true when the sanning plane is the same as the maximum axis of the organ/region examined. Zooming the picture is helpful for looking at the more detailed structures, making use of the unequaled high resolution capacity of ultrasound especially in parenchymatous organs.

2.3. Sequence of scanning

Figure 2. Topographical anatomy of the abdomen 1 common hepatic bile duct, 2 celiac trunc, 3 superior mesenteric artery,      4 superior mesenteric vein,      5 aorta,      6 inferior vena cava

 

The axis of the aorta and the inferior vena cava  is longitudinal (to the body axis).

  The first abdominal scans should therefore comprise a series of midline-longitudinal sections. Variations in the course of the vessels -  e.g. in ectasia of the aorta  or in severe kyphoscoliosis - must  automatically lead to adaptive variations in the scanning probes position or appropriate angulation to achieve optimal slices from these vessels.

 

1st scans 1 aorta, 2 celiac axis, 3 superior mesenteric artery, 4 splenic vein, 5 pancreas, 6 gastric antrum, 7 left renal vein

 

	1st scans 1 hepatic artery 2 celiac axis 3 superior mesenteri artery 4 left kidney vein
	1st scans 1 abdominal wall, 2 intestine (slightly compressed), 3 iliac artery, 4 iliac vein
	1st scans  1 liver, 1c caudate lobe, 2 inferior cava, 3 superior mesenteric vein, 4 pancreas 4u uncinate process, 5 fatty tissue (part of omentum), 6 layers of the abdominal wall, 7 gastric antrum, 8 intestine (“panorama view“)
	1st scans   1 hepatic artery, 2 inferior cava, 3 right hepatic artery, 4 confluens (junction splenic vein+5), 5 superior mesenteric vein, 6 pancreas, 7 gastric antrum, 8  intestine (duodenum?)
	1st scans   1 liver, 2 vena portae 3 right renal artery 4 vertebral body 5 inferior vena cava 6 diaphragma

The second scanning sweeps - to demonstrate the pancreas and adjacent structures - are transverse  to the body axis (preferably high in the epigastrium) since the main axis of this organ is a transverse one with a tendency for the tail region to lie in the upper left abdomen.

2nd scans   1 vena portae, 2 inferior cava, 3 aorta, 4 celiac axis, 5 splenic artery, 6 hepatic artery, 7 liver

	2nd scans   1 pancreas - h head, u uncinatus, b body,  2 confluens - p portal vein, s splenic vein junction; 3 splenic vein, 4 celiac axis (trunk), 5 inferior cava, 6 right renal artery, 7 aorta, 8 left renal vein,
	2nd scans 1 liver, 2 anterior gastric wall, 3 gastric lumen, 4 posterior gastric wall, 5 right renal artery, 6  common bile duct, 7 cava inferior, 8 pancreas - h head, b body, t tail, 9 splenic vein, 10 left renal vein, 11 superior mesenteric artery, 12 aorta, 13 vertebral body
	2nd scans 1 liver ; 2 pancreas - h head, b body,           t tail; 3 splenic vein, 4 superior mesenteric artery, 5 cava inferior (inspiration), 6 aorta, 7 gastric wall
	2nd scans 1 liver, p peripheral portal vein brnching, 2 pancreas, 3 main pancreatic dutrunc, 4 common bile duct, 5 confluens, 6 splenic vein
	2nd scans 1 liver, 2 gastric a anterior, p posterior wall, 3 pancreas, 4 confluens, 5 duodenal C, 6 cava inferior
	2nd scans 1 pancreas, 2 cava inferior, 3 vertebral body, 4 aorta, 5 left renal vein, 6 confluens

Third, the main axis of the liver is oblique or transverse in the right upper abdomen with the organ best seen in  deep inspiration rather than in expiration. The position of the probe should be parallel to the right costal margin with the scanning planes angulated steeply upwards (subcostal sections). This allows for a careful study  of the liver tissue in multiple parallel sections which represent (once scanning is performed slowly) slices of two-three mm in thickness only. These scanning planes will find the gallbladder more or less rectangular to its longitudinal axis; therefore, the fourth scanning sweeps are more  appropriate for the study of this organ and the liver hilum.

With the fourth scannings - the right lateral in a left oblique position, the right arm over the head -  covers the long axis of right liver lobe, liver hilum, gallbladder and right kidney. Again, variations according to  individual anatomy in a given patient will lead to adaptive variations in scanning sweeps and in respiratory manoeuvers.

The fifth scanning planes are the left lateral - the patient in a right oblique position, with the left arm elevated over the head - for scanning of the spleen, the pancreatic tail, and the left kidney.

In a final series of sections, the pelvis is studied in both longitudinal, transverse and oblique scans in order to visualise urinary bladder, iliac vessels, and genitals.

The scanning probe is not a bulldozer and should always be handled gently and pressure applied only when it is intended to push away disturbing intestinal gas formations or when a combination of visualization plus palpation with the probe is intended (e.g. to exclude a thrombosis in the femoral vein). Ultrasound guided palpation of all organs visualized will give important information regarding the consistency of the organ  and  localization of pain secondary to an inflammatory process (as e.g. in acute cholecystitis). This possibility of “touching” an organ under direct vision is often undervalued by non-clinicians.