The abdominal aorta is the part of the aorta from the aortic hiatus of the diaphragm to the aortic bifurcation.

The abdominal aorta is located to the left of the inferior vena cava and runs down to the bifurcation where it splits into the two iliac arteries. The abdominal aorta descends anterior to the lumbar vertebral column.

The level of the bifurcation corresponds to the umbilicus.

Between the diaphragm and the bifurcation the abdominal aorta has some important branches.

Evaluation of pleural effusion corresponding to zone 3 on the right side of the thorax is performed by:

1. Placing the ultrasound transducer in the medioaxillary line at the lower limit of the right hemithorax
2. Identifying the liver
3. Moving the transducer cranially until the diaphragm is seen
4. Demonstrating or excluding the presence of a pleural effusion using:
– Presence or abscence of curtain sign?
– Presence or abscence of spine sign?

The principles for assessment of zone 5 are the same, the only difference being that the transducer is typically placed in the medioclavicular line at the posterior side of the chest

The focused question regarding pleural effusion is:

Is fluid present in the pleural space?

The question is answered by using ultrasound imaging for detection of an anechoic (black) area above the diaphragm on either the left or the right side of the lower, posterior part of the thorax

The patient must be in supine or sitting position, preferably with elevated thorax so that the fluid is moved down/back

Beware: Patients placed in the Trendelenburg position may not show fluid due to movement of fluid into the apical area of the lung

The videos recorded at the lower limit of the right side of the thorax show presence and absence of pleural effusion in two different patients

In the recording from the patient without pleural effusion (right), a black area is absent above the diaphragm and during inspiration the “curtain sign” is present

Presence of normal lung ultrasound signs and the “curtain sign” hiding the organs below the transducer during inspiration rule out pleural effusion.

The recording in the patient with pleural effusion (left) shows a black area above the diaphragm consistent with pleural effusion

No lung ultrasound signs are visible in the costophrenic recess, and no “curtain sign” is seen

Examination of the pleural sinus is performed in order to exclude or confirm the presence of pleural effusion

The examination involves three steps:

1. Find the abdominal reference point

A systematic approach will help:
– Place the probe beam parallel to the vertical plane

– Ensure that the orientation marker of the transducer is oriented cranially and that the corresponding orientation indicator is placed on the left side of the screen. (In this way the cranial end of the transducer is always displayed towards the left side of the monitor)

– Find the spleen

A systematic approach will help:

– Place the beam of the probe parallel to the vertical plane

– Ensure that the orientation marker of the transducer is oriented cranially, and that this side of the transducer corresponds to the left side of the ultrasound screen

In dynamic views B-lines move back and forth in synchrony with the lung sliding in real time

This video shows both

B-lines look different dependent on the transducer type used

The images show B-lines recorded with a curved array (abdominal) transducer and a phased array (cardiac) transducer