2: Introduction and Focused Questions

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1.5 Ultrasound Artifacts

The operator should be especially knowledgeable of the sonographic artifacts that

can mislead him/her. Nevertheless, some artifacts are useful for diagnosing different

conditions. The most common artifacts seen are as follows.

Shadow artifact and posterior enhancement : Ultrasound will not be able to

image what is behind a solid structure (like the ribs) causing a shadow artifact

(Fig. 1.10 ). The shadow artifact is occasionally useful, for example, in detecting

Pitfalls

1. Having a wrong orientation of the transducer especially when performing

interventional ultrasound.

2. Using high gain when looking for pelvic ﬂ uid in Douglas pouch.

3. Starting with superﬁ cial limited depth when looking for deep intraperitoneal

ﬂ uid.

4. Judging quickly that a B mode study is negative. B mode is only a

two- dimensional image of less than 1 mm thick. You should have a three-

dimensional orientation.

Shadows

Liver

Fig. 1.10 Ultrasound will not be able to image what is behind a solid structure like the rib. This

will cause a shadow artifact ( S ) behind the ribs

1 Basic Ultrasound Physics, Instrumentation, and Knobology

gallstones (Fig. 1.11 ). The posterior enhancement may occur when imaging ﬂ uid-

ﬁ lled structures. More ultrasound waves will penetrate ﬂ uid-ﬁ lled structures, like

the gallbladder and urinary bladder, and a white enhancement area will appear

behind them compared with adjacent tissues. Small amount of pelvic ﬂ uid can be

missed in Douglas Pouch if the gain was high. It is important to use the proper gain

once looking for pelvic ﬂ uid , otherwise it can be missed.

Edge artifact : The edge artifact occurs when a beam of ultrasound refracts at the

edge of a rounded structure like the urinary bladder and kidney (Fig. 1.12 ). This

Liver

Posterior enhancement

Fig. 1.11 Gallstones within the gallbladder ( GB ) causing shadow artifact behind them. The posterior

enhancement is shown on both sides of the shadow artifact

Urinary

bladder

Edge artifact

Fig. 1.12 Edge artifact caused by refraction of the ultrasound at the edge of the urinary bladder

F.M . A b u-Zidan

should not be misinterpreted as intraperitoneal ﬂ uid. This artifact will change by

changing the angle of the probe.

Mirror artifact : High acoustic impedance tissues like the diaphragm or the pelvic

ﬂ oor work like a mirror reﬂ ecting sonographic waves by an angle. Similar to a real

mirror, the mirror artifact will show as a virtual object (Fig. 1.13 ). The mirror effect

is a normal artifact in RUQ view: it disappears in case of pleural effusion. Ultrasound

artifacts are useful in diagnosing gall stones (Fig. 1.2 ) and in showing the normal

sonographic lung characteristics (Fig. 1.14 ).

Reverberation artifact : Reverberation artifact occurs when ultrasound bounces

between two interfaces, especially with high acoustic impedance like the pleura.

The waves will move forward and backward between these interfaces. The machine

will recognize these waves as parallel lines with equal distances between them and

decreased density for the deeper lines, because the reﬂ ected waves become gradually

less (Fig.

1.14 ).

1. You should be careful not to interpret the mirror artifact of the urinary bladder as

a pelvic ﬂ uid.

2. You should be careful not to interpret a rib shadow or edge artifact as intraperi-

toneal ﬂ uid.

In summary the operator should be familiar with basic physics of ultrasound and

know their ultrasound machine, the type of probes used, how to control its outcome,

and, more importantly, how to correlate sonographic ﬁ ndings with clinical ﬁ ndings

so as to maximize ultrasound beneﬁ t.

Mirror

artifact

Mirror plane

Urinary

bladder

Fig. 1.13 Sagittal section of the pelvis showing a mirror artifact of the urinary bladder mimicking

a ﬂ uid collection

1 Basic Ultrasound Physics, Instrumentation, and Knobology

Fig. 1.14 Reverberation artifact of the lung occurs as ultrasound waves bounce between the trans-

ducer and the pleura ( head arrow ). The reverberation lines ( arrows ) are called A lines, represent-

ing “repetition” of the pleural line. The distances between these lines are equal

Remember!

• “The right side of the patient on the right side of the screen” (transversal)

• “The upper part of the patient on the right side of the screen” (sagittal or

coronal)

• The key buttons of an US machine are ( ﬁ ll yourself – look at pages 7 and

8 of this chapter )

1. _______________________________

2. ___________& TGC _____________

3. ______________________________

4. __B-________/ -mode____________

5. ____________________________

6. ______________________________

• Artifacts are not always enemies

F.M . A b u-Zidan

Introduction and Focused Questions

Mauro Zago

• How is the physiology of my patient? And anatomy?

• Does my patient require US?

• Could I better understand/anticipate physiologic derangements in this

patient by EFAST?

Doubting the appropriateness of US might be surprising in a US manual, but

indeed in major trauma patients even a few minutes are lifesaving, and all proce-

dures that are not strictly necessary should be avoided, unless they could really

change the clinical decision.

Any ﬂ ow chart should start from the patient physiology and not from the US

ﬁ ndings .

The immediate identiﬁ cation of the so-called hemodynamic instability is a clini-

cal prerequisite.

It is an information you can get in a few seconds (RTS score, on the scene hypo-

tension, vital parameters on road and at arrival, etc.), and anticipates the following

steps if damage control resuscitation is required. We recommend you to be exces-

sively careful in starting by this key point. Sort the US probe from your pocket

immediately after.

Finally, you have the probe in your hands.

Your aim is to identify free ﬂ uid and air and to correlate the US ﬁ ndings with the

patient status.

You must ﬁ rst discover signs of two main killers: hemorrhage and pneumothorax.

Simple questions, simple binary answers!

Wherever and whenever during the primary and secondary survey, the EFAST

exam is for answering only these questions.

Every other adjunctive ﬁ nding observed on the screen (for instance, dishomoge-

neous spleen suspected for rupture) could be for sure “taken into account,” but we

cannot forget to remain simple in the reasoning.

This is the only way to be adherent to the master law: “clinical decision before

deﬁ nitive diagnosis.”

The three EFAST key questions depicted in the box above help you in answering

the basic clinical questions: becomes.

Is there

In other words, you need to understand, for example, if the amount of blood you

found in the abdomen justiﬁ es the shock in your patient. You might assess it using

simple scores.

• Is there free ﬂ uid in the abdomen ? Yes ◻ No ◻

• Is there free ﬂ uid in the thorax ? Yes ◻ No ◻

• Is there free air in the chest ? Yes ◻ No ◻

• A hemoperitoneum?

• A hemothorax?

• A pericardial effusion? Is it a cardiac tamponade?

• A pneumothorax?

• Do the US ﬁ ndings correlate with the patient status ?

M. Zago

Or you would like to quickly answer to the following questions:

• Hemorrhagic? → Where?

• Nonhemorrhagic? → Where is the cause of shock?

EFAST is an effective tool for ruling in/ruling out some of the hemorrhagic/

nonhemorrhagic causes of shock: hemoperitoneum, hemothorax, tension pneumo-

thorax (if not already clinically detected and treated), and cardiac tamponade.

Imagine a less emergent situation: a young female sustained a blunt abdominal

trauma, she is hemodynamically normal and stable, and you found a little amount of

ﬂ uid in the abdomen.

There is a slight abdominal pain in the RLQ on physical examination.

CT (when available) showed no solid organ injuries and minimal amount of ﬂ uid

in right iliac fossa.

“ Might it may be a hollow viscus lesion or not ? Operation ? Observation ?

Literature allows both options ….”

Could US help you ?

Maybe yes, with a US-guided diagnostic peritoneal aspiration (DPA):

• Bile → Operation

• Blood → It depends!

• Clear ﬂ uid → Physiologic peritoneal ﬂ uid in childbearing age females

In other chapters (Algorithms), you will ﬁ nd some examples of US-driven sug-

gested management of trauma cases and test yourself.

EFAST has certainly some limits and pitfalls, and it really not always solves the

problem: be aware about that, go ahead with your clinical reasoning like as you

don’t have US, and ask your team and if needed for a help!

Having clear questions in mind is mandatory for getting the best clinical result

from EFAST.

Your US performance is important, but more important is to take the right clini-

cal decision: that is why you have decided to read this book! Frequently, “unsatis-

factory” or “doubtful” exams can help your decision-making process.

Even in more advanced application of US in trauma patients (ABCDE-FAST,

interventional maneuvers, monitoring of shock, CEUS-FAST, etc.), surgeon should

always ask himself/herself if and what US can add to decision-making process: Can

US help me? Can US shorten the time to deﬁ nitive treatment? Can US change my

diagnostic algorithm?

Remember!

• Assess physiology and anatomy ﬁ rst

• Basic US questions (liquid? air?)

• Clear clinical questions (according to the patient status)

• Link EFAST ﬁ ndings to your clinical reasoning

2 Introduction and Focused Questions

M. Zago (ed.), Essential US for Trauma: E-FAST, Ultrasound for Acute Care Surgeons,

3.1 Introduction

Trauma care has evolved all over the world with more efﬁ cient integrated emer-

gency medical systems. Many of these systems are achieving lower mortality rates

comparatively to the past because of expeditious trauma management that starts

immediately on scene all the way to the trauma resuscitation bay often extending

into the operating room.

The approach to these patients requires dedicated surgeons that must determine

the extent of injuries in minutes with E-FAST (extended focused assessment with

sonography for trauma) and decide if a patient is bleeding and from which body com-

partment. This may diminish time to deﬁ nitive care (operating/angiography suite)

with possible improvements in length of stay, lower cost of hospitalization, morbidity,

and mortality if deﬁ nitive surgical trauma care (DSTC) is accordingly executed.

E-FAST is most useful in the emergency room for the patient who is too hemo-

dynamically unstable to perform a CT exam. This modality has proven to decrease

the number of nontherapeutic laparotomies because it decreases the need for a

F. Ferreira , MD (*)

Emergency and Trauma Surgery, Upper Gastrointestinal Surgery Unit,

Department of Surgery, U.L.S. – Matosinhos, E.P.E. , Pedro Hispano Hospital ,

Rua Dr. Eduardo Torres , Senhora da Hora 4464-513 , Portugal

The Faculty of Medicine , University of Oporto, Porto , Portugal

e-mail:

med1873@gmail.com

E. T. Barbosa , MD, MSc • A. R. Silva , MD

Emergency and Trauma Surgery, Colorectal Surgery Unit, Department of Surgery,

U.L.S. – Matosinhos, E.P.E. , Pedro Hispano Hospital ,

Rua Dr. Eduardo Torres , Senhora da Hora 4464-513 , Portugal

The Faculty of Medicine , University of Oporto, Porto , Portugal

e-mail:

evatamar@gmail.com; rs31785@gmail.com

Abdominal Views: Technique,

Anatomy, Abnormal Images,

Scanning Tips, and Tricks

Fernando Ferreira , Eva T. Barbosa , and António R. Silva

diagnostic peritoneal lavage and its false positives. It is the modality of choice in

shock evaluation in Advanced Trauma Life Support (ATLS™) and DSTC™ proto-

cols for trauma management. One should never forget to repeat an E-FAST exam

after a few minutes placing the patient in reverse Trendelenburg for the pericardial

view and regular Trendelenburg to scan the abdomen if the patient shows any sign

of shock despite resuscitation. You must also repeat the primary assessment and

exclude all other types of shock. It is important for the surgeon to integrate E-FAST

into the evaluation protocol to help determine any indication for a trauma lapa-

rotomy and/or thoracotomy.

This chapter will aid the surgeon in understanding E-FAST as a powerful diag-

nostic modality by reviewing the following aspects:

• Scanning technique

– How to scan

– Normal anatomy

– Basic abnormal ﬁ ndings (what to search) and the clinical meaning

• Scanning tips and tricks

3.2 Scanning Technique

3.2.1 How to Scan

The main objective of performing focused ultrasound is to detect blood in areas

where it should not exist. E-FAST views involve thoracic views discussed previ-

ously and the abdominal views of the 4 P ’ s ( pericardial , perihepatic , perisplenic ,

and pelvic ) (Fig. 3.1 ).

Recent bleeding is represented by an anechoic “dark line” in these spaces, yet

older blood may have a heterogeneous echogenicity owing to clots .

Attaining E-FAST views requires basic knowledge of ultrasound physics and

knobology of ultrasound machines. We prefer the use of curved probes with a fre-

quency between 3 and 5 MHz. Optimal depth settings will depend on patient body

habitus , but a setting of 8 – 15 cm is usually sufﬁ cient. Adjust gain settings in a way

that blood vessels are black and the surrounding tissues are not too bright . Hold the

probe like you hold a pen or a pencil. Grasp it with the ﬁ rst three ﬁ ngers of the

dominant hand, and use the remaining ﬁ ngers to stabilize the probe touching the

patient if needed avoiding inadequate pressure. Do not forget the basic transducer

movements known as ART ( alignment for sliding movements , rotation , and

tilting ).

The patient must be in a supine position, and the operator should stand to the

right.

According to international ultrasound consensus, the transverse view of our

patients is a perspective from the feet (Fig. 3.2 ). Therefore, the images on the right

of the patient should show on the left of the monitor. The sagittal and coronal views

also corresponds to an image on the left of the monitor which corresponds to the

cranial direction (Fig. 3.3 ). The scanning probe has a marker on the probe which

F. Ferreira et al.