Ultrasound Needling Technique
THERE ARE 2 COMMON NEEDLE INSERTION APPROACHES AND 2 TYPES OF NEEDLE TO
TRANSDUCER ALIGNMENT
Approach # 1 IN PLANE (IP) Needle Approach
The needle is placed inline
with and parallel to the
transducer (ultrasound
beam). Both the needle
shaft and tip are visualized.
Axillary block is used as an
example.
Needle to nerve contact
can be followed in real
time. The full length of the
needle shaft and tip can be
visualized.
The needle tip is seen in
contact with the nerve
(honeycomb structure)
AA = axillary artery.
APPROACH # 2: OUT OF PLANE (OOP) NEEDLE APPROACH
The needle is placed
perpendicular to the
transducer. The needle
shaft and tip are visualized
as a hyperechoic dot on
ultrasound.
The femoral nerve block is
used as an example.
In this case, needle, nerve
and tissue movements are
observed. The needle tip
(NT) may be difficult to
locate accurately without
the use of echogenic tip
needles.
Actual needle to nerve contact can be confirmed by nerve stimulation and
local anesthetic (LA) spread pattern.
FA, FN & FV = femoral artery, nerve & vein; IPM = iliopsoas muscle
NEEDLE HANDLING
Proper needle handling skills are required for accurate and smooth needle insertion during ultrasound
guided nerve blocks. If the operator is not ambidextrous, and prefers to use the dominant hand to
handle the needle and inject local anesthetic, then the operator must choose a proper body location
and orientation in relationship to the patient.
This is an example of a
right handed operator
using the right hand to
hold the needle for a left
sided interscalene block.
Note that the operator is
standing on the left side of
the patient below the
clavicle.
This is an example of a
right handed operator
using the right hand to
hold the needle for a right
sided interscalene block.
Note that the operator is
now standing on the right
side of the patient above
the clavicle.
BODY ERGONOMICS
Proper body ergonomics to handle the transducer and the needle, to view the screen, and to position
the patient are essential for block success and to avoid operator fatigue and body injury. Below are
some examples of proper and improper body ergonomics.
Proper operator and
screen orientation; note
that the ultrasound
machine is placed directly
in front of the operator to
provide a direct line of
vision.
Improper operator and
screen orientation; note
that the operator’s head is
turned almost 90 degrees
to view the ultrasound
image on the screen.
Proper body position and
bed height for the
procedure
Improper body position; the
bed is too low for the
procedure
Proper transducer holding
skill; the hand is placed
close to the transducer
contact surface
Improper transducer
holding position; the hand
is high up on the
transducer
Proper hand and arm
positions; both hands and
arms are comfortably
supported
Improper hand and arm
positions; both the arm
holding the transducer and
the hand holding the
needle are not supported
NEEDLE TO NERVE CONTACT AND INJECTION STRATEGY
1. Perineural Injection


The goal is to place the needle tip on each side of the target nerve (i.e., perineural) but not
inside the nerve (i.e., intraneural).
Avoid direct head-on needle to nerve contact (figure A).

Aim to inject local
anesthetic around
the nerve and not
inside the nerve
(figures B and C).
Perineural
injection is
visualized as an
expanding
collection of
hypoechoic fluid
around the nerve.
Circumferential
spread is
generally a good
indication of
adequate local
anesthetic spread
(“donut sign”).
Figure A shows needle in
contact with nerve
Figures B & C show local
anesthetic injection around
the nerve
LA = local anesthetic
White arrows = block
needle
Yellow arrowhead = nerve
2. Recognition of Improper Local Anesthetic Spread
An Illustration of Local Anesthetic Spread During Femoral Nerve Block
Figure A shows an
improper injection outside
the fascia iliaca (FI).
Arrows show tissue
expansion outside the
fascia.
Figure B shows a proper
injection deep to the fascia
iliaca (FI). Arrows show
fluid expansion deep to the
fascia.
FA = femoral artery
An Illustration of Proper and Improper Local Anesthetic Spread During Popliteal Sciatic Nerve
Block
Figure A illustrates
improper injection and
subsequent hypoechoic
local anesthetic spread
(asterisk) outside the
fascial sheath of the sciatic
nerve (hyperechoic
structure) in the popliteal
region.
Figure B illustrates proper
injection (asterisks) inside
the fascia sheath of the
sciatic nerve.
An Illustration of Proper and Improper Local Anesthetic Spread During Supraclavicular
Brachial Plexus Block
Figure A illustrates
improper injection and
hypoechoic local
anesthetic (LA) spread
outside the brachial plexus
sheath.
Arrowheads = nerve
trunks
FR = first rib
PL = pleura
SA = subclavian artery
Figure B illustrates proper
injection (LA) inside the
expanded brachial plexus
sheath.
3. Recognition of Intraneural Injection


Intraneural injection is manifested by an expansion of nerve diameter (yellow arrowheads)
with as little as 1mL of injection (figure B).
Another hint of an intraneural puncture is nerve movement towards the needle as the needle
is withdrawn. The nerve should be moving away from the needle under normal circumstances.
Ultrasonographic Appearance of An Intraneural Injection
Pre-injection
Post-injection
4. Hydro Dissection Technique


The hydro dissection technique is most useful for “dissecting” out the intermuscular or
interfascial plane in which a small nerve lies.
Injection of 5-10 mL of fluid (saline or D5W) through the needle can distend and open up the
narrow space so that the small nerve is more clearly visualized before local anesthetic
injection.

Hydro dissection is particularly useful for blockade of smaller nerves located between
muscular planes e.g., 1) ilioinguinal and iliohypogastric nerves; 2) the rectus sheath block; 3)
obturator nerve; 4) saphenous nerve and 5) transverse abdominis plane block.
Figure A shows
hypoechoic
ilioinguinal/iliohypogastric
nerves (arrowheads) within
the plane between the
internal oblique muscle
(IOM) and the transverse
abdominis muscle (TAM).
Figure B shows needle
(arrows) approaching the
nerves using the in plane
needle approach. It is
difficult to tell if the needle
tip is indeed inside the
intermuscular plane.
Figure C shows injection
of a small amount of fluid
(“hydro dissection”) to
open up the narrow plane.
A small hypoechoic fluid
collection is now seen
above the nerves.
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