Diagnostic ultrasound ( PDFDrive )

1946 PART V Pediatric Sonography
placed through the skin toward the target. he needle and
transducer need to be precisely in the same plane. his can be
checked by looking directly down onto the top of the transducer
and needle just before the initial placement is made (Fig. 56.4).
he depth of the target should be measured and remembered
before needle placement.
he needle should be initially advanced about one-half of the
distance to the target under direct ultrasound monitoring. If
necessary, the preplanned distance of insertion can be marked
on the needle with a Steri-Strip. Inexperienced operators oten
have an uncontrollable urge to keep pushing the needle, hoping
that it will magically make the needle visible. Radiologists who
usually work with adults may not appreciate the short insertion
distances required in small children and babies.
FIG. 56.3 Locating the Entry Site Laterally. The exact point of
entry can be tested by rotating the transducer toward the body wall
and palpating potential entry sites with a inger that is readily visible on
the ultrasound real-time images.
Locating the Needle After Insertion
With experience, it is possible to keep the needle visible starting
from the moment of insertion, but if not, the needle must be
localized before any further advancement is made. Check that
the transducer and needle are parallel to each other by looking
down the cable of the transducer with one eye closed. If the two
are not parallel, adjust the position of the transducer, not the
needle. Once the transducer and needle are parallel, keep the
transducer in that plane and move the transducer a few millimeters
back and forth strictly in the plane of the needle (Fig. 56.5). It
is oten useful to anchor the transducer hand on the patient by
placing the fourth and ith digits or the hypothenar border of
A
B
C
FIG. 56.4 Needle Alignment. (A) After the entry site is located,
the needle is inserted in a plane strictly parallel with the transducer
([B] and [C]).