Diagnostic ultrasound ( PDFDrive )

1950 PART V Pediatric Sonography
FIG. 56.8 The Surface Anatomy of the Diaphragm—Posterior View. The pleural space normally extends inferior to the 12th rib medially
(position A), and superior to the lateral third of the 12th rib (position B). A line drawn from position B to the xiphoid process of the sternum (the
xiphisternum) (position C) will map out the surface markings of the peripheral attachment of both the normal and the pathologically elevated diaphragm.
Even if the dome of the diaphragm is grossly elevated by a pathologic process, the peripheral attachment remains unchanged.
it more conspicuous during ultrasound guidance. he holes also
aid in aspiration of luid.
Biopsy Devices
Aspiration cytology is not widely used in children because there
is a much more diverse group of potential lesions in children
than in adults. Many of the pediatric tumors depend partly on
cellular arrangement for diagnosis, and pediatric pathologists
are generally uncomfortable with making important diagnoses
based on cytology specimens alone. Automated suction-core or
slotted needle instruments are most oten used.
Although it may seem logical that small-diameter devices
should be used in children, in general, 16- to 18-gauge needles
are most commonly used in order to obtain suicient material
for pathology examination. he larger needles may seem more
dangerous, but if they are placed and monitored under ultrasound
guidance, the risk is minimized.
ANATOMY
Diaphragm
A thorough knowledge of regional anatomy is essential. If a
procedure is to take place in an unfamiliar area, there is always
time to look up the anatomy in a text before proceeding. he
surface anatomy of the diaphragm must be thoroughly understood
(Fig. 56.8). It is important to remember that even if the apex of
the diaphragm is grossly elevated by a mass or a subphrenic
luid collection, the diaphragm is still attached to the chest wall
in the same relative position as it was at birth. If the pleural
space is to be avoided, one must still enter a subphrenic collection
below the peripheral attachment of the diaphragm. he diaphragm
generally passes posteriorly across the junction of the middle
and outer thirds of the 12th or last palpable rib posteriorly. From
this point, a line drawn around the chest to the xiphoid process
of the sternum (xiphisternum) will trace out the peripheral
attachment of the diaphragm. It is important to be aware that
the pleural space extends inferior to the medial third of the 12th
rib (see Fig. 56.8).
Colon or Bowel
he colon lies just anterior to the kidneys and may be inadvertently
punctured when entering from the posterior-lateral
position during percutaneous nephrostomy. A nondistended
colon may not be easily detectable by ultrasound, and one
must be careful to avoid placing a nephrostomy too laterally
or too anteriorly. If there is any doubt, a contrast enema can
be performed and the position of the colon can be localized
by luoroscopy before or during the procedure. If available,
cross-sectional imaging should be referenced before the
procedure.
SEDATION
Few children younger than 12 years will cooperate during an
invasive procedure, and a thorough familiarity with pediatric
sedation is necessary, together with skilled personnel and adequate
resuscitation facilities. It is better to perform a procedure using
general anesthesia than to attempt the procedure without adequate
sedation. If the child is uncomfortable or moving excessively,