9%20ECOGRAFIA%20ABDOMINAL%20COMO%20CUANDO%20DONDE

THE PAEDIATRIC ABDOMEN 221
probe demonstrates excellent detail. A water-based
drink may be given to provide an acoustic window.
In cases of blunt injury to the abdomen with suspected
pancreatic damage, CT is the imaging
modality of choice in the acute situation, although
sonography should be used during follow-up to
detect the presence of a pseudocyst.
URINARY TRACT
Ultrasound is the first line of investigation in both
antenatally detected abnormalities and in symptomatic
children.
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Table 9.1
Paediatric pancreatic abnormalities
Increased echogenicity
Cystic fibrosis
—fatty replacement of the pancreas, calcifications, ectatic
pancreatic duct, coarse texture, cysts
Pancreatitis
—hereditary
—trauma (physical abuse, road traffic accident)
—congenital anomaly, e.g. choledochal cyst
—drug toxicity
—viral and parasitic infection
Haemochromatosis
—pancreatic fibrosis, iron deposition in liver and pancreas
Focal lesions
Cysts
—isolated congenital cyst
—autosomal dominant polycystic disease
—von Hippel–Lindau disease
—Meckel–Gruber syndrome
Solid lesions
—primary pancreatic neoplasms are very rare in children
The bladder should be scanned first, as voiding
may often occur during the examination.
Measurements of both kidneys, either length
or renal volume, should be taken to highlight
any difference in size and to provide a baseline
for further growth comparison.
A variety of planes can be used to view the
kidneys in children. Often a posterior approach
is best for obtaining an accurate bipolar length.
Ensure that renal pelvic dilatation is not
physiological, by rescanning postmicturition.
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Measure the anteroposterior diameter of any
renal pelvic dilatation in transverse section
through the renal hilum.
Always scan the bladder immediately after
micturition, paying attention to the ureteric
orifice and looking for any ureteric or renal
dilatation which may suggest reflux. Measure
any residual volume.
Colour Doppler may be helpful in identifying
the ureteric orifice, by locating the jets of urine
entering the bladder (Fig. 9.10D).
Normal appearances
After birth the renal cortex is relatively hyperechoic
compared to the adult kidney, in strong contrast to
the hypoechoic medullary pyramids. The outline of
the kidney is often lobulated due to a persistent
fetal lobulation. The renal pelvis is relatively
hypoechoic, as the fat deposition seen in the adult
is not yet present (Fig. 9.5A).
Gradually the cortex becomes less hyperechoic
with age, the corticomedullary differentiation
lessens and fat deposition in the renal sinus becomes
more evident. The outline becomes smooth,
although fetal lobulations do persist in some adult
kidneys.
Normal postnatal growth of the kidneys, in terms
of length and volume, is closely related to the height,
weight and age of the child. Charts giving normal
age- and weight-related values should routinely be
referred to. 12 Errors do occur in measurements of
renal length with a potential error in the order of 1
year’s growth. 13 Thus follow-up measurements for
renal growth should not be undertaken at intervals
of less than 1 year.
Anatomical variants and pathology
The duplex system
The duplex system is one of the more common
congenital anomalies, occurring in up to 9% of
referrals. 14 It stems from aberrant budding of
the Wolffian duct in utero, and can take a variety
of forms, from complete duplication with two
kidneys, each with a separate ureter, to a partial
duplication involving the kidney only. Complete