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

THE PAEDIATRIC ABDOMEN 225
+ 78
A
20.3 mm
C
B
Figure 9.8 (A) Multicystic dysplastic kidney. (B) This multicystic dysplastic kidney, diagnosed antenatally, has shrunk
to little over 2 cm in length by the age of 1 year. (C) Large, hyperechoic kidneys in a neonate in autosomal recessive
polycystic disease.
in childhood with the milder, juvenile form of the
disease. Prenatally the less severe forms appear normal
on ultrasound. ARPCDK is associated with
hepatic fibrosis and portal hypertension.
Autosomal dominant polycystic disease of the kidney
(ADPCDK: adult) also has a wide spectrum of
severity. Although it tends to present later in life, the
more severe forms can present in childhood and can
occasionally be diagnosed prenatally. Frank cysts can
usually be demonstrated on ultrasound, but may not
be detected until the second or third decade of life.
The disease is also associated with cysts in the liver
and pancreas, and with intracranial berry aneurysms.
Renal dilatation
Hydronephrosis is frequently detected antenatally,
although the cause may be difficult to demonstrate.
Dilatation is due either to obstructive uropathy, for
example vesico- or pelviureteric junction obstruction,
posterior urethral valves or obstructed upper moiety
of a duplex kidney (Fig. 9.9), or it may be nonobstructive,
for example due to reflux (Fig. 9.10).
Postnatal ultrasound scans should be performed
when the infant is more than 4 days old, because
there is commonly a period of dehydration immediately
after birth. This may cause an obstructed or
otherwise dilated kidney to appear normal for the
first few days of life. If normal a follow-up scan is generally
recommended at about the age of 6 weeks.
The presence of any calyceal dilatation or ureteric
dilatation, as opposed to dilatation confined to the
renal pelvis, is an important factor to note, indicating
a greater degree of severity. A measurement of the
anteroposterior diameter of the dilated intrarenal
pelvis is a useful baseline from which to compare subsequent
follow-up scans (Fig. 9.9D). It should be
noted that slight separation of the renal pelvis is a
normal finding in the newborn: an anteroposterior
renal pelvis of 5 mm is the upper limit of normal.
The presence of a baggy, extrarenal pelvis, less
than 10 mm, without pelvicalyceal system (PCS)
dilatation is usually managed conservatively using
ultrasound monitoring to demonstrate any increasing
dilatation. PCS dilatation with a renal pelvic
diameter of between 10 and 20 mm is more serious