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

154
ABDOMINAL ULTRASOUND
THE NORMAL RENAL TRACT
Ultrasound technique
The right kidney is readily demonstrated through
the right lobe of the liver. Generally a subcostal
approach displays the (more anterior) lower pole
to best effect, while an intercostal approach is best
for demonstrating the upper pole (Fig. 7.1).
The left kidney is not usually demonstrable
sagittally because it lies posterior to the stomach
and splenic flexure. The spleen can be used as an
acoustic window to the upper pole by scanning
coronally, from the patient’s left side, with the
patient supine or decubitus (left side raised),
but, unless the spleen is enlarged, the lower pole
must usually be imaged from the left side posteriorly.
Coronal sections of both kidneys are particularly
useful as they display the renal pelvicalyceal system
(PCS) and its relationship to the renal hilum (Fig.
7.2A). This section demonstrates the main blood
vessels and ureter (if dilated).
A
B
C
D
Figure 7.1 (A) Sagittal section through the normal right kidney (RK), using the liver as an acoustic window. The
central echoes from the renal sinus are hyperechoic due to the fat content. The hypoechoic, triangular, medullary
pyramids are demonstrated in a regular arrangement around the sinus. The cortex is of similar echogenicity to the liver.
(B) TS through the hilum of the RK, demonstrating the renal vein (arrow) draining into the inferior vena cava (IVC)
(arrowhead). (C) Left kidney (LK) in coronal section. The renal hilum is seen furthest from the transducer (s = spleen).
(Compare this with the sagittal section of the RK in which cortex is seen all the way around the pelvicalyceal system.)
(D) The renal cortex lies between the capsule and the lateral margin of the medullary pyramid (arrowheads).