Don't let a case of hydronephrosis block your clinical mojo. By the end of this video, you'll know how to identify a case of hydronephrosis using ultrasound imaging.
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Diagnosing hydronephrosis using ultrasound
[00:00:00] Hydronephrosis is defined as, a dilation of the urinary collecting system of the kidney, due to obstruction. We can see the psoas muscle and we see the dilated renal pelvis of the right kidney. Following the identification of hydronephrosis, we must investigate further to find the underlying cause. There are many possible causes for this obstruction including urolithiasis, ureteropelvic junction obstruction, and malignancies
[00:00:30] such as cervical cancer and retroperitoneal fibrosis. In ultrasound, a dilated renal pelvis and dilated calyces leads us to the diagnosis of hydronephrosis, the large echo-free structure, here in the middle of the kidney, is the renal pelvis. Here, you can see the fluid-filled calyces, suggesting hydronephrosis. If the ureter is dilated as well, like here, we say it is hydroureteronephrosis. There are four grades of hydronephrosis.
[00:01:00] Take a second to look at this image. This is a long section over the right kidney, showing also the liver. Here, we have Grade 1 hydronephrosis. The renal pelvis is dilated more than five millimeters and echo-free fluid can be seen in the calyces but there's no calyx dilation. The renal tissue is normal. In Grade 1 hydronephrosis, we see dilation of the renal pelvis and fluid-marked
[00:01:30] calyces, like here. The calyces themselves are not dilated. Take a second to look at this image. This is a long section over the left kidney, showing the spleen and the vertebral column, bordering the left kidney. Here, we see the echogenic structure, which is the stone in the renal pelvis. In Grade 2 hydronephrosis, we have a dilation of the renal pelvis, the infundibula, and the calyces.
[00:02:00] We have no tissue atrophy. Here's an example of the dilation of the renal pelvis, the infundibula, and the calyces. We have no tissue atrophy. We see the echogenic stone formation in the renal pelvis with its acoustic shadowing. And we can also see a double J catheter that was installed to relieve the hydronephrosis. Take a second to look at this picture.
[00:02:30] In Grade 3 hydronephrosis, we see dilation of the infundibula and the calyces as well as the renal pelvis. The renal sinus is completely occupied by dilated structures. There is blunting of the fornices and there is mild cortical thinning. Here, we see moderate dilation of the renal pelvis. We see a loss of calyx borders, right here, then the blunting of the fornices and we see cortical thinning. Take a second to look at this image.
[00:03:00] In this long section over the right kidney, we can see the example of Grade 4 hydronephrosis, due to an occluding stone in the ureteropelvic junction. In the ultrasound image, we can see an extensive dilation of the renal pelvis and calyces, which appear ballooned. We can see the loss of borders between the renal pelvis and the calyces, and we can see renal atrophy as well as cortical thinning. Take a moment to
[00:03:30] look at this picture. So, if we see hydronephrosis, we have to investigate the reason. As we said before, the most probable reason for hydronephrosis is occluding kidney stones, especially when it's acute onset with right or left flank pain. In this long section on the right kidney, we can see an occluding stone, with acoustic shadow, within the proximal part of the ureter. Here, we see the dilation of the renal pelvis and the proximal
[00:04:00] ureter. The ultrasound image shows the dilated renal pelvis, here and the dilated proximal ureter going up to the occluding stone, which is here, which is the echogenic structure here, forming the acoustic shadow. Take a second to look at this image. Another benign reason for hydronephrosis is the ureteropelvic junction obstruction. It is caused by an accessory lower renal artery crossing the renal pelvic junction
[00:04:30] of the right kidney. In this cross section over the right kidney, we can also see the psoas muscle. In the ultrasound image, we can see the renal artery obstructing the ureteropelvic junction, right here. We use Doppler to investigate the vessel. Take a second to look at this. Now, this is a live presentation of hydronephrosis. We see dilated
[00:05:00] renal pelvis structures. We see dilated calyces. We see no cortical thinning but a small bit of free-fluid around the right kidney. Now, when we look for the reason for the hydronephrosis, we have to go down to the pelvis. We see the bladder, right here. The uterus, right here and then we see a dilated ureter coming down, here and suddenly, there's this echogenic structure right in the lumen of this dilated ureter, which is the occluding stone
[00:05:30] and the reason for the hydronephrosis.