Renal quiz

1.The kidneys may be difficult to image because of their proximity to the ribs and to air in the bowel and .  What can you do to optimise scanning?

  1. Turn the patient in the lateral decubitus position
  2. Have the patient breath in . This will lower the liver on the right which will cause the kidney to slide down and away from the ribs.On the left, breathing manoevres can be used also but often a deep inspiration will not improve the visualisation of the kidney  and the lung curtain may get in the way.
  3. Get the patient to distend their abdomen
  4. Have the patient raise their arm
  5. Use the liver or spleen as acoustic windows.
  6. Try several approaches if one doesn’t work. These include the lateral or posterolateral approach (similar to doing an EFAST exam), anterior subcostal approach, posterior approach (great in slim people and children)

Reference: Clinical ultrasound Paul Allen 3rd edition

2.  What are the sonographic characteristics of the normal kidney?

  1. The renal capsule is echogenic
  2. The parenchyma is generally  hypoechoic to either the normal spleen or liver
  3. Within the parenchyma the medullary pyramids appear hypoechoic
  4. The renal sinus is echogenic
  5. In the normal kidney the urinary collecting system in the renal sinus is not visible

3. How is hydronephrosis classified?

The most common system used for grading hydronephrosis is the following (SFU classification)

  • Grade I  Mild  – Dilated renal pelvis. No calyceal dilatation. Normal parenchymal thickness
  • Grade II  Mild – Dilatation of the renal calyces
  • Grade III Moderate – Cystic dilatation of the renal pelvis and calyces which become convex.Thinning of the of the parenchyma
  • Grade IV Severe – Gross dilatation of the renal pelvis and calyces which appear ballooned The parenchyma is no longer demonstrated

Grade  I            Grade II                     Grade III              Grade IV

4. What are 2 causes of physiologic hydronephrosis?

  1. The most common is an  overfull bladder. If the bladder is overfull then the renal ultrasound should be repeated after voiding
  2. Pregnancy is another common cause of hydronephrosis due to hormones and due to the gravid uterus.  It can involve one or both ureters. It can start from 12 weeks gestation.
    By 20 weeks ¾ of women affected. By 36 weeks 2/3 of women affected. The right side is more affected than the  left. Appearances usually resolve after delivery (within 48 hours) but may persist 3 months post partum

5. What are 5 criteria which are associated with simple cysts?

Cysts are common. 1/3 of the population will develop cysts. They may be solitary, multiple, unilateral or bilateral. They don’t require further investigations unless they have features of complex cysts. They may rupture and haemorrhage causing pain and haematuria. The criteria which identify a cyst are

  1. No internal echoes
  2. They have smooth round margins
  3. There are associated with posterior acoustic enhancement
  4. They are round or oval shaped
  5. They have a thin sharp posterior wall
  6. No signal on colour Doppler

Reference: Clinical ultrasound Paul Allen 3rd edition

6. What are features of a cyst would be concerning for a tumour ?

Features which may indicate a lesion is not a simple cyst include

  1. increasing complexity of the cyst such as septa visible within the cyst
  2. thick nodular septa within the cyst
  3. calcification of septa
  4. poor acoustic enhancement
  5. not anechoic

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