Module 2 - Ultrasonography II

Question 1

What are the relative positions of the left and right kidneys relative to surrounding organs?

Answer 1

The left kidney is delimited cranially by the greater curvature of the stomach, left lobe of the pancreas and head of the spleen; left adrenal gland and aorta dorsomedially and ventrolaterally by there is the spleen, causally by the ovary, jejunal loops and descending colon.
The right kidney has its cranial pole in contact with the renal fossa of the caudate liver lobe, medially there is the right adrenal gland, the CVC is located medially and ventrally, ventrally there is the descending duodenum, ascending colon and right lobe of the pancreas. Caudally there is the right ovary and jejunal loops.
The right adrenal is located lateral/dorsolateral to the aorta.

Question 2

How are the renal arteries divided before entering the kidneys?

Answer 2

Renal arteries divide into dorsal and ventral branches before entering the kidneys and in 20% of dogs they may be double, specially on the left renal artery.

Question 3

The left renal vein is longer than the right. True or false?

Answer 3

True.

Question 4

How are the kidneys of dogs and cats shaped?

Answer 4

Usually the kidney is bean shaped (dogs) to ovoid (cats), and should be symmetrical.

Question 5

In a transverse plane of the kidney, what are the normal dimensions of the renal pelvis?

Answer 5

In the transverse plane, the width of the renal pelvis can measure up to 2mm in dogs and 1.6mm in cats.

Question 6

Why is the renal sinus more hyperechoic than the renal cortex?

Answer 6

Because of peripelvic fat - appearing as a v-shaped hyeprehcoic region.

Question 7

What causes increased echogenicity of the renal cortex in cats, appearing hyperechogenic to the liver parenchyma?

Answer 7

Fat vacuoles (physiological fat infiltration) in the cortical tubular epithelium. It´s more common in older male cats, specially if neutered; it can also happen in pregnant cats.

Question 8

In longitudinal plane, what are considered the dimensions of the kidney of a standard cat?

Answer 8

3 - 4.5 cm

Question 9

In a longitudinal plane, what are the normal dimensions of a kidney of a standard dog?

Answer 9

The kidney measures in dogs vary greatly with size of the patient (there are tables to correlate kidney size to patient body weight).
Another form is to calculate the ratio of kidney length to aorta, which should be between 5.5 - 9.1.

Question 10

On a radiograph, what is the formula used to calculate kidney size in cats?

Answer 10

1.8 +/- 0.2 X the length of L6 ventral body

Question 11

In cats, is there a difference between kidney size in neutered versus intact patients?

Answer 11

Kidneys are also typically larger in intact cats and often become smaller with advancing age.

Question 12

Is there one kidney that is generally larger than the other?

Answer 12

The right kidney may be longer than the left.

Question 13

How does one obtain a dorsal versus a sagittal plane of the kidney on US?

Answer 13

Typically, imaging the kidney from the lateral abdominal wall creates the dorsal plane, and imaging the kidney from the ventral aspect of the abdomen creates the sagittal plane.

Question 14

What is the ultrasonographic difference between the dorsal and the sagittal plane of the kidney?

Answer 14

In dorsal place, the beam “cuts” the kidney lateromedially, giving a characteristic bean shape appearance. Three areas of the kidney can be clearly distinguished. These regions consist of a bright echogenic area corresponding to the renal sinus zone and peripelvic fat, around which a hypoechogenic area representing the renal medulla is seen, and an outmost zone of intermediate echogenicity, which is the renal cortex.

In sagittal plane, examined from medial to lateral, the kidney appears with more of an oval shape, the hyperechoic central zone of the renal sinus disappears and a hypoechoic central zone bordered by two hyperechogenic lines appears. The central hyperechogenic region represents the renal crest, and the dorsal and ventral echogenic lines are the pelvic diverticula (recesses) accompanied by the interlobular vessels. Arcuate and intralobular arteries can sometimes be identified, with discrete echogenicity at the corticomedullary junction and in the cortex.

Question 15

What is the US sign that confirms pregnancy?

Answer 15

The US sign that confirms pregnancy is the presence of gestational sacs.

Question 16

When can the gestational sacs be seen in the bitch (dog) and queen (cat)?

Answer 16

The gestational sacs can be seen after the 17th day post LH peak in the bitch and after the 9th day post LH peak in the queen.

Question 17

Is it possible to estimate the days until birth of a pregnant bitch with US?

Answer 17

Yes. The number of the days remaining until birth in the dog can be estimated using formulas that use the internal diameter of the embryonic vesicle in the first phase of pregnancy (ICC: internal chorionic cavity) or the transverse biparietal diameter of the skull (BPD: biparietal diameter) or the diameter of the fetal body (BD: body diameter) in the second phase of the pregnancy.

Question 18

Near the delivery time, how is the fetal viability assessed with US?

Answer 18

By observing the cardiac activity and measuring fetal HR (the normal range is between 200-240 bpm). A healthy fetus will have at least twice the HR of the mother´s.

Question 19

What fetal heart rate is indicative of fetal distress and increased risk of fetal mortality?

Answer 19

Fetal HR values lower than 160-180 bpm are indicative of fetal distress and below 120 bpm is considered a high risk of fetal mortality.

Question 20

What US features may help us to distinguish the normal uterus from intestines?

Answer 20

The majority of the uterus does not have layering (useful to distinguish it from small intestine), it may have a hyperechoic central region which is most prominent in oestrus and dioesetrus.

Question 21

When should be the first US of a pregnant bitch?

Answer 21

Normal pregnancy scanning should be performed at about 28 days after mating.

Question 22

When if the fetal HR first present on US (dog)?

Answer 22

Heartbeat present from day 23-25 after the LH surge.

Question 23

After how many days post breeding should one calculate the fetal HR?

Answer 23

• 21 days (better 25-35d) post breeding in dogs
• 10-25 days in cats

Question 24

What is the fetal HR measure using M mode used for?

Answer 24

Used to assess gestation aging, fetal stress and viability.

Question 25

What is the typical size of a dog´s prostate?

Answer 25

The prostate size depends on patient weight.
<10kg: 3cm
<25kg: 4cm
>25kg: 5cm

Question 26

What is the ultrasonographic appearance of a prostate of a neutered dog?

Answer 26

It depends on certain variables including hormones, age and body size.
In a normal neutered dog, the prostate is generally smaller comparing to an entire male with the same body weight due to atrophy and it´s more hypoechoic with coarse echotexture.
If the dog was neutered at a young age (lets say before 6 months of age) the prostate may look homogenous.
If the patient was neutered due to prostatic pathology then the prostate tends to have an irregular parenchyma.

Question 27

a) In a transverse plane, how is the prostate volume measured?
b) In what plane is the prostate length assessed?

Answer 27

a) length x width x height x 0.523

b) Longitudinal plane

Question 28

At what age does testicular size peak in a dog?

Answer 28

6 years old (decreases thereafter).

Question 29

A positive association between body size and testicular volume has been demonstrated in dogs. True or False?

Answer 29

True.

Question 30

In regards to diffuse parenchymal changes in the kidney, name disease processes that cause hyperechogenic and hypoechogenic appearances of the kidney.

Answer 30

Hyperechogenic:
- congenital malformations
- acute inflammatory and toxic processes
- chronic kidney disease

Hypoechogenic:
Infiltrative disease

Question 31

What is the US appearance of familial nephropathies?

Answer 31

On US, the kidneys are small, with irregular margins, and diffusely hyperechoic, with loss of the corticomedullary junction. Additionally, renal pelvis dilatation may be observed.
Bilateral changes.

Question 32

What is the age range where we can see familial nephropathies in dogs?

Answer 32

Generally, affect dogs from 4 months to 2-3 years of age.

Question 33

Name 3 dog breeds that tend to have familial nephropathies.

Answer 33

Bull Terrier
Chow Chow
CKCS

Question 34

What breed is highly predisposed to juvenile nephropathy?

Answer 34

Boxers.

Question 35

Is renal dysplasia exclusively hereditary?

Answer 35

No. This abnormality may be hereditary or can result from a neonatal infection, such as feline panleukopenia virus or canine herpesvirus.

Question 36

Name one disease that particularly causes an enhancement of the corticomedullary junction in cats.

Answer 36

Kidney necrosis caused by ethylene glycol poisoning produces a very pronounced enhancement of the corticomedullary junction.

Question 37

What ultrasonographic change is one expected to encounter in the kidneys of dogs and cats with lymphoma?

Answer 37

The kidneys of a dog with lymphoma are generally hypoechoic but in cats with diffuse renal lymphoma, the kidneys appear hyperechogenic.

Question 38

List differentials for corticomedullary rim sign.

Answer 38

Hypercalcemic nephropathy
Ethylene glycol poisoning
Leptospirosis
Renal lymphoma
FIP (pyogranulomatous vasculitis)

Question 39

List differentials for cortical hypoechogenicity.

Answer 39

Infiltrative disease (lymphoma in cats; MCT)
Renal venous thrombosis associated with increased kidney volume.

Question 40

List 2 differentials for subcapsular rim sign.

Answer 40

Neoplasia (namely LSA)
FIP

Question 41

What is more likely to be associated with kindey disease in cats: a thin rim sign or a thick band sign?

Answer 41

A thick hyperechoic ill-defined band (for which the term medullary band sign is proposed) was more frequently associated with KD in cats, whereas a thin hyperechoic well-defined line (true MRS) may be seen in cats with or without KD (in other words, the band signs is more concerning than the CM rim sign).

Question 42

List differentials for renomegaly.

Answer 42

Infiltrative disease (neoplasia)
FIP
Urinary tract obstruction
Pyelonephritis
PSS
PCKD

Question 43

List the most common focal lesions of the kidneys.

Answer 43

Renal cysts
Nephrolithiasis
Dystrophic mineralisation, Cortical infarts
Metastatic or primary neoplasia
Granulomas
Abscesses

Question 44

Name a breed of cat and dog predisposed to hereditary polycystic kidney disease.

Answer 44

Persian cats and
Cairn Terriers (dog).

Question 45

In regards to renal cystic lesions, what disease is common in female GSD?

Answer 45

Renal cystadenocarcinomas occur in female German Shepherd Dogs and are accompanied by nodular dermatofibrosis.

Question 46

What is the characteristic ultrasonographic appearance of a renal infart?

Answer 46

A renal infart is characterized ultrasonographically by a hyperechoic triangular-shaped lesion with identation of the capsule. An acute infart is generally much fainter then a chronic one.

Question 47

List differentials for focal hypoechogenic vs hyperechogenic lesions of the kidneys.

Answer 47

Hypoechoic masses or nodules are often compatible with lymphoma and malignant histiocytosis.
Hyperechoic mases are less common and are related to chondrosarcomas, haemangiosarcomas and metastatic adenocarcinomas.

Question 48

what is the most common renal tumour in dogs and cats?

Answer 48

The most common renal tumour in dogs is carcinoma and in the cat is lymphoma.

Question 49

When the renal pelvis in transverse plane is greater than 13 mm, what is it indicative of?

Answer 49

When the height of the renal pelvis in transverse plane is measured as greater than 13mm on US examination, it is considered as a predictive reference measure to establish that there is an obstruction (and hydronephrosis).

Question 50

Dilation of the renal pelvis below 4mm can be physiologic. True or false?

Answer 50

True.

Question 51

List causes of pyelonephritis.

Answer 51

Fluid therapy (overload)
Sedation (dexmedetomidine f.e is slightly diuretic)
Renal failure
Pyelonephritis
Congenital malformations (e.g ectopic ureter)
Low urinary tract obstruction

Question 52

Describe hydronephrosis ultrasonographically.

Answer 52

Hydronephrosis is a more marked dilation of the pelvis and pelvic diverticula than pyelectasia, mainly secondary to mechanical obstruction, distorting and compressing the renal parenchyma. As this process worsens, renal parenchyma undergoes progressive atrophy. The renal diverticula are rounded and appear as finger-like anechoic projections extending from the anechoic renal pelvis.

Question 53

List different causes of peri-renal fluid accumulation.

Answer 53

Bilateral:
Acute renal failure due to nephrotoxicity
Leptospirosis
Interstitial nephritis

Unilateral:
Peri-renal pseudocyst
Urinoma
Hemorrhage
Abscess
Neoplasia (Lymphoma)

Question 54

Is subcapsular hypoechoic thickening of the renal capsule associated with renal lymphossarcoma in cats?

Answer 54

Yes.
The predictive value of hypoechoic subcapsular thickening for lymphosarcoma was 80.9% and the negative predictive value was 66.7%. The sensitivity and specificity of hypoechoic subcapsular thickening for the diagnosis of renal lymphosarcoma were 60.7% and 84.6%, respectively.

Question 55

Are congenital ectopic ureteres more common in female or male dogs?

Answer 55

Female.

Question 56

How are ureteroceles classified?

Answer 56

Ureterocele is a focal cystic dilatation in the distal submucosal portion of the ureter that protrudes into the bladder lumen. It can be classified as orthotopic when it is located in the normal area of the opening of the ureter or ectopic when it is located in the neck of the bladder or urethra.