Topic 12 - paediatric small parts

Question 1

IN what time frame ae different are DDH examinations done?

Answer 1

• undertaken in infants less than six months of age however can be attempted in infants up to 12 months.
• The limits of any ultrasound examination should be documented.
• Plain x-rays are taken when there is too much calcium within the ossification centre of the femoral head to clearly delineate the acetabulum.

Question 2

What are some risk factors for DDH?

Answer 2

o	Family history of DDH
o	Firstborn child
o	Oligohydramnios
o	Breech delivery (female breech is the highest DDH risk category)
o	Skull-molding deformities
o	Congenital torticollis
o	Foot deformities

Question 3

What is the ideal timing of an ultrasound DDH scan?

Answer 3

• ideally performed initially at a corrected age of 6 weeks

* should not be done until at least 3 to 4 weeks of age because hip instability may resolve on its own

Question 4

Which infants should have a DDH scan?

Answer 4

• Screening by clinical examination is recommended, and ultrasound is reserved for infants having abnormal examination findings or risk factors

Question 5

What is transient synovitis?

Answer 5

This is also known as toxic synovitis or irritable hip. It has no known allergic, viral or bacterial cause. There is a sudden, acute onset of limping and symptoms subside with rest.

Question 6

What can cause bilateral hip effusions?

Answer 6

The most common presentation of an effusion is toxic synovitis
The are three major causes of a hip effusion These are trauma, allergy or viral infection.
Trauma is excluded as an option because this would be unilateral.
Bilateral effusion can be part of many systemic disease processes (eg Crohn’s) however this this instance it was the result of juvenile rheumatoid arthritis.

Question 7

What is the best way to identify a hip effusion on a neonate?

Answer 7

• Use a dual screen with both hips imaged side by side for those subtle effusions, subtle thickening or bulging of the anterior joint capsule that requires close comparison

Question 8

Describe the sonographically visible anatomical landmarks seen when in the coronal mid-acetabular plane. Both hip and knee are flexed at 90 degrees (coronal-flexion view).

Answer 8

• Superiorly the iliac bone is seen as a straight horizontal line.
It connects inferiorly with the bony superomedial margin of the acetabulum, the cartilaginous acetabular roof and its cartilaginous lateral margin.
The tip of this margin is called the limbus.
The acetabulum medially has a gap where no bone is seen – this is the triradiate cartilage.
Sitting within the acetabulum is a round femoral head, which may or may not have an ossification centre.

Question 9

What are the measurement of a normal hip?

Answer 9

• According to Graf, the α angle should be > 60 degrees and the β angle < 55 degrees.
Both Harcke and Graf agree the superomedial bony margin of the acetabulum must be sharp.
According to Harcke, the hip must be stable, showing no signs of laxity or movement with stress.
Millis and Share agree with all of the above but also make sure the femoral head is covered by the acetabulum by at least 50 percent or greater.

Question 10

What is the point of the coronal hip assessment?

Answer 10

• Images are obtained with no measurements and then with Graf alpha and beta angles.
• A coronal image with a calculation of the percentage coverage of the hip is made using machine software.

Question 11

What makes a good coronal hip image?

Answer 11

• The hip and knee are both flexed at 90 degrees and slightly internally rotated to put the hip joint in the anatomically correct AP position.
• The transducer is placed in the coronal plane along the lateral surface of the hip joint and moved in an anterior to posterior direction to find the mid- acetabular plane.
• This is where the ilium is a straight flat line, the triradiate cartilage is seen in the medial acetabulum, and the femoral head is as round as possible

Question 12

What is the point of the transverse hip assessment?

Answer 12

• Images are taken at rest and with a Barlow stress manoeuvre to assess for stability.

Question 13

What makes a good transverse hip image?

Answer 13

• The hip and knee are both flexed at 90 degrees and slightly internally rotated to put the hip joint in the anatomically correct AP position.
• The transducer is then rotated 90 degrees from the coronal plane and placed on the lateral surface of the hip.
• The image shows part of the metaphysis of the femur and the femoral head in contact with the posterior portion of the acetabulum, the ischium.

Question 14

What is the Barlow test?

Answer 14

The Barlow test determines whether the hip can be dislocated.
The hip is flexed and the thigh brought into the adducted position.
The gentle push posteriorly can demonstrate instability by causing the femoral head to move out of the acetabulum

Question 15

What makes a coronal image diagnostic by Graf criteria?

Answer 15

For the US image to be diagnostic by the Graf criteria, the iliac bone must be straight and both the acetabular labrum and the lower limb of the os ilium must be visible.

Question 16

What are the appropriate equipment settings for paediatric testicular ultrasound?

Answer 16

• A 12-5 MHz linear transducer
• high dynamic range to pick up subtle differences in contrast.
• Power or colour Doppler should be set to low flow with high priority and colour gain set to optimise colour.

Question 17

What if the testes aren’t in the scrotum?

Answer 17

• If both testes are not seen in the scrotum, then the inguinal canals need to be assessed to look for undescended testes.
• If they are not there, an attempt should be made to find them between the kidney and groin
• this is difficult.
• The undescended testis is usually of a small size, hypoechoic and can be confused with a lymph node.

Question 18

Describe the variability of testes appearance with age

Answer 18

• vary with age.
• Over the entire age spectrum they are homogeneous
• prepubertally, they have low to medium level echogenicity and a mean testicular volume of about four centimetres.
• Pubertal and post pubertal testes are of medium level echogenicity and of greater volume.
• Blood flow prepubertally is low and within the testis, the resistance is high.
• Once puberty is attained, resistance decreases as diastolic flow increases.

Question 19

What are some indications for a testicular ultrasound?

Answer 19

• undescended testes
• inflammation
• torsion
• trauma
• masses.

Question 20

What is the most common indication for testes ultrasound?

Answer 20

Cryptorchidism

Question 21

What is cryptorchidism?

Answer 21

• three to four percent of all term babies have undescended testes.
• They still may descend over the next twelve months.
• A baby has true cryptorchidism if the testes remain undescended after this time.
• Most undescended testes (up to 80 percent) will be in the inguinal canal.
• If the undescended testis is not in the inguinal canal, the examination should be extended into the abdomen as the testis can be anywhere along the path of descent of the testis.
• In rare cases, the testis location can be ectopic within the femoral canal or even in the abdominal wall

Question 22

Explain your choice of transducer, B-mode and colour Doppler parameters when scanning prepubertal testes.

Answer 22

• A linear 12-5 MHz transducer should be used on the highest possible frequency.
• Use a high dynamic range to show subtleties in echotexture.
• A high frame rate can be traded off for higher resolution by increasing the number of focal zones depending on how cooperative the patient is.
• Adjust depth set to show near field.
• Colour requires low velocity scale, low filter, high colour priority and high colour gain. If the patient is noncompliant, the filter and the colour gain may need to be increased due to artefact.

Question 23

Describe patient preparation for neonatal scrotal ultrasound

Answer 23

• Make sure the baby is well fed and the gel is warm.
• Introduce yourself to the parents and type the patient name into your machine ready to go.
• Undress the baby from the waist down and place a towel over the penis.
• Wear gloves

Question 24

A four year old boy presents with cryptorchidism. Describe your scan technique

Answer 24

• Scan each hemi-scrotum from superior to inferior and lateral to medial.
• Make sure there is overlap from lateral to medial in the midline and in the longitudinal plane inferior and superior to the penis.
• Scan from the base of the penis to the symphysis pubis: this is your landmark.
• Then scan in transverse to the inguinal canal along each inguinal canal to the ASIS.
• If the testes are not seen, scan from the lower pole of the kidney in transverse along the psoas and iliacus muscles.

Question 25

What are the common causes of acute scrotal pain and swelling?

Answer 25

1. Testicular torsion
2. Epididymitis with and without orchitis
3. Torsion of testicular appendages
4. Testicular trauma
5. Acute hydrocele
6. Incarcerated hernia

Question 26

What is the most important setting when assessing for torsion?

Answer 26

• It is imperative that the colour and power Doppler factors are set up correctly on your machine to pick up low flow in the neonatal testes and determine with high confidence levels if flow is present or not.

Question 27

How does testes infection appear on ultrasound?

Answer 27

• With infection, the testes will display hyperaemia and commonly, a reactive hydrocoele.
• Intratesticular flow is confirmed and surgery is avoided.

Question 28

How does testicular rupture appear on ultrasound?

Answer 28

• Rupture requires surgical intervention and as with torsion time is of the essence if the testes are to be salvaged.
• Testicular rupture can often be difficult to determine due to haematoma but an irregular, poorly defined testicular outline is strongly suggestive of rupture.

Question 29

How do testicular tumours appear in neonates?

Answer 29

• rare
• most commonly will be metastases, most likely from neuroblastomas.
• Testicular masses are usually solid, echogenic and well-defined.
• Areas of haemorrhage and necrosis may occur.

Question 30

Describe the sonographic appearances of acute torsion and inflammation. What are the differences?

Answer 30

Torsion:
The affected testis is more hypoechoic and enlarged due to oedema.
The epididymis is enlarged.
There may be oedema of the scrotal soft tissues and a reactive hydrocoele.
Absent or markedly reduced blood flow is seen with colour Doppler.

Inflammation:
The affected testis and epididymis are more hypoechoic and enlarged due to oedema.
There may be oedema of the scrotal soft tissues and a reactive hydrocoele.
Increased blood flow is seen with colour Doppler in both epididymis and testis.

As the B-mode images are the same, colour Doppler can differentiate between torsion and inflammation.

Question 31

Why is it important to differentiate infection and torsion?

Answer 31

This is important as it affects patient management. Torsion requires immediate surgery to save the testis whereas inflammation requires antibiotics.

Question 32

Where will you find the conus medularis?

Answer 32

The level of the conus will depend on the age of the patient.
• At term, the conus medullaris will normally be located above the mid- level of the L2 vertebral body, however, the normal range can be from T10/11 to L2/3.
• In pre-term infants, the tip of the conus may be located as inferiorly as the upper border of the L3 vertebral body.

Question 33

Where should the spinal cord lie in a prone position?

Answer 33

• The cord should lie half to a third the way between the anterior and posterior walls of the spinal canal when the patient is prone.
• A more posterior location may indicate tethering.

Question 34

What is the ventriculus terminalis?

Answer 34

a persistent fetal terminal ventricle and appears as smooth dilation of the central echo complex within the conus medullaris. This normal finding is seen often in the neonate and regresses or disappears soon after birth

Question 35

Describe the normal filum terminale

Answer 35

visible and mobile with cerebrospinal fluid (CSF) pulsations.
The center of the filum tends to be relatively hypoechoic compared with its bright outer margins.
extends from the tip of the conus medullaris, crosses the subarachnoid space, and inserts on the first coccygeal vertebral body.
surrounded by the cauda equina, and the normal thickness is 1 to 2 mm

Question 36

What anatomy should always be located on a spinal ultrasound?

Answer 36

• Determination of the position of the tip of the conus medullaris is the most common indication for spinal ultrasound and should always be included in a neonatal spine sonographic examination

Question 37

What is spinal dysraphism?

Answer 37

• This term is used to describe a group of disorders that display incomplete or absent fusion of midline structures.
• It includes meningocoele, diastematomyelia and congenital dermal sinus.
• All of these conditions can be associated with a tethered cord.

Question 38

What is tethered cord?

Answer 38

• clinical condition that can be seen with a spectrum of pathologic causes that tether the spinal cord in a lower-than-normal position

Question 39

How does tethered cord cause spinal cord injury?

Answer 39

• Spinal cord injury is theorized to result from cord ischemia caused by excessive tension or stretching of nerve fibers.

Question 40

What are some high risk cutaneous markers for tethered cord?

Answer 40

o	focal hypertrichosis
o	infantile hemangioma
o	atretic meningocele
o	dermal sinus tract
o	subcutaneous lipoma
o	caudal appendage

Question 41

What are some low and moderate risk cutaneous markers for tethered cord?

Answer 41

• Intermediate-risk cutaneous markers include
o capillary malformations (salmon patches or port-wine stains).
• Low-risk cutaneous markers do not require routine neuroimaging or follow-up and include
o coccygeal dimples
o light hair
o isolated café au lait spots
o mongolian spots
o hypomelanotic and hypermelanotic macules or papules
o and deviated or forked gluteal clefts