Yasser Asiri , R2

Longitudinal ultrasound shows an enlarged mesenteric lymph node (white solid arrow) acting as a lead point for an intussusception. From outer to inner there is the intussuscipiens (black open arrow), returning limb (white open arrow), mesentery (white curved arrow), entering limb of intussusceptum (black solid arrow).

Transverse transabdominal ultrasound shows thickening of the pyloric muscle (caliper #2) of 5 mm and elongation of the pyloric channel (caliper #1) of 22 mm in this patient with HPS. Notice the close proximity of the gallbladder (white solid arrow).

Appendicitis, intussusception, and hypertrophic pyloric stenosis (HPS) are three of the most common reasons for emergent abdominal imaging in pediatric patients .

Children are particularly at risk for adverse effect of ionizing radiation and although low dose radiation is associated with small but significant increase in life time risk of fatal cancer. The use of MRI is Impractical .

US doesn’t involve ionizing radiation , relatively inexpensive , widely avilable, and doesn’t require sedation. But most of all, it allows for dynamic

assessment of bowel peristalsis and compressibility .

Therefore , the ability to diagnose or exclude diseases with US should be part of a core radiology skills set for any practice that include a pediatric population.

Appendicitis

Appendicitis occurs in all age groups but has a higher incidense in children between 5-15 years of age.

It is generally understood that it’s a result of obstruction of the appendiceal lumen.

Obstructed lumen becomes distended. => pressure across it’s wall increase =>subsequent decrease in mural perfusion occur. And because the appendix has only arterial supply, any decrease in mural perfusion may result in gangrene and perforation quickly.

it’s been estimated that the prevalence of ruptured appendicitis in children ranges between: 30%-70% of cases. This may be explained by:

Younger children cannot describe their symptoms.

One third have atypical clinical findings.

the sensitivity and specficity for US alone in diagnosis of appendicitis in children were 88% and 94% . These can be achieved by focused re-imaging by the radiologist following the US tech examination to make sure that alternative diagnosis is not overlooked.

Most accurate US findings for acute appencitis is an outer wall diameter greater than 6 mm under compression “posivite and negative predicitve value of 98%”.

Other less sensitve and specific findings include:1. hyperemia on color doppler. 2. Echogenic inflammed periappendicieal fat.3. Visualization of the appendicolith.

Pitfalls

Operator dependant! Therefore every radiology resident should be taught how to perform appendeacal US and achieve and maintain competence.

Other limitations of US may include:1. Patient obesity. 2. Sever tenderness which prevent adequate

compression. 3. If perforation has occurred , the appendix may not

be recognized as a discrete structure.

Transverse color Doppler ultrasound shows increased vascularity in the appendiceal wall (white solid arrow) and mesoappendix (white open arrow). The absence of wall vascularity should raise the concern of gangrene.

Transverse ultrasound shows markedly distended appendix (white open arrow) containing echogenic material and an area of acoustic shadowing related to an appendicolith (white solid arrow).

Longitudinal color Doppler ultrasound in a 10 year old with right lower quadrant pain shows a dilated, blind-ending tubular structure with very hyperemic wall (black open arrow). There is increased echogenicity of the periappendiceal fat. The findings are consistent with acute appendicitis.

Longitudinal ultrasound image shows a dilated, blind-ending structure with thick wall (white open arrow) and internal shadowing echogenic foci (white solid arrow), consistent with appendicitis and appendicoliths.

Mimics

Mesientric addenitis. 2nd most common cause of RLQ pain. Dx of exclusion, usually self-limiting and requires no surgical intervention.

Infectious: terminal ilitis or ileocecitis: Yersenia , Salmonella, Campylobacter infections.

Chron’s Disease : one/third of patients initially presents with symptoms mimicking appendicitis.

Non-surgical mimincs

Intussusception

Usually occurs in children between 6 months and 2 years.

The “classic” clinical presentations consist of:1. Acute colicky abd. pain.2. Current jelly or frankly bloody stool. 3. Palpable abdominal mass. 4. Vomiting.

US is a highly sensitive and specific test for intussusception.

Easily identifiable even by inexperinced users and non-pediatric radiologist.

In recent study in which large proportion of examination were interpreted by radiology residents and general radiologists during oncalls and weekend shifts , US had sensitivity of 97.9% and specificty of 97.8% and a negative predictive value of 99.7% for intussusception.

Reimaging the patient after US technologist’s examination is advised to increase diagnostic confidence.

Target or donut sign.

Pseudokidney sign.

The intussception contains multiple limps of bowel and the attached mesentry as well as the lymph nodes which will create a mass measures up to 4-5 cm.

Transverse ultrasound shows an ileocolic intussusception. The intussusceptum (white open arrow) with a "target" appearance is visible medial to the right kidney #SP#(white curved arrow).

Longitudinal ultrasound shows an enlarged mesenteric lymph node (white solid arrow) acting as a lead point for an intussusception. From outer to inner there is the intussuscipiens (black open arrow), returning limb (white open arrow), mesentery (white curved arrow), entering limb of intussusceptum (black solid arrow).

Longitudinal transabdominal ultrasound shows multilayered appearance of intussusception (white open arrow) giving rise to "pseudokidney" sign. Note minimal fluid trapped between layers (white curved arrow).

Longitudinal color Doppler ultrasound of intussusception shows central leash of mesenteric vessels (white curved arrow) that are pulled along with intussusceptum (white solid arrow) into outer intussuscipiens (white open arrow). Presence of vascularity predicts reducibility.

Transverse color Doppler ultrasound shows mural vascularity (white curved arrow) in central intussusceptum (white open arrow). Note minimal fluid around the intussusception (white solid arrow).

Transverse transabdominal ultrasound shows classical "target" or "doughnut" sign of intestinal intussusception (white open arrow). Note ring in ring appearance formed by different layers (white solid arrow) of intestine & central lymph node (white curved arrow) acting as lead point.

Hypertrophic Pyloric Stenosis

95% of cases are seen between 3rd and 12th week of life.

HPS was associated with very high mortality rate, rate has dropped to 2% with surgical treatment.

Nonbilious vomiting is the main presenting symptoms.

If diagnosis was delayed , dehydration , electrolyte imbalance , or weight loss can result.

US is accepted as the first line option. Highly accurate, with specificity and sensitivity

approaching 100% in experienced hands.

Persistent abnormal thickening of the pyloric muscle is the most important parameter to establish the diagnosis of HPS.

The apperance of HPS in long-axis US images has been termed the “Cervix” sign. Due to its resemblence to the uterine cervix.

The threshold value of the pyloric thickness for diagnosis of HPS is generally greater than 3.5mm.

An abnormal lenghth typically measures from about 14mm-20mm.

The actual numeric value is less important than the overall MORPHOLOGY of the canal and the real time observations.

Pitfalls

Gastric overdtisention, which displaces the antrum and pylorus posteriorly may leads to false negative result. gastric decompression with entric tube can be an effective method to optimaize the exam.

Changing the patient’s position.

Ultrasound shows a normal pylorus between open arrows (white open arrow) with anechoic fluid in gastric antrum and in distended duodenal bulb (white curved arrow).

Ultrasound shows cursors measuring single wall thickness of the pyloric muscle and formula mixed with air distending the stomach (white curved arrow). On most ultrasound exams, the pylorus is located close to the gallbladder (white open arrow), but if the stomach is very full, it may be displaced into the right lower quadrant.

Ultrasound in the same baby with HPS shows cursors measuring the pyloric channel length. Notice the echogenic mucosa within the pyloric channel, which also hypertrophies and contributes to obstruction.

Ultrasound shows cursors measuring the length of the pyloric channel in a baby with HPS. In this infant, enough fluid leaves the stomach to distend the duodenal bulb (white solid arrow), which is a useful landmark. Antral wall thickening seen in antritis should not be confused with pyloric stenosis if the duodenal bulb is identified.

Ultrasound scan at 90° to the pyloric channel shows the "donut" sign of HPS: Thickened hypoechoic muscle (between cursors) and redundant echogenic mucosal lining.

Transverse transabdominal ultrasound shows thickening of the hypoechoic pyloric muscle (calipers), measuring 5 mm in this patient with HPS.

Transverse transabdominal ultrasound shows thickening of the pyloric muscle (caliper #2) of 5 mm and elongation of the pyloric channel (caliper #1) of 22 mm in this patient with HPS. Notice the close proximity of the gallbladder (white solid arrow).

Transverse ultrasound shows a cross-sectional view of the thickened pyloric channel; diameter is measured between cursors #1 and single wall thickness measured with cursor #2.

Pitfall

If the exam was done quickly, Transient pylorospasm can mimic HPS.

In transient pylorospasm, the muscle thickness usually doesn’t exceed 3mm.

At observation, the pylorus relaxes with corresponding change in shape.

Ultrasound shows pylorospasm which can mimic HPS, but typically does not meet measurement criteria and usually resolves with time and glucose water feeding. Channel length is marked by cursors.

In patient with persistent unexplained vomiting, upper GI series may be performed to evaluate for hiatal hernia , antral web, or duodenal obstruction.

Conclusion

US is an important tool in the evaluation of pediatric abdominal conditions such as addendicitis, intusscesption , and HPS.

Assessment with these conditions should be part of a core radiolgy skills set for any practice that include a pediatric population.

Thank you