Peds Radiology Case - Pyloric Stenosis

Question 1

What is the classical presentation of hypertrophic pyloric stenosis?

Answer 1

Previously healthy infant between 2-12 weeks presents with repeated non-bilious emesis which is sometimes forceful or projectile; gradual onset of symptoms.

Question 2

Treatment of choice for HPS?

Answer 2

Pyloromyotomy

Question 3

How is HPS diagnosed clinically?

Answer 3

Palpation of the classic “olive” of hypertrophied pyloric muscle

Question 4

What are the U/S imaging findings in pyloric stenosis?

Answer 4

• Thickened hypoechoic pyloric muscle (doughnut, target, or cervix sign) and a double layer of redundant echogenic mucosa (sonographic double-track sign)
• Muscle thickness greater than 3.0-3.5 mm measured in the long axis of the pylorus
• Pyloric channel length greater than 15-18 mm
• Real time observation of little or no passage of gastric contents through the pylorus

Question 5

What are the upper GI imaging findings in pyloric stenosis?

Answer 5

• Partial or complete gastric outlet obstruction, hyperperistalsis of the stomach, elongation of the pyloric channel
• String sign or train track sign streaks of barium with the lumen of the channel
• Shoulder sign of a pyloric mass indenting the barium-filled stomach and the base of the duodenal bulb

Question 6

What is the standard imaging method for diagnosing HPS?

Answer 6

U/S (highly accurate, allows direct measurement and real-time imaging of the pyloric muscle and channel without the need for radiation exposure)

Question 7

What other imaging can be used to evaluate HPS?

Answer 7

• Contrast Upper GI series - excellent for dx obstructive causes of vomiting, but is not first choice if HPS is the primary concern
• Radiographs - may show gastric distention in HPS, not very helpful in HPS diagnosis
• Nuclear scintigraphy - if all other causes of vomiting have been excluded in an infant with vomiting, it may be useful for functional evaluation of gastric emptying

Question 8

What is the difference between pyloric stenosis and pyloric spasm?

Answer 8

Stenosis: thickened muscle is a fixed abnormality that does not change with time

Pylorospasm: muscle enlargement is transient, treated non-operatively; degree of thickening is often less pronounced (usually <3.0 mm)

Thus, extending the length of time of observation of the pylorus to at least 5-10 minutes is essential to prevent false positive diagnoses of pyloric stenosis.

Question 9

What are the appropriateness criteria for imaging vomiting in infants up to 3 months?

Answer 9

Abdominal U/S is first line for a patient with new onset projectile nonbilious vomiting

If inconclusive or non-diagnostic, f/u in 24-28 hours or an X-ray upper GI series; if emesis is bilious, upper GI is preferred over US because malrotation is higher on the differential

Question 10

What are the risk factors for developing pyloric stenosis?

Answer 10

First born
Male
Positive family history