SONOWORLD : Hypertrophic Pyloric Stenosis Ultrasound Case
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Abdomen » Gastrointestinal
Hypertrophic Pyloric Stenosis
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Presentation A 25 days old male infant presented with complaints of non-bilious vomiting and failure to thrive. The baby was normal at birth with no other obvious abnormality. On abdominal palpation, a lump was felt in the upper abdomen with visible peristalsis.
Caption: Longitudinal (1a) and Transverse (1b) plane through right upper quadrant
Description: 1a. Longitudinal plane showing the elongated pylorus with thickened pyloric muscle. 1b. Transverse plane showing ‘target sign’ with thickened pyloric muscle.
Caption: Longitudinal plane through right upper quadrant
Description: In longitudinal plane the pyloric canal length is 18mm.
Caption: Longitudinal plane through right upper quadrant
Description: The pyloric muscle thickness measuring 4.6 mm and the pyloric diameter measuring 14 mm.
Differential Diagnosis Hypertrophic pyloric stenosis
Final Diagnosis Hypertrophic pyloric stenosis
Discussion Ultrasonography was performed with a linear transducer in supine position. On transverse image the pylorus was identified to the left of gallbladder. The typical ‘target sign’ or ‘doughnut sign’ was seen due to thickened pyloric muscle. On the longitudinal image the pylorus was elongated. The pyloric canal length measured 18 mm. The pyloric muscle thickness measured 4.6 mm and the pyloric diameter measured 14mm. The stomach was distended and there was failure of the pyloric canal to open during the scan.

The diagnostic accuracy of ultrasonography for hypertrophic stenosis is high. The sensitivity and specificity approach 100 % [1] and ultrasonography is now the procedure of choice for the detection of pyloric stenosis.


Muscle thickness >- 3mm.
Pyloric canal length >- 1.2 cm.
No peristalsis through pylorus.

Other important features to look for are the double mucosal canal of pylorus, excessive antral peristalsis, delayed or absent passage of fluid into the duodenum. It is important to note these additional features, as pylorospasm may mimic hypertrophic pyloric stenosis and to avoid false –positive diagnosis[3].

Pylorospam is a condition which is typically transient.
Case References [1] Neilson D, Hollman AS. The ultrasonic diagnosis of infantile hypertrophic stenosis: technique and accuracy. Clin.Radiol 1994; 49; 246-247.
[2] Diagnostic Ultrasonography- Carol Rumack.
[3] Pediatric Ultrasound- Rose de Bruyn.
[4]Janet R Reid, emedicine
Technical Details GE Voluson E8 machine, linear transducer of 7.5 to 13.5 mHz was used. Scanning in both transverse and longitudinal planes. The plane of image for the measurements should be technically correct
Follow Up The baby was referred to a pediatric surgery unit. Pyloromyotomy was done. Baby doing well at 3 months follow up.
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