Hypertrophic pyloric stenosis.
Sonographic images of the upper abdomen show thickening and
elongation of the pylorus, consistent with hypertrophic pyloric
As the name implies, hypertrophic pyloric stenosis represents a
progressive hypertrophy of the pylorus muscle, resulting in gastric
outlet obstruction. The disease presents in infancy, usually
between the ages of 1-2 months, with progressive onset of
projectile nonbilious vomiting. On physical examination, a palpable
lump (or "olive") and reverse peristalsis may be apparent in the
right upper quadrant or epigastrium. Imaging may include plain
films, ultrasound, and occasionally fluoroscopy. Plain films may
show gaseous gastric distention or mottled gastric contents, as
well as diminished air distal to the pylorus. Ultrasound has become
the imaging mainstay in the diagnosis of hypertrophic pyloric
stenosis. Sonographic findings include thickening (>4mm) and
elongation (>14mm) of the pylorus muscle (Note that these values
vary from institution to institution). The thickness measurements
should be performed on the hypoechoic (muscular) portion a single
wall, which is a more sensitive measurement and the total diameter
of the pylorus. Ultrasound images, as in this case, may demonstrate
shouldering of the interim body hypertrophic muscle. Real-time
imaging aid in the diagnosis by demonstrating diminished or absent
passage of gastric contents through the pylorus, as well as
vigorous gastric peristalsis. Note that pseudo-thickening can be
seen if the pylorus is imaged in an oblique projection. Treatment
is surgical (pyloromyotomy).
Provenzale JM, Nelson RC. Duke Radiology Case Review. pp 424-425.
Lippincott-Raven , Philadelphia, 1998.