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Features Departments Information |
 Cynthia K. Rigsby, MD
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Radiology quiz CYNTHIA K. RIGSBY, MD aFall 1999 HISTORY: A 19-day-old full-term male was admitted for failure to thrive and frequent post-prandial non-bilious emesis. For the two days prior to admission, the frequency of emesis had increased and one episode may have been projectile. An upper gastrointestinal series (UGI) was performed.  FIGURE 1. Spot radiograph of the gastric outlet. QUESTION: What is the diagnosis? ANSWER: Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis (HPS) occurs as a result of hypertrophy of the circular muscle of the stomach. The etiology of the disorder is unknown, but it is likely multifactorial including genetic and environmental factors. HPS is common, affecting 2.5 to 3 of every 1000 live births. Boys are affected 4 to 5 times as frequently as girls, with first-born males most frequently afflicted. Patients generally present between 2 and 8 weeks of age with non-bilious emesis that is often projectile, difficulty feeding, and weight loss. Physical examination yields a palpable olive-shaped mass in the epigastric region in up to 80% of affected infants, indicating the hypertrophied circular muscle. Additionally, exaggerated gastric peristalsis can be seen through the anterior abdominal wall. The major differential diagnoses for infants with non-bilious emesis include HPS and gastroesophageal reflux (GER). Imaging is necessary only when the clinical findings are not diagnostic. The imaging diagnosis of HPS can be confidently established by performing an UGI series or by pyloric sonography. Sonography has become the imaging modality of choice for clinically suspected HPS because of its lack of ionizing radiation and its direct visualization of the pyloric musculature. If HPS is not the primary clinical consideration, then an UGI series becomes the imaging modality of choice as the entire UGI tract can be visualized and reflux can be diagnosed.   FIGURE 2. Pyloric stenosis, various roentgenographic signs on UGI series. In this case, the clinical findings were not clear, so an UGI series was performed yielding the diagnosis of pyloric stenosis (Figure 1). The classic roentgenographic signs of pyloric stenosis on an UGI series are shown in Figure 2. A pyloric sonogram was electively performed for confirmation of the diagnosis. The classic findings of HPS on pyloric sonography include a pyloric channel elongation, pyloric muscular thickening, and lack of opening of the pyloric channel.  FIGURE 3. Longitudinal sonogram of the pylorus. The pyloric channel measures 22 mm (+–+) and the single wall thickness measures 5 mm (arrows). Considerable variation exists in the literature for the sonographic values considered diagnostic of pyloric stenosis. Recent studies have proposed a pyloric channel length of 15 mm or greater, a pyloric muscle thickness of 3 mm or greater with lack of opening of the pyloric channel as being diagnostic with high accuracy (Figure 3). The treatment of HPS is pyloromyotomy, which splits the muscle longitudinally. Patients generally remain hospitalized until post-operative re-feeding is established. REFERENCES 1. Poon TS, Ahang AL, Cartmill T, Cass DT: Changing patterns of diagnosis and treatment of infantile hypertrophic pyloric stenosis: A clinical audit of 303 patients. J Ped Surg 1996;31(12):1611–5. 2. Rohrschneider WK, Mittnacht H, Darge K, Troger J: Pyloric muscle in asymptomatic infants: sonographic evaluation and discrimination for idiopathic pyloric stenosis. Pediatr Radiol 1998;28(6):429–34. 3. Siegel MJ: Gastrointestinal Tract. In Pediatric Sonography. 2nd edition. Siegel MJ (ed) Philadelphia: Lippincott-Raven, 1996:266–68. |