Peristaltic Waves in Infantile Hypertrophic Pyloric Stenosis

Abstract

Figure 2. The transverse plane of abdominal ultrasonography showed characteristic target lesion with enlarged pylorus (DistanceA: pylorus diameter 15.2mm) and thickened pylorus muscle (Distance B: wall thickness 6.3 mm). The longitudinal view showed indentation of the pylorus into the fluid-filled antrum (cervix sign) with elongated pylorus canal (measured length of pyloric canal: 23.3 mm). A 2-month-old first-born full-term male infant presented to our hospital with nonbilious, sometimes projectile vomiting, which persisted for 1 month. His weight gain was inadequate. There was no fever, diarrhea, jaundice, hematemesis, or dehydration. Initial physical examination was unremarkable and no olive-shaped mass was palpated in the abdomen. After admission, blood tests showed hypochloremic metabolic alkalosis. Gastric peristaltic waves traveling from the left side of the upper abdomen toward the right side were observed (ie, “caterpillar sign”; Figure 1 and Video; Video available at www.jpeds. com). Abdominal ultrasonography revealed a characteristic target lesion with enlarged pylorus and thickened pylorus muscle with elongated pyloric canal (Figure 2). Infantile hypertrophic pyloric stenosis (IHPS) was diagnosed. The patient underwent a successful pyloromyotomy and had adequate growth in a 4-year follow-up. IHPS is the most common cause of intestinal obstruction in infancy.The incidence of IHPS in theUS is approximately 2per 1000 live births, and timely corrective surgery is suggested in infants with IHPS. Although the classic triad as visible peristalsis, palpable pyloric lump, and projectile vomiting are well known, they are relatively rarely encountered and not well recognized. Diagnosis of IHPS is straightforward when the classic manifestations are presented; otherwise, it can be difficult to differentiate from gastroesophageal reflux. Although abdominal ultrasonography is a convenient and sensitive diagnostic modality, the importance of physical examination is reinforced. Peristaltic waves are rhythmic movements caused by the stomach attempting to force its contents past