Hypertrophic pyloric stenosis (HPS) is typically a disease seen in infants with a reported incidence of 0.1 to 0.8% but it has also been reported in about 300 adults [1] [2] [3] [4]. HPS in infants has higher incidence amongst first-born males and is encountered more frequently in Caucasian babies [5]. Maternal history of HPS is a reported risk factor [6]. Infantile HPS can be associated with syndromes like Turner's, tracheoesophageal fistula, esophageal atresia, trisomy 18 [6].

HPS is classified as primary and secondary.

Primary HPS is also called idiopathic HPS (IHPS) and is seen in infants, while it is rare in adults probably because they are asymptomatic and remain undiagnosed. The exact etiology of IHPS is unknown. It is characterized by pyloric muscle hypertrophy and hyperplasia. IHPS in infants typically develops in the first to the third month after birth with symptoms of non-bilious projectile vomiting immediately following feeds. As the disorder progresses, the infant does not gain weight and develops dehydration. There is visible gastric peristalsis. An olive-shaped mass, due to the hypertrophied pylorus, can be palpated in the epigastrium or right upper abdominal quadrant. Features of associated syndromes like Turner's may also be present. Adult onset IHPS presents in middle-aged men with epigastric pain, early satiety, nausea, and vomiting following meals [7] [8]. Unlike infants, an upper abdominal mass is rarely palpable in adult IHPS.

Secondary HPS occurs secondarily with the healing of duodenal or gastric ulcers, hypertrophic gastritis, malignant tumors, gastrointestinal stromal tumors, bezoars, vagal hyperactivity, and postoperative extrinsic adhesions [4] [9] [10]. It is associated with replacement of the pyloric muscle fibers by fibrous tissue and there is minimal or no hypertrophy of the pyloric muscle.

• Weight Loss

  Depending on the duration of symptoms, patients may suffer significant weight loss, even falling below birth weight. [mdedge.com]

  Patients present with projectile vomiting, weight loss and dehydration. Five susceptibility loci have been identified through genome-wide linkage analysis and candidate gene approaches. [ncbi.nlm.nih.gov]

  Persistent hunger, weight loss, dehydration, lethargy, and infrequent or absent bowel movements may be seen. Stomach wall peristalsis may be visible. [patient.info]

• Vomiting

  A 34-day-old girl was admitted with chief complaints of projectile vomiting and poor weight gain. HPS was diagnosed on the basis of the clinical course and results of imaging studies. [ncbi.nlm.nih.gov]

• Projectile Vomiting

  A 34-day-old girl was admitted with chief complaints of projectile vomiting and poor weight gain. HPS was diagnosed on the basis of the clinical course and results of imaging studies. [ncbi.nlm.nih.gov]

  Projectile vomiting (without bile) occurs shortly after eating. Until dehydration sets in, children feed avidly and otherwise appear well, unlike many of those with vomiting caused by systemic illness. [msdmanuals.com]

• Failure to Thrive

  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. [sonoworld.com]

  […] to thrive References: [1] [4] Diagnostics Initial imaging : Abdominal ultrasound → shows an elongated and thickened pylorus Elongated pylorus (normal: 15–17 mm ) Thickened pylorus muscle (normal: < 3 mm ) Pylorus transverse diameter (normal: < 13 mm [amboss.com]

  There may be a history of failure to thrive or poor weight gain. Infants often present with “projectile” vomiting. [cdemcurriculum.com]

  The classical presentation of IHPS includes persistent copious non-bilous vomiting (which may become projectile), visible intestinal peristalsis, palpable epigastric tumour, constipation, failure to thrive despite sucking hungrily, dehydration and electrolytes [panafrican-med-journal.com]

  Severe or neglected cases can result in significant weight loss and failure to thrive. [ipeg.org]

• Nausea

  In this case report, we describe a 14-year-old boy who presented with nausea, intermittent vomiting, and abdominal pain. He underwent upper gastrointestinal series, which demonstrated persistent narrowing of the pylorus. [ncbi.nlm.nih.gov]

  Adult onset IHPS presents in middle-aged men with epigastric pain, early satiety, nausea, and vomiting following meals. Unlike infants, an upper abdominal mass is rarely palpable in adult IHPS. [symptoma.com]

• Vomiting in Infancy

  BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) is the most common surgical cause of nonbilious vomiting in infancy. The etiology of IHPS is not completely understood. [ncbi.nlm.nih.gov]

  Of course, clinically it is important to consider other causes of vomiting in infancy. A degree of pylorospasm is common in infancy and is responsible for some delay in gastric emptying. The pylorus, however, appears sonographically normal. [radiopaedia.org]

  Infantile hypertrophic pyloric stenosis (IHPS) is one of the surgical causes of protracted vomiting in early infancy. [panafrican-med-journal.com]

  […] during infancy, with a reported incidence of one to three per 1000 live births 1. [journals.lww.com]

The diagnosis of IHPS can be suspected in an infant presenting with typical manifestations of non-bilious projectile vomiting after feeds and weight loss but they are not often seen in the initial course of the disease. A careful history of onset and progression of the manifestations is essential before proceeding with the physical examination which may reveal visible peristalsis, and a palpable olive-shaped enlarged pyloric mass [11] [12]. Hypochloremic, hypokalemic metabolic alkalosis is the classical result on serum biochemistry testing. Ultrasonography is the preferred method of confirming the diagnosis in infants with endoscopy being reserved for infants with atypical clinical presentation.

Clinical diagnosis of adult HPS is difficult and upper gastrointestinal (UGI) endoscopy is necessary to exclude gastric outlet obstruction. A fixed, severely narrowed pylorus with a smooth border described as "cervix sign" is typically seen on endoscopy [13]. Video capsule endoscopy is a newer modality which has been used to detect adult HPS and differentiate it from idiopathic gastroparesis [14].

A plain X-ray of the abdomen is not helpful and may only show a distended stomach with mildly distended intestines in HPS. Fluoroscopic UGI series with barium (barium meal) will demonstrate delay in gastric emptying, peristaltic waves (caterpillar sign), an elongated pylorus with a thin lumen (string sign) which appears duplicated due to puckering of the mucosa (double-track sign), indentation of the antrum by the pylorus (shoulder sign) or base of the duodenal bulb (mushroom sign) and beak shaped pyloric entrance (beak sign). In adult HPS, UGI series findings include delayed gastric emptying due to pyloric stenosis, a narrow, elongated pyloric canal, and a mushroom sign.

Ultrasound is preferred to the UGI series in infants as it avoids radiation and can visualize the pyloric muscle. Various sonographic signs have been described such as the antral nipple sign, cervix sign, and target sign. However, sonography is not useful in adult IHPS, although some do advocate it [13]. Computed tomographic (CT) scans help to exclude secondary causes of HPS.

Distal gastrectomy with gastroduodenostomy is the treatment of choice. [ncbi.nlm.nih.gov]

Significant medical advances have improved its diagnosis, treatment and prognosis, and there is now almost a 100 per cent success rate ( Panteli 2009 ). [journals.rcni.com]

More attention should be paid to early discovery and diagnosis, which will help to improve the curative effect and prognosis of IHPS. [ncbi.nlm.nih.gov]

Prognosis Prognosis is excellent unless diagnosis is delayed and prolonged severe dehydration occurs. Mortality is rare after pyloromyotomy. Peters B, Oomen MW, Bakx R, et al ; Advances in infantile hypertrophic pyloric stenosis. [patient.info]

[…] gastric emptying of fluid into duodenum Complications Hypochloremic metabolic alkalosis DDx Infantile pylorospasm Muscle thickness between 1.5 and 3 mm Variable caliber of antral narrowing Antral peristalsis Delayed gastric emptying Elongation of pylorus Prognosis [learningradiology.com]

Treatment Conservative measures : before surgery Treatment of choice : Ramstedt pyloromyotomy (definitive management once the patient is rehydrated and electrolyte disturbances have been corrected) References: [1] [4] Prognosis [amboss.com]

Furthermore, it attempts to demonstrate that newer research regarding an NOS1 genetic etiology does not exclude, but rather can be consistent with, an infectious etiology. [ncbi.nlm.nih.gov]

The NHI database provides an opportunity to conduct a population-based epidemiological study of IHPS. [journals.plos.org]

In this review, the latest advances in IHPS regarding epidemiology, etiology, diagnostics and treatment will be discussed. [ncbi.nlm.nih.gov]

References: [1] [2] Epidemiological data refers to the US, unless otherwise specified. [amboss.com]

[…] of infantile hypertrophic pyloric stenosis in the United States: A multistate, population-based retrospective study, 1999-2010. ( 30549250 ) Kapoor R...Romitti PA 2018 21 Infantile Hypertrophic Pyloric Stenosis: An Epidemiological Review. ( 30567916 [malacards.org]

We believe these three conditions are due to an underlying pathophysiologic mechanism. [ncbi.nlm.nih.gov]

Newborn Surgery, Third Edition provides a comprehensive compendium of the pathophysiology, investigation and management of neonatal disorders. [books.google.com]

Nathan Askew Practice educator and ward manager, Great Ormond Street Hospital, London Nathan Askew outlines the pathophysiology, diagnosis, treatment and prognosis of this highly treatable disease process In paediatric general surgery hypertrophic pyloric [journals.rcni.com]

The accurate diagnosis delays with elimination of severe alkalosis and electrolyte disorder and prevention of malnutrition with administered parenteral nutrition. [omicsonline.org]

OBJECTIVE: To analyze the clinical and epidemiological features of patients with infantile hypertrophic pyloric stenosis (IHPS) so as to provide scientific evidence for diagnosis and prevention of IHPS. [ncbi.nlm.nih.gov]

Early recognition and surgical treatment for infantile hypertrophic pyloric stenosis can prevent dehydration, electrolyte disturbances, and weight loss in young infants. [mdedge.com]

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