I. Overview
Congenital hypertrophic pyloric stenosis (CHPS) is an obstruction of the output tract due to hypertrophy and edema of the pyloric muscle. It is most often seen in infants within the first 6 months of life, and its etiology is unclear, with a tendency to be familially concentrated. Patients who develop pyloric stenosis in adults also have an infantile form of hypertrophic pyloric stenosis in childhood, thus demonstrating a genetic component.
II. Etiology
The etiology is still inconclusive.
1. Genetic factors
Genetic factors play an important role in the etiology of the disease, and there is a clear familial pattern of development. Studies have pointed out that the genetic mechanism of pyloric stenosis is polygenic, consisting of a dominant gene and a sex-modified multifactor with a directed genetic predisposition. This genetic predisposition is influenced by certain environmental factors, such as social class, type of diet, and various seasons, and the incidence is higher in spring and autumn, but the associated factors are unknown. It is common in high-weight male infants, but is not associated with gestational age.
2.Nerve function
Structural changes and dysfunction of peptidergic nerves may be one of the main etiological factors. The number of enkephalin-containing and vasoactive intestinal peptide nerve fibers in the circular muscle was observed to be significantly reduced by immunofluorescence technique, and the content of substance P in the tissue was reduced by application of radioimmunoassay, thus it is presumed that the changes of these peptidergic nerves are related to the pathogenesis.
3.Gastrointestinal hormone
In recent years, the study of gastrointestinal stimulants, the determination of the concentration of prostaglandins (E2 and E2a) in the serum and gastric juice, suggesting that the content in the gastric juice of the affected children is significantly increased, thus suggesting that the pathogenesis is caused by the increased concentration of local hormones in the pyloric muscle layer, which puts the muscle in a state of constant tension. Serum cholecystokinin has also been studied and no abnormal changes were observed.
4, functional muscle hypertrophy
Mechanical stimulation can cause mucosal edema and thickening. On the other hand, it also leads to dysfunction of the cerebral cortex to the viscera, causing spasm of the pylorus. Both factors contribute to the formation of severe obstruction of the pyloric stenosis and the appearance of symptoms. However, there are negative opinions that it is inappropriate that pyloric spasm first causes functional hypertrophy of the pyloric muscles, since the hypertrophy is mainly of the cricothyroid muscle and the spasm should cause some initial symptoms, however, in some patients with vomiting episodes and very early surgery, a mass is usually found to have formed, and the size of the mass is not related to the age of the disease. The muscle hypertrophy reaches a certain threshold before showing the pyloric obstruction sign.
5.Environmental factors
There is a clear seasonal peak in incidence, predominantly in spring and autumn. Leukocyte infiltration around ganglion congenital cells was found in tissue sections of biopsies, presumably related to viral infection. However, no coxsackievirus was isolated from the blood, feces, or pharynx of the child and his mother, and there was no change in serum neutralizing antibodies. No pathological changes have been observed in animals infected with coxsackievirus, and research is continuing.
Clinical manifestations
Typical clinical manifestations: three main signs: gastric peristaltic waves, pyloric masses and ejectile vomiting.
1. Vomiting The symptoms appear 3-6 weeks after birth, or earlier, and rarely occur after 4 months of age. Vomiting is the main symptom, at first it is only the return of milk, followed by jet vomiting. The vomiting starts occasionally, but as the obstruction worsens, vomiting occurs after almost every feeding. The vomit is mucus or milk, and if it is retained in the stomach for a longer period of time, curds are vomited without bile.
In a few cases, due to irritable gastritis, the vomit contains fresh or denatured blood, and cases of pyloric stenosis have been reported in neonates with high gastric acidity, with massive vomiting of blood from gastric ulcers, and also reported with duodenal ulcers. After vomiting, the infant still has a strong appetite for food and can still suckle vigorously if fed again. In immature infants, the symptoms are often atypical and the vomiting is not significant.
As vomiting increases, the infant’s weight does not increase at first due to insufficient milk and water intake, then decreases rapidly, urine output decreases significantly, and the infant passes stool once every few days in small, hard amounts, occasionally passing brownish-green stool, called starvation stool. Due to malnutrition and dehydration, the infant is visibly thin, has loose wrinkled skin, reduced subcutaneous fat, and is depressed with a distressed look. Early vomiting loss of large amounts of gastric acid can cause alkalosis, shallow and slow breathing, and may have laryngospasm and hand and foot convulsions and other symptoms.
2, with jaundice incidence of 2% to 8%, indirect bilirubin elevation is the main. The cause is not clear. Some people point out that it is due to low glucuronosyltransferase activity of the liver caused by repeated vomiting and insufficient caloric intake. It has also been suggested that extrahepatic obstructive jaundice may be caused by a pyloric mass or dilated stomach compressing the bile ducts. Once the pyloric obstruction is lifted the jaundice subsides within 3 to 5 days.
Four, examination
1.Ultrasound examination
Diagnostic criteria for pyloric hypertrophy: pyloric duct length > 16 mm, pyloric muscle thickness ≥ 4 mm, pyloric duct diameter > 14 mm, if the above three criteria are not met at the same time, only one or two meet the criteria, the ultrasound scoring system is used. The diagnosis of CHPS was made with a score of ≥4, negative with ≤2, and further examination was recommended with a score of =3. Ultrasound images of CHPS: a substantial moderate or hypoechoic mass with clear contours and borders in the hypertrophied pyloric annulus, a strong echogenic central mucosal layer in the pyloric duct, and a linear silent pyloric duct lumen. A small amount of fluid can be seen passing through the pyloric duct when gastric peristalsis is strong. A stenosis index greater than 50% has been proposed as a diagnostic criterion. It is also possible to observe the opening and closing of the pyloric duct and the passage of food. It has been found that the opening of the pyloric duct is normal in a few patients, which is called non-obstructive pyloric hypertrophy, and the mass gradually disappears with follow-up observation.
2.Barium meal examination
The main basis of diagnosis is the growth (>1 cm) and narrowing (<0.2 cm< span="">) of the pyloric duct lumen. Gastrointestinal fluoroscopy shows a “beak-like” protrusion of the anterior pylorus and a “thread-like” elongation of the pyloric duct. The gastric sinus and lumen are enlarged, and the stomach is filled with light spots and liquid dark areas of echo. In some cases after pyloromyotomy, this sign is still seen for several days, and later the pyloric duct gradually becomes shorter and wider and may not return to normal. After the examination, the barium must be aspirated through the gastric tube and the stomach must be washed with warm saline to avoid aspiration pneumonia due to vomiting.
VI. Diagnosis
Based on the typical clinical manifestations, the diagnosis can be determined by seeing three main signs such as gastric peristaltic wave, pyloric mass and ejection vomiting. The most reliable diagnostic basis is real-time ultrasonography or barium meal examination to help clarify the diagnosis.
Differential diagnosis
Infant vomiting has various etiologies and should be differentiated from various diseases such as improper feeding, systemic or localized infections, pneumonia and congenital heart disease, central nervous system diseases that increase intracranial pressure, progressive renal disease, infectious gastroenteritis, various intestinal obstructions, endocrine diseases, and gastroesophageal reflux and esophageal hiatal hernia.
VIII. Treatment
1.Surgical treatment
The use of pyloromyotomy is the best treatment method with short course and good effect. It must be prepared for 24-48 hours before surgery to correct dehydration and electrolyte disorders and to supplement potassium salts. Those with malnutrition are given intravenous nutrition to improve the general condition.
The “I” group: the plasma membrane and superficial muscle fibers are incised along the longitudinal axis of the pylorus, and then the submucosa is bluntly separated so that the mucosa is completely expanded out of the plasma membrane surface, paying attention not to damage the duodenal mucosa, and the proximal end should exceed the gastric end to ensure the efficacy, and then the muscle layer is cut open to the deeper layers with a blunt instrument to expose the mucosa, and the incision is propped up to a width of more than 5 mm, so that the mucosa to come out freely, and compression to stop bleeding is sufficient.
Inverted “Y” group: The incision of about 2/3 of the pyloric annulus muscle is started from the sinus of the stomach, and then the incision is made obliquely to both sides with an angle of about 100°, forming an inverted “Y” incision. In the latter method, the muscle layer is cut sufficiently and the mucosal expansion is increased, which can significantly enlarge the pyloric canal lumen and significantly reduce the incidence of duodenal mucosal injury and postoperative vomiting. The pulpy muscularis incision should be of sufficient length and depth, and the separation must reach the full length of the lesion, with the depth of mucosal expansion reaching the level of the pulpy membrane.
Postoperative vomiting may be related to pyloric duct edema and incomplete pyloric muscle incision, so preoperative isotonic warm saline gastric lavage is necessary. The postoperative feeding should be started in the following morning, with a trial dose of 15-30 ml of sugar water, and after 2 hours without vomiting, an equal amount of breast milk or milk will be given, which will be gradually increased to the normal amount 48 hours after surgery. Most of the postoperative vomiting is the result of rapid increase in diet, so the amount should be reduced and then gradually increased. Bowel function is normal and the incidence of ulcer disease does not increase, however, X-ray review studies have seen successful pyloromyotomy sometimes showing the presence of a narrow pylorus for as long as 7 to 10 years.
2.Medical treatment
Feeding diet therapy with a diet every 2 to 3 hours, regular warm saline gastric lavage, and an atropine-like antispasmodic 15 minutes before each meal. This therapy requires long-term care, hospitalization for 2 to 3 months, is susceptible to infection, and the effect progresses very slowly and unreliably. Internal therapy is not recommended at present. Attention is paid to the correction of dehydration, electrolyte disturbance and nutritional support therapy.
IX. Complications
1.Dehydration
Severe dehydration, insufficient body fluid.
2.Electrolyte disorders
Alkalosis, breathing becomes shallow and slow, and there may be symptoms such as laryngospasm and hand and foot convulsions. Later, the kidney function is low, acidic metabolites are retained in the body, and some alkaline substances are neutralized, so there are few obvious alkalosis.
3.Nutritional disorders
Lower than the body’s needs.
4.Absorption
There is a risk of asphyxiation.
5.Infection
There is a risk of infection after surgery.
X. Prevention
The disease is a congenital gastrointestinal malformation, there is no effective preventive measures, drug treatment can not correct the malformation, early detection and early treatment is the key to prevention and treatment, so it is necessary to perform pyloromyotomy at the hospital as early as possible, the prognosis is better.