bubble_chart Overview

Vomiting is an extremely common gastrointestinal symptom in pediatric clinical practice, which can occur in various diseases involving multiple systems and all age groups. Careful differentiation is required.

bubble_chart Etiology

The causes of vomiting can be divided into acute and chronic, organic and functional, as well as medical and surgical. Clinically, vomiting typically includes both regurgitation and vomiting, with numerous underlying causes. For ease of discussion, they are addressed separately below:

(1) Regurgitation

refers to the non-forcible flow of digestive secretions or gastric contents from the stomach or esophagus out of the mouth. It is usually not accompanied by nausea or forceful abdominal muscle contractions. Regurgitation can be physiological or caused by pathological factors.

1. Physiological: In newborns within the first few weeks, milk (with or without curds) may be seen in the mouth about 0.5 to 1 hour after feeding, commonly referred to as "spitting up." The infant's appetite, sleep, mental state, and weight gain remain normal. Often, no obvious cause can be identified, and it usually resolves naturally within 7 to 8 months without intervention.

2. Pathological: 1) Feeding issues: This refers to "vomiting" caused by improper feeding techniques. For example, incorrect breastfeeding posture (such as poor latch of the nipple and areola, nose too close to the breast, incorrect lying position, etc.), rapid milk ejection, excessive milk flow leading to fast sucking and swallowing, overfeeding, nipple inversion causing difficulty in sucking, or in artificial feeding, low milk temperature, small nipple hole diameter, insufficient caloric content in the milk, or infrequent feeding. Infants often engage in non-nutritive sucking, leading to excessive air in the stomach, and failure to burp the infant after feeding or performing various care activities (changing diapers, bathing, administering medication, etc.). Feeding solid foods to infants who cannot chew, forcing premature infants to eat, or feeding during or after crying can also cause vomiting.

2) Congenital esophageal obstruction: Often diagnosed through X-ray examination.

(1) Intraluminal and mural: Complete or incomplete obstruction caused by structural abnormalities of the esophagus itself.

① Congenital esophageal atresia: Esophageal atresia is a congenital malformation of unknown cause. It is not uncommon clinically, occurring in about 1 in 4000 live births. Esophageal atresia may or may not be associated with tracheoesophageal fistula but is often complicated by vertebral, anal, cardiac, renal, and limb malformations. It is generally classified into five types: Type I (both proximal and distal ends of the esophagus are blind, with no tracheoesophageal fistula), Type II (proximal esophagus has a fistula connected to the trachea, distal end is blind, not connected to the stomach), Type III (proximal esophagus is blind, distal end has a fistula connected to the trachea), Type IV (esophageal atresia with both upper and lower segments connected to the trachea via fistulas), and Type V (esophagus is patent but has a fistula running from below upward to the trachea) or Type N. Type III is the most common, accounting for over 90%, followed by Type I, which accounts for only 5-7%.

Infants with congenital esophageal atresia exhibit significant swallowing difficulties. Early after birth, they may produce frothy saliva, regurgitate milk, and expel it from the mouth or nostrils. Since the milk has not been exposed to stomach acid, the vomitus does not contain curds or bile. Newborns often experience respiratory distress and cyanosis due to aspiration, which improves significantly after suctioning. Repeated episodes can lead to early-onset pneumonia, threatening life. Diagnosis is primarily made by inserting a No. 10 rubber or silicone tube into the esophagus and taking an upright chest and abdominal X-ray.

② Congenital esophageal stenosis: Rare. The cause is unknown, with various theories proposed. Histologically, it can be divided into three types: thickening of a segment of the esophageal wall, membranous web or septum, and intramural tracheobronchial cartilage remnants. The membranous type can clinically resemble esophageal atresia. Esophagoscopy can both diagnose and treat. Infants with esophageal stenosis often present with vomiting, dysphagia, aspiration, recurrent respiratory infections, weight loss, and malnutrition when starting solid foods. Diagnosis is made through X-ray esophagography and endoscopy. However, cartilage remnants in the lower third of the esophagus are often diagnosed during surgery or pathological examination. This condition may coexist with congenital esophageal atresia.

③Congenital esophageal duplication: Among congenital digestive tract duplications, its incidence is second only to the ileum. It is not uncommon clinically. It can manifest as cysts, tubular structures, or diverticulum-like formations. It is most commonly found in the lower right posterior mediastinum of the esophagus. Some cases communicate with the spinal canal and are accompanied by vertebral deformities or intraspinal masses. Statistics show that among 65 cases, 8 (12.3%) were associated with intra-abdominal duplication. Sometimes there are no symptoms, and the mass is only discovered incidentally during chest X-ray examinations. Some cases present primarily with respiratory symptoms such as cough, wheezing, pneumonia, hemoptysis, and chest pain. Approximately 15% of affected children exhibit symptoms like dysphagia, heart issues, vomiting, upper abdominal pain, and hematochezia. Preoperative diagnosis can be made using X-ray anteroposterior and lateral views of the chest and abdomen, esophageal contrast studies, B-ultrasound or color Doppler ultrasound, CT, nuclear imaging, and MRI. If an intraspinal mass is suspected, spinal canal contrast imaging is also required. Differential diagnosis should consider lymphoma, neurogenic tumors, and hemangiomas.

④ Achalasia (cardiospasm, idiopathic esophageal dilation): The cause of the disease is unknown. Among 167 pediatric cases, 5.3% were neonates. Due to dysfunction of the cholinergic nerves in the esophageal wall, the lower esophageal muscles contract, the pressure of the lower esophageal sphincter increases, food stagnates in the esophagus, gradually dilating, leading to inflammatory changes in the mucous membrane and ulcer formation. The degree of dysphagia varies, progressively worsening, sometimes influenced by psychological factors. The contents, which are milk without curds or undigested food, reflux or are vomited from the esophagus to the mouth, sometimes containing coffee bean-colored mucus. Over time, emaciation, anemia, and malnutrition may occur. Children may complain of heartburn or chest pain caused by peptic esophagitis. Diagnosis can be made with X-ray imaging and barium meal contrast. Esophagoscopy and manometry are increasingly used.

⑤ Gastroesophageal reflux (GER) refers to the phenomenon where stomach and part of the duodenal contents reflux into the esophagus. In children, except for some physiological cases that disappear around 8-10 months after birth, other pathological cases can cause serious complications. This disease has been a hot topic in pediatric surgery research both domestically and internationally in recent years. The causes are complex and varied, mainly due to the abnormally sustained decrease in the lower esophageal sphincter pressure (LESP). Other factors such as a larger His angle, diaphragmatic elasticity, abdominal pressure, esophageal mucosal folds, and gastric capacity reduce the anti-reflux barrier function and esophageal clearance ability, leading to abnormal gastric and duodenal function, causing gastroesophageal reflux, and further resulting in esophageal mucosal inflammatory changes, ulcers, bleeding, and stenosis.

Some believe that 50% of GER occurs in neonates and infants, with 60-80% experiencing projectile vomiting within the first week of life, and 40% having pyloric stenosis. The vomitus may contain bile and coffee bean-colored bloody fluid. Older children may experience retrosternal burning, painful swallowing, dysphagia, wheezing, asthma, choking, and symptoms of chronic respiratory infections. Statistics indicate that 25-80% of children with asthma and about 46-63% of those with chronic respiratory diseases have GER! Some diseases related to neuropsychiatric factors, such as cerebral palsy, mental retardation, rumination, and Sandifer syndrome with different movement postures of the head, neck, and upper trunk, as well as some cases after esophageal atresia surgery, can also be associated with GER. Over time, hematochezia, anemia, chronic malnutrition, and even delayed growth and development in children can occur.

Common diagnostic methods for GER include X-ray imaging of the esophagus and stomach with barium contrast. It can confirm the diagnosis and distinguish between mild and severe cases. Measuring LESP, a value of <1.96 kPa (20 cm H₂O) is diagnostically significant. In recent years, Wang Weilin et al. have used esophageal and gastric dual pH microelectrodes to monitor fasting (excluding meals and the subsequent 2 hours) and 24-hour periods in children in both standing and lying positions. Results: Acidic gastroesophageal reflux is defined as when the esophageal pH is <4 for more than 4% of the total monitoring time. A preliminary standard for alkaline reflux is set as gastric pH >4 during fasting, and gastric pH >7 for alkaline gastroesophageal reflux. If gastric pH >4 and esophageal pH <7, it is considered alkaline gastroesophageal reflux. The conclusion is that gastroesophageal reflux occurring on the basis of duodenal regurgitation is one of the main types of gastroesophageal reflux in children, and dual pH monitoring of the gastroesophageal segment during fasting and lying positions has greater diagnostic significance in pathological reflux. Additionally, endoscopy, isotope scanning, and ultrasound examinations also aid in comprehensive judgment and differential diagnosis.

⑥ Hiatal hernia: This condition is a relatively common congenital malformation. The esophageal hiatus becomes abnormally wide due to poor development of the diaphragm. When lying flat or when abdominal pressure increases, the gastric fundus, cardia, and part of the esophagus slide into the mediastinum, causing gastric contents to reflux into the esophagus, leading to mucosal inflammation, even ulcers and bleeding, and eventually forming scar stenosis. The child vomits food, which may contain coffee bean-colored or red blood. Symptoms worsen when lying flat and at night. Eventually, esophageal stenosis, dysphagia, anemia, and malnutrition occur. Respiratory symptoms such as coughing, wheezing, and inflammation can be caused by aspiration, and in severe cases, apnea or sudden death may occur. Diagnosis is mainly based on X-ray barium contrast imaging of the esophagus and stomach. Iodized oil and meglumine diatrizoate are used in young infants to prevent barium aspiration. Changing to a semi-sitting position and increasing the viscosity of food can significantly reduce vomiting in small infants.

⑦Congenital short esophagus: Very rare. The cardia and part of the gastric fundus are located in the mediastinum. Compression can cause dysphagia and gastric fluid reflux, leading to esophageal inflammation and ulcers, resulting in "vomiting" blood. Diagnosis can only be confirmed by X-ray barium contrast. It should be distinguished from hiatal hernia.

(2) Extraluminal: Congenital diseases outside the esophagus cause esophageal compression, leading to obstruction. Dysphagia occurs after eating, especially when swallowing solid foods. Vomiting, aspiration, or choking may occur. This can be seen in cases of congenital vascular rings surrounding the esophagus. Clinically rare.

3. Acquired esophageal diseases: 1) Esophageal inflammation and stenosis: Due to various congenital and acquired diseases, such as gastroesophageal reflux, achalasia, pneumonia, scarlet fever, diphtheria, Helicobacter pylori infection, asthma, etc., causing repeated vomiting, gastric acid stimulation, and inflammation, ulcers, and stenosis of the esophageal mucosa. Acute cases of regurgitation or vomiting also include common cases of young children accidentally ingesting household alkali, battery alkali, or industrial strong acids and alkalis, causing acute mucosal or/and muscular layer injury, leading to inflammation, perforation, or stenosis.

2) Esophageal foreign bodies: Such as coins, pins, fish bones, melon seeds, peanuts, beans, jujube pits, plastic toys, etc. Mild cases can cause excessive saliva, difficulty swallowing, and vomiting; severe cases can cause retrosternal burning and pain, even perforation, abscess formation, and esophageal fistula after rupture. In young children, foreign bodies can compress the trachea anteriorly, causing difficulty breathing.

3) Esophageal abscess: Causes include retropharyngeal abscess extending downward, esophageal perforation due to various reasons, secondary abscess, mediastinal lymph abscess, tracheostomy tube pressure ulcers, and spinal subcutaneous nodular abscess. Due to compression obstruction, dysphagia, or pain, regurgitation and vomiting occur. There are also reports of local esophageal dilation and pseudodiverticulum formation due to post-inflammatory adhesions of tracheobronchial lymph nodes, causing food retention and mucosal inflammatory changes, leading to regurgitation.

4) Trauma: Esophageal trauma, apart from foreign bodies, is mostly iatrogenic, such as injury during endoscopy and injection treatment for esophageal varices, insertion of gastrointestinal decompression tubes, or artificial ventilation. Vomitus is often bloody. Diagnosis is not difficult based on history, X-ray contrast, and imaging. After esophageal atresia surgery, foam-like fluid in the thoracic drainage tube often indicates anastomotic leakage, and the child may also have foam-like mucus reflux in the mouth.

5) Rumination: Rarely reported in domestic literature. Mostly seen in 3-4 month-old infants who re-chew and re-swallow food. They lift their heads, extend their tongues and jaws, and rhythmically chew and swallow until regurgitation occurs. Some food spills out, while some is swallowed. The infant is in good spirits and appears alert. Parents often complain of vomiting or failure to gain weight. Sometimes it occurs when the mother is frightened, depressed, or unable to intervene due to the infant's illness. Infants with intellectual disabilities or mental abnormalities may show persistent rumination. At this time, increased care and affection from nurses or others can help recovery.

6) Others: When intra-abdominal pressure increases due to tumors, ascites, organ enlargement, and aerophagia causing intestinal distension, diaphragmatic elevation, lower esophageal or gastric torsion, and neonatal anesthesia withdrawal may cause reflux or regurgitation.

(2) Vomiting

Refers to the forceful expulsion of gastric or partial small intestine contents through the mouth. Often accompanied by nausea and strong abdominal muscle contractions.

The numerous causes of vomiting can be divided into obstructive, reactive, and central categories. The former is often due to surgical reasons, while the latter two are mostly caused by internal diseases.

1. Obstructive vomiting: Can be caused by congenital gastrointestinal malformations or certain acquired diseases causing gastrointestinal obstruction.

1) Congenital gastrointestinal malformations include luminal atresia, stenosis, or dysplasia of the wall or external compression. In neonates, this is the most common cause of surgical vomiting. From top to bottom of the digestive tract, there are esophageal atresia, gastric volvulus, pylorospasm, hypertrophic pyloric stenosis, pyloric membrane, duodenal atresia or stenosis, annular pancreas, malrotation of the intestine, jejunal or ileal atresia or stenosis, aganglionosis (Hirschsprung's disease), Hirschsprung's disease-related enterocolitis, anorectal malformations (including anal atresia or stenosis and sometimes associated rectourinary fistula, rectovaginal fistula, rectovestibular fistula, cloaca, etc.), and gastrointestinal duplication. In addition, small left colon syndrome and megacystis-microcolon-intestinal hypoperistalsis syndrome are rare. Gastric wall muscle dysplasia with gastric perforation, meconium plug syndrome, and meconium peritonitis are not uncommon clinically. Meconium ileus is rare among all ethnic groups in China.

Extrinsic compression of the intestinal wall can be caused by congenital abnormalities such as abnormal fibrous membranes or bands in the duodenum or jejunum, adhesions following meconium peritonitis, preduodenal portal vein, mesenteric hiatal hernia, incarcerated inguinal hernia, or diaphragmatic hernia. Hiatal hernia is also a congenital disease that causes incomplete gastrointestinal obstruction and vomiting.

2) Acquired gastrointestinal diseases, such as adhesions following intestinal or peritoneal inflammation, common acute intussusception in infants (ileocecal, ileocolic, or ileoileal types), gastrointestinal foreign bodies (hairballs, gastric bezoars, etc.), and rare sigmoid volvulus. Premature infants may experience milk curd obstruction. Young children may suffer from abdominal pain and vomiting due to constipation, accompanied by urinary retention. Ascaris-induced intestinal obstruction and volvulus have become rare due to the widespread use of chemical fertilizers in large and medium-sized cities.

Due to the different causes of intestinal obstruction, varying disease courses (acute or chronic), different natures (complete, incomplete, or sudden), and different lesion locations (high, middle, or low), the timing, nature, content, color, and volume of vomiting vary significantly. The cause of the disease is closely related to age.

2. Reflex vomiting is often caused by biological, physical, or chemical stimulation of the gastrointestinal tract, sometimes due to a combination of factors.

1. Medical causes

(1) Swallowing syndrome: Neonates swallow amniotic fluid, maternal blood, or meconium during delivery, leading to vomiting shortly after birth, which usually resolves within 1-2 days.

(2) In infants and young children, respiratory infections can cause mucus in the nasopharynx to trigger a gag reflex, or occasionally, edema of the uvula or inserting fingers into the mouth may cause vomiting.

(3) Viral, bacterial, mycoplasma, and fungal infections of the respiratory and digestive tracts are common causes in children. Acute upper respiratory infections, pneumonia, and certain other infectious diseases such as whooping cough can induce vomiting due to severe coughing, which causes contractions of the abdominal wall and diaphragm muscles. Digestive disorders, acute gastroenteritis, infectious diarrhea, viral hepatitis, and necrotizing enterocolitis in neonates and premature infants often present with vomiting as a primary symptom. Neonatal tetanus may also cause refusal to feed and vomiting.

(4) Allergic conditions, such as the addition of gluten-containing foods or allergic purpura, can cause intestinal spasms leading to vomiting.

(5) Peptic ulcers, often associated with Helicobacter pylori infection, can lead to significant vomiting in advanced stages due to pyloric obstruction caused by ulcer scarring.

(6) Food, drug, and chemical poisoning, such as from copper, ipecac, digitalis, theophylline, salicylates, withdrawal from anesthetics, iodine preparations, mustard, hyacinth beans, or spoiled meat. Administering medication to infants and young children can also induce vomiting.

(7) Metabolic and endocrine disorders, such as adrenal insufficiency, acidosis, phenylketonuria, fructosemia, hereditary tyrosinemia, and galactosemia.

2. Surgical causes

(1) Inflammation, perforation, and peritonitis of gastrointestinal organs, such as gastric or duodenal ulcers, trauma, or tumors causing perforation, acute appendicitis, cholecystitis, or pancreatitis.

(2) Ischemic enteritis, which can be caused by vascular diseases or insufficient blood flow, such as superior mesenteric artery syndrome, volvulus due to various reasons (e.g., malrotation with midgut volvulus in neonates or young infants, ascaris-induced intestinal obstruction, or mesenteric hiatal hernia), and hypovolemic shock causing spasms in the gastric and intestinal muscle layers, leading to abdominal pain, nausea, and vomiting.

(3) Gastrointestinal bleeding, such as acute or chronic ulcer bleeding, esophageal variceal rupture, or significant bleeding caused by hemangiomas or vascular malformations.

3) Urogenital diseases, such as acute pyelonephritis, glomerulonephritis, renal insufficiency, uremia, hydronephrosis, urinary tract stones; ovarian cyst torsion in girls, and dysmenorrhea in older girls.

4) Otolaryngology and Ophthalmology Diseases Otitis media with labyrinthitis, motion sickness, Ménière's disease, etc. Glaucoma accompanied by headache and vomiting.

5) Others, such as gastroparesis syndrome, which is an idiopathic gastric neuromuscular disorder of unknown cause, can be seen in diabetes, connective tissue diseases, and uremia. Symptoms include postprandial epigastric discomfort, intermittent nausea, delayed vomiting, and delayed gastric emptying. The disease cause of chronic pseudo-intestinal paralysis (chronic pseudo-intestinal obstruction) has various theories and is also a disease of muscle or/and nerve abnormalities. In addition to abdominal distension and fullness and vomiting, it can be complicated by diarrhea or constipation. There are reports of its occurrence in hypothyroidism, scleroderma, amyloidosis, Down syndrome, and cytomegalovirus infection. Reflex vomiting is also seen during radiotherapy and chemotherapy for tumor diseases in children.

3. Central vomiting

1) Central nervous system disorders account for the vast majority of central vomiting. It can be caused by increased intracranial pressure (brain edema, brain tumors, stirred pulse tumors, sun exposure, etc.), inflammation (encephalitis, meningoencephalitis, brain abscess, subdural effusion), craniocerebral injury (intracranial hemorrhage, subdural hematoma, cerebral contusion, cerebral hypoxia, postoperative cerebrospinal membrane protrusion, etc.), and toxic encephalopathy (pneumonia, toxic enteritis, sepsis).

2) Others, such as lead poisoning, hypoglycemia, mountain sickness, psychogenic vomiting due to school or family conflicts, cyclic vomiting, nervous anorexia, bulimia, and autonomic dysfunction (intestinal spasm, paroxysmal tachycardia) can also cause vomiting.

Common causes of vomiting in different age groups are shown in Table 5-1.

bubble_chart Pathogenesis

(1) The mechanism of disease-induced vomiting is a complex neural reflex. External or endogenous biological, physical, and chemical stimuli received by peripheral organs and tissues are transmitted to the central nervous system via somatic and visceral nerves or the bloodstream. In the medulla oblongata, the vomiting center (which receives impulses from the gastrointestinal tract and other visceral nerves) and the chemoreceptor trigger zone (CTZ) located at the base of the fourth ventricle (which receives chemical and drug stimuli from the bloodstream) process these signals. The reflex signals are then transmitted via the vagus and spinal nerves to the corresponding organs, triggering the vomiting response. Recent studies have shown that dopamine receptors play a significant role in mediating vomiting in the CTZ. The CTZ also contains serotonin, norepinephrine, substance P, enkephalins, and gamma-aminobutyric acid (GABA). Certain endogenous neurotransmitters and neuropeptides can induce vomiting by acting on the CTZ either through the bloodstream or directly.

Swallowing refers to the movement of food from the pharynx to the stomach, a complex physiological process involving coordinated actions of nerves (somatic and autonomic, voluntary and involuntary, central and peripheral), muscles (striated and smooth, voluntary and involuntary), and multiphase (chemical and physical) activities. Any organic or functional disorder in these processes can lead to dysphagia or other abnormalities (including vomiting).

Typically, stimuli from the lips, pharynx, gastrointestinal tract, biliary tract, peritoneum, heart, and genitourinary systems, as well as unpleasant visual, olfactory, auditory, or gustatory sensations, or even pain, can be transmitted via sensory nerves as emetic impulses that exceed the threshold of the vomiting center. Additionally, psychological factors or increased intracranial pressure can also induce vomiting. Emetic medications act directly on the vomiting center. Abnormal metabolic products in the body, such as ketoacidosis in diabetics, liver disease, or uremia, can stimulate the vomiting center or CTZ to trigger vomiting.

The vomiting response involves multiple functional changes, including contractions of the abdominal, diaphragmatic, and intercostal muscles, increased intra-abdominal pressure, breath-holding, palpitations, sweating, peristalsis of the upper small intestine and stomach, relaxation of the lower esophageal sphincter, and increased salivation. Nausea often precedes vomiting. Older children may describe a premonitory sensation of throat or abdominal discomfort, which can be somewhat controlled by the cerebral cortex. Infants and young children often exhibit dysphoria, grimacing, yawning, pallor, sweating, drooling, and an inability to suck their fists. Premature infants, full-term newborns, and some young infants may show no pre-vomiting signs due to immature nervous systems. Vomitus can be expelled simultaneously from the mouth and nostrils, and due to uncoordinated swallowing and glottal reflexes, aspiration is highly likely. Newborns are also prone to overfeeding due to small stomach capacity and high fluid requirements. The gastric mucosa is sensitive to temperature, volume, hypoxia, and chemical stimuli. Frequent supine positioning, underdeveloped esophageal muscle elasticity, and immature lower esophageal sphincter with a more obtuse angle of His contribute to the ease of gastric contents refluxing into the esophagus during reverse peristalsis.

(2) Pathophysiology Due to the diverse causes of vomiting, varying durations and severities, and differences in age, the impact on the body can vary significantly. Mild cases may cause only transient discomfort with no lasting effects. Chronic vomiting can lead to peptic esophagitis, hypovolemia, hypokalemia, hyponatremia, and metabolic alkalosis. Further complications include anemia, malnutrition, and growth retardation. In severe acute cases, vomiting can cause fluid and electrolyte imbalances, shock, aspiration, asphyxia, arrhythmias, or even death. Surgical causes may lead to gastrointestinal perforation, diffuse peritonitis, shock, or sepsis. Children with impaired motor function are particularly susceptible to post-vomiting aspiration and require heightened vigilance.

bubble_chart Diagnosis

Since vomiting is merely a symptom, its disease causes are complex and varied, with different accompanying symptoms and similar manifestations. Therefore, it is necessary to carefully collect medical history, conduct a thorough physical examination, and selectively choose laboratory and imaging tests as needed. Only after objective comprehensive analysis can a preliminary diagnosis be made.

I. History Collection

Since the spectrum of diseases varies among different age groups, the focus of history collection should also differ. Generally, vomiting in children of various age groups is mostly caused by internal medical reasons. For example, in the neonatal period, out of 266 cases of vomiting reported by Shanghai Xinhua Hospital, 233 cases (87.9%) were due to internal medical reasons, while the remaining 33 cases (12.1%) were caused by surgical diseases. Among internal diseases, infectious causes are the most common, while among surgical diseases, infections of abdominal organs and gastrointestinal obstructions are predominant. Since vomiting is a symptom of the digestive system, history collection should first focus on feeding methods, dietary content, timing, and habits. For newborns, in addition to noting the occurrence and development of vomiting, it is also important to understand the mother's pregnancy and delivery history, as well as medication history. In recent years, there have been significant changes in the dietary habits of urban children, with many commonalities as well as unreasonable and unscientific aspects, which need to be carefully understood. Changes in weight can objectively reflect the severity of vomiting and its impact on the child, and should be emphasized during questioning. It is also important to listen carefully to the accounts of parents and older children themselves.

II. Analysis of Several Symptoms

Always consider age factors and the disease spectrum. Strive to distinguish as early as possible whether the vomiting is functional or organic, and whether it is medical or surgical, in order to determine the diagnostic and treatment principles.

1. Vomiting: Pay attention to its occurrence, manifestation, and changes

(1) Time and frequency: The time when vomiting begins and the number of vomiting episodes per day can vary significantly depending on the disease. For example, a newborn vomiting coffee-ground-colored mucus within a few hours after birth and a 3-year-old child repeatedly vomiting coffee-ground-colored material for over two years clearly stem from different causes. The former may be due to swallowing maternal blood, while the latter is more likely to be caused by a hiatal hernia.

Table 5-1 Common Causes of Vomiting by Age Group

(2) Manner It may present as overflow, such as a small amount of milk flowing from the corner of a newborn's mouth; or regurgitation from the mouth; or a large amount of vomiting from the mouth; or simultaneous ejection from the mouth and nostrils. In the neonatal period, the former may be physiological, while the latter is more common in congenital hypertrophic pyloric stenosis.

(3) Content and Nature It has important reference value for the diagnosis of gastrointestinal obstruction.

① Clear or foamy mucus, undigested milk or food Indicates obstruction above the cardia due to blocked saliva flow. Seen in congenital esophageal atresia in newborns, esophageal stenosis due to food inflammation in all age groups, and achalasia.

② Mucus, milk curds, gastric contents Indicates obstruction at the pylorus. Seen in hypertrophic pyloric stenosis in newborns, pyloric membrane, and pyloric cicatricial stenosis in older children with gastric ulcers. Occasionally seen in young children after accidental ingestion of corrosive chemicals. When containing a small amount of blood or coffee bean-like material, it can be seen in esophageal hiatal hernia and gastroesophageal reflux in children of all ages. Overeating can cause acid regurgitation with undigested food.

③ Yellow or green clear mucus, sometimes mixed with a small amount of milk curds or food Often indicates obstruction at the duodenum. Seen in severe functional vomiting in all age groups; in newborns, it is more common in duodenal atresia or stenosis, annular pancreas, and malrotation.

(4) Yellow-green liquid mixed with a small amount of chyme Indicates obstruction near the proximal jejunum. Seen in high jejunal atresia or adhesive intestinal obstruction, and intestinal paralysis.

(5) Light brown-green fecal-like, foul-smelling Indicates obstruction in the mid to lower jejunum or its distal end. In the neonatal period, it is more likely to be jejunal or colonic atresia, aganglionosis, or anorectal malformation. In other age groups, it indicates low gastrointestinal obstruction due to various causes.

(6) Bloody Depending on the amount, speed, and location of bleeding, the amount and color of blood in the vomitus vary. A small amount of blood mixed with gastric acid appears brown, seen in newborns who have swallowed amniotic fluid containing maternal blood or sucked on a cracked nipple, neonatal hemorrhagic disease, early gastric perforation, advanced hypertrophic pyloric stenosis; esophageal hiatal hernia in all age groups, severe repeated vomiting due to various causes, and critical illness with disseminated intravascular coagulation, with a small amount of blood, brown or dark red. Thrombocytopenic purpura, hemophilia, aplastic anemia, especially at a certain stage of leukemia, may cause hematemesis due to gastrointestinal bleeding. Portal hypertension with esophageal variceal rupture, gastric mucosal ulcer bleeding after burns or asphyxia, acute hemorrhagic gastritis caused by oral salicylates or theophylline, can all lead to hematemesis. Massive jejunal bleeding can also result in vomiting fresh blood. In children, rare expectoration of blood is difficult to distinguish from hematemesis and requires reliance on other symptoms and signs.

It is noteworthy that the content and characteristics of vomiting can change with the progression of the disease. For example, in the early stages of low small intestine atresia in newborns, colorless mucus may be vomited, which may turn into gall fel after 1 to 2 days. After systemic infection or severe sepsis treatment, as the condition improves and intestinal paralysis alleviates, the content of vomiting or gastrointestinal decompression may change from yellow-green turbid fecal juice to clear mucus. Therefore, it is necessary to combine other accompanying symptoms and signs and dynamically observe to accurately determine the clinical significance of vomiting.

2. Abdominal distension and fullness often accompany vomiting symptoms. It is necessary to differentiate whether abdominal distension and fullness is caused by abdominal masses, large amounts of fluid or gas accumulation in the abdominal or intestinal cavity, whether it is localized or generalized, whether it is accompanied by intestinal or gastric patterns or peristaltic waves, and whether the degree of abdominal distension and fullness is mild, moderate, or grade III.

3. Abdominal pain is also a symptom frequently associated with vomiting. It is important to carefully understand the timing of the onset of abdominal pain, the nature of the pain (paroxysmal, persistent, or persistent with paroxysmal exacerbations), and the location of the abdominal pain. Vomiting accompanied by abdominal pain should raise suspicion of a surgical acute abdomen. Special attention should be paid to newborns, especially premature infants, who may lack the expression of abdominal pain even in cases of complete intestinal obstruction due to gastrointestinal malformations, and may only appear lethargic without abdominal muscle tension even in cases of perforative peritonitis.

4. Abnormal stools can manifest in various ways, including changes in consistency, volume, timing, frequency, and site of passage. If a child has several episodes of vomiting over a short period, along with reduced frequency and volume of stools, and no other obvious discomfort, digestive dysfunction is likely. If accompanied by loose stools and fever, gastroenteritis is indicated. Vomiting accompanied by abdominal pain and cessation of bowel movements should first raise suspicion of a surgical acute abdomen, which is particularly significant in newborns. Typically, over 90% of full-term newborns should pass meconium within 24 hours of birth, and about 98% within 48 hours, with complete passage within 2-3 days, totaling about 60-90%. In congenital hypertrophic pyloric stenosis, severe vomiting leads to constipation, sometimes even presenting as the main complaint. In newborns with ileal or colonic atresia, the distal colon is narrow, with no meconium, sometimes only passing small amounts of gray-green mucus. In newborns with intestinal aganglionosis, there is no history of spontaneous meconium passage after birth, but after rectal examination, glycerin enema, or colonic irrigation, a large amount of gas and meconium may be expelled explosively, accompanied by obvious greenish-yellow bilious vomiting. In other age groups, intestinal aganglionosis often only presents with constipation and abdominal distension, without vomiting. In congenital anal stenosis, the amount of meconium is significantly reduced. In rectal atresia, there is no passage of meconium (without fistula) or abnormal passage site (perineum, vestibule, vagina, scrotum, urethra, or bladder). Additionally, when intestinal torsion, strangulation, intussusception, duplication malformation, Meckel's diverticulum, or other causes lead to gastrointestinal bleeding, varying degrees of bloody stools (tarry, dark red, bright red, etc.) or only positive occult blood tests may be observed. When stools are green, with mucus and milk curds, watery, purulent, or mucoid bloody, they are often due to medical causes.

5. Other symptoms In pediatric clinical practice, vomiting is an extremely common symptom but often not the only one. Along with vomiting, in addition to the aforementioned abdominal distension, abdominal pain, and abnormal stools, there may be other digestive system symptoms such as loss of appetite, increased appetite, hiccups, belching, acid reflux, heartburn, etc. One or more symptoms related to the respiratory, cardiovascular, urinary, endocrine, or nervous systems may coexist with vomiting. Fever is also common. These symptoms should all be taken seriously and carefully considered to guide the focus during physical examination, laboratory tests, and imaging.

III. Physical Examination

A thorough and comprehensive physical examination (including inspection, palpation, percussion, and auscultation) is essential for diagnosis and differential diagnosis, with particular attention to symptoms-related aspects. Besides mental state, complexion, and consciousness, weight and height are important indicators of nutritional and developmental status. Head circumference and anterior fontanelle are also important in infants and children with chronic vomiting. A detailed abdominal examination should include the inguinal region. Measurement of body temperature, pulse, and respiratory rate is essential. Blood pressure measurement may be used as appropriate.

During physical examinations, it is essential to first gain the cooperation and trust of the child and their parents through words and actions. The hands should be warm, movements gentle and swift, with a clear focus and logical sequence. Infants can be soothed by breastfeeding or using a pacifier. For toddlers, if persuasion and coaxing are ineffective, oral sedatives (10% chloral hydrate at 0.5ml/kg) should be administered promptly. Older children are often cooperative. Uncomfortable examinations, such as throat inspections, should be conducted last. When palpating the abdomen, the most painful areas should be checked last. Rectal examination is often necessary in cases of infantile vomiting and various abdominal disorders. It provides crucial information about stool characteristics, whether the rectum is collapsed and airless, the presence of pelvic masses, and rectal temperature. Additionally, it can reveal the presence, position, shape, and size of the anus, which is particularly important for newborns and infants with vomiting suspected of having low intestinal obstruction. Due to the discomfort and pain caused by rectal examinations, they should be performed last.

IV. Laboratory Tests

Should be selectively conducted based on the initial impressions from medical history, symptoms, and physical examination. Routine blood, urine, and stool tests are preferred. Others should be screened around aspects of inflammation, trauma, tumors, deformities, or endocrine metabolic disorders and related laboratory items of various systemic diseases.

V. Imaging Examinations

The development of science, technology, and industry, with the continuous emergence of new instruments and equipment, has increasingly improved diagnostic accuracy. Among these, imaging examinations play an extremely important role in the development and enhancement of modern medicine, sometimes becoming the sole means of definitive diagnosis. They should be fully utilized when conditions permit.

1. X-ray Examination The most commonly used, including fluoroscopy and plain films of different parts and positions, and various methods of contrast imaging (oral, percutaneous venous or biliary contrast, selective stirred pulse contrast, double contrast of the intestine with gas and barium, endoscopic retrograde cholangiopancreatography, etc.).

2. B-mode Ultrasonic Diagnostic Instrument (B-ultrasound) and Color Doppler Flow Imaging (Color Ultrasound) The non-invasive nature of these examinations is particularly suitable for children and has been increasingly widely used in clinical practice. Interventional ultrasound technology has also been introduced into the pediatric field.

3. X-ray Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) In recent years, these have gradually become important examination tools in pediatrics in large and medium-sized cities.

4. Others Such as radionuclide examinations, endoscopic examinations, polymerase chain reaction (PCR), and certain genetic diagnoses should be selected when necessary and conditions permit.