Pyloric stenosis is a narrowing of the pylorus, the lower part of the stomach through which food and other stomach contents pass to enter the small intestine. When an infant has pyloric stenosis, the muscles in the pylorus have become enlarged and cause narrowing within the pyloric channel to the point where food is prevented from emptying out of the stomach.Also called infantile hypertrophic pyloric stenosis, pyloric stenosis is a form of gastric outlet obstruction, which means a blockage from the stomach to the intestines. It's about four times more likely to occur in firstborn male infants and also has been shown to run in families — if a parent had pyloric stenosis, then an infant has up to a 20% risk of developing it. Pyloric stenosis occurs more commonly in Caucasian infants than in babies of other ethnic backgrounds.
Most infants who develop symptoms of pyloric stenosis are usually between 3 to 5 weeks. It is one of the more common causes of intestinal obstruction during infancy that requires surgery.
CAUSES
It is believed that babies who develop pyloric stenosis are not born with it, but that the progressive thickening of the pylorus occurs after birth. A baby will start to show symptoms when the pylorus is so thickened that the stomach can no longer empty properly.
It is not known exactly what causes the thickening of the muscles of the pylorus. It may be a combination of several factors; for example, the use of erythromycin in the first 2 weeks of life has been associated with pyloric stenosis, and there is also a connection in babies whose mothers took this antibiotic at the end of pregnancy or during breastfeeding.
PATHOPHYSIOLOGY
The gastric outlet obstruction due to the hypertrophic pylorus impairs emptying of gastric contents into the duodenum. As a consequence, all ingested food and gastric secretions can only exit via vomiting, which can be of a projectile nature. While the exact cause of the hypertrophy remains unknown, Rogers has assembled compelling evidence that neonatal hyperacidity is involved.
This physiological explanation for the development of clinical pyloric stenosis at around 4 weeks and its spontaneous long term cure without surgery if treated conservatively, has recently been further reviewed.The vomited material does not contain bile because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach.
Persistent vomiting results in loss of stomach acid (hydrochloric acid). The chloride loss results in a low blood chloride level which impairs the kidney's ability to excrete bicarbonate. This is the significant factor that prevents correction of the alkalosis.
A secondary hyperaldosteronism develops due to the decreased blood volume. The high aldosterone levels causes the kidneys to avidly retain Na+ (to correct the intravascular volume depletion), and excrete increased amounts of K+ into the urine (resulting in a low blood level of potassium).
The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO2.
SIGNS AND SYMPTOMS
Symptoms of pyloric stenosis generally begin around 3 weeks of age. They include:
Vomiting. The first symptom of pyloric stenosis is usually vomiting. At first it may seem that the baby is simply spitting up frequently, but then it tends to progress to projectile vomiting, in which the breast milk or formula is ejected forcefully from the mouth, in an arc, sometimes over a distance of several feet. Projectile vomiting usually takes place soon after the end of a feeding, although in some cases it may be delayed for hours.
In some cases, the vomited milk may smell curdled because it has mixed with stomach acid. The vomit will not contain bile, a greenish fluid from the liver that mixes with digested food after it leaves the stomach.
Despite vomiting, a baby with pyloric stenosis is usually hungry again soon after vomiting and will want to eat. The symptoms of pyloric stenosis can be deceptive because even though a baby may seem uncomfortable, he may not appear to be in great pain or at first look very ill.
Changes in stools. Babies with pyloric stenosis usually have fewer, smaller stools because little or no food is reaching the intestines. Constipation or stools that have mucus in them may also be symptoms.
Failure to gain weight and lethargy. Most babies with pyloric stenosis will fail to gain weight or will lose weight. As the condition worsens, they are at risk for developing fluid and salt abnormalities and becoming dehydrated.
Dehydration. Dehydrated infants are less active than usual, and they may develop a sunken "soft spot" on their heads, sunken eyes, and their skin may appear wrinkled. Because less urine is made it may be more than 4 to 6 hours between wet diapers.
After feeds, increased stomach contractions may make noticeable ripples, or waves of peristalsis, which move from left to right over the baby's belly as the stomach tries to empty itself against the thickened pylorus.
It's important to contact your doctor if your baby experiences any of these symptoms.
Other conditions can have similar symptoms. For instance, gastroesophageal reflux (GER) usually begins before 8 weeks of age, with excess spitting up, or reflux — which may resemble vomiting — taking place after feedings. However, the majority of infants with GERD do not experience projectile vomiting, and although they may have poor weight gain, they tend to have normal stools.
A baby with allergy to milk protein may also spit up or vomit, as well as have diarrhea. However, these babies do not have projectile vomiting or vomit up bile.
In infants, symptoms of gastroenteritis — inflammation in the digestive tract that can be caused by viral or bacterial infection — may also somewhat resemble pyloric stenosis. Vomiting and dehydration are seen with both conditions; however, infants with gastroenteritis usually also have diarrhea with loose, watery, or sometimes bloody stools. Diarrhea usually isn't seen with pyloric stenosis.
TESTS AND DIAGNOSIS
1. On physical exam, palpation of the abdomen may reveal a mass in the epigastrium.'olive mass'.
2. pyloric stenosis are diagnosed/confirmed with ultrasound, if available, showing the thickened pylorus
3. Although somewhat less useful, an upper GI series (x-rays taken after the baby drinks a special contrast agent) can be diagnostic by showing the narrowed pyloric outlet filled with a thin stream of contrast material; a "string sign" or the "railroad track sign"
4. Blood tests will reveal low blood levels of potassium and chloride in association with an increased blood pH and high blood bicarbonate level due to loss of stomach acid (which contains hydrochloric acid) from persistent vomiting. There will be exchange of extracellular potassium with intracellular hydrogen ions in an attempt to correct the pH imbalance. These findings can be seen with severe vomiting from any cause.
TREATMENT
Infantile pyloric stenosis is typically managed with surgery;very few cases are mild enough to be treated medically.
The danger of pyloric stenosis comes from the dehydration and electrolyte disturbance rather than the underlying problem itself. Therefore, the baby must be initially stabilized by correcting the dehydration and the abnormally high blood pH seen in combination with low chloride levels with IV fluids. This can usually be accomplished in about 24–48 hours.
Intravenous and oral atropine may be used to treat pyloric stenosis. It has a success rate of 85-89% compared to nearly 100% for pyloromyotomy, however it requires prolonged hospitalization, skilled nursing and careful follow up during treatment.It might be an alternative to surgery in children who have contraindications for anesthesia or surgery, or in children whose parents do not want surgery.
Surgery
The definitive treatment of pyloric stenosis is with surgical pyloromyotomy known as Ramstedt's procedure (dividing the muscle of the pylorus to open up the gastric outlet). This surgery can be done through a single incision (usually 3–4 cm long) or laparoscopically (through several tiny incisions), depending on the surgeon's experience and preference.
Today, the laparoscopic technique has largely supplanted the traditional open repairs which involved either a tiny circular incision around the navel or the Ramstedt procedure. Compared to the older open techniques, the complication rate is equivalent, except for a markedly lower risk of wound infection.This is now considered the standard of care at the majority of children's hospitals across the US, although some surgeons still perform the open technique. Following repair, the small 3mm incisions are hard to see.
The vertical incision, pictured and listed above, is no longer usually required, though many incisions have been horizontal in the past years.
Once the stomach can empty into the duodenum, feeding can begin again. Some vomiting may be expected during the first days after surgery as the gastrointestinal tract settles. Rarely, the myotomy procedure performed is incomplete and projectile vomiting continues, requiring repeat surgery. Pyloric stenosis generally has no long term side-effects or impact on the child's future.
Most infants who develop symptoms of pyloric stenosis are usually between 3 to 5 weeks. It is one of the more common causes of intestinal obstruction during infancy that requires surgery.
CAUSES
It is believed that babies who develop pyloric stenosis are not born with it, but that the progressive thickening of the pylorus occurs after birth. A baby will start to show symptoms when the pylorus is so thickened that the stomach can no longer empty properly.
It is not known exactly what causes the thickening of the muscles of the pylorus. It may be a combination of several factors; for example, the use of erythromycin in the first 2 weeks of life has been associated with pyloric stenosis, and there is also a connection in babies whose mothers took this antibiotic at the end of pregnancy or during breastfeeding.
PATHOPHYSIOLOGY
The gastric outlet obstruction due to the hypertrophic pylorus impairs emptying of gastric contents into the duodenum. As a consequence, all ingested food and gastric secretions can only exit via vomiting, which can be of a projectile nature. While the exact cause of the hypertrophy remains unknown, Rogers has assembled compelling evidence that neonatal hyperacidity is involved.
This physiological explanation for the development of clinical pyloric stenosis at around 4 weeks and its spontaneous long term cure without surgery if treated conservatively, has recently been further reviewed.The vomited material does not contain bile because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach.
Persistent vomiting results in loss of stomach acid (hydrochloric acid). The chloride loss results in a low blood chloride level which impairs the kidney's ability to excrete bicarbonate. This is the significant factor that prevents correction of the alkalosis.
A secondary hyperaldosteronism develops due to the decreased blood volume. The high aldosterone levels causes the kidneys to avidly retain Na+ (to correct the intravascular volume depletion), and excrete increased amounts of K+ into the urine (resulting in a low blood level of potassium).
The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO2.
SIGNS AND SYMPTOMS
Symptoms of pyloric stenosis generally begin around 3 weeks of age. They include:
Vomiting. The first symptom of pyloric stenosis is usually vomiting. At first it may seem that the baby is simply spitting up frequently, but then it tends to progress to projectile vomiting, in which the breast milk or formula is ejected forcefully from the mouth, in an arc, sometimes over a distance of several feet. Projectile vomiting usually takes place soon after the end of a feeding, although in some cases it may be delayed for hours.
In some cases, the vomited milk may smell curdled because it has mixed with stomach acid. The vomit will not contain bile, a greenish fluid from the liver that mixes with digested food after it leaves the stomach.
Despite vomiting, a baby with pyloric stenosis is usually hungry again soon after vomiting and will want to eat. The symptoms of pyloric stenosis can be deceptive because even though a baby may seem uncomfortable, he may not appear to be in great pain or at first look very ill.
Changes in stools. Babies with pyloric stenosis usually have fewer, smaller stools because little or no food is reaching the intestines. Constipation or stools that have mucus in them may also be symptoms.
Failure to gain weight and lethargy. Most babies with pyloric stenosis will fail to gain weight or will lose weight. As the condition worsens, they are at risk for developing fluid and salt abnormalities and becoming dehydrated.
Dehydration. Dehydrated infants are less active than usual, and they may develop a sunken "soft spot" on their heads, sunken eyes, and their skin may appear wrinkled. Because less urine is made it may be more than 4 to 6 hours between wet diapers.
After feeds, increased stomach contractions may make noticeable ripples, or waves of peristalsis, which move from left to right over the baby's belly as the stomach tries to empty itself against the thickened pylorus.
It's important to contact your doctor if your baby experiences any of these symptoms.
Other conditions can have similar symptoms. For instance, gastroesophageal reflux (GER) usually begins before 8 weeks of age, with excess spitting up, or reflux — which may resemble vomiting — taking place after feedings. However, the majority of infants with GERD do not experience projectile vomiting, and although they may have poor weight gain, they tend to have normal stools.
A baby with allergy to milk protein may also spit up or vomit, as well as have diarrhea. However, these babies do not have projectile vomiting or vomit up bile.
In infants, symptoms of gastroenteritis — inflammation in the digestive tract that can be caused by viral or bacterial infection — may also somewhat resemble pyloric stenosis. Vomiting and dehydration are seen with both conditions; however, infants with gastroenteritis usually also have diarrhea with loose, watery, or sometimes bloody stools. Diarrhea usually isn't seen with pyloric stenosis.
TESTS AND DIAGNOSIS
1. On physical exam, palpation of the abdomen may reveal a mass in the epigastrium.'olive mass'.
2. pyloric stenosis are diagnosed/confirmed with ultrasound, if available, showing the thickened pylorus
3. Although somewhat less useful, an upper GI series (x-rays taken after the baby drinks a special contrast agent) can be diagnostic by showing the narrowed pyloric outlet filled with a thin stream of contrast material; a "string sign" or the "railroad track sign"
4. Blood tests will reveal low blood levels of potassium and chloride in association with an increased blood pH and high blood bicarbonate level due to loss of stomach acid (which contains hydrochloric acid) from persistent vomiting. There will be exchange of extracellular potassium with intracellular hydrogen ions in an attempt to correct the pH imbalance. These findings can be seen with severe vomiting from any cause.
TREATMENT
Infantile pyloric stenosis is typically managed with surgery;very few cases are mild enough to be treated medically.
The danger of pyloric stenosis comes from the dehydration and electrolyte disturbance rather than the underlying problem itself. Therefore, the baby must be initially stabilized by correcting the dehydration and the abnormally high blood pH seen in combination with low chloride levels with IV fluids. This can usually be accomplished in about 24–48 hours.
Intravenous and oral atropine may be used to treat pyloric stenosis. It has a success rate of 85-89% compared to nearly 100% for pyloromyotomy, however it requires prolonged hospitalization, skilled nursing and careful follow up during treatment.It might be an alternative to surgery in children who have contraindications for anesthesia or surgery, or in children whose parents do not want surgery.
Surgery
The definitive treatment of pyloric stenosis is with surgical pyloromyotomy known as Ramstedt's procedure (dividing the muscle of the pylorus to open up the gastric outlet). This surgery can be done through a single incision (usually 3–4 cm long) or laparoscopically (through several tiny incisions), depending on the surgeon's experience and preference.
Today, the laparoscopic technique has largely supplanted the traditional open repairs which involved either a tiny circular incision around the navel or the Ramstedt procedure. Compared to the older open techniques, the complication rate is equivalent, except for a markedly lower risk of wound infection.This is now considered the standard of care at the majority of children's hospitals across the US, although some surgeons still perform the open technique. Following repair, the small 3mm incisions are hard to see.
The vertical incision, pictured and listed above, is no longer usually required, though many incisions have been horizontal in the past years.
Once the stomach can empty into the duodenum, feeding can begin again. Some vomiting may be expected during the first days after surgery as the gastrointestinal tract settles. Rarely, the myotomy procedure performed is incomplete and projectile vomiting continues, requiring repeat surgery. Pyloric stenosis generally has no long term side-effects or impact on the child's future.
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