Pyloric stenosis: Clinical sciences

Pyloric stenosis occurs from hypertrophy of the circular and longitudinal muscle fibers of the pylorus, which acts as a muscular valve between the stomach and the duodenum.

This most commonly presents between 2 and 6 weeks of age. Pyloric stenosis often leads to complete or near complete gastric outlet obstruction, which can present as forceful vomiting.

Excessive vomiting can in turn cause further complications, such as dehydration and metabolic abnormalities like hypokalemic, hypochloremic metabolic alkalosis with paradoxical aciduria.

Management of pyloric stenosis includes fluid resuscitation and correction of metabolic derangements, as well as surgical pyloromyotomy, which is considered curative.Alright, if a patient presents with a chief concern suggesting pyloric stenosis, you should first perform an ABCDE assessment to determine whether your patient is unstable or stable.

If the patient is unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access and initiate IV fluids for resuscitation.

Most infants will show signs of severe dehydration and severe electrolyte abnormalities that need to be corrected during resuscitation.

Finally, make sure to continuously monitor vital signs and keep the patient NPO.Okay, once you’ve done acute management, your next step is to obtain a focused history and physical exam, along with labs like a CBC and CMP.

The history is typically obtained from your patient’s caregivers, who may report episodes of immediate, post-prandial, nonbilious, projectile vomiting, as well as fewer wet diapers, which suggests dehydration.Here’s a clinical pearl for you!

“Projectile” vomiting refers to vomiting so forcefully that stomach contents are launched across a long distance. Be sure to ask caregivers for details when taking the history, because they might describe vomiting as “projectile” when their infant is simply spitting up!Now, on physical exam, you might find signs of severe dehydration, such as hypotension, tachycardia, dry mucous membranes, a sunken fontanelle, or delayed capillary refill.

Additionally, you might feel an olive-like mass that’s palpable in the right upper quadrant of the abdomen. On laboratory analysis, CBC is typically normal, while CMP shows electrolyte abnormalities consistent with a hypokalemic, hypochloremic metabolic alkalosis, as well as unconjugated hyperbilirubinemia in some cases.

These findings together should make you suspect pyloric stenosis in the setting of severe hypovolemia. Your next step is to get an abdominal ultrasound to confirm your diagnosis.

Okay, findings on ultrasound that suggest a hypertrophic pylorus include pyloric wall thickening of 3 mm or greater, or a “target sign,” which indicates concentric hypertrophy.

If these findings are found on ultrasound, you can diagnose pyloric stenosis. Now that you have made the diagnosis, you will proceed with management.

For patients that present in an unstable fashion, they will require continued fluid resuscitation and electrolyte management, as well as emergent consultation of your surgery team for pyloromyotomy.Alright, now that we have discussed unstable patients, let's go back and talk about stable patients.

Your first step is to obtain a focused history and physical, as well as labs like a CBC and CMP. History will often reveal patients between 2 to 6 weeks of age with recurrent episodes of immediate, postprandial vomiting.

Infants with pyloric stenosis are often called “hungry vomiters,” as they are persistently hungry despite the episodes of postprandial emesis.

They also have poor weight gain and fewer wet diapers consistent with dehydration from poor oral intake. Additionally, patients might have risk factors for pyloric stenosis, such as preterm birth, family history of pyloric stenosis, macrolide use within the first 2 weeks of birth, maternal smoking, bottle feeding, and first born males.

On physical exam, you may find signs of mild dehydration, such as tacky mucous membranes or delayed capillary refill. Abdominal exam might reveal an olive-like mass in the right upper quadrant and even peristaltic waves moving across the abdomen.

On labs, CBC is typically normal, while CMP might show hypokalemic, hypochloremic metabolic alkalosis and elevated unconjugated bilirubin.

This constellation of clinical and lab findings should make you suspect pyloric stenosis, so your next step is to order an abdominal ultrasound.

Now, if the ultrasound shows a normal pylorus, you should consider an alternative diagnosis for emesis, such as gastroenteritis.

On the other hand, if the abdominal ultrasound shows a thickened, hypertrophic pylorus or the “target sign”, you can diagnose pyloric stenosis.

Lastly, let's talk about the management. You will first want to give the patient fluid resuscitation and manage any electrolyte derangements.

You should also urgently consult surgery for pyloromyotomy. In many cases, you can resume feeds post-operatively.Alright, as a quick recap… Patients with pyloric stenosis may present with projectile vomiting, signs of dehydration, and an olive shaped mass in the right upper quadrant.

Labs may reveal metabolic abnormalities like hypokalemic, hypochloremic metabolic alkalosis with paradoxical aciduria. To confirm the diagnosis, obtain an abdominal ultrasound, which usually shows pyloric hypertrophy or the “target sign.” Once you’ve confirmed your diagnosis, give the patient fluids, manage their electrolytes, and consult the surgery team for a