Vomiting In A Neonate

A four-week-old infant born at 39 weeks’ gestation, exclusively breast fed and has been healthy was brought in for an evaluation following a 2 day history of projectile vomiting that occurs after each feeding without with increased fussiness. The child's father mentioned that the baby appears to be without distress after vomiting and wants to feed immediately afterwards. Parents deny the infant has had fever, diarrhea or skin lesion; in addition, has not had exposure to individuals with similar symptoms. His last BM was about 18 hours ago, described as small and firm. Physical exam reveals an alert, active infant with a small palpable mask that is appreciated in the right upper quadrant of the abdomen. The most likely diagnosis is:

A. Viral gastroenteritis

B. Pyloric stenosis

C. Intussusception

D. Gastroesophageal reflux
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Transcript

Voiceover: Welcome to NP certification Q&A presented by Fitzgerald Health Education Associates. This podcast is for NP students studying to pass their NP certification exam. Getting to the correct test answers means breaking down the exam questions themselves. Leading NP expert Dr. Margaret Fitzgerald shares her knowledge and experience to help you dissect the anatomy of a test question, so you can better understand how to arrive at the correct test answer. 

So, if you're ready, let's jump right in. 

Margaret Fitzgerald: A 4-week-old infant born at 39 weeks gestation, exclusively breastfed, and has been healthy, was brought in for an evaluation following a 2-day history of projectile vomiting that occurs after each feeding with increased fussiness. The child's father mentioned that the baby appears to be without distress after vomiting and wants to eat immediately afterwards. Parents deny the infant has had fever, diarrhea, or skin lesion. 

In addition, has not had exposure to individuals with similar symptoms. His last BM was about 18 hours ago, described as small and firm. Physical exam reveals an alert, active infant with a small, palpable mass that is appreciated in the right upper quadrant of the abdomen. The most likely diagnosis is: 

A: Viral gastroenteritis. 

B: Pyloric stenosis. 

C: Intussusception.  

D: Gastroesophageal reflux. 

And the correct answer here is B: Pyloric stenosis. Where should we start with a question like this? First, determine what kind of a question it is. Clearly this is a diagnosis question because we're presented with four different reasons why an infant would vomit. And we have to choose which one is correct. Some background information: pyloric stenosis, also called infantile hypertrophic pyloric stenosis, or IHPS, is caused by an abnormal thickening of the muscles surrounding the pyloric valve.  

As this hypertrophy progresses, the gastric wall outlet is obstructed, preventing feedings from moving from the stomach into the small intestine. Its cause is not fully understood, but risk factors for the condition include male birth sex assignment; preterm birth; maternal tobacco use during pregnancy; and a family history of pyloric stenosis, particularly if the mom had pyloric stenosis. 

Post-birth exposure to macrolide antibiotics such as azithromycin, clarithromycin, and erythromycin also poses risk. Although I do need to say those antibiotics are seldom used in kids that young. Pyloric stenosis is most often noted in an otherwise well infant who is between the ages of 3 to 6 weeks. So, this little one is 4 weeks old. Right in the target there. 

And general rule, if the child's greater than 8 weeks old, they'll never develop pyloric stenosis. Usually, the child has had an uneventful neonatal period. Remember neonatal period, first 28 days of life. With the parents and caregivers reporting that the child has been well, gaining weight appropriately and generally thriving. Even in the early presentation of pyloric stenosis, as we have in this child because he's only been vomiting for 2 days, is that the baby is tending to do otherwise well, it is quite hungry after vomiting their feeding. 

In other words, it looks like this little one does not appear to be nauseated. I suspect everyone listening to this podcast has at one time or another had viral gastroenteritis, food poisoning, or something like that, where once you vomited the last thing you wanted to do was eat again. These little ones with pyloric stenosis are just the opposite. 

They want to eat because they're so hungry, because they have high caloric needs given their body mass, because they're neonates, they're growing by leaps and bounds. Early signs of pyloric stenosis include non-bilious vomiting, usually reduced stool, and with fewer wet diapers. The latter two make sense. Not that much is getting through the GI tract. Of course, without intervention, malnutrition, metabolic acidosis, and jaundice can follow. 

Untreated, this condition can be fatal. What would be the next steps with suspected pyloric stenosis is to promptly get an abdominal ultrasound to confirm the condition, promptly correct hydration and electrolyte disorders, and refer to a pediatric tertiary medical center for surgical correction. I practice 30 miles outside of Boston, so what we would do with a little one like this, we would still send to the local hospital, because what you want to do is these little kids are dry. 

Makes sense. They've been throwing up all their feeds. You want to get some fluids into them, correct their electrolytes, and then you go from there. Is the child stable enough to be ground transported? Do they need to be air vac’d? Usually once they have the pyloric stenosis surgically corrected, they do very well, and the condition does not appear to be associated with other health consequences. 

With that information in mind, let's take a look at the question and the options we are given. A 4-week-old infant born at 39 weeks gestation, exclusively breastfed and has been healthy, is brought in for evaluation following a 2-day history of projectile vomiting occurring after each feed with increased fussiness, the child's father mentioned the baby appears to be without distress after vomiting and wants to feed immediately afterwards. 

The parents deny that the infant has fever, diarrhea, or skin lesions, or exposure to individuals with similar symptoms. His last BM was about 18 hours ago, described as small and firm. Physical exam reveals an alert active infant with a small, palpable mass appreciated in the right quadrant of the abdomen. All right, what I want to do is just before we go to the answers, I want to take one moment and go over a few of the things here. 

This baby was born at 39 weeks gestation. So that's considered to be term. Exclusively breastfed, wonderful. Breastfed babies make a lot of poop. In fact, a lot of times parents will come in and say, ‘I think the baby has diarrhea.’ And what it is, is usually kids around this age, they're making frequent soft BMs like maybe 4 or 5 a day that looks kind of like chopped up, scrambled eggs. 

He hasn't had a BM in 18 hours, and it's described as small and firm. That is an alteration in the typical bowel movement of a little one who's being exclusively breastfed. So those are some of the things that you need to be able to pick up in this description. So, the most likely diagnosis is A: Viral gastroenteritis. This is incorrect. To consider viral gastroenteritis as a diagnosis, likely we would hear about stooling issues.  

In other words, vomiting plus diarrhea. And we'd also be hearing that the child not wanting to feed after vomiting because the little one is nauseated. Whereas in adults, fever is relatively uncommon in viral gastroenteritis, it's actually often seen in the little ones who have this. We probably also would be given a history that there are other household members who have similar signs and symptoms. B: Pyloric stenosis. 

This is, of course, the correct answer. And this child has the classic presentation of pyloric stenosis, and particularly in early disease, because he's only been sick for a couple of days. As I mentioned, getting this child to appropriate evaluation and intervention is key. Young infants like this do not have much of a way of, shall we say, margin of error for tolerating electrolyte disorders and dehydration. 

The finding of the mass in the right quadrant of the abdomen is also commonly noted in kids with pyloric stenosis, and it is sometimes described, is feeling like in all of what you're really feeling is literally the hypertrophic area or around the pyloric valve. And another point to keep in mind, little ones like this have rather thin abdominal walls. 

So doing this type of germinal palpation where you feel the olive like structure is not uncommon. C: Intussusception. This is also incorrect intussusception is a lower GI obstruction and most commonly seen in kids beyond 6 months, but less than 12 months of age. So a couple of things with intussusception. First, this child's in the wrong age group. 

The other part is intussusception typically causes bowel issues, but not vomiting. What happens in intussusception is the colon telescopes on itself, causing the lower GI obstruction. The result is that a section of this ball is without proper blood supply and resulting ischemia, which is terribly painful. These kids cry, God bless them, do they cry. And they often will have their little legs drawn up over the abdomen, and they're really inconsolable because they're dealing with a chunk of ischemic bowel. 

Bloody diarrhea is often part of the clinical presentation, and this is as a result or the bowel ischemia. Most of the time, the kids with intu can be managed fairly conservatively. And once they're treated, they do quite well. I'll talk some more about intussusception in a future podcast, but general rule intussusception will once again be a transfer to a tertiary pediatric medical center. 

Option D: Gastroesophageal reflux, GERD, can be seen in younger babies and usually what will happen with GERD and the little ones is they spit up a little bit of milk or whatever they're feeding on after each feed or nearly every feed. Now there is something called physiologic reflux that's quite common in babies this young, where the babies spit up a little bit after they feed and they there is right as rain. 

They feel fine with it. They don't seem to be bothered by it at all. For a child of this age to be diagnosed with GERD, what you have is the spitting up after all, or most feeds, but they seem to be upset about it. It looks like they're uncomfortable. Generally with the pediatric diagnosis of GERD, it's been going on for a number of days or even weeks prior to the parents or caregivers bringing the child in. 

Because you know what? Most babies spit up and they're not distressed. So what causes this spitting up? It's usually due to the immaturity of the lower esophageal sphincter, the vomiting in this child is really quite counter to the typical spitting up. When we see in clinically significant GERD, this little one is having projectile vomiting very sudden onset. Key takeaway: there are just a few true emergencies that we see an otherwise healthy younger infants. While pyloric stenosis is not common, it is a "can't miss diagnosis" in the younger infant. 

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