Hi, I'm Bargave Muliudi, a pediatric surgeon at Cincinnati Children's Hospital. And today, we're going to review pyloric stenosis. What is pyloric stenosis? Pyloric stenosis is hypertrophy and hyperplasia of the inner circular layer with associated mucosal hypertrophy. It leads to gastric outlet obstruction in infants between 2 to 10 weeks of age. The etiology is likely multifactorial. It's more common in males. There is increased risk for first born infants with a positive family history. How do these infants present? Patients with pyoric stenosis typically present with non-bilious vomiting, usually seen between 2 to 10 weeks of life. Infants are otherwise well appearing and hungry after vomiting. Emesis will progress until it is projectile. Excessive vomiting can lead to dehydration and eventually lethargy. Hyperbilirubinemia can also occur in up to 14% of patients due to downregulation of hepatic enzymes associated with starvation. What are other differential diagnoses for non-bilious vomiting in an infant? Our differential diagnosis should include gastroesophageal reflux, gastroenteritis, pylorospasm, and other anatomical abnormalities such as duodenal or anral webs, pyloric atresia, but these tend to present very early after feeding. Bilas emesis should always be worked up to rule out intestinal malrotation with midgut volvulus. How do you diagnose pyloric stenosis? The workup should start with a good history. Onset and duration of symptoms, character and nature of emesis are important. The most important part during a physical exam is to look for signs of dehydration. A depressed fontanyl, decreased capillary refill, and low urine output are important. You may find a palpable epigastric mass, known as an olive, but this is more likely to be seen once the patient is asleep. Laboratory data can be obtained to check for electrolyte imbalances, with particular attention to bicarb, chloride, and potassium. Next, an ultrasound, which is the gold standard, can be obtained. Easy way to remember this is to remember the value of pi as 314, 3 millimeters thick and 4 millimeters long, and anything above this is diagnostic. Once you diagnose pyloric stenosis, what electrolyte abnormalities are you concerned about? The classic electrolyte abnormality is a hypochloremic, hypokalemic, metabolic alkalosis. The mechanism is simple. Prolonged gastric outlet obstruction leads to persistent vomiting and loss of hydrochloric acid, which leads to hypochloremia and loss of protons leading to metabolic alkalosis. Then the kidneys try to compensate for dehydration, and they increase the activity of the sodium potassium pump in an attempt to retain fluid. This leads to urinary excretion of potassium to preserve sodium and water. Eventually this leads to hypokalemia, and in later stages, excretion of protons leads to paradoxical aiduria, which further worsens metabolic alkalosis. How is pyloric stenosis treated? First step is to resuscitate, to correct volume and electrolyte abnormalities. In the US, poloomyotomy is the standard of care. In some countries, atropine is used as a non-surgical option, with a success rate of about 60 to 90%. Institutions may have their own protocols involving fluid bolus, increasing maintenance fluid rates, and repeating lab draws. At Cincinnati Children's, we follow a protocol published by the Children's Mercy Group in Kansas City that takes the guesswork out of how many bonuses to give and how frequently you should draw labs. Essentially, you first resuscitate based on chloride levels. If chloride is less than 85, give 3 boluss, which are usually separated by an hour, and then recheck labs. If chloride is between 85 and 97, give two boluss. If chloride is greater than 97, give 1 bolus. If chloride is normal, the resuscitation is based on bicarb. If bicarb is greater than 40, give 3 bonuses. If bicarb is greater than or equal to 33, give 2 bonuses. If chloride and bicarb are normal, but potassium is low, give one bolus. The bolus can be followed by 1 to 1.5 times maintenance fluids with dextrose. Prior to going to the operating room, electrolytes must be corrected. Serum chloride corrected to greater than 100, and most importantly, bicarb to less than 30. And ensure adequate urine output. Now that we've resuscitated and brought the patient back to the operating room, what are the key steps of a pyloroyotomy? After a general anesthesia and intubation, the patient is usually positioned transversely on the table. If you're performing the operation laparoscopically, one approach is to insert a 5 millimeter umbilical cord for the camera. Then make 2 working stab incisions, one for the grasper and the other for performing the palloromyotomy. Usually, the stab incision for the grasper is more lateral, while the incision for pyromyotomy is more medial to make sure you're able to work perpendicular to the pylorus. Either laparoscopic or open, the surgical principle of myotomy is the same. You need to understand the anatomic landmarks that guide the extent of incision. The proximal edge can be easily identified as the antrum transitions to a thick pylorus. The distal extent is generally to the crossing vein of Mayo or the white line. This marks the pyloroduodenal junction. The paloric channel needs to be held in place so that the incision and spreading is exact. A superficial longitudinal incision is made in the serosa between the proximal and distal end of the pylorus, staying within the edges. This can be done with a pyoromyotomy blade or a bogy. After the incision, you use the pyoric spreader to extend the myotomy down to the submucosa. This should be done gently with multiple spreads. It is important to identify a mucosal perforation right away. Not everyone does a leak test, but it's usually done by insufflating some air into the stomach, although this is not very reliable. How do you know your myotomy is adequate? After the palloromyotomy is completed, you notice the submucosa bulge into the myotomy site. Each side of the pylorus should move independently. You can also insufflate air through the NG tube and see the mucosa bulge, and the air pass into the first part of duodenum. What are potential complications from surgery? The complications usually are incomplete myotomy, mucosal perforation, aspiration, wound infection, and incisional hernias. Statistically, there is a slight increased risk of incomplete myotomy and perforation with a laparoscopic approach, but the overall low incidence of complications decreases the clinical significance of the differences between the two approaches. While doing the pyelomyotomy, you perforate mucosa. What do you do? Depending on the extent of perforation, you can either close the mucosa, typically using a low profile needle and a suture like a fibervicro on a TF needle. Or you could perform a full thickness repair of the myotomy. And redo a myotomy about 180 degrees from the first one, usually on the posterior wall of the pellarus. When this happens, usually an NG tube is left in place for a day or so. And upper GI can also be performed based on surgeon's discretion. When can infants begin feeding after the operation? Most infants can be fed immediately after the operation. Different institutions use different protocols. Evidence supports ad-lib feeds. Once the infant is alert and awake, these infants achieve full feeds sooner with no increase in readmission rates. An infant continues to have persistent vomiting after surgery. What is your differential diagnosis? Small episodes of emesis are almost to be expected as the stomach recovers from days to weeks of progressive dilation, and they should not deter feeding. Studies show that odds of emesis is slightly higher in early and ad-lib feedings compared to gradual or delayed feedings, but the length of the stay for ad-lib feedings is much shorter. However, your differential should also include an incomplete myotomy. This may require a repeat myotomy, but is usually very rare. A leak from mucosal perforation can have other signs such as tachycardia and worsening abdominal tenderness. Esophageal reflux disease can also present as post-op emesis. It is important to ask history of reflux prior to developing pyoric stenosis symptoms, as they may persist after the surgery. It can also be from gastric dysmotility from prolonged symptoms. Now that you've worked through pyoric stenosis, what would you say are your key takeaways from today? Be sure to understand the typical presentation of these patients with progressively worsening non-bilious emesis, persistent hunger, and increasing dehydration. Know their typical physiologic derangement of hypochloremic, hypokalemic, metabolic alkalosis. And finally, understand the mainstay of treatment. First, with appropriate resuscitation. And second A pylomyotomy along the length of the hypertrophied pylorus. This video cast was created and edited by Ray Hankey, Gillian Goddard, Zach Korb, Bargava Mulaudi, and Todd Ponsky.
