Necrotizing enterocolitis: Clinical sciences

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Introduction0:00–1:07

Necrotizing enterocolitis, or NEC for short, is a life-threatening condition most often seen in premature infants that can lead to intestinal necrosis and perforation.
NEC commonly presents with feeding intolerance, bloody stools, and abdominal distension soon after enteral feeds are initiated.
Infants who survive NEC face many long-term sequelae, including short-gut syndrome, intestinal strictures, and neurodevelopmental delays.
On the basis of history and physical exam findings, you can make a clinical diagnosis of NEC, and imaging can be used to support the diagnosis.Now, here’s a clinical pearl!
Breast milk contains macronutrients, micronutrients, natural prebiotics, and antibodies that offer protection against NEC in premature and low birth weight infants!
For this reason, donor breast milk is often given to premature neonates whose caregiver is absent or cannot produce sufficient breast milk.
When a pediatric patient presents with a chief concern suggesting NEC, you should first perform an ABCDE assessment to determine if they are unstable or stable.

Unstable patient1:07–1:40

If unstable, stabilize the airway, breathing, and circulation; and you may even need to intubate the patient. Next, obtain IV access and start broad-spectrum IV antibiotics.
Put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry, and begin supplemental oxygen, if needed.Once you stabilize the patient, obtain a focused history and physical exam, and order abdominal X-rays in the anteroposterior and lateral views.

Unstable patient - H&P, Imaging1:40–3:18

When obtaining the history, be sure to note any risk factors for NEC, which include prematurity or low birth weight. The infant may have developed a sudden change in feeding tolerance, or you may note vomiting, diarrhea, or bloody stools.
Additionally, some infants with NEC might have apneic episodes lasting 20 seconds or more. On the physical exam, the infant may show signs of hemodynamic instability, like hypotension; and signs of respiratory distress, such as tachypnea, retractions, or grunting.
Meanwhile, the abdominal exam typically reveals distension, tenderness, and decreased or absent bowel sounds. You may even detect a palpable abdominal mass due to intestinal edema.
Finally, in some infants, you might notice abdominal wall erythema from intestinal necrosis or crepitus from free air in the abdominal cavity after intestinal perforation.
As far as X-ray results go, you will typically see dilated loops of bowel and pneumatosis intestinalis, which is visible gas within the necrotic intestinal wall, and is a pathognomonic finding for NEC.
Later findings can include portal venous gas, which is gas that has escaped into the hepatic portal vein and its branches, and pneumoperitoneum, which is free air within the abdominal cavity.
A large amount of free air can be identified by the “football” sign on AP films.With this combination of clinical and X-ray findings, you can diagnose NEC with intestinal perforation.

Unstable NEC with perforation3:18–4:37

Because this is a life-threatening condition, consult the surgery team immediately for exploratory laparotomy and resection of necrotic bowel.
As far as medical management goes, be sure to stop all enteral feeds, continue broad-spectrum IV antibiotics, start IV fluids, and, if needed, transfuse blood products.
After surgery, the neonate will require bowel rest and parenteral nutrition.Now, here’s a clinical pearl to keep in mind!
Radiographic evidence of pneumoperitoneum in a premature or low birth weight neonate almost always indicates NEC with intestinal perforation.
However, pneumoperitoneum can also be seen in spontaneous intestinal perforation, or SIP, which is a single perforation site in an otherwise healthy bowel.
SIP is associated with early use of postnatal corticosteroids and indomethacin. Clinically, neonates with SIP usually aren’t as ill as neonates with NEC, and a definitive diagnosis can be made by surgical exploration.
Moreover, the presence of a healthy bowel indicates SIP while a necrotic bowel indicates NEC.Now, let’s go back to the ABCDE assessment and look at stable infants with NEC.

Stable patient4:37–5:31

In this case, obtain a focused history and physical exam, and order a CBC, CMP, and blood culture. When obtaining the history, again, be sure to assess the infant’s risk factors for NEC, which include prematurity and low birth weight.
Additionally, the infant might have developed sudden feeding intolerance, vomiting, diarrhea, or bloody stools. Meanwhile, the physical exam findings may include abdominal distension or tenderness, as well as decreased bowel sounds.
Next, the CBC may show thrombocytopenia or neutropenia; the CMP may reveal electrolyte derangements like hyponatremia or metabolic acidosis; and the blood culture might be positive for infectious organisms.

NEC5:31–6:11

With these clinical findings, you should suspect NEC, and promptly order abdominal X-rays in the anteroposterior and lateral views.
Typically, X-rays reveal dilated loops of bowel, and sometimes, you might visualize pneumatosis intestinalis. With these findings, you can diagnose NEC!Here’s another clinical pearl!
NEC is usually diagnosed clinically, on the basis of history and physical exam findings. Although radiographs can support the diagnosis of NEC, they are not required to confirm it, since characteristic X-ray findings are not always visible in neonates with early NEC.
Alright, once you have diagnosed NEC, begin medical management immediately. First, it’s crucial to promote bowel rest by stopping enteral feeds and beginning gastric decompression, using an orogastric or nasogastric tube.

Stable NEC - Treatment6:11–6:51

Next, start broad-spectrum IV antibiotics, such as Ampicillin and Gentamicin, administer IV fluids, and begin parenteral nutrition.
If needed, don’t forget to transfuse blood products. Finally, you should also consult the surgical team, because although some neonates respond well to medical management, others could clinically deteriorate, so they might require surgical intervention.

Assess treatment response6:51–7:01

Once you initiate the management, your next step is to assess the neonate’s treatment response by reviewing the physical exam, lab results, and abdominal X-ray.
If the patient’s response is adequate, you will notice clinical improvement. Specifically, vital signs will likely return to normal, and the abdomen will decrease in girth and become softer with palpation.

Adequate treatment response7:01–7:37

Additionally, you will likely notice resolving lab abnormalities, such as hyponatremia or metabolic acidosis, with no new abnormalities on X-rays.
Moreover, if there’s an adequate response to treatment, you should continue the current medical management, which typically is bowel rest, total parenteral nutrition, and up to 14 days of antibiotic therapy.On the other hand, if the response to the treatment is inadequate, you will observe clinical deterioration.

Inadequate treatment response7:37–8:52

On exam, the vital signs might become unstable, with the development of hypotension or tachycardia. You may detect a palpable abdominal mass due to intestinal edema; abdominal wall erythema, from intestinal necrosis; or crepitus, due to free air in the abdominal cavity after intestinal perforation.
Lab derangements such as hyponatremia or metabolic acidosis may continue to worsen. Finally, the X-ray might also demonstrate pneumoperitoneum, indicating intestinal perforation.If these signs are present, immediately consult the surgical team for management of intestinal perforation.
The surgical team may perform primary peritoneal drainage, by placing drains in the abdomen in order to relieve abdominal pressure by evacuating air and draining ascitic fluid.
Alternatively, they might perform an exploratory laparotomy, to assess the entire intestine for necrosis or perforation and to resect the necrotic bowel if needed.
Postoperative recovery is often tenuous, so continue medical management as before, with ongoing close monitoring.Alright, as a quick recap… Necrotizing enterocolitis is a life-threatening condition that often presents with feeding intolerance, bloody stools, and abdominal distension.

Review8:52–9:57

If left untreated, it can lead to intestinal necrosis and even death. Unstable neonates require acute management and surgical consultation, as they likely have intestinal perforation requiring emergent surgical intervention with exploratory laparotomy.
On the other hand, stable neonates with clinical and X-ray findings consistent with NEC, such as pneumatosis intestinalis, are medically managed with bowel rest, broad-spectrum IV antibiotics, IV fluids, parenteral nutrition, and transfusion.
These patients are then monitored closely to assess the treatment response. If the response is adequate with clinical improvement, continue with current medical management; however, if there is an inadequate response and clinical deterioration, consult the surgery team for possible primary peritoneal drainage or