Necrotizing Enterocolitis

Pediatric Surgery
Discussion between Dr. Todd Ponsky, and  Dr. Gail Besner about necrotizing enterocolitis

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  • History:
    • Patients will often present with abdominal distention, high gastric residuals and bloody stools.
    • First make sure the problem is in the abdomen.
      • Patients with respiratory disease may get a pneumothorax that can necessitate into then abdomen and appear as free air.
    • It is important to know the feeding regimen.
    • Certain medications are known to predispose patients to NEC, such as indomethacin and acid suppression medications.
      • Indomethacin:
        • Predisposes the patient to isolated ileal perforation and NEC.
      • Acid suppression medications:
        • You do not want to stop the acidification of the stomach, so avoid medications that neutralize the gastric acid.
        • Historically, acid was administered into the stomach to prevent NEC.
  • Abdominal Exam:
    • Evaluate for abdominal wall discoloration.
      • Erythema may occur from an inflammatory response.
      • If there is darkish discoloration, it may signify necrosis of the underlying bowel.
    • Evaluate for abdominal distention.
      • This may occur from dilated loops of intestines, intestinal content leaking out from a perforation, or from inflammatory ascites.
    • Evaluate for pain or tenderness, peritonitis, and for a palpable mass.
    • Always perform a scrotal examination.
      • Swelling or discoloration of the scrotum may occur if the patient has a patent processus vaginalis, which may signify leakage of intestinal contents.
  • Laboratory Values:
    • Complete blood count:
      • WBC:
        • Will have leukocytosis because of inflammation.
        • If the patient is neutropenic, this is worrisome for overwhelming sepsis that is not being compensated for.
      • Platelets:
        • Thrombocytopenia may occur from endotoxemia and gram-negative septicemia.
      • Hemoglobin is important to evaluate if the patient has bloody stools.
    • Arterial blood gas will help evaluate for acidosis and base deficit. 
    • May also consider obtaining a lactic acid.
  • Imaging:
    • Cross-table lateral or lateral decubitus X-rays will pick up free air.
    • X-rays will also evaluate for pneumatosis and fixed loops of bowel.
    • Frequency of the X-rays epends on the institution. Dr. Besner recommends obtaining an X-ray at least every 8 hours to evaluate for interval change.

MEDICAL MANAGEMENT OF NEC

  • Medical management of NEC includes gastric decompression, broad-spectrum antibiotics, and serial labs/imaging and abdominal examination.
    • Gastric decompression:
      • Withhold all feeds
      • Insert an orogastric tube to decompress the stomach and take the pressure off the intestinal loops.
    • Broad-spectrum antibiotics:
      • Specific antibiotics vary by facility, and usually depends on the bacterial colonization of the NICU in that particular hospital.
      • Some hospitals use antifungals.
    • Serial labs/imaging and abdominal exams:
      • Allows you to see longitudinally the direction the patient is going in.
      • Specific frequency of imaging and labs is facility dependent.
  • How long to continue medical management?
    • Recommend 1 week to 10 days.
    • If patient shows clinical improvement, then consider slowly advancing feeds. 
    • If patient is not tolerating the feeds well, consider either a repeat episode of NEC or post-NEC stricture.
  • Post-NEC Stricture: 
    • Most commonly occurs in the left colon by the splenic flexure, by may occur anywhere.
    • Imaging:
      • May be helpful to discuss with the radiologist first.
      • Consider contrast enema and UGI with small bowel follow through.
        • Important to perform the contrast enema first to avoid waiting for the contrast from the UGI to pass through.

WHEN TO OPERATE ON NEC

  • Absolute indications are:
    • Clinical deterioration when the patient is on maximum medical management
    • Free air
  • Consider operating when you have a multiple relative indications (i.e. portal venous air, fixed loop on X-ray, pneumatosis, worsening clinical status, worsening abdominal examination and laboratory values).
  • It is difficult to decide when to operate after one assessment, but usually becomes more obvious over serial examinations.

PERITONEAL DRAIN VS LAPAROTOMY

  • There are two randomized control trials currently in the literature comparing the outcomes.
    • Moss et al. trial1 (http://bit.ly/2j8B1w6) and Pierro et al. trial2 (http://bit.ly/2iHeHWT).
      • Both found no difference in overall mortality.
      • Both studies only looked at early end points and did not look at delayed end points of neurological recovery.
        • It appears that patients with peritoneal drains may have worse neurological outcomes 1-2 years after NEC recovery compared to laparotomy patients.
  • NEST (Necrotizing Enterocolitis Surgery Trial):
    • This is an ongoing trial that is randomizing 300 patients to either a laparotomy or peritoneal drain.
    • It will follow patients 18-22 months after recovery from NEC to evaluate for neurological outcomes.
  • How to decide between drain and laparotomy?
    • At this time, it is not known which is better, although peritoneal drains may have worse neurological outcomes because of the ongoing inflammatory response from the necrotic tissue.
    • Consider a peritoneal drain in patients with a focal area of perforation.
    • Also discuss with the family and you can offer them the choice.

 PERITONEAL DRAIN

  • Technique:
    • May be performed at bedside with local anesthesia.
    • Make a transverse incision at the right lower quadrant, large enough to allow the passage of a quarter inch penrose drain.
      • If you make the incision too large, you may get a hernia when the drain is removed.
    • Enter the abdominal cavity using a hemostat. You Will often get a rush of air or stool.
    • Some surgeons advocate instilling saline to wash the baby out but Dr. Besner does not do this.
    • Place the drain carefully. Pass it several times and do not force it to avoid bleeding.
      • Goal is to have the drain curve to all corners of the abdomen but this is hard to achieve.
      • Some surgeons make counter incisions on the other side of the abdomen and pull the drain through there.
    • Secure the drain in place.
  • Drain Management
    • Irrigate the drain regularly to keep it patent.
    • Start to slowly remove the drain 7-10 days after placement.
      • Do not perform this if there is continued leakage of stool from the drain. Recommend an UGI with small bowel follow through first.
      • Otherwise, recommend pulling it out slowly over the course of several day.
  • When to feed?
    • If patient is doing clinically well, may start feeds.
    • If there is any evidence of feeding intolerance, obtain a contrast study.

 OPERATIVE MANAGEMENT OF NEC

  • Pre-operative management:
    • Resuscitate the patient pre-operatively and correct any coagulopathies.
    • Set up PRBC, platelets and FFP for the OR.
  • Surgical Technique:
    • May perform in the OR or at bedside in the NICU if the patient is on high oscillator settings.
    • Perform a supraumbilical transverse incision.
      • Skin is very thin so take care when entering the abdomen to avoid an enterotomy.
      • Be careful to not hurt the liver or spleen.
        • The liver is very prone to a subcapsular hematoma that premature patients may exsanguinate from.
    • Assess the integrity of the intestines that evaluate for necrotic loops of bowel or areas of perforation.
    • Segmental necrosis:
      • Some surgeons will resect and perform a primary anastomosis.
      • Recommend creating a proximal stoma and mucous fistula if there is any concern about the healing of the anastomosis, and close this when the patient is a minimum of 2kg and stable.
    • Stoma creation:
      • Bring the stoma out through the incision.
        • Attempt to bring out the functional end and mucous fistula next to each other, to simplify the future takedown of the stoma.
      • Tack both ends to the fascia so they don’t fall back into the abdomen.
      • The distal end almost always sloughs off, so leave a little length to avoid it receding behind the fascia.
      • It is not necessary to mature the stoma.
        • Dr. Besner does not, and if interstomal therapies are high quality, placing an ostomy applicance is not difficult. 

MANAGEMENT OF DIFFUSE NEC

  • Will usually see diffuse pneumatosis and unhealthy, but not necrotic, bowel.
  • This usually occurs if you go to the OR too early.
  • Need to decide if there is something to resect. If you are unsure, it is respectable to not resect and return for a second look operation.
    • Consider leaving the abdomen open if there are dilated loops of bowel, so you do not add to the intra-abdominal pressure, potentially worsening intestinal blood flow.

MANAGEMENT OF SKIP LESIONS

  • Consider resecting all together and just have one anastomosis if the lesions are close together and this may be done without creating short bowel syndrome.
  • If not, you may resect the individual lesions and create multiple anastomoses; however, leave a proximal diverting stoma.
  • Clipping and dropping:
    • Usually performed on an unstable patient if there is not enough time to create multiple anastomoses.
    • Resect the necrotic bowel and return another day to create the anastomoses when the patient is more stable.

MANAGEMENT OF NEC TOTALIS

  • Currently we do not have the technology to manage this problem.
  • Likelihood of surviving through potentially years of TPN to be able to undergo a small bowel liver transplant is close to 0%.
    • Reasonable to close the abdomen and pursue comfort care for the patient.
  • Discuss with the family and give them realistic expectations.

MANAGEMENT OF EXTREMELY FRIABLE BOWEL DURING LAPAROTOMY

  • Results from being forced to operate when the inflammatory process in the abdomen is at the peak.
  • Smartest decision a surgeon can make is to know when to stop the operation and return another day.
    • Continuing the operation and potentially creating more enterotomies and serosal tears will result in worse outcomes for the patient.
  • If possible, consider identifying the proximal bowel and creating a diverting ostomy.

MANAGEMENT OF TENSION PNEUMOPERITONEUM

  • Compartment syndrome may occur from free air.
  • Decompress using an angiocath as a temporizing maneuver as patient may not be stable enough to go to the OR.

POST-OPERATIVE MANAGEMENT

  • Reversing the stoma:
    • Consider after the patient is stable and tolerating feeds.
    • Also wait until the patient is at least 2 kg to simplify the creation of the anastomosis.
    • May consider re-feeding through the mucous fistula if the patient has a high stoma.
    • If patient is having signs of TPN-induced cholestasis or you cannot nourish the patient because of a high stoma, then consider reversing sooner.
  • Refeeding through the mucous fistula:
    • Recent article in Journal of Pediatric Surgery reported a substantial decrease in TPN use in patients who undergo refeeding3 (http://bit.ly/2jAt27G).
    • Be careful when creating the mucous fistula, as they often stricture.
      • Consider leaving a soft catheter in the fistula post-operatively to keep it open.

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