Necrotizing Enterocolitis with Dr. Gail Besner

Topic overview

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

• 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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