Atresia, Stenosis, and Other Obstruction of the Colon Treatment & Management

Initial treatment of newborns with colonic atresia is directed toward resuscitation. The child is often distended and dehydrated. Usual treatments prior to operative intervention include the following:

• Nasogastric decompression
• Intravenous fluid resuscitation
• Intravenous antibiotics (These are often used, although this is not particularly evidence-based.)

Following the prompt initiation of these basic measures, the child should be transferred to a neonatal intensive care unit at a center with pediatric surgeons capable of correcting the malformation. Associated abnormalities of other organ systems may require attention and treatment.

The management of colonic atresia is directed at eliminating the bowel obstruction and establishing intestinal continuity. In selected cases (with limited comorbidities and limited associated malformations), this may be performed in one operation by resecting the atretic ends and anastomosing the colon. If the child has significant comorbidities, a diverting enterostomy may be brought out just proximal to the atresia, and intestinal continuity may be restored during a second operation.

Historically, some authors have advocated resection with primary anastomosis for right colon lesions and colostomy diversion with subsequent reconstruction for left-sided atresia and stenosis. Theoretically, the liquid feces in the right colon pose less risk to a fresh anastomosis than formed stool. However, in practice, Davenport et al noted that the type of procedure had no effect on survival rates, and outcomes were excellent using either technique.^[5] A 2009 series showed excellent outcomes using primary anastomosis in 10 of 12 patients, two of whom had gastroschisis.^[44]

Colonic atresia associated with Hirschsprung disease can be associated with abnormal distal colonic fixation.^{[45, 29]} The association of nonfixation with aganglionosis seems significant enough to warrant obtaining biopsy results prior to establishing intestinal continuity in those selected cases. Diverting enterostomy alone is always a safe option if the suspicion of aganglionosis is significant and experienced pediatric pathology services are unavailable. Because of the rarity of this association, it may be reasonable to reserve biopsy for patients with intestinal fixation abnormalities, postoperative feeding or elimination difficulties, or failure to thrive.

In congenital colonic stenosis, one usually finds less difference in the sizes of the proximal and distal limbs, making resection with primary anastomosis the preferred treatment.

In acquired colonic stenosis following necrotizing enterocolitis, primary excision and anastomosis is the treatment of choice for stable patients without life-threatening comorbidities.

Basic preoperative laboratory measurements for all neonates should include a CBC count, electrolyte assessment, and a crossmatch. If time permits, a contrast enema can be quite useful in assessing the colon and excluding any other narrowing, which can be difficult during surgery.

Primary Repair in One Stage

Laparotomy

A transverse supraumbilical laparotomy is usually performed. The abdomen is eviscerated, and the bowel is inspected. The atresia should be readily visible by the dilated bulbous proximal portion and a microcolon on the other side. A large mesenteric or intestinal gap may be observed between the proximal and distal ends, reflective of the region that would have been supplied by the vessel that had the prenatal vascular accident, which hypothetically caused the atresia.

Full exploration

The abdomen must now be fully explored. The full intestinal length must be examined for the presence of other atresias. This may require passing a catheter distally into the open end of the distal segment and distending the bowel with saline to ensure the lumen is patent. The presence of multiple atresias may require multiple resections and should be assessed together to minimize intestinal loss and the number of anastomoses.

Proximal segment

In preparing to put the two ends of the colon together, the dilated proximal portion must be resected. The dilated proximal bowel functions poorly due to dysmotility. Resecting the proximal intestine back to an area of normal caliber is essential for postoperative function and lessens the size discrepancy when performing the anastomosis.

Distal segment

Minimal distal bowel is removed, although the atretic end is thickened and should not be used in closure. That end is resected, and the distal colon is usually divided on a bias, removing more bowel on the antimesenteric side than the mesenteric side (to promote better blood supply at the anastomosis). The antimesenteric side is usually opened further to counter the size discrepancy with the proximal end.

Mesenteric gap

If present, the mesenteric gap is usually closed primarily, if possible.

Diversion with Primary Repair at a Second Stage

The operation is much the same as for primary repair above.

Proximal segment

The proximal end of the atresia is again resected back to a normal-caliber bowel. This end is then brought out onto the anterior abdominal wall and matured as an ostomy.

Distal segment

If the patient is critically ill, the distal segment may be left completely undisturbed until the patient's status changes in the future. For stable patients, the distal end of the atresia should have its end removed, and the fresh end should be brought up to the abdominal wall skin as a mucous fistula.

Ostomy location and maturation

Both ostomies can be brought out at the same location, which may be at the corner of the laparotomy incision or may be through a separate incision. They may also be separated by a skin bridge; however, that is nonessential. What is most important is that the colostomy be matured and positioned on the abdominal wall in such a way that an appliance can be securely placed around it.

Mucous fistula

The mucous fistula should not be matured like a mushroom but should be flush with the skin and should only be large enough to be able to admit a catheter for irrigations or contrast radiography. If it is placed immediately next to the colostomy with no skin bridge, it should be small enough to allow appliance placement over both. If the surgeon prefers a skin bridge between the ostomy and mucous fistula, it should be either small enough to be directly covered by the ostomy appliance wafer or should be far enough away as to not interfere with ostomy appliance placement.

The neonate who has undergone surgical correction of atresia or stenosis requires neonatal critical care in conjunction with the pediatric surgical care.

In the early postoperative period, the intestine and soft tissues absorb fluid, which surgeons refer to as third-space losses. This requires significant hydration to ensure the maintenance of intravascular volume and adequate tissue perfusion. Inadequate hydration can lead to pressor administration, which can impair intestinal perfusion. Third-space losses usually persist for 24-48 hours if no source of sepsis is present.

All children who undergo laparotomy need adequate analgesia. Narcotics should only be administered to babies in a monitored setting (ie, a neonatal intensive care unit with apnea, pulse-oximetry, and cardiac monitors). No baby should be prevented from getting adequate analgesia simply because they cannot articulate the need for it.

Antibiotics are usually administered to all patients, although the indications are not clearly evidence based. Within the first 3 days of life, the intestinal flora is not yet colonized with anaerobes, so gram-positive and gram-negative coverage is sufficient at that time.

Early parenteral nutrition should be started in all patients. Patients with atresia, despite having their bulbous dysmotile proximal portions resected, can have prolonged postoperative ileus and usually benefit from early parenteral nutrition.

If a nasogastric tube was placed during the operation, it usually remains in place at the discretion of the surgeon. The most traditional approach is to keep a nasogastric tube to suction (taking care to replace its output with intravenous fluids) until the child is passing flatus or stool. When that occurs, the tube may be placed to bedside gravity drainage; if that is well tolerated, the tube may be removed. Some surgeons clamp the tube prior to removal as a final test to see if the child can truly tolerate their own intestinal gases and secretions.

When the tube is removed, the diet may be started. Most surgeons start with clear liquids, such as sugar water or a balanced electrolyte solution. When that is well tolerated, the diet is advanced to either breast milk or formula.

Patients who have undergone a colostomy require specific care for the stoma and its output. Return of bowel function in these patients is usually faster after colostomy than in those who undergo resection and anastomosis. Colostomy closure is performed electively at a future date. Most surgeons prefer to wait a minimum of 6-8 weeks to allow intraperitoneal inflammation to subside.

Follow-up imaging studies are not performed unless indicated by clinical issues. Children who have had a stoma created usually undergo contrast enema prior to stomal closure to evaluate the distal limb for stricture or obstruction.

Follow-up in the office is essential. Many of these babies have residual intestinal motility problems that may manifest in either the proximal or distal segments. Close follow-up is essential to ensure that they are appropriately managed. Failure to thrive or long-standing intestinal motility issues may be a sign of missed Hirschsprung disease and should prompt a biopsy.^[23]

Complications of surgery for colonic atresia and stenosis are those of any bowel resection with stoma creation or anastomosis. Wound infection or incisional hernia can occur after any surgery.

The complication surgeons are most concerned about is anastomotic leak. Leaks may manifest at any time but usually become noticeable several days to a week after surgery. Signs may be as subtle as mild tachycardia and fever, or the patient may rapidly progress from mild illness into full-blown septic shock. Radiography may reveal intra-abdominal free air. CT scanning could reveal abscesses. Anastomotic leak requires exploration and diverting enterostomy.

Intra-abdominal abscesses may occur without leak but are rare. Intraoperative bleeding that leads to postoperative clot can be a setup for abscess, which may be amenable to drainage by interventional radiology.

Anastomotic narrowing may occur and may be related to technical error, ischemia, or leakage.

Patients who undergo colostomy may have stoma narrowing, prolapse, or parastomal herniation.

Survival of patients with colonic atresia and stenosis is related to the patient's condition before surgery, technical difficulties with colonic anastomosis, sepsis, and associated anomalies.^{[46, 11]}

Whereas older series reported high mortality rates for colonic atresia, modern series report survival of all patients, except those with significant life-threatening comorbidities.

Patients with Hirschsprung disease and colonic atresia have more complicated courses and a mortality rate of 10%.^[29]

Colonic stenosis outcomes have also improved significantly since Gross reported the death of the single patient treated at the Boston Children's Hospital before 1952.^[10] Improvement in resuscitation and perioperative care presently results in survival rates of approximately 90%.^{[47, 1]}

Table. Outcomes of Surgery in Colonic Atresia and Stenosis (Open Table in a new window)

Summary

Colonic atresia and congenital stenosis are uncommon lesions. Infants present with abdominal distension and vomiting and often fail to pass meconium. Associated anomalies are common, and their severity directly affects outcome. Although the etiology of colonic atresia has traditionally been believed to be related to antenatal mesenteric vascular accidents, a 2005 study suggests that defects in the FGF10 pathway may be involved.^[40]

The combination of Hirschsprung disease and colonic atresia remains rare; however, missing the association prior to reconnecting the intestinal tract can lead to reoperations, poor outcome, and increased mortality.

Surgical correction is the mainstay of therapy for atresia and stenosis. In the absence of significant comorbidity, primary resection and anastomosis is the recommended surgical treatment and appears to have an equivalent outcome to resection with creation of a colostomy and subsequent closure.

Controversies

The question of the necessity for routine rectal biopsy prior to establishing intestinal continuity is not so much controversial as it is difficult to definitively answer. The small number of cases that associate Hirschsprung disease with colonic atresia is such that the association is greater than random but still exceedingly rare. The downside to taking a staged approach if Hirschsprung disease is a possibility is minimal when compared with the risk of multiple operations and increased mortality when the association is missed prior to anastomosis. Knowing both sides of this issue allows the surgeon to choose the approach that best serves their patient.