Intestinal Obstruction in the Newborn Treatment & Management

Intestinal obstruction causes fluid and electrolyte losses from vomiting in proximal obstructions and from sequestration of fluid (within the intestines) in distal obstructions. To minimize morbidity and mortality, these deficits must be corrected while obtaining appropriate diagnostic studies. In addition, the clinician must perform the following:

• Decompress the intestinal tract (orogastric tube)
• Provide respiratory and cardiovascular support, as needed
• Administer intravenous antibiotics, in anticipation of surgery

Consultations

Treatment of neonatal intestinal obstruction requires collaboration between the neonatologist and pediatric surgeon to ascertain the correct diagnosis and proceed with appropriate treatment. When the acute problem is associated with another chronic disease, such as cystic fibrosis, early and ongoing consultation between these specialists is appropriate and appreciated.

Distal small bowel obstruction

A Gastrografin (diatrizoate) enema study should be obtained in babies with distal small bowel obstruction. Contrast enemas are diagnostic and may be therapeutic, because Gastrografin acts as a detergent, loosening the sticky meconium and promoting evacuation (>50% success rate).

Multiple enemas may be required in babies with meconium plug syndrome. If the previous enema elicited an evacuation but the baby is still obstructed, another enema may be tried. However, if the previous enema was ineffective, it may be time to consider surgery. Before success is declared, the enema fluid must reach the terminal ileum. Diatrizoate and N-acetylcysteine may also be instilled via a nasogastric tube. Hyperosmolar solutions suck fluid into the bowel and soften the thick meconium; however, their use entails a slight risk of perforation (3%-10%).

Intussusception

Air insufflation has supplanted hydrostatic reduction in intussusception. Findings from a meta-analysis of 32,451 children with intussusception (ages 1 day to 22 years) found the following ^[25] :

• Air insufflation success: 83%
• Hydrostatic success: 70%
• Similar rates of perforation (0.39% air vs 0.43% hydrostatic reduction) and recurrence (6% vs 7.3%) between the two groups
• Higher morbidity of perforation in hydrostatic reduction group (spillage of contrast into the peritoneal cavity)

​Esophageal atresia (EA) and tracheoesophageal fistula (TEF)

Traditionally, infants with EA/TEF have been segregated according to the following features:

• Maturity (term vs premature)
• Weight (appropriate for gestational age or small for gestational age)
• Associated lung disease (hyaline membrane disease [HMD])
• Accompanying congenital heart disease and other anomalies

The lungs of term babies with EA/TEF are in optimal condition at birth, whereas premature infants suffer from HMD.

Delay (in both groups) risks antegrade passage of air through the TEF into the stomach, and positive pressure in the stomach facilitates reflux of gastric secretions (acid) into the lungs. As general rule, the body can withstand one insult with minimal sequelae but not repeated insults.

Positive-pressure ventilation exacerbates the above dynamics. The lungs in HMD are noncompliant; surfactant is given to expand the alveoli. Positive-pressure ventilation forces air through the TEF into the gastrointestinal tract, which increases intra-abdominal pressure, thereby elevating the diaphragm and increasing the amount of pressure required to inflate the lungs.

HMD tends to improve over time, as long as the baby’s lungs are not injured by ventilator-induced barotrauma (excessive pressure) or high oxygen concentration. Neonatologists carefully avoid excess pressure and oxygen, and ventilators that are specially designed for premature infants are available.

Definitive repair of EA/TEF may be performed soon after birth in term babies, but for premature babies, it is desireable to wait until their lungs recover—but how is that possible, given the following dynamics?

• Positive-pressure ventilation causes air to pass through the TEF into the stomach.
• Distention of the stomach and intestines increases the intra-abdominal pressure.
• Greater pressure is required to expand the lungs.
• More air passes through the fistula into the stomach and intestines.
• A vicious cycle ensues.
• Gastric rupture has even occurred from excessive ventilatory pressures.

Insertion of a gastrostomy tube breaks the vicious cycle and allows the definitive operation to be postponed until the baby's lungs are in optimal condition. ^[26]

 

If the lungs are so stiff that too much of the inspired gas escapes through the gastrostomy tube, the tube may be placed to “underwater seal drainage,” and the depth of the water level may be altered to resist the escape of inspired gas (through the gastrostomy tube) that is meant to inflate the lungs. ^[27]

Or a Fogarty embolectomy catheter can be inserted through the gastrostomy tube into the esophagus to the origin of the TEF (utilizing fluoroscopy); inflating the balloon at the tip of the catheter occludes the fistula. ^[28]

Note: Routine placement of gastrostomy tubes in babies with EA/TEF is not currently practiced for the following reasons:

• Gastrostomy tubes tether the stomach to the anterior abdominal wall, making the intrathoracic esophageal anastomosis more difficult.
• These tubes increase the incidence of gastroesophageal reflux and, therefore, the necessity for medications and surgery to correct this problem.

Despite these negative considerations, insertion of gastrostomy tubes (in selected cases) may allow the baby's lungs to recover sufficiently for the definitive operation to be performed safely.

Duodenal atresia

Babies with duodenal obstruction require fluid and electrolyte restoration and nasogastric tube decompression. These infants should also be evaluated for trisomy 21.

Duodenal atresia is considered a “midline embryologic defect,” and evaluation for associated anomalies should include echocardiography, head and renal ultrasonography, and vertebral radiography.

Malrotation/volvulus

If malrotation/volvulus is suspected, expeditious diagnostic studies must be obtained, followed by urgent relief of the (strangulation) obstruction. In addition to nasogastric decompression and fluid resuscitation, these infants may require intubation and mechanical ventilation, as well as vasopressor agents for cardiovascular support. Administer broad-spectrum antibiotics because ischemic or necrotic bowel may be encountered. Delay in treating malrotation/volvulus may lead to catastrophic loss of intestine.

Jejunal atresia

In patients with jejunal atresia, nasogastric suction decompresses the proximal atretic bowel. Intravenous (IV) fluids are given for maintenance and replacement of fluid losses. A contrast enema corroborates the diagnosis and excludes a second, more distal obstruction. Postoperative parenteral nutrition as well as respiratory, cardiovascular, and/or hemodynamic support may be necessary.

Meconium ileus

In cases of meconium ileus, nasogastric decompression, IV fluids, and antibiotics are administered. A diatrizoate enema may be effective in loosening the meconium impaction. The volume of enema fluid must be carefully proportioned in premature infants. ^[29] Diatrizoate diluted with N-acetylcysteine may also be administered by nasogastric tube. By sucking fluid into the lumen of the bowel, hyperosmolar solutions (10% acetylcysteine) loosen meconium, but they also exacerbate electrolyte disturbances and hypovolemia. Use of hyperosmolar enemas also entails a small risk of perforation and sepsis.

Pyloric stenosis

Surgical intervention (pyloromyotomy) is the treatment for pyloric stenosis. This procedure divides the muscles of the pylorus are  to open up the gastric outlet.

Duodenal atresia

Correction of duodenal atresia requires identifying the cause of the obstruction (ie, atresia, annular pancreas, or web), approximating the duodenum above and below the obstruction, and determining how best to retore continuity.

Malrotation/volvulus

Malrotation/volvulus is a surgical emergency. Delay in diagnosis may result in catastrophic necrosis of the twisted midgut. If the entire midgut is lost, the patient will be dependent upon parenteral nutrition while awaiting an intestinal transplant.

The initial step in correcting malrotation/volvulus is to eviscerate all of the intestines and then look at the retroperitoneum; the colon will be found wrapped transversely around the base of the mesentery. The volvulus is reduced by twisting the entire midgut in a counter-clockwise direction; this maneuver unwinds the colon and restores blood flow to the midgut. Bands attaching the duodenum to the colon are divided, and the proximal and distal limbs of the midgut are separated as widely as possible. The intestines are returned to the abdomen: duodenum to the right, colon to the left; this spreads apart the superior mesenteric vessels, which fuse to the retroperitoneum, and prevents further twisting.

 

Whereas normally the mesentery spreads from the ligament of Treitz in the left upper quadrant to the cecum in the right lower quadrant, the ”Ladd procedure” reverses the orientation: The duodenojejunal junction is moved to the right lower quadrant and the cecum to the left upper quadrant. The mesentery becomes adherent to the retroperitoneum, and this prevents recurrent volvulus. The appendix is removed, because in its new location, diagnosing appendicitis would be chalenging.

Jejunoileal atresia

Surgical treatment of jejunoileal atresia involves resection and anastomosis of the proximal and distal segments of intestine. A diverting enterostomy is generally avoided. Similar to duodenal atresia, tapering the proximal, dilated segment may be necessary to improve peristalsis. The ileocecal valve is preserved, as this structure prevents egress of bacteria from the colon into the small intestine, causing bacterial overgrowth and malabsorption.

Meconium ileus

Calcifications seen on plain x-rays indicate that an intestinal perforation occurred in utero and spontaneously sealed. Alternatively, the extruded meconium may be walled off by adjacent loops of intestine, creating a pseudocyst. Affected babies have "meconium peritonitis"; their appearance is unmistakable: a distended, erythematous abdomen. Laparotomy is undertaken to drain the meconium pseudocyst and identify the site of the perforation, which is converted to an enterostomy. In uncomplicated meconium ileus, an enterotomy (or appendicostomy) with irrigation and evacuation of the obstructing meconium relieves the intraluminal obstruction. Alternatively, an ostomy for diversion and access for distal instillation of N-acetylcysteine may be necessary.

Meconium plug syndrome

Operative intervention is indicated in infants with meconium plug syndrome, if contrast enemas are unsuccessful in loosening the meconium obstruction and prompting evacuation.

Hirschsprung disease

Treatment of Hirschsprung enterocolitis entails rectal irrigations, antibiotics, and fluid resuscitation. A colostomy may be necessary to decompress the colon and allow the infant to resume feedings expeditiously.

In the absence of enterocolitis, a pull-through procedure may be performed during the neonatal period; however, some surgeons open a "leveling colostomy" (at the transition zone) and perform the pull-through procedure (bring the colostomy to the anus) when the baby is 3-6 months old.

Innovations in the treatment of Hirschsprung disease include transanal and laparoscopic pull-through procedures.

 

Imperforate anus

Low imperforate anus (perianal or perineal fistula) may be repaired during the neonatal period (perineal anoplasty). In babies with high imperforate anus, a colostomy is performed, and the definitive repair (posterior sagittal anorectoplasty) is performed when the baby is 3-6 months old. ^[30] The ultimate outcome depends upon the precision of the surgery, the presence or absence of normally innervated musculature, and the degree of colonic dysmotility.

In the postoperative period, fluid and electrolyte imbalance, altered glucose metabolism, and need for ventilatory assistance may occur. Patients may have third-space fluid sequestration, causing their intravenous (IV) fluid requirements to be increased 1.5-2 times normal.

Heart rate, blood pressure, capillary refill, and urine output reflect the adequacy of fluid resuscitation. Closely monitor electrolyte levels; third-space fluid sequestration may be replaced with half normal saline (0.45%) or normal saline (0.9%).

Nasogastric tube decompression “puts the injured part at rest” and provides time for healing. The duration and depth of the anesthetic reflect the length and complexity of the surgical procedure; the analgesic requirement relates to respiratory depression and the duration of postoperative ileus. Abdominal distention impairs diaphragmatic excursion and increases the necessity of respiratory support.

The duration of antibiotic therapy depends on how much contamination occurred during the operative procedure.

Total parental nutrition (TPN) may be advisable until bowel function returns. Even after resumption of peristalsis, enteral feedings may not be tolerated. The intestinal mucosa must regenerate following ischemic or infectious injury before it is able to absorb nutrients. Trophic feedings stimulate adaptation, and predigested or elemental formulas may be tolerated more readily. If the terminal ileum is resected, anticipate derangements in folate metabolism and in enterohepatic circulation of bile salts.

Cardiovascular and coagulation complications, shock, and disseminated intravascular coagulation may occur in patients with intestinal ischemia or necrosis. Management of these issues may challenge even the most experienced clinicians.

Wound care is usually straightforward, and antibiotics generally are not required beyond the immediate preoperative period.

General complications

General complications of intestinal obstruction include the following:

• Intestinal obstruction from strictures and adhesions
• Prolonged ileus because of impaired gut motility
• Malabsorption caused by massive resection or intestinal injury from ischemia or infection
• Inadequate venous access, including catheter sepsis

Percutaneously inserted catheters (PIC) are increasingly used, but the caliber of these catheters is small and infusion of blood products may require alternative routes.

Complications of total parenteral nutrition (TPN) include cholestatic liver disease, nutritional deficiencies, and problems related to venous access. Meticulous attention to the composition of TPN solutions and strict protocols regarding insertion and maintenance of central venous catheters may minimize complications. Fish-oil lipid emulsion has proved to be less toxic to the liver than soybean oil lipid formulations. ^[31]

Normal oropharyngeal activities (eg, sucking) should be encouraged and the skills of occupational therapists employed to overcome oral aversion.

Development of adhesions is always worrisome, as are anastomotic strictures. In 1,541 children who had intestinal surgery, approximately 10% developed adhesions proximate to the operative site, and 5% occurred remotely. ^[32]

Handling the bowel gently, limiting contamination of the peritoneal cavity, and employing meticulous technique may limit anastomotic strictures and postoperative adhesions.

Decreased gut motility may occur following intestinal resection. Dilatated intestine above an obstruction may be slow to recover normal caliber and function. Interruption of vagal neuroenteric pathways by an atresia or by resection and anastomosis may contribute to abnormal intestinal motility.

Two promotility pharmacologic agents are useful: metoclopramide and erythromycin. Note the following:

• Randomized controlled trials of these drugs yield varied results relative to placebos.
• Both drugs have side effects that may limit their usefulness.
• Their effectiveness is substantiated by anecdotal reports and personal experience, rather than evidence-based medicine.

The length of small bowel in a normal term infant is approximately 250 cm. In adults, it is 600-800 cm. The minimum length for normal function in a term infant is estimated to be 75 cm. Resection of more than 60% of the small bowel or resection of crucial anatomic areas (eg, the ileocecal valve) may cause malabsorption and failure to thrive. Bacterial overgrowth also may contribute to malabsorption.

Short-gut syndrome occurs when the intestine cannot absorb enough nutrients for normal growth and development. Note the following:

• Children with short-gut syndrome require supplemental parenteral nutrition or elemental formulas.
• Pharmacologic agents are used to slow motility.
• Probiotics have been shown to normalize bowel flora and improve absorption of nutrients.
• Bowel-lengthening procedures require dilated bowel, which may be surgically created by intraluminal valves.
• Pharmacologic manipulations, including nutritional and hormonal treatments, may assist in weaning children from dependence upon parenteral nutrition.
• Techniques such as the serial transverse enteroplasty (STEP) procedure may offer improved bowel function and length in some patients.

Patients with infarction of the midgut or multiple intestinal atresias may lack enough intestine to survive. Whether or not life support should be continued is a difficult ethical decision, and communication with insightful colleagues is advisable. Small-bowel transplantation, with or without other viscera such as the liver and pancreas, is performed in select centers in the United States, with varying results.

Complications associated with specific conditions

Malrotation

With malrotation, complications depend upon the condition of the bowel at the time of presentation and surgical treatment. The most feared complication is necrosis of the entire midgut.

Reduction of volvulus and the Ladd procedure, followed in 24 hours by a "second look" procedure, may permit salvage of intestine that initially appeared nonviable. If a large amount of intestine is removed and a proximal jejunostomy created, large volumes of fluid and electrolytes will be lost, making the formulation of parenteral nutrition solutions extremely challenging. After the jejunostomy is closed, the colon will absorb fluid and electrolytes and simplify the patient’s management; however, severe diarrhea and its attendant complications may occur (at least temporarily).

Duodenal atresia

The most frequent complication of a duodenal anastomosis is delayed emptying. Patience is required, because the anastomosis usually will function by the third postoperative week. Revision of the anastomosis is rarely necessary.

Jejunoileal atresia

In uncomplicated intestinal atresia, complications are not common. The obstruction resulted from an in utero event injuring a segment of intestine. If the bowel is in good condition, primary repair is possible. Small bowel atresia may occur in conjunction with gastroschisis; however, the exposed bowel may be inflamed and not amenable to performing an anastomosis. Also, it may be difficult to differentiate dilatation from an in utero kink to that from an actual atresia. A correct assessment may not be possible until the inflammation has subsided.

Abnormal bowel motility and function longer than 4 weeks postoperatively should be evaluated by a contrast study, to look for a mechanical obstruction from extrinsic bands, or an atresia or ischemic stricture.

Meconium ileus and meconium plug syndrome

Complications in treating babies with meconium plug syndrome are rare. Babies with meconium ileus and cystic fibrosis may require enzyme replacement, although predigested or elemental formulas may be sufficient during the neonatal period.

Hirschsprung disease

Infants with Hirschsprung disease may present with enterocolitis, characterized by abdominal distention and explosive diarrhea, especially following dilation of the anal sphincter (by digital examination).

Sepsis (enteric organisms) may result from bacterial overgrowth in dilated, poorly motile bowel. The mechanism is bacterial mucosal translocation and invasion of the mesenteric vasculature.

Management includes intravenous (IV) fluids and antibiotics, and rectal irrigation with a tube inserted through the anus. Stool should be tested for Clostridium difficile toxin; if positive, oral vancomycin or metronidazole is indicated. A diverting colostomy may be necessary, if rectal irrigations and Botulinum toxin and anal internal sphincterotomy all fail in preventing episodes of enterocolitis.

Imperforate anus

Babies with low imperforate anus typically suffer from constipation, although the anus is widely patent. The major complication in babies with high imperforate anus is incontinence, which may occur if the rectum is improperly situated within the striated muscle complex, or because the muscle complex is defective. Constipation or diarrhea may occur, depending on the motility of the colon.

Other minor complications, such as mucosal prolapse through the neoanus are readily repaired. Dr Alberto Pena has devised a bowel-training program that is helpful in managing anorectal patients with constipation or incontinence. ^[30]