Intussusception is a common cause of intestinal obstruction afflicting one in 2000 infants and children. This curious anatomic condition is characterized by the invagination of one segment of the gastrointestinal tract into the lumen of an adjacent intestinal segment. The advancing tube of proximal intestine is referred to as the intussusceptum , whereas the distal recipient intestine is referred to as the intussuscipiens. First described in 1674 by Paul Barbette of Amsterdam, intussusception remained a descriptive diagnosis only until the first successful operative repair by John Hutchinson in 1873. The obstructive process may involve any segment of the gastrointestinal tract; yet most will be confined to the ileocolic distribution. In these cases, the intussusception originates in the terminal ileum, advances through the ileocecal valve, and often terminates near the hepatic flexure. Of note, cases extending to the rectum or prolapsing through the anus have been reported. Asymptomatic, isolated small intestinal intussusception is often noted as an incidental finding on computed tomography scans. Retrograde intussusception has also been reported, but is exceedingly rare. Regardless of the location and extent, two distinct clinical problems arise: complete obstruction of the proximal intestine and progressive vascular compromise. A sense of urgency is paramount owing to the morbidity and mortality associated with intestinal obstruction and bowel ischemia in young children. Mortality rates of less than 1% are to be expected in developed countries.
Incidence
Idiopathic intussusception may occur at any age; however, the incidence is highest in the first 2 years of life. Most cases will arise between 3 months and 3 years of age. Two-thirds of patients are male. The majority of these toddlers are healthy, well nourished, and have no significant past medical history. Although uncommon, this condition has been described in premature infants. Intussusception in utero has been reported and may potentially lead to atresia of the small intestine.
Pathophysiology
Regardless of etiology, a case of intussusception has the following five definable components: (1) the intussusception develops within an antegrade bowel peristalsis; (2) the proximal bowel (intussusceptum) carries its mesentery into the distal, receiving bowel (intussuscipiens); (3) a partial to complete bowel obstruction develops; (4) the mesenteric vessels are compressed between the layers of the intussusception; and (5) vascular compromise arises. Unabated, intestinal ischemia progresses, leading to gangrenous changes and ultimately bowel necrosis.
In the minority of cases, a pathologic lead point such as a Meckel’s diverticulum or intestinal polyp will be identified. Less common etiologies include vasculitis from Henoch-Schönlein purpura, duplication cysts, lymphoma, ectopic pancreatic rests, and appendiceal mucoceles ( Table 51-1 ). Early theories proposed that the lead point is projected into the peristaltic stream and was pulled downstream. However, this hypothesis is not adequate for the majority of cases, where no definable lead point exists. In these idiopathic cases, lymphoid hyperplasia within the wall of the bowel is thought to produce the functional equivalent of a pathologic lead point. The terminal ileum is noted to be rich in gut-associated lymphoid tissue (GALT), and it is this tissue that likely initiates the intussuscepting process.
| Lead Point | Total (n = 179) |
|---|---|
| Meckel’s diverticulum | 41% (73) |
| Intestinal polyps | 19% (34) |
| Duplication cyst | 11% (19) |
| Lymphoma | 10% (17) |
| Henoch-Schönlein purpura | 5% (9) |
| Lymphoid hyperplasia | 3% (6) |
| Cystic fibrosis | 3% (6) |
| Appendiceal pathology | 3% (6) |
| Other | 5% (9) |
Clinical Presentation
Intussusception is most common among infants and toddlers. Sixty percent of cases present in children younger than one year of age, with a peak between 5 and 9 months of age. However, the incidence appears to be increasing in older children. Although many of these cases are classified as idiopathic, the majority of cases in children younger than the age of 2 occur secondary to lymphoid hyperplasia. Pathologic lead points are more common in older children.
Given the risk of acute bowel ischemia, intussusception represents an abdominal emergency in the pediatric population. Symptoms are initially related to intestinal obstruction, as intussusception accounts for up to 50% of pediatric small bowel obstructions in some series. Children, particularly infants, are typically previously healthy, although some have a history of antecedent gastrointestinal infection. Pain is severe and colicky in nature, with intermittent periods of relief. In preverbal or nonverbal children, periods of inconsolable crying interposed with phases of relative normalcy lasting minutes to hours is common. Parents may note symptoms of altered mental status in their child. Indeed, up to 17% of patients with intussusception will have significant neurologic symptoms ranging from lethargy and hypotonia to grossly altered consciousness.
Additional signs and symptoms may include irritability, nausea, vomiting, fever, and anorexia. Vomiting typically progresses from nonbilious to bilious and should warrant prompt isotonic fluid resuscitation and nasogastric decompression. Frank hypovolemic shock may be present in up to 5% of children with intussusception. The classic triad includes abdominal pain, vomiting, and red “currant jelly” stools. This characteristic stool pattern occurs late in the disease process and is a sequela of mucosal sloughing as bowel compromise ensues.
Although important, physical examination findings are often nonspecific. Despite focusing on the abdomen, a physician may note generalized hypotonia. Abdominal tenderness is common, although overt signs of peritonitis are rarely present. The classic described finding of a “sausage-like” mass can be elusive. Eighty-five percent of patients have ileocolic intussusception, and often the mass appears in the right upper quadrant. However, the intussusceptum may extend through the large bowel, even presenting as a rectal mass. This may be differentiated from simple rectal prolapse by observing a sulcus between the anus and the protruding mass.
Although present in only 25% of cases, the classic triad of symptoms has a high positive predictive value. Findings of pain and vomiting may appear in 80% of cases, and an abdominal mass in up to 65%. In a child with pain, vomiting, and a palpable mass in the right upper quadrant, a positive predictive value (PPV) of 93% is achieved. If the same child also presents with rectal bleeding, the PPV increases to nearly 100%. In the absence of one or more of these symptoms, the diagnosis may yet be present and imaging studies should be undertaken.
In children with advanced cases of intussusception, significant systemic symptoms may be present. Metabolic acidosis, hypotension, peritonitis, and altered mental status are late findings. These children require quick, aggressive fluid resuscitation followed by operative exploration. Although this picture may present in neonates, it is rare and often misdiagnosed as necrotizing enterocolitis. Given the consequences of a delay in diagnosis, surgery is often indicated in this susceptible population.
Therapeutic Options
The risk of bowel ischemia and subsequent perforation must always be considered when determining the optimal treatment for intussusception. Both operative and nonoperative options exist. Choice of technique is predicated on the condition of the patient. Findings that are concerning for perforation, failed nonoperative reduction, and physiologic instability should lead to immediate operative intervention.
Nonoperative Management
Following resuscitation with intravenous fluids and the initiation of broad-spectrum antibiotics, nonoperative management may be undertaken. Reduction via positive pressure with direct monitoring of movement via imaging has become the standard of care. As early as 1876, Hirschsprung advocated the use of enemas to reduce the intussusception. He later published a series of successful reductions in 1905. The use of barium enemas for reduction was initially adopted in the early 20th century in Europe and South America. First conducted in the United States in 1939, Ravitch and McCune suggested that this became the preferred method in their landmark report in 1948. With improved experience and near universal acceptance, reported success rates range from 60% to 90%.
Predominantly of historical significance is the use of gravity-fed enemas to reduce intussusception. A 60% barium solution held at a column height of 100 cm will generate a retrograde pressure of 100 to 120 mm Hg. Care must be taken to prevent excessive pressure, which may lead to perforation of the intestine and gross contamination of the peritoneal cavity. Intraluminal pressure is maintained in the enema for 3 to 5 minutes during fluoroscopy monitoring for reduction ( Figure 51-1 ). Traditionally, success was noted by visualizing reflux of contrast into the terminal ileum, although this has been proven to be unnecessary for confirmation of reduction. Some studies advocate observation for 12 to 24 hours with nil per oral (NPO) status maintained for this time, as recurrence is a possibility. However, in otherwise asymptomatic and stable patients, discharge with early follow-up has been deemed safe.
More recently, air reduction with the occasional addition of barium, has become the nonoperative technique of choice ( Figure 51-2 ). Several advantages have been noted with this technique. The radiation dose is often decreased when using fluoroscopy, with total times quoted as low as 94 seconds. This corresponds to about one-half to one-third the expected radiation dose with hydrostatic enemas. Ultrasound is also used in many institutions, in which case radiation may be completely eliminated when using an air enema. In addition, there have been several studies documenting the safety of pneumatic reduction over barium. This is most often attributed to the risk of significant peritonitis in the event of perforation with barium, versus the relative benign nature of the air enema. Adequate pressure of 120 Torr, is also more easily monitored and maintained with air when compared with contrast. Finally, higher success rates are often quoted for pneumatic enema. The underlying cause of this may well be multifactorial, as air is thought to dissect between the intussusceptum and intussuscipiens more easily than contrast material. However, other studies provide the caveat that, given the decreased risk of peritonitis, providers may be slightly more aggressive with air than with contrast. Overall, success rates of 80% to 90% have been reported for air enema reduction versus 55% to 70% with contrast enema reduction.
Given recent concerning reports not only in scientific journals but also in the lay media, radiation exposure to a developing child should be minimized when possible. Correspondingly, efforts have been made to decrease the amount of radiation exposure incurred with enema decompression. Ultrasound has become an option for both diagnosis as well as monitoring during reduction. As ultrasound has gained acceptance, it has also been shown to have success rates similar to fluoroscopy (92% to 95%). In hopes of eliminating the need for imaging all together, a 1986 series of some 6000 Chinese patients touted the efficacy of reduction without monitoring. This approach has been slow to gain acceptance, as many physicians remain uncomfortable with claiming success based only on clinical factors.
Yet another change in reduction technique is the use of saline rather than contrast for fluid reduction. As with air decompression, the use of saline decreases the risk of overt peritonitis in the event of iatrogenic perforation. However, saline has been shown to provide better imaging when ultrasound is used, as fluid transmits the signal more effectively than air. Saline enema, like air decompression, has been shown to be more effective than contrast (70% to 90% success rate), although it remains slightly less effective than air alone.
Traditionally, failure of initial reduction has constituted a surgical emergency. However, recent evidence has led many to believe that repeated attempts at pneumatic reduction with a short period of observation is warranted. Indeed, some patients undergo attempted reduction at outside hospitals prior to being transferred to a dedicated children’s hospital. Even in this population, some studies have shown no difference in success rates for pneumatic reduction versus those patients who initially presented to a children’s hospital. Notably, most studies advocate repeat attempts and monitoring only for patients who are hemodynamically stable, without signs of peritonitis, and often in the setting of at least partial reduction as noted on imaging.
Although the use of barium has led to significant peritonitis with perforation, the use of pneumatic reduction has added a new risk—tension pneumoperitoneum. Although perforation rates are as low as 2%, this rare occurrence represents a life-threatening situation. Surgery is most definitely indicated in these cases; however, significant physiologic derangements may occur secondary to compression of the inferior vena cava, impedance of preload, and decreased excursion of the diaphragm. As a result, temporization prior to transferring to the operating room may be required. One approach advocated in the literature has been needle decompression of the abdomen. Small-gauge angiocatheters are readily available and when placed successfully, they will facilitate release of the tension component and restoration of venous flow. Although case studies have shown this to be a feasible bridge to surgery, it requires that radiologists be trained to recognize the signs and symptoms of tension pneumoperitoneum as well as training for performing the procedure. Consequently, most studies continue to recommend the notification and attendance of a member of the pediatric surgery team when a pneumatic reduction is planned.
Recent data suggest that most intussusceptions are amenable to at least partial reduction; however, there are certain characteristics that have long been thought to be signs of possible failure. These include children younger than 3 months or older than 5 years, those who have had symptoms for greater than 48 hours, presence of a pathologic lead point, hematochezia, significant dehydration, evidence of small bowel obstruction on plain radiography, and visualized prolapse through the anus. As experience with reduction has improved, some of these contraindications have been refuted. In particular, patients with symptoms for 48 hours or more, who are hemodynamically stable and without overt peritonitis, are being managed initially with pneumatic reduction attempts. Multiple attempts may be undertaken as long as the child remains stable. The increased duration of symptoms would seem to lead to a higher rate of perforation with pneumatic reduction; this has not proven to be the case. As a result, essentially all stable patients are given an initial pneumatic reduction attempt prior to surgical intervention.
The presence of a pathologic lead point on imaging confers a decrease in success rates of nonoperative management. However, even with complete reduction, the risk of recurrence often requires surgical intervention to remove the identified lead point. In most studies, Meckel’s diverticulum is the most common example, with others including duplication cysts, polyps, and certain types of lymphoma. Burkitt’s lymphoma, in particular, may present primarily as intussusception. Oftentimes, these patients present early in the disease course, and resection of the affected bowel allows for complete neoplastic resection. Complete reduction in the presence of a pathologic lead point is highly unlikely, but not unheard of. As a result, in older patients with intussusception, repeat postreduction imaging is necessary to search for and/or confirm the presence of a lead point.
Observation alone is an appropriate option for asymptomatic patients. Most of these cases are limited to the small intestine and are incidentally discovered on abdominal ultrasonography or computed tomography performed for unrelated reasons. Close observation and serial abdominal examinations will likely avoid an unwarranted contrast enema.
Surgical Management
Open Approach
With the success of nonoperative treatment, surgical management for intussusception is becoming increasingly rare. Current indications include unsuccessful or incomplete reduction, perforation during reduction, peritonitis, or presence of a pathologic lead point. Successful operative intervention begins with preoperative preparation including the use of broad-spectrum antibiotics, appropriate fluid resuscitation, and maintenance of normothermia. In addition, preoperative of nasogastric tube placement is recommended not only to reduce gastric distension but also to lessen the risk of aspiration on induction of general anesthesia.
Operative approach may vary between surgeons, yet the traditional right upper quadrant transverse incision remains popular. Serous and sometimes lymphatic ascites may be encountered once the peritoneum is entered. Occlusive sticky drapes are recommended to prevent abdominal fluid from saturating bed sheets, potentially leading to the child becoming hypothermic. The cecum and terminal ileum are delivered out of the wound and the full extent of the obstructive process is evaluated. With intussusceptions involving the sigmoid colon, the incision should be carried to the left, across the midline, to facilitate exposure.
The leading edge is identified, and the surgeon carefully manipulates the bowel back toward its normal position in the terminal ileum. Although it may seem tempting to provide countertraction, this maneuver may lead to bowel injury, perforation, and abdominal cavity contamination. Following reduction, the bowel often appears ischemic ( Figure 51-3 ). Warm saline-soaked laparotomy pads and surgeon patience will often lead to improved appearance of the bowel within a few minutes. Further interrogation of bowel health includes visualization of peristalsis, presence of Doppler signals, or Wood’s lamp evaluation using fluorescein. In cases of suspected lymphoma, a thorough abdominal survey is recommended including inspection of peritoneum, liver, spleen, mesentery, and retroperitoneal nodes. In these cases, collection of abdominal ascites is commonly performed and sent for cytology. Inability to manually reduce the intussusception often indicates a gangrenous intussusceptum, and resection will be required. In most cases, a routine bowel anastomosis may safely be performed with single- or double-layer suture technique being equally acceptable. In children who are unstable, a clip and drop technique with second look may be performed or a temporary enterostomy created.
