1. Introduction (epidemiology, embryology, pathophysiology)
Intussusception is an invagination of a part of the bowel into itself, and it can involve either the small or large intestine or both. The bowel that is more proximal and telescopes into the more distal bowel is known as the intussusceptum, while the bowel that contains it is known as the intussuscipiens. Most commonly, intussusception is found near the ileocecal junction. Other described locations include ileo-ileal, jejuno-ileal, and colo-colic. Because the associated mesentery is also involved, venous and lymphatic congestion ensues. This results in intestinal edema and obstruction, and if not reduced, can lead to intestinal ischemia, perforation, and peritonitis. It is second to pyloric stenosis as the most common cause for obstruction in children.
Intussusception most commonly develops between the ages of 6 months and 3 years, and is the most common abdominal emergency among children in this age group. Approximately 80 percent of children develop an intussusception are younger than 2 years old. It is much less common before 3 months of age and after 6 years. Incidence in the United States is 56 children/ 100,000/ year.
The vast majority of intussusceptions cases in children are idiopathic (75 percent), as there is no clear pathologic lead point. Some evidence suggests that viral factors may be important in these cases. For example, peak incidence of intussusception coincides with seasonal viral gastroenteritis. It has been reported that up to 30 percent of patients experience some kind of viral illness (upper respiratory tract infection, flu-like symptoms, otitis media, or viral gastroenteritis) before the onset of intussusception. There have also been postulated associations with adenovirus, rotavirus vaccine, and bacterial enteritis. It is thought that these lead to lymphoid tissue hypertrophy, particularly within Peyers patches in the terminal ileum, which then act as a lead point for intusussception.
A Meckel’s diverticulum, duplication cyst, polyp, tumor, hematoma, or vascular malformations are common pathologic lead points, which can herniate into a distal segment of intestine, causing intussusception. These are present in 25 percent of cases of intussusception and most children with these are either younger than 3 months old or older than 5 years.
Intussusceptions are also reported to occur post-operatively at a rate of 0.08 to 0.5 percent and cause approximately 5 to 10 percent of all post-operative bowel obstructions in children. A wide range of procedures have been implicated, most of which involve prolonged or extensive bowel manipulation: nissen fundoplication, Wilms’ or neuroblastoma tumor resection, and Ladd’s procedure. They have also been reported to occur around feeding tubes. Other sited factors include abnormal electrolyte levels, chemotherapy, radiotherapy, anesthetic agents, and other medications administered in the post-operative period. A high index of suspicion is needed in children with evidence of bowel dysfunction in the post-operative period such that diagnosis and management is prompt.
2. Typical Clinical Presentation
At presentation, the classic triad of abdominal pain, a palpable, “sausage-shaped” abdominal mass, and currant-jelly stool, is seen in less than 15 percent of cases. Patients usually present one of two ways: either with crampy abdominal pain or lethargy. For those children who present with abdominal pain, the onset is sudden, and the quality is severe and crampy. The pain occurs intermittently and is progressive in nature. Parents may note inconsolable crying, decreased oral intake, emesis, and bloody stools. Emesis is initially non-bilious, but may progress to bilious as the obstruction becomes more pronounced. Stools are a mixture of blood and mucous, giving it the classic “currant jelly” appearance. Episodes typically occur at 15 to 20 minute intervals and may become more frequent over time. In between episodes, the child may behave normally. Because of this, diagnosis is often delayed and mistaken for gastroenteritis. Other children with intussusception don’t demonstrate this classic pain pattern. Instead, they become lethargic and parents bring them to the clinic or emergency department for that reason.
3. Evaluation (Diagnosis)
The study of choice to identify intussusception is abdominal ultrasonography. Depending on the experience of the ultrasonographer and the radiologist, sensitivity and specificity approach 100 percent with the technique. Duplex mode can be used to assess for perfusion in the intussusceptum. It can also be used to monitor for successful reduction. The classic ultrasound is described as a “bull’s eye” lesion or “target sign”. Other suspicious features are location in the paraumbilical or lower abdominal region, and lesion size ≤ 3 cm.
Other modalities which are sometimes used include: abdominal x-ray (will often shows signs of small bowel obstruction), CT A/P (when the US doesn’t yield a clear diagnosis or to further characterize a pathologic lead point), and fluoroscopy.
Intussusception which is found incidentally on a CT or US in an otherwise asymptomatic patient does not need treatment. These usually resolve spontaneously.
In a stable patient with ileocolic or colo-colonic intussusception, without signs of bowel perforation, pneumatic (air enemas) and hydrostatic (contrast or saline) reduction have both been used as first line, non-operative measures. This is done under either ultrasound or fluoroscopic guidance. On the other hand, surgery is indicated in patients who have jejuno-jejunal, ileo-ileal or jejunal-ileal intussusception as there is a high incidence of a pathologic lead point in these regions. Those patients who are hemodynamically unstable or have evidence of perforation must also be managed operatively.
Non-operative reduction: Ileocolic or colo-colonic Intussusception
Using either fluoroscopic or ultrasound guidance, reduction of intussusception can be performed with air (i.e. pneumatic) or contrast (i.e. hydrostatic) enemas. The only proven benefit of the ultrasound-guided technique is the decreased radiation exposure. Of note, a water soluble contrast agent should be used, rather than barium, in the event that perforation should occur.
Although debated in the literature, antibiotics to cover colonic flora are commonly given prior to enematic reduction attempts. The child is then placed in the prone position, the enema tip should be placed within the child’s rectum and securely taped in place. An assistant is needed to squeeze the child’s buttocks in place to avoid air or fluid leakage. For the pneumatic technique, air is then insufflated rapidly into the colon. The air pressure must be kept below a maximum limit of 120 mm Hg to minimize the risk of perforation. Alternatively, if contrast is used, the enema bag is placed approximately 3 feet above the level of the rectum. Intraluminal pressure usually ranges between 60 and 80 mm Hg, however may be raised to 120 mm Hg by manual insufflation of air into the enema bag.
Reduction is confirmed by free flow of air or contrast or air into the small bowel. A significant portion of the distal ileum should fill, thereby ruling out ileo-ileal intussusception. Other signs of successful reduction include symptom resolution, disappearance of the abdominal mass if initially present, and disappearance of the target if present on initial ultrasound. Idiopathic intussusceptions are more likely to be successfully reduced non-operatively.
Intussusception can be successfully reduced non-operatively 80-95 percent of the time. Equivalent success rates have been found with both imaging technique, but the literature is mixed regarding success rates based on enema medium. Some studies site equal reduction rates. Other sources, however suggest that pneumatic reduction is preferred because it is safer, faster, requires less radiation, and has a higher success rate (90 percent vs. 75 percent).
If initial attempt at non-operative treatment results in partial but not complete reduction, and the patient is not acutely ill, a repeated attempt can be made anytime between 15 minutes and 3 hours later. The partial unfolding leads to a reduction in both vascular congestion and edema, which increases the potential for success on the second attempt. The literature sites up to a 50-60 percent success rate of repeat enema if partial reduction occurred during the initial attempt.
Alternatively, surgery is indicated under the following circumstances:
• when non-operative reduction is either incomplete or unsuccessful
• when a persistent filling defect is noted, characteristic of a mass or lead point
• if perforation occurs or is suspected during attempted non-operative reduction
• if the patient suffers acute hemodynamic instability or
• if the intussusception is noted to be jejuno-jejunal, ileo-ileal or jejunal-ileal
Antibiotics to cover colonic flora should be given pre-operatively if not given pre-enema. Exploratory laparoscopy or laparotomy is performed, with manual reduction of the intussusception. Great care should be taken not to tear the bowel, which is usually edematous and somewhat friable, during this process. Rather than pulling the intussusceptum out, the intussuscipiens should be gently squeezed in an attempt to reduce the telescoped bowel. If unable to manually reduce, or if necrotic bowel is seen, resection and primary anastomosis should be performed. This is more common as duration of symptoms increases.
Laparoscopy: Technique and Evidence
Starting out laparoscopically is useful because often times the intussusception will spontaneously reduce between the radiology suite and the operating room. This happens as a result of decreasing edema from the partial reduction and can also be helped by general anesthesia. Therefore, we recommend starting with a small umbilical port to assess the ileocecal area. If the intussusception has reduced, the procedure is over. If it is still present, additional ports should be placed for attempted manual unfolding of the intestines using two atraumatic graspers. While a “push” technique of the bowel from the distal aspect of the intussusception is advocated in the open approach, it may be necessary to use a pull technique on the intussusceptum to unfold the bowel with laparoscopy. As with radiographic reduction, a 15 minute period of time after partial reduction may lead to decreased bowel edema and subsequent successful completion of reduction with laparoscopy. Pneumatic assistance can also be used. If neither of these is successful, then a transverse, right lower quadrant incision is made to complete the operation via laparotomy. Inability to reduce the intussusception by either laparoscopic or open techniques is suggestive of non-viable bowel and may warrant segmental resection. Several recent studies have demonstrated that the laparoscopic approach to operative reduction, compared to laparotomy, is a safe and effective one:
• In 2008, the French Study Group for Pediatric Laparoscopy published a study in the Journal of Pediatric Surgery stating that the risk of conversion to open surgery is significantly linked to the following factors: the length of time between symptom onset and diagnosis, whether obvious peritonitis was noted on initial exam, and whether or not a pathologic lead point was present. Therefore, according to this study, the best candidates for the laparoscopic approach are those children who are seen and diagnosed early (in the first 1.5 days of symptom onset) who do not have peritonitis.
• The pediatric surgeons at C.S. Mott Children’s Hospital retrospectively analyzed their experience with both laparoscopic and open reduction of intussusceptions which could not be reduced radiologically. They published their results in 2005 in the Journal of Pediatric Surgery. They found no significant differences in operative times or complication rates either intra- or post-operatively between the two approaches. They did, however, note a statistically significantly shorter hospital length of stay in the laparoscopic group and a trend toward lower total hospital charges. They noted a 12.5 percent conversation rate from laparoscopy to laparotomy. They concluded that the laparoscopic approach should be considered both safe and effective. A similar study was published in the Journal of the Society of Laparoendoscopic Surgeons in 2007. They noted an 85 percent success rate with laparoscopic reduction.
Both pneumatic and hydrostatic reduction carry a ≤ 1 percent risk of perforation, most commonly occurring on the distal side of the intussusception. Risk factors for this complication are: longer duration of symptoms (≥ 3 days), age < 6 months, evidence of small bowel obstruction, and using higher pressures during reduction attempts. If perforation occurs, surgical exploration is necessary.
After successful, non-operative pneumatic or hydrostatic reduction, intussusception recurs in approximately 10 percent of patients. This most commonly occurs in the first 12-24 hours after successful reduction, likely secondary to bowel edema. Therefore, patients should be closely observed in-patient during this period. Recurrence after surgery with manual reduction of the intussusception is approximately 5 percent, and close to zero after surgical resection.
Importantly, recurrence is not necessarily an indication for surgery: each episode should be treated as the first. Multiple recurrences, however, may be associated with a pathological lead point and this should be investigated.
• Intussusception is an invagination of a part of the bowel into itself, and can involve either the small or large intestine or both.
• Most commonly, intussusception is found near the ileocecal junction and ~75 percent of cases are idiopathic. It most commonly occurs in children between the ages of 6 months and 3 years old.
• At presentation, the classic triad of abdominal pain, a palpable, “sausage-shaped” abdominal mass, and currant-jelly stool, is seen in less than 15 percent of cases. Pain is typically crampy, severe, progressive, and intermittent in nature, occurring in 15-20 minute cycles. Other children present with lethargy.
• The study of choice to identify intussusception is abdominal ultrasonography. Classically, a “target sign” is seen.
• Non-operative reduction should be attempted first, as long as the patient is stable, without signs of perforation, and has an ileocolic or colo-colonic intussusception. This can be done using either pneumatic or hydrostatic techniques, and under either ultrasound or fluoroscopic guidance. This is successful 80-95% of the time.
• Surgery is indicated if non-operative reduction is unsuccessful, if perforation is suspected or occurs during non-operative treatment, if hemodynamic instability and peritonitis are present, or if the intussusception is jejuno-jejunal, ileo-ileal or jejunal-ileal.
• Laparoscopic reduction has been proven both safe and effective in several recent studies.
• Recurrence is most likely in the first 12-24 hours after reduction. The patient should be monitored in the hospital during this time period. If recurrence occurs, further repeat non-operative management can be attempted.
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