Intussusception is the most frequent cause of bowel obstruction in infants and toddlers. It is an acquired invagination of the proximal bowel (intussusceptum) into the distal bowel (intussuscipiens). It was first described in 1674 by Paul Barbette of Amsterdam, defined by Treves in 1899, and operated on successfully in 1873 by John Hutchinson. ,
Pathophysiology
The intussusceptum telescopes into the distal bowel by peristaltic activity. There may or may not be a lead point. As the mesentery of the proximal bowel is drawn into the distal bowel, it is compressed, resulting in venous obstruction and bowel wall edema. If reduction of the intussusception does not occur, an intussusception can progress to bowel ischemia from arterial insufficiency and subsequent necrosis unless the condition is recognized and treated appropriately.
Primary Intussusception
Most cases, especially in infants, do not have a lead point and are classified as primary or idiopathic intussusceptions. The cause is generally attributed to hypertrophied Peyer patches within the bowel wall. Intussusception occurs frequently in the wake of an upper respiratory tract infection or an episode of gastroenteritis, providing an etiology for the hypertrophied lymphoid tissue. Adenoviruses in children older than age 2 and, to a lesser extent, rotaviruses have been historically implicated in up to 50% of cases. , Other contributing evidence that viruses may play a role in intussusception includes the rise in cases during seasonal respiratory viral illnesses and the increased risk associated with rotavirus immunization. The initial rotavirus vaccine was removed from the market due to a significant increase in the incidence of intussusception. The current immunization formulas available in the United States, RotaTeq and Rotarix, also have been associated with a small increased risk, but these risks are widely thought to be outweighed by the benefits of vaccination. Further evidence for a viral etiology is demonstrated by global decreases in emergency room presentations for ileocolic intussusceptions during implementation of COVID-19 infection control guidelines ,
Secondary Intussusception
An intussusception can have an identifiable lesion that serves as a lead point, drawing the proximal bowel into the distal bowel by peristaltic activity. The incidence of a lead point varies from 1.5% to 20%, and the presence of a lead point increases in proportion with age. The most common lead point is a Meckel diverticulum, followed by polyps and intestinal duplications. Other benign lead points include the appendix, hemangiomas, carcinoid tumors, foreign bodies, ectopic pancreatic or gastric mucosa, hamartomas from Peutz-Jeghers syndrome ( Fig. 36.1 ), and lipomas. Malignant causes, although rare, increase in incidence with age and include lymphomas and small bowel tumors. Systemic diseases, including Henoch-Schönlein purpura and cystic fibrosis, have been associated with intussusception. Other diseases that may be related to intussusception include celiac disease and Clostridium difficile colitis.
(A) Operative view of the outside of the jejunum shows a palpable mass as the lead point of a reduced intussusception. (B) A hamartomatous polyp is characteristic of Peutz-Jeghers syndrome. (C) Mucocutaneous macular lesions are seen in this patient with Peutz-Jeghers syndrome. Note extension of the pigmentation beyond the vermilion border.
Incidence
Idiopathic intussusception can occur at any age. Most affected patients are well-nourished, healthy infants, and approximately two-thirds are boys. The highest incidence occurs in infants between ages 4 and 9 months, and it is the most common cause of small bowel obstruction in this age group. Intussusception is uncommon younger than 3 months and after 3 years of age. The condition has been described in premature infants and has been postulated as the cause of small bowel atresia in some cases.
Clinical Presentation
The classic presentation is an infant or a young child with intermittent, cramping abdominal pain associated with “currant jelly” stools and a palpable mass on physical examination, although this triad is seen in less than a fourth of children. The abdominal pain is sudden, and the child may stiffen and pull their legs up to the abdomen. Pain can be associated with hyperextension, writhing, breath holding, and vomiting. Attacks often cease as suddenly as they start. Between attacks, the child may appear comfortable but eventually will become lethargic. Small or normal bowel movements will stop as the obstruction progresses and becomes associated with bilious emesis and increasing abdominal distention. Stools may be blood tinged as impending ischemia causes mucosal sloughing and compression of mucous glands leading to evacuation of dark red mucoid clots or currant jelly stools. This is often a late sign, as are laboratory derangements. A pitfall is to wait for the currant jelly stool, leukocytosis, and electrolyte abnormalities that are often the hallmarks of ischemic bowel.
Physical Examination
The child’s vital signs are usually normal early in the disease course. During painless intervals, the child may appear comfortable, and the physical examination may be unremarkable. However, the cramping episodes usually occur every 15–30 minutes, and reexamination may prove difficult. There may be audible peristaltic rushes, and a sausage-shaped or curved mass might be palpable anywhere in the abdomen or even visualized if the child is relatively thin ( Fig. 36.2 ). The right lower abdominal quadrant can appear flat or empty (Dance sign) as the intussuscepted mass is drawn cephalad. On rectal examination, blood-stained mucus or blood may be encountered as a later sign. If the obstructive process worsens, bowel ischemia can result in the rapid progression of dehydration, fever, tachycardia, hypotension, and even bacteremia.
This 10-year-old boy has a palpable sausage-shaped mass ( arrows ) due to an intussusception.
Prolapse of the intussusceptum through the anus is a grave sign, particularly when the intussusceptum is ischemic. The greatest danger in a case of prolapsed intussusceptum is that the examiner will misdiagnose the condition as a rectal prolapse and attempt reduction. Careful physical examination is mandatory and can be done by inserting a lubricated tongue blade along the side of the protruding mass before reduction. If the blade can be inserted more than 1–2 cm into the anus along the side of the mass, the diagnosis of intussusception should be considered.
Diagnosis
Abdominal Radiography
In half of cases the diagnosis of intussusception can be suspected on flat and upright abdominal radiographs ( Fig. 36.3 ). Suggestive radiographic abnormalities include an abdominal mass, abnormal distribution of gas and fecal contents, sparse large bowel gas, and air-fluid levels in the presence of bowel obstruction. However, plain films have limited value in confirming the diagnosis and are perhaps best used in risk stratification when there is otherwise a low clinical index of suspicion. ,
This abdominal radiograph in a patient with intussusception shows dilated loops of small bowel in the right lower quadrant and a right upper quadrant soft tissue mass density in the vicinity of the transverse colon near the hepatic flexure ( arrow ).
Ultrasonography
The use of abdominal ultrasound (US) for the evaluation of intussusception was first described in 1977. It has subsequently become a standard screening tool because of a lack of radiation exposure, ability to identify pathologic lead points, and low cost. , The characteristic finding on US has been referred to as a “target” or “doughnut” lesion ( Fig. 36.4 ), which consists of alternating rings of low and high echogenicity representing the bowel wall and mesenteric fat within the intussusceptum in a transverse plane. The “pseudokidney” sign is seen on longitudinal section ( Fig. 36.5 ). This pattern is secondary to the edematous walls of the intussusceptum within the intussuscipiens. US can also be used to guide the therapeutic reduction of an intussusception. ,
This transverse sonographic image shows the alternating rings of low and high echogenicity due to an intussusception. This finding has been called a “target” sign.
Sonogram showing the “pseudokidney” sign seen with intussusception on longitudinal section.
Computed Tomography and Magnetic Resonance Imaging
Neither computed tomography (CT) nor magnetic resonance imaging (MRI) is routinely used in the evaluation of a patient with intussusception, although either may confirm this diagnosis and/or pathologic causes for intussusception, such as a malignancy (i.e., lymphoma). The characteristic CT finding is a target or doughnut sign ( Fig. 36.6 ). Transient small bowel intussusceptions that are discovered on CT or MRI are usually not clinically significant. Radiographic or operative treatment should be based on clinical findings in symptomatic patients. Laparoscopy is an excellent means to evaluate these patients if surgical intervention is needed.
Concurrent contrast enema and pelvic CT images of an intussusception. (A) Contrast study showing the intussusception low in pelvis. (B) CT image of the intussusception. (C) CT image of the “layered” intussuscepted mass. This is the target sign on CT.
Nonoperative Management
If the diagnosis of intussusception is suspected, a nasogastric tube may be helpful to decompress the stomach. Bowel rest and intravenous fluid resuscitation should be initiated. A complete blood cell count and serum electrolytes are obtained. Routine antibiotic administration is unnecessary. An air or contrast enema is first-line treatment if there are no contraindications to nonoperative reduction. Contraindications include intestinal perforation (free intraperitoneal air), peritonitis, or hypotension refractory to resuscitation. The advantages of nonoperative reduction are decreased morbidity, cost, and length of hospitalization.
Hydrostatic and Pneumatic Reduction
The conceptual methodology for hydrostatic reduction has not changed significantly since its first description in 1876. While hydrostatic reduction with barium under fluoroscopic guidance was historically used, children’s hospitals have transitioned to air or water-soluble isotonic contrast because of the potential hazard of barium peritonitis in patients with intestinal perforation. , , , Successful reduction ( Fig. 36.7 ) in uncomplicated patients is seen in about 85% of cases and ranges from 42% to 95%.
Fluoroscopic examination using isotonic contrast for hydrostatic reduction of intussusception. (A) Intussusception ( arrow ) seen in midtransverse colon. (B) Reduction has occurred to the hepatic flexure. (C) Complete reduction with reflux of contrast medium into the terminal ileum. Note the edematous ileocecal valve ( arrow ).
Although pneumatic reduction was first described in 1897, it began to gain popularity only in the late 1980s. In addition to eliminating the risks associated with barium extravasation, the technique is quicker, less messy, and decreases the exposure time to radiation. Reductions are fluoroscopically monitored as air is insufflated into the rectum ( Fig. 36.8 ). The maximum safe air pressure is 80 mmHg for younger infants and 110–120 mmHg for older infants. Potential drawbacks of pneumatic reduction include the possibility of developing tension pneumoperitoneum and poor visualization of lead points and/or the intussusception reduction process, resulting in false-positive reductions. Rates of perforation range from 0.4% to 2.5%, with the most recent publications citing rates approaching 0.3%. , ,
Plain radiography and fluoroscopic examination using air for pneumatic reduction of an intussusception. (A) Plain radiograph showing a mass effect in the right upper quadrant. (B) Pneumatic reduction to the vicinity of the cecum with the intussusception still present ( arrow ). (C) Complete reduction with reflux of air into multiple loops of small intestine.
Courtesy Charles Maxfield, MD.
Tension pneumoperitoneum is best treated with immediate cessation of the procedure and immediate release of the pneumoperitoneum using a 14-, 16-, or 18-gauge needle or angiocatheter above or below the umbilicus. This should be followed by immediate operative exploration.
For unsuccessful reduction, several studies have shown improved safe reduction rates using repeat attempts after waiting 30 minutes to 4 hours after the initial attempt. , An apparent decrease in benefit is noted with more than three attempts. Some recommend repeated pneumatic reduction at 2- to 4-hour intervals only if there was progression with each prior attempt. , In some instances, this is done in the operating room prior to laparoscopy or in conjunction with laparoscopic reduction. Premedication with midazolam may increase the chances of successful reduction.
Although traditionally patients were admitted following successful reduction, numerous recent studies have documented safe discharge home of select patients after a brief observation period in the emergency department. The optimal length of observation after successful enema reduction of ileocolic intussusception appears to be 4 hours, based on currently available studies. The parents/caregivers of these patients should be counseled about the risk of recurrence over the next few days after the initial intussusception and warning signs that should prompt return. , Any clinical signs of abdominal pain after reduction could be a sign of ischemic bowel or recurrent intussusception, and repeat US is needed. Early discharge has been associated with decreased hospital and patient-related costs as well as improved patient satisfaction. ,
Operative Management
An operation is needed when nonoperative reduction is unsuccessful or incomplete, for signs of peritonitis, in the presence of a lead point, or with radiographic evidence of pneumoperitoneum. Preoperative preparation includes administration of broad-spectrum antibiotics, intravenous fluid resuscitation, bladder decompression, and placement of a naso- or orogastric tube.
Laparoscopic Approach
Initially, the use of laparoscopy in the operative management of intussusception was strictly diagnostic, was used in cases with equivocal radiographic studies or in patients with suspected lead points, and was associated with conversion rates in up to 70% of cases. As surgeons have become more comfortable with laparoscopy, the laparoscopic approach has become the initial operation of choice in many centers. More recent studies have shown improved postoperative pain and shorter time to full feeds and length of stay with laparoscopic reduction. Reported rates of conversion to open are variable (12%–40%), but most report around 30% with a low overall complication rate. ,
Contraindications to laparoscopy include hemodynamic instability, peritonitis or evidence of pneumoperitoneum, and severe bowel distention that limits visualization. Risk factors for increased conversion rates to an open procedure have included an intussusceptum extending beyond the ascending colon as well as presence of known pathologic lead points. A retrospective analysis of 65 cases found that in patients unable to be reduced laparoscopically, 33% had a lead point that necessitated conversion to open ( Fig. 36.9 ). Both conventional and single-incision laparoscopic techniques are described with comparable outcomes based on small comparative studies. , The majority of minimally invasive approaches describe the use of three abdominal ports: one in the infraumbilical region, with two other ports along the left side of the abdomen. Laparoscopic reduction is accomplished by applying gentle pressure distal to the intussusceptum using atraumatic graspers. Although counterintuitive to the conventional open method, traction is usually required proximal to the intussuscipiens to complete the reduction ( Fig. 36.10 ). Excessive force should be discouraged, and if the bowel reduces to a point at which there is dusky-appearing bowel or the surgeon is noticing more serosal tears, the procedure should be converted to open. Appendectomy is not routinely performed with laparoscopic reduction unless it is felt to be the lead point. Careful inspection of the bowel is performed to evaluate for any signs of ischemia, necrosis, or perforation. A criticism of laparoscopic reduction is the loss of tactile sense that can lead to missed pathology. If resection is required, this often can be accomplished by exteriorizing the bowel through an enlarged periumbilical incision. If this is not possible, the operation is usually converted to a laparotomy.
