This preview shows page 1. Sign up to view the full content.
Unformatted text preview: What is intussusception?Intussusception is the telescoping of one segment of intestine into another adjacent distal ("downstream") segment of the intestine. (The term "intussusception" is pronounced "in-tuh-suh-sep-tion" with the accent on the "in." It comes from the Latin "intus", within + "suscipere", to receive = to receive within). Common mispellings of intussusception include: intususception, intussuseption, intersusception. Intussusception is the most common cause of intestinal obstruction in children between 3 months and 6 years of age. It is extremely rare in children under 3 months of age or in older children and adults.What happens during intussusception?During intussusception, a segment of bowel (intussusceptum) telescopes into a more distal segment (intussuscipiens), and drags the associated mesentery, vessels, and nerves with it. This results in compression of the veins, followed by swelling of the region leading to obstruction and a subsequent decrease in blood flow to the affected part of the intestine. Almost 90% of cases affect the ileocolic region of the intestine (where the small intestine meets the large intestine). The compression of blood vessels in the involved intestine reduces the supply of blood to the affected intestine. If the blood supply is greatly reduced, the involved intestine may swell, causing an obstruction, or even die (become gangrenous) and bleed. It also may rupture and lead to abdominal infection and shock.Is intussusception an urgent problem?Intussusception is an emergency and requires immediate attentionWho is at greatest risk for intussusception?Most cases of intussusception occur in children between 5 months and 1 year of age. Boys develop the condition two times more often than girls. Intussusception can also occur in adults and older children, although it is uncommon.What causes intussusception?The causes of intussusception are not fully known. Most cases in young children are idiopathic, (meaning the cause is unknown), although some viral and bacterial infections of the intestine may possibly contribute to intussusception in infancy. Intussusception is very rare in older children and adults. In this population, the causes are believed to be due to polyps or tumors, which are often referred to as the "lead point" of the intussusception.Why is rapid diagnosis of intussusception important?Early diagnosis and treatment of intussusception is essential in order to prevent injury to the intestine and the associated sequelae, including surgical removal of the bowel, sepsis, and even death.What are the symptoms of intussusception?Most describe the symptoms of intussusception as a triad of colicky abdominal pain, bilious vomiting, and "currant jelly" stool. The primary symptom of intussusception is described as intermittent crampy abdominal pain. This is often called "colicky pain." Intussusception in an infant usually starts with the infant suddenly crying very loudly, as if in great pain. The infant intermittently draws the knees up to the chest while crying. This reaction is caused by the abdominal pain which recurs frequently and increases in intensity and duration. These intermittent painful episodes are believed to be caused by the telescoping of the bowel and resultant compression of blood vessels and nerves. In addition to the abdominal pain, most children will also have episodes of vomiting associated with the pain. This vomiting is usually not associated with eating and may be bilious (yellow-green colored)Some affected individuals who do not seek early medical attention may pass "currant jelly stool". This is stool that is bloody and mucousy and may be a sign that the affected bowel has lost its blood supply and that the bowel may be necrotic (non-viable). As the condition progresses, the infant becomes may become weaker and develop additional symptoms, including those associated with shock, such as paleness, lethargy, and even fever, though these are not an integral part of the associated "triad." Thankfully, most cases are diagnosed early, and some studies describe the development of the bloody stools as occurring in only one-third of the cases diagnosed.How is intussusception diagnosed?The history of abdominal pain and vomiting as described above, may suggest the diagnosis of intussusception. Additionally, the examining doctor may feel an abdominal "sausage-shaped" mass (the intussusception itself) or upon auscultation with a stethoscope, may hear diminished or absent bowel sounds. Lab tests are usually not helpful, although plain abdominal X-rays can reveal signs of an intestinal obstruction, including air-fluid levels, decreased gas, and unexplained masses, usually seen in the right lower quadrant of the abdomen. Ultrasound and CT scans are generally not required to make the diagnosis. A barium, water-soluble contrast or air enema is considered both diagnostic and therapeutic in the management of intussusception. This radiologic procedure involves the introduction of the contrast into the lower intestine. If an intussusception is present, it will be seen during the imaging. Often just the introduction of the contrast will reduce the telescoped bowel to its normal position and shape. In these cases there is a high risk of for re-intussusception in the first 24 hours following the enema.Is it necessary to operate when there is intussusception?The treatment of intussusception may or may not require surgery. In some cases, the intestinal obstruction can be reversed with an enema. The enema carries a risk of intestinal rupture and cannot be done if the bowel has already perforated. The procedure also requires the availability of a surgeon, in case the patient's bowel ruptures or the intussusception cannot be reduced. If the intestinal obstruction cannot be reversed by a barium enema, surgery is necessary to reverse the intussusception and relieve the obstruction. If a portion of the intestine has become gangrenous, it must be removed. After surgery, intravenous feeding and fluids are continued until normal bowel movements resume.What is the prognosis (outlook) for patients with intussusception?The outlook for intussusception is usually good with early diagnosis and treatment. Early detection and treatment are paramount.Intussusception At A GlanceyIntussusception is the infolding (telescoping) of one segment of the intestine within another.y yIntussusception usually results in a blockage of the intestine.Intussusception occurs primarily in infants (boys more often than girls) but can also occur in adults and older children.y yThe primary symptoms of intussusception include abdominal pain and vomiting.Early diagnosis and treatment of intussusception are essential to save the intestine and the patient.Background Intussusception is a process in which a segment of intestine invaginates into the adjoining intestinal lumen, causing bowel obstruction. A common cause of abdominal pain in children, intussusception is suggested readily in pediatric practice based on a classic triad of signs and symptoms (see Clinical). Intussusception presents in 2 variants: idiopathic intussusception, which usually starts at the ileocolic junction and affects infants and toddlers, and enteroenteral intussusception (jejunojejunal, jejunoileal, ileoileal), which occurs inolder children. The latter is associated with special medical situations (eg, Henoch-Schnlein purpura [HSP], cystic fibrosis, hematologic dyscrasias) and can occur secondary to a lead point and occasionally in the postoperative period. This discussion concentrates on idiopathic intussusception, which is the more common of the 2 variants.Abdominal radiograph shows small bowel dilatation and paucity of gas in the right lower and upper quadrants.Air contrast enema shows intussusception in the cecum.Barium enema shows intussusception in the descending colon.CT scan reveals the classic ying-yang sign of an intussusceptum inside an intussuscipiens.Abdominal ultrasonography reveals the classic target sign of an intussusceptum inside an intussuscipiens.Laparoscopic view of a jejuno-jejunal intussusceptionPathophysiology The pathogenesis of intussusception is believed to be secondary to an imbalance in the longitudinal forces along the intestinal wall. This imbalance can be caused by a mass acting as a lead point or by a disorganized pattern of peristalsis (eg, an ileus in the postoperative period). Electrolyte derangements associated with various medical problems can produce aberrant intestinal motility, leading to its invagination. Recent experimental studies in animals showed that abnormal intestinal release of nitric oxide,1 an inhibitory neurotransmitter, caused relaxation of the ileocecal valve predisposing to ileocecal intussusception. Other studies have demonstrated that the use of certain antibiotics leads to ileal lymphoid hyperplasia and intestinal dysmotility with resultant intussusception. As a result of the imbalance, an area of the intestinal wall invaginates into the lumen, with the rest of the intestine following. The invaginating portion of the intestine (ie, intussusceptum) completely invaginates into the receiving portion of the intestine (ie, intussuscipiens). This process continues and more proximal areas follow, allowing the intussusceptum to proceed along the lumen of the intussuscipiens.If the mesentery of the intussusceptum is lax and the progression is rapid, the intussusceptum can proceed to the distal colon or sigmoid and even prolapse out the anus. The mesentery of the intussusceptum is invaginated with the intestine, leading to the classic pathophysiologic process of any bowel obstruction. Early in this process, lymphatic return is impeded; then, with the rise in the pressure within the wall of the intussusceptum, venous drainage is impaired. Finally, the pressure reaches a point at which arterial inflow is inhibited, and infarction ensues. The mucosa is most sensitive to ischemia because it is farthest away from the arterial supply. Ischemic mucosa sloughs off, which initially leads to the heme-positive stools and then the classic "currant jelly stool" (a mixture of sloughed mucosa, blood, and mucus). If untreated, the process progresses to transmural gangrene and perforation of the leading edge of the intussusceptum. FrequencyUnited StatesA wide geographic variation in incidence of intussusception among countries and cities within a country makes determining a true prevalence of the disease difficult. Studies for the absolute prevalence of intussusception in the United States are not available. Its estimated incidence is approximately 1 case per 2000 live births.InternationalIn Great Britain, incidence varies from 1.6-4 cases per 1000 live births. Mortality/Morbidity With early diagnosis, appropriate fluid resuscitation, and therapy, the mortality rate from intussusception in children is less than 1%. The morbidity rate is very low after treatment of intussusception. Race No significant difference in the incidence of intussusception is reported between races. Sex Most series report a slight preponderance of males, with a male-to-female ratio of approximately 3:2. Age Two thirds of children with intussusception are younger than 1 year; most commonly, intussusception occurs in infants aged 5-10 months. Although extremely rare, intussusception has been reported in the neonatal period. Intussusception can account for as many as 25% of abdominal surgical emergencies in children younger than 5 years, exceeding the incidence of appendicitis. Intussusception is the most common cause of intestinal obstruction in patients aged 5 months to 3 years. From a clinical perspective, using a cutoff age of 3 years is helpful for dividing patients with intussusception into 2 groups. Patients aged 5 months to 3 years who have intussusception rarely have a lead point (ie, idiopathic intussusception) and are usually responsive to nonoperative reduction. Older children and adults more often have a surgical lead point to the intussusception and require operative reduction.ClinicalHistory The constellation of signs and symptoms of intussusception represents one of the most classic presentations of any pediatric illness; however, the classic triad of vomiting, abdominal pain, and passage of blood per rectum occurs in only one third of patients. The patient is usually an infant who presents with vomiting, abdominal pain, passage of blood and mucus, lethargy, and a palpable abdominal mass. These symptoms are often preceded by an upper respiratory infection. In rare circumstances, the parents report one or more previous attacks of abdominal pain within 10 days to 6 months prior to the current episode. These patients are more likely to have a surgical lead point causing recurrent attacks of intussusception with spontaneous reduction.Symptoms include the following:yyy yyPain is colicky, severe, and intermittent. The parents or caregivers describe the child as drawing the legs up to the abdomen and kicking the legs in the air. In between attacks, the child appears calm and relieved. Initially, vomiting is nonbilious and reflexive, but when the intestinal obstruction occurs, vomiting becomes bilious. Any child with bilious vomiting is assumed to have a condition that must be treated surgically until proven otherwise. Parents also report the passage of stools that look like currant jelly. This is a mixture of mucus, sloughed mucosa, and shed blood as described in Pathophysiology. Lethargy is a relatively common presenting symptom with intussusception. o The reason lethargy occurs is unknown because lethargy has not been described with other forms of intestinal obstruction. o Lethargy can be the sole presenting symptom, which makes the diagnosis challenging. Patients are found to have an intestinal process late, after initiation of a septic workup. Diarrhea can also be an early sign of intussusception.Physical Upon physical examination, the patient is usually chubby and in good health. Intussusception is uncommon in children who are malnourished. The child is found to have periods of lethargy alternating with crying spells, and this cycle repeats every 15-30 minutes. The infant can be pale, diaphoretic, and hypotensive if shock has occurred.yy y y y yy yThe hallmark physical findings in intussusception are a right hypochondrium sausage-shaped mass and emptiness in the right lower quadrant (Dance sign). This is hard to detect and is best palpated when the infant is quiet between spasms of colic. Abdominal distention frequently is found if obstruction is complete. If intestinal gangrene and infarction have occurred, peritonitis can be suggested on the basis of rigidity and involuntary guarding. Early in the disease process, occult blood in the stools is the first sign of impaired mucosal blood supply. Later on, frank hematochezia and the classic currant jelly stools appear. Fever and leukocytosis are late signs and can indicate transmural gangrene and infarction. A rare presentation of intussusception is prolapse of the intussusceptum through the anus. o This prolapse of the intussusceptum can be confused with rectal prolapse. Careful examination can differentiate between the 2 presentations. o The anal crypts are everted with rectal prolapse and not with intussusception. o An examining finger can be passed between the prolapse and the anus in patients with intussusception but not in patients with rectal prolapse. Patients with intussusception often have no classic signs and symptoms, which can lead to an unfortunate delay in diagnosis and disastrous consequences. Maintaining a high index of suspicion for intussusception is essential when evaluating a child younger than 5 years who presents with abdominal pain or when evaluating a child with Henoch-Schnlein purpura (HSP) or hematologic dyscrasias.Causes In most infants and toddlers with intussusception, the etiology is unclear. This group is believed to have idiopathic intussusception. One theory about the etiology of idiopathic intussusception is that it occurs because of an enlarged Peyer patch; this hypothesis is derived from 3 observations: (1) often, the illness is preceded by an upper respiratory infection, (2) the ileocolic region has the highest concentration of lymph nodes in the mesentery, and (3) enlarged lymph nodes are often observed in patients who require surgery. Whether the enlarged Peyer patch is a reaction to the intussusception or a cause of it is unclear.yyy y yIn approximately 2-12% of children with intussusception, a surgical lead point is found. Occurrence of surgical lead points increases with age and indicates that the probability of nonoperative reduction is highly unlikely. Examples of lead points are as follows: o Meckel diverticulum2 o Enlarged mesenteric lymph node o Benign or malignant tumors of the mesentery or of the intestine, including lymphoma, polyps, ganglioneuroma,3 and hamartomas associated with Peutz-Jeghers syndrome o Mesenteric or duplication cysts o Submucosal hematomas, which can occur in patients with HSP and coagulation dyscrasias o Ectopic pancreatic and gastric rests o Inverted appendiceal stumps o Sutures and staples along an anastomosis o Intestinal hematomas secondary to abdominal trauma Other theories have implicated a viral etiology; however, no theory has proven to be reliable. o A seasonal variation in the incidence of intussusception that corresponds to the peaks in frequency of gastroenteritis (spring and summer) and respiratory illnesses (midwinter) has been described but has not been corroborated universally. o An association was found between the administration of a rotavirus vaccine (RotaShield) and the development of intussusception.4 RotaShield has since been removed from the market. These patients were younger than usual for idiopathic intussusception and were more likely to require operative reduction. The vaccine is hypothesized to cause a reactive lymphoid hyperplasia, acting as a lead point. o In February 2006, a new rotavirus vaccine (RotaTeq) was approved by the US Food and Drug Administration (FDA). RotaTeq did not show an increased risk for intussusception compared with placebo in clinical trials. o A study that involved more than 63,000 patients who received Rotarix or placebo at ages 2 and 4 months reported a decreased risk for intussusception in those patients receiving Rotarix.5 The intussusception data was determined over a 31-day observation period (inpatient or outpatient) after each dose of the Rotarix vaccine; this also included a 100-day surveillance period for all serious adverse events. Familial occurrence of intussusception has been reported in a few cases. Intussusception in dizygotic twins has also been described; however, these reports are extremely rare.Intussusception DiagnosisWhen making an intussusception diagnosis, a doctor will ask a number of questions, perform a physical exam, and may recommend certain tests, such as imaging tests and the use of enemas. In possible cases of intussusception, diagnosis of the conditions also involves ruling out other medical conditions with similar symptoms, such as colic, appendicitis, and sepsis.Intussusception Diagnosis: An OverviewIn order to make an intussusception diagnosis, the doctor will ask a number of questions, including questions about:y y y ySymptoms Current medical conditions Current medications Family history of medical problems.The doctor will also likely perform a physical exam, looking for signs and symptoms of intussusception. If the doctor suspects intussusception, he or she may order additional tests.Tests Used to Make an Intussusception DiagnosisA range of diagnostic tests may be required to make an intussusception diagnosis. Some of these tests include the following:y y y yX-rays of the abdomen may suggest a bowel obstruction (blockage) An upper and lower gastrointestinal (GI) series will locate the intussusception and show the telescoping CT scan (computed tomography) can also help with the intussusception diagnosis When intussusception is suspected, an air or barium enema can often help correct the problem by pushing the telescoped section of bowel into its proper position.Intussusception Diagnosis and Other Medical ConditionsIntussusception symptoms can be similar to symptoms seen with a number of other medical conditions. The doctor will consider these conditions and attempt to rule them out before making an intussusception diagnosis. These conditions include:y y y y y yColic Volvulus Appendicitis Gastroenteritis Sepsis Incarcerated hernia....
View Full Document
- Spring '11