An 18 month old male presents to the emergency department with six hours of stomach pain. He awoke at 0400 crying. His mother carried him and he settled down after a few minutes and then fell back asleep. Over the next few hours, he woke up intermittently crying. His appetite has been poor since the onset of these symptoms. He is able to walk but prefers to be carried by his mom this morning. He is less playful than usual. He would sometimes bend down crying. There is no vomiting or diarrhea. His last stool yesterday was normal. There is no fever, cough, or runny nose. There is no history of abdominal trauma.
Exam: VS T37.6, P 118, R 24, BP 85/55, weight 11kg. He is awake, alert, and being carried by mom. His skin is pink with good perfusion and brisk capillary refill. His oral mucosa is pink and moist. There are no ulcers in the posterior pharynx. His tympanic membranes are normal. Heart regular rhythm and normal rate. Lungs are clear with good aeration. His abdomen is soft and not distended, with normoactive bowel sounds, and no masses noted. It is difficult to determine if any abdominal tenderness is present. His genitalia are normal (no scrotal/testicular swelling or tenderness). His distal extremities are warm and the distal pulses are strong. He is responding to mom appropriately.
An abdominal series reveals a soft tissue density in the right lower quadrant. Intussusception is suspected. A water-soluble contrast enema is performed. An intussusception is identified at the hepatic flexure. The ileocolic intussusception is successfully reduced. There was reflux of the contrast into the ileum. Admission to the hospital is discussed with the mother, but she refuses. He is observed in the emergency department. After a short nap, he is able to tolerate oral fluids and his behavior normalizes. The risk of recurrence is discussed with his mother. His pediatrician is contacted and the patient is then discharged home.
Intussusception is a common abdominal emergency in children. Intussusception is best described as a portion of the intestine which telescopes into a more distal intestinal segment. It is one of the most common causes of abdominal obstruction in infants. Intussusception occurs most often in patients between 3 to 12 months of age. There is a male to female predominance of 2:1. It is often difficult to diagnose because of the variable presentation of symptoms in a young infant.
The most common type of intussusception is ileocolic (also known as ileocecal) (90%). A portion of terminal ileum intussuscepts through the ileocecal valve into the colon. The intussusception may sometimes extend all the way to the rectum. Other types of intussusception that are rarer include ileoileal, colocolic, and ileoileocolic. The majority of intussusceptions are idiopathic. An anatomic lead point (a piece of intestinal tissue which protrudes into the bowel lumen such as a polyp) occurs in approximately 10% of intussusceptions. This is most often found in children older than 2 years. Possible lead points include Meckel's diverticulum (most common), polyps, an inflamed appendix, neoplasm (lymphoma), and ileal duplications. Intussusceptions with lead points are more common in patients with Henoch-Schonlein purpura (intestinal wall hematoma) and cystic fibrosis (hypertrophied mucosal glands). In infants it is hypothesized that hypertrophied Peyer's patches, following a respiratory infection or gastroenteritis, may serve as the lead point.
The mesentery is pulled along with the intussusceptum (leading invaginating segment) into the intussuscipiens (receiving segment). The intussusceptum is propelled distally through peristalsis. The mesenteric vessels are compressed leading to venous obstruction. The intussusceptum becomes engorged causing bleeding from the mucosa (bloody mucusy stools, sometimes known as currant jelly stool since extreme amounts of blood in the stool will loosely resemble the red jelly of currant berries). However, it should be noted that any blood in the stool may be caused by an intussusception. With a prolonged intussusception, perfusion to the intestine may be compromised, which can then lead to bowel necrosis, perforation, and shock.
The classic triad of intussusception include crampy (intermittent, also known as colicky) abdominal pain, vomiting, and bloody stools. The classic triad was found in only 21% of cases and two symptoms were found in 70% of cases in one series of patients with intussusception (1). The colicky abdominal pain usually appears first and is the most common symptom. The pain is intermittent lasting for 4 to 5 minutes. It may return in 5 to 30 minute intervals. The patient may pull up his knees with crying. In between the episodes the patient may be asymptomatic. The patient may develop vomiting (90% of cases). The emesis may become bilious because of the obstruction. Bloody stools, found in 50% of cases, can be a late sign of intussusception. The absence of blood (even occult blood) does not rule-out intussusception. Patients with an intussusception may also present with lethargy/altered level of consciousness and pallor. The etiology of this lethargic presentation is not known, but it tends to occur in younger infants. Some hypothesize that this is due to release of endogenous opioids or endotoxins released from ischemic bowel. Intussusception in a child presenting with lethargy is often difficult to diagnose since other causes of lethargy such as dehydration, hypoglycemia, sepsis, toxic ingestion, post-ictal state, etc., must also be considered.
The physical examination of a patient with an intussusception may be unremarkable. If the patient is between attacks of the crampy abdominal pain, he may appear normal and the abdominal examination may be unrevealing. Also, examining the abdomen of an active or crying child can often be difficult. Lethargic or tired infants with very soft abdomens are the easiest to examine. In some patients, a mass may be palpable in the right upper quadrant. It is often described as sausage-shaped. A sausage-like mass in the right upper quadrant and emptiness (the absence of bowel) in the right lower quadrant is clinically indicative of an intussusception. Blood may be found on rectal examination. If the intussusception has been present for a longer period of time, the abdomen may be distended and there may be findings of peritonitis.
There are several findings described on plain film abdominal radiographs of patients with intussusception. There may be evidence of a soft tissue mass or signs of bowel obstruction (air fluid levels and distended loops of bowel). The absence of gas in the right lower quadrant or flank may be seen with an intussusception. A target sign, crescent sign or indistinct liver margin sign may be present. A target sign is viewing the intussusception on cross-section which appears as two concentric circles (created by bowel fat density differences) usually in the right upper quadrant. The crescent sign is formed by the leading edge of the intussusception outlined by gas in the colon forming a crescent (intussusceptum protruding into a gas filled pocket). The absent liver margin sign can be seen if the soft tissue mass of the intussusception is resting at the hepatic flexure of the colon or there is absence of gas in the right upper quadrant making the lower edge of the liver indistinct. Free air may be visible on the radiograph if there has been intestinal perforation. An abdominal series may be normal especially early on. More recently, ultrasound has been advocated as it is highly specific (100%) and sensitive (98%) in making the diagnosis of intussusception, but only when interpreted by highly skilled radiologists. It may be helpful with confirming the diagnosis if an enema is contraindicated. The major problem with utilizing ultrasound is that it must be able to definitively rule out intussusception, since if diagnostic uncertainty still exists following the ultrasound, a contrast enema must still be performed. Additionally, if the ultrasound does identify an intussusception, a contrast enema must still be performed to reduce the intussusception. Thus, before considering an ultrasound, the diagnostic ultrasonography skills of the available radiologist must be determined. The high specificity and sensitivity percentages are published from studies done in ultrasound pediatric super centers and thus, these numbers are not necessarily applicable to general radiologists.
A barium enema has been the gold standard in the past for confirming the diagnosis and nonsurgical reduction of an intussusception. Water-soluble contrast has been used and more recently air enema reduction has been introduced. There are several reasons why radiologists have different preferences for which type of contrast they choose to use for the procedure. After the radiologist reduces the intussusception, they look for the contrast to reflux into the ileum. This is necessary to eliminate the possibility of an ileoileal intussusception. This is more difficult to see with an air contrast enema compared to a barium or water-soluble contrast enema. Air leaking into the peritoneal cavity because of intestinal perforation may also be difficult to see. Those in favor of using the air contrast enema technique argue that with perforation, the sudden loss of pressure would signal to the radiologist to stop the procedure. If a tension pneumoperitoneum results, this should be decompressed immediately with an 18-gauge needle. Barium leaking into the peritoneal cavity may cause a chemical peritonitis. Using a water-soluble contrast may decrease this complication. An air contrast enema is advocated as the preferred method by many pediatric radiologists (2), but since there is no clear consensus among radiologists of the best contrast enema option, this decision is best left to the radiologist performing the contrast enema procedure. The success rate of nonsurgical reduction is about 60% to 80%. Several factors are associated with a contrast enema being unsuccessful in reducing the intussusception. These include ileo-ileocolic intussusception, longer duration of symptoms (>12 hours), dehydration, small bowel obstruction, and age greater than 2 years or less than 3 months. The intussusception being present for 24 hours or more, is no longer a contraindication for attempting contrast enema reduction. The rate of intestinal perforation with nonsurgical reduction of an intussusception is 1% to 3%. A contrast enema is contraindicated in patients who have a bowel perforation, shock, or peritonitis. Ultrasound has also been used to monitor reduction of the intussusception using saline rather than contrast under fluoroscopy. The advantage of using ultrasound is that there is no radiation exposure. This is not commonly used in the United States. Computed tomography can also identify an intussusception. This usually occurs incidentally when the patient is having a CT scan for the evaluation of abdominal pain and intussusception was not initially suspected. If the intussusception is not reduced by an enema, or if there is intestinal perforation, shock, or peritonitis present, the patient is sent for surgical reduction. An intravenous line, a nasogastric tube, and consultation with a surgeon should be considered. If the patient is dehydrated, a fluid bolus with NS or LR should be given.
If the intussusception is reduced successfully by enema, some may discharge the patient home from the emergency department after observing the patient. However, most feel that the patient should be observed in the hospital for 24 hours. The risk of recurrence is about 4%. Intussusception recurs in up to 5% to 10% of the cases reduced by contrast enema and about 1 to 5% of those reduced by surgery, though most recurrences are late recurrences (after the patient has been discharged).
1. The most common type of intussusception is:
. . . . . a. ileoileal
. . . . . b. colocolic
. . . . . c. ileocolic
. . . . . d. ileo-ileocolic
2. Contraindications for non-surgical reduction of an intussusception include all of the following except:
. . . . . a. symptoms for longer than 24 hours
. . . . . b. shock
. . . . . c. intestinal perforation
. . . . . d. peritonitis
3. Which is the most common pathological lead point found with intussusception?
. . . . . a. neoplasm
. . . . . b. appendicitis
. . . . . c. polyps
. . . . . d. intestinal duplication
. . . . . e. Meckel's diverticulum
4. A pathologic lead point can be identified in approximately what percentage of
patients with intussusception?
. . . . . a. 1%
. . . . . b. 5%
. . . . . c. 10%
. . . . . d. 15%
. . . . . e. 25%
5. The "classical triad" of symptoms of intussusception include:
. . . . . a. diarrhea
. . . . . b. vomiting
. . . . . c. fever
. . . . . d. bloody stools
. . . . . e. abdominal pain
6. Which element of the "classical triad" usually appears first?
. . . . . a. diarrhea
. . . . . b. vomiting
. . . . . c. fever
. . . . . d. bloody stools
. . . . . e. abdominal pain
7. All three of the "classical triad" of symptoms is found in what percentage of patients with intussusception?
. . . . . a. 9%
. . . . . b. 21%
. . . . . c. 50%
. . . . . d. 70%
. . . . . e. 90%
8. True/False: A normal abdominal series rules-out intussusception.
9. If a mass is palpable on physical examination, it is most often found in the:
. . . . . a. right upper quadrant
. . . . . b. right lower quadrant
. . . . . c. left upper quadrant
. . . . . d. left lower quadrant
Intussusception Case and Radiographs: Young LL, Yamamoto LG. The Stomach Flu? - The Target, Crescent, and Absent Liver Edge Signs. In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1994, volume 1, case 2. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v1c02.html
Abdominal Radiographs and Intussusception: Chan-Nishina CC, Tim-Sing PML. Test Your Skill In Distinguishing Obstruction From Ileus. In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1995, volume 3, case 18. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v3c18.html
Intussusception Case: Yamamoto LG. Lethargy and Vomiting Following Child Abuse. In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1999, volume 5, case 10. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v5c10.html
Intussusception Radiographs: Yamamoto LG. Find the Intussusception Target and Crescent Signs. In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 2002, volume 7, case 18. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v7c18.html
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Answers to questions
5. b, d, e