Intussusception

Gastroenterology (12%) Core Clinical Conditions

1B The Physician Associate is able to identify the condition as a possible diagnosis: may not have the knowledge/resources to confirm the diagnosis or to manage the condition safely, but can take measures to avoid immediate deterioration and refer appropriately.

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management

Intussusception is a medical condition that occurs when a part of the intestine invaginates or slides into an adjacent section of the intestine, causing a blockage. This condition primarily affects infants and young children, usually between the ages of 3 months and 3 years.

Viral Infections: It has been observed that viral infections, particularly gastroenteritis caused by certain viruses like adenovirus, rotavirus, or enteric adenovirus, can trigger intussusception in infants and young children. These viruses can lead to inflammation and swelling of the lymph nodes in the intestines, making the affected area more prone to invagination.
Structural Abnormalities: Structural abnormalities within the intestine can also play a role in the development of intussusception. Some individuals may have conditions like polyps, tumours, or diverticula (outpouchings of the intestinal wall). These anatomical irregularities can serve as a starting point for the telescoping process to initiate.
Meckel’s Diverticulum: Meckel's diverticulum is a congenital abnormality where a small pouch forms in the wall of the small intestine. When this pouch becomes inflamed, it can lead to intussusception. Meckel's diverticulum is most commonly found in children, but it can also affect adults.
Hypertrophy of Peyer's Patches: Peyer's patches are lymphoid tissue clusters in the intestines that serve as an important part of the immune system. In some cases, these patches may become enlarged or abnormally hypertrophied due to infections or inflammation, making them susceptible to invagination.
Idiopathic Cases: In a significant number of intussusception cases, the underlying cause may remain unknown. This is referred to as idiopathic intussusception. Although the precise trigger cannot be determined, some theories suggest that weakened intestinal muscles or abnormal peristaltic movements could contribute to invagination.
Age and Gender: Intussusception predominantly affects infants and young children, most commonly between the ages of 3 months and 5 years. Boys are more likely to develop this condition compared to girls, with a higher incidence observed in males.

The exact cause is often unknown, but several factors are thought to contribute to its development.
One potential mechanism involves the presence of a lead point. This can be an abnormal growth, such as a polyp or tumour, within the intestine. The bowel telescopes around this lead point, causing the intestines to become trapped. In infants and children, lymphoid hyperplasia, which is the hyperactivity of the lymphoid tissue in the intestine, is the most common lead point.
The process usually begins in the ileocecal region, where the small intestine joins the large intestine. Peristalsis, the coordinated muscular contractions that propel food through the digestive system, becomes disturbed, leading to continued telescoping of the intestine. As this continues, the blood supply to the affected segment may be compromised, resulting in impaired oxygenation, inflammatory changes, and potentially ischemia.
The invagination leads to a progressive occlusion of the lumen, causing pain and discomfort in the affected individual. This can manifest as intermittent, severe abdominal pain, often accompanied by vomiting. The pain may come in waves as the invagination intermittently releases and reoccurs.
As a consequence, distention of the intestines occurs proximal to the site of the obstruction, leading to swelling and accumulation of gas and fluid. This abdominal distention may be palpable during a physical examination. The trapped segment of intestine may also cause blood and mucus to be passed in the stool.
The compromised blood supply to the affected segment of intestine may lead to inflammation and edema, contributing to the intensity of symptoms. If the condition is not promptly treated, tissue necrosis and perforation may occur, resulting in peritonitis and septic shock.
While the exact cause of intussusception is often unknown, some triggering factors have been identified. Viral infections, particularly those caused by the Rotavirus, have been associated with an increased risk of intussusception. Additionally, abnormalities of the intestine's muscular contractions, alterations in gut motility, and congenital anomalies may predispose individuals to developing intussusception.

See aetiology

• Severe abdominal pain: children might cry inconsolably, draw their legs up to their chest, or exhibit signs of distress. The discomfort typically comes and goes in waves, with short periods of relief in between. This pain can be so intense that it becomes difficult for the child to eat, drink, or even walk.

• Distended or swollen abdomen: the abdomen might appear bloated or feel firm to the touch. This swelling occurs as a result of the trapped intestine becoming enlarged and obstructed, leading to an accumulation of gas and fluid.

• Blood in stools: the stools might also take on a jelly-like consistency, resembling red currant jelly. This occurs due to the pressure applied to the walls of the intestine, which can cause bleeding and mucous production.

• Changes in bowel movements can indicate intussusception.

• Frequent vomiting, which can be forceful and projectile. This vomiting may be accompanied by bile-stained fluid, indicating an obstruction. Conversely, children might also develop diarrhoea, which might be mixed with blood and mucus.

• Other signs can include a general feeling of unwellness or lethargy, with children appearing unusually tired or irritable. They might also exhibit a loss of appetite and have difficulty maintaining their usual weight.

• History and physical examination: a PA will carefully evaluate the patient's symptoms, such as abdominal pain, bloody stools, and episodes of intermittent colicky crying. Additionally, they might palpate the abdomen, searching for any abnormal masses or tenderness.

• Abdominal ultrasound: this non-invasive procedure allows for visualisation of the bowel loops and can often identify the characteristic "target" or "donut" sign, indicative of intussusception. The target sign represents a concentric pattern of alternating hypoechoic and hyperechoic layers within the intestine, representing the layers of invaginated bowel. Ultrasonography can help confirm the diagnosis and determine the location, length, and severity of the intussusception.

• Abdominal X-ray.

• Barium enema: during this procedure, a contrast material is introduced into the colon through the rectum, allowing visualisation of the intussusception on X-ray or fluoroscopy. The contrast material helps delineate the telescoped bowel loop and aids in reducing the intussusception by hydrostatic pressure.

• Computed tomography (CT) scan: provide detailed cross-sectional images of the abdomen and can help assess the extent of bowel involvement, presence of ischemia, or any other complications associated with intussusception.

Surgical Management

This is the main source of treatment.

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