Intussusception

Intussusception

Intussusception is a life-threatening cause of intestinal obstruction in infants and young children, typically aged between 3 months and 6 years. It occurs when a segment of the bowel “telescopes” into the adjacent, distal segment. This leads to vascular compromise, swelling, and eventually, bowel ischaemia and perforation. In the UK, it is the most common cause of acute bowel obstruction in this age group and requires prompt diagnosis and management.

Pathophysiology

The most common type is ileocolic intussusception, where the ileum telescopes into the colon. In over 90% of cases in children, there is no identifiable cause (idiopathic), but a leading point, such as a viral infection causing swelling of the Peyer’s patches in the small intestine, is often suspected. In older children, a pathological lead point, such as a Meckel’s diverticulum or an intestinal polyp, is more likely.

Clinical Triad

The classic triad of symptoms is:

• Intermittent abdominal pain: The child presents with episodes of severe, colicky pain, often crying loudly, drawing their legs up, and appearing pale and unwell.

• Redcurrant jelly stools: A late sign consisting of a mixture of blood and mucus, indicative of mucosal ischaemia.

• Palpable abdominal mass: A sausage-shaped mass may be felt, typically in the right upper quadrant.

It is important to note that this classic triad is rare. A more common presentation is a previously well infant who suddenly becomes irritable, has episodes of screaming and pain, and may appear well in between episodes. Progressive symptoms include bilious vomiting, abdominal distension, and signs of circulatory shock.

Investigation and Management

Prompt diagnosis and intervention are critical to prevent bowel necrosis.

Investigation

• Ultrasound Abdomen: This is the gold standard for diagnosis. A transverse view shows the characteristic “doughnut” or “target” sign, representing layers of telescoped bowel.

• Abdominal X-ray: While not diagnostic, it may show signs of bowel obstruction (dilated bowel loops) or a paucity of gas in the right lower quadrant.

• Air Enema: This is a diagnostic and therapeutic procedure. Under fluoroscopy, air is gently insufflated into the rectum, which can both confirm the diagnosis and reduce the intussusception.

Management

1. Initial Stabilisation: First, stabilise the child with the “drip and suck” approach. This involves:

   • IV Fluids: Establish intravenous access for rehydration and give fluid boluses if there are signs of shock.

   • Nasogastric Tube (NGT): Insert an NGT on free drainage to decompress the stomach and prevent further vomiting.

   • Pain Management: Administer appropriate analgesia.

2. Radiological Reduction: In the absence of a suspected bowel perforation or peritonitis, the intussusception is typically reduced using a rectal air enema under fluoroscopic guidance. This is a non-surgical procedure with a high success rate.

3. Surgical Intervention: Surgery is required if:

   • The child has signs of perforation or peritonitis.

   • The radiological reduction is unsuccessful.

   • A pathological lead point is suspected.

Surgical reduction involves a laparotomy to manually reduce the intussusception. If the bowel is gangrenous or cannot be reduced, a bowel resection may be necessary. Recurrence is rare but can occur after both radiological and surgical reduction.