Acute intussusception

Acute intussusception

This occurs when one portion of the gut invaginates into an immediately adjacent segment; almost invariably , it is the proximal into the distal. The condition is encountered most commonly in children, with a peak incidence between 5 and 10 months of age. About 90% of cases are idiopathic but an associated upper respiratory - tract infection or gastroenteritis may precede the condition. It is believed tha t hyperplasia of Peyer’s patches in the terminal - ileum may be the initiating event. Weaning, loss of passively ptoki - acquired maternal immunity and common viral pathogens have all been implicated in the pathogenesis of intussusception in infancy (see Chapter 17 ). Children with intussusception associated with a patholog - ical lead point such as Meckel’s diverticulum, polyp, duplica - tion, Henoch–Schönlein purpura or appendix are usually older than those with idiopathic disease. After the age of 2 years, a pathological lead point is found in at least one-third of a ff ected children. In adults, cases are almost invariably associated with a lead point, which is usually a polyp (e.g. Peutz–Jeghers syn- drome), a submucosal lipoma or other tumour. The phenomenon of transient intussusception in younger patients is now recognised. Imaging of the small bowel (with CT scanning, capsule endoscopy or enteroscopy) is required to exclude intraluminal disease. Pathology An intussusception is composed of three parts ( Figure 78.5 /uni25CF the entering or inner tube (intussusceptum); /uni25CF the returning or middle tube; /uni25CF the sheath or outer tube (intussuscipiens). The part that advances is the apex, the mass is the intus- susception and the neck is the junction of the entering layer with the mass. Intussusception may be anatomically defi ned according to the site and extent of invagination ( Table 78.2 ). In most children, the intussusception is ileocolic. In adults, colocolic intussusception is more common. The degree of ischaemia is dependent on the tightness of invagination, which is usually greatest as it passes through the ileocaecal valve. John Law Augustine Peutz , 1886–1968, Chief Specialist for Internal Medicine, St John’s Hospital, The Hague, The Netherlands. Harold Joseph Jeghers , 1904–1990, Professor of Internal Medicine, New Jersey College of Medicine and Dentistry , Jersey City , NJ, USA. Robert Edward Gross , 1905–1988, paediatric surgeon, Harvard Medical School, Boston, MA, USA. On CT scanning the target sign may be evident and, if present, is pathognomonic ( Figure 78.6 ). It is worth noting that occasionally an asymptomatic intussusception can be observed on CT scanning in adults. This may be transient or intermittent. Summary box 78.4 Intussusception /uni25CF ): /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF

Intussuscipiens Intussusceptum Intussusception Figure 78.5 Small bowel intussusception showing components: intussusceptum (purple arrow); intussuscipiens; lead point; middle tube (red arrows). TABLE 78.2 Types of intussusception in children (after RE Gross) ( n = 702). Percentage of series Ileoileal 5 Ileocolic 77 Ileoileocolic 12 Colocolic 2 Multiple 1 Retrograde 0.2 Others 2.8 Intussusceptum Lead point Neck Apex Intussusception 78.05 Most common in children Adult cases are secondary to intestinal pathology, e.g. polyp, Meckel’s diverticulum Ileocolic is the most common variety Can lead to an ischaemic segment Radiological reduction is indicated in most paediatric cases Adults who present acutely require surgery Figure 78.6 Abdominal computed tomography scan illustrating the ‘target sign’ of the ileocolic intussusception seen in Figure 78.5 .

A volvulus is a twisting or axial rotation of a portion of bowel about its mesentery . The rotation causes obstruction to the lumen (>180° torsion) and if tight enough also causes vascular occlusion in the mesentery (>360° torsion). Bacterial fermentation adds to distension and increasing intraluminal pressure impairs capillary perfusion. Mesenteric veins become obstructed as a result of the mechanical twisting; thrombosis results and contributes to ischaemia. V olvuli may be primary or secondary . The primary form is caused by congenital malrotation of the gut, abnormal mesen teric attachments or congenital bands. Examples include vol vulus neonatorum, caecal v olvulus and sigmoid volvulus (see Chapter 65 ). A secondary volvulus, which is the more com mon variety , is due to rotation of a segment of bowel around an acquir ed adhesion or stoma. Summary box 78.5 Volvulus /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF This occurs secondary to intestinal malrotation (see Chapters 17 and 65 ) and is potentially catastrophic. Sigmoid volvulus This is uncommon in Europe and the USA but more common in eastern Europe and Africa. Indeed, it is the most common cause of large bowel obstruction in the indigenous black African population. Rotation nearly always occurs in the anticlockwise direction. The predisposing clinical features are summarised in Figure 78.7 . Other predisposing factors include a high-residue - diet and constipation. In western populations, the condition is - seen most often in elderly patients with chronic constipation; comorbidities are common and chronic psychotropic drug - use is associated with this condition. Y ounger patients present earlier and the prognosis is inversely related to the duration of symptoms. Presentation with volvulus can be classified as: /uni25CF fulminant : sudden onset, severe pain, early vomiting, rapidly deteriorating clinical course; /uni25CF indolent : insidious onset, slow progressive course, less pain, late vomiting. Compound volvulus This is a rare condition that is also known as ileosigmoid knotting. The long pelvic mesocolon allows the ileum to twist around the sigmoid colon, resulting in gangrene of either or both segments of bowel. The patient presents with acute intestinal obstruction, but distension is comparatively mild. Plain radiography reveals distended ileal loops in a distended sigmoid colon. At operation, decompression, resection and anastomosis are required.

May involve the small intestine, caecum or sigmoid colon Neonatal midgut volvulus secondary to midgut malrotation is life-threatening The most common spontaneous type in adults is sigmoid volvulus Sigmoid volvulus can be relieved by decompression per anum Surgery may be required to prevent or relieve ischaemia Band of adhesions (peridiverticulitis) Overloaded pelvic colon Long pelvic mesocolon Narrow attachment of pelvic mesocolon Figure 78.7 Causes predisposing to volvulus of the sigmoid colon. Idiopathic megacolon usually precedes the volvulus in African people.