INTUSSUSCEPTION ENTERIC DUPLICATION CYSTS

Intussusception
Intussusception is the invagination of a segment of bowel into the lumen of the adjacent bowel. It is a common paediatric emergency, especially in younger children aged 3 months to 3 years, and tends to affect the ileocaecal region. The child presents with abdominal pain, sometimes with a palpable mass, vomiting or rectal bleeding. Intussusception can result in bowel necrosis and subsequently perforation requiring surgery.

The ultrasound appearances of bowel within bowel are characteristic. In cross-section, the bowel assumes a ‘doughnut’ configuration, with concentric rings of bowel wall. Dilated loops of fluid-filled obstructed bowel may be demonstrated proximal to the intussusception. The use of ultrasound to diagnose this condition is highly reliable, reducing or eliminating the need for contrast radiology. An air enema is most commonly used to reduce the intussusception using inflation pressures of up to 120 mmHg. Hydrostatic reduction (that is, with water/saline) under fluoroscopic or ultrasound control is also an accepted treatment.

The main contraindications to attempting a nonsurgical reduction are peritonitis and free intraperitoneal air. A number of sonographic features have been reported to be associated with a decreased success rate of non-surgical reduction, including a hypoechoic rim greater than 10 mm, absent blood flow on colour flow Doppler sonography, or a large amount of fluid trapped within the intussusception, but these findings are not contraindications to a careful attempt at non-surgical reduction. Approximately 10% of cases recur whether the initial intussuception was treated surgically or non-surgically.

Enteric duplication cysts
These comparatively rare lesions present in infancy or early childhood with nausea, gastrointestinal bleeding, intestinal obstruction and, occasionally, a palpable mass. Most are intra-abdominal but oesophageal duplication cysts cause a thoracic lesion with respiratory symptoms.

Multiple cysts may be present. The fluid-filled lesion may demonstrate a spectrum of ultrasonic appearances, from anechoic to hyperechoic, sometimes with gravity-dependent debris or blood.

The wall is well defined and a hyperechoic inner rim of mucosa may be identified in some cases of intestinal duplication. The cyst is closely related to the adjacent bowel and this can be appreciated on real-time scanning as the bowel peristalses. CT and MRI rarely add anything to the ultrasound information. Contrast radiography may show an extrinsic defect but communication with the cyst is rare.

There are many causes of intra-abdominal cystic masses in children. The main differential diagnosis in the infant girl is from an ovarian cyst as the ovary is generally an intra-abdominal organ at this age.

Useful indicators of an ovarian origin can be detected on careful sonography, by detecting some residual ovarian tissue in the cyst wall, and the finding of a clearly seen multifollicular ovary on one side with absent visualization of a definite ovary on the other side.