'Milk' scan for gastroesophageal reflux

Brief introduction

Principle

Swallowed food (solid as well as liquid) passes through the oesophagus ('food pipe') to reach the stomach. The junction between the oesophagus and stomach is known as gastroesophageal junction (GEJ), which in turn contains ring-like muscles. They relax to increase size of the lumen during swallowing and then shut tight to prevent retrograde ascent of food into the oesophagus.

In some individuals, the GEJ does not shut tightly enough or opens at incorrect times, and the food from stomach passes into the oesophagus. This is known as gastroesophageal reflux (GER). Severity of GER is assessed in terms of frequency and how higher up the refluxed contents are able to rise within the oesophagus. In most severe cases, the refluxed contents could reach all the way up to the mouth.

The fluids produced by the stomach are strongly acidic. The mucosa (cells forming the inner lining) of stomach are inherently resistant to this acidity. But, the oesophageal mucosa does not have the same adaptive mechanisms, and acidic refluxed contents cause chemical injury.

GER can be normal in infants of up to 7 to 8 months' age. However, severe GER in infants can cause concerning problems like lung infection (pneumonia) or slow growth (failure to thrive).

When GER happens with abnormally high frequency, it is known as gastroesophageal reflux disease (GERD). Early symptom of GERD is 'heartburn'. Long-term untreated complications of GERD include oesophagitis (inflammation of oesophagus, which makes swallowing painful), oesophageal narrowing and oesophageal perforation. Some other consequences outside of oesophagus could include dental caries and hoarseness of voice.

GERD is diagnosed through tests like barium swallow and endoscopy. However, these are difficult to carry out in infants. 'Milk' scan or radionuclide GER study involves introducing a very minute quantity of radioactivity into the stomach. If there are any episodes of reflux for the duration of the scan, radioactivity would rise up to a level higher than that of the GEJ. Radionuclide scan is much more sensitive than the X-ray based barium swallow study, however, the anatomical details are far worse.

Indications (conditions in which advised)

• In infants with recurrent coughing or proved pneumonia.
• In infants with failure to thrive.