Manometry · What Is It, When Is It Performed, and More

Manometry is a diagnostic test that evaluates the pressure and constriction of muscles within various parts of the gastrointestinal tract. Most commonly, manometry is used to evaluate for disorders of the esophagus, a test known as esophageal manometry or an esophageal motility study. During esophageal manometry, a thin, flexible tube, or catheter, is used to measure the pressure generated by the upper and lower esophageal sphincters. The sphincters are round, striated muscles that help prevent the entry of air into the stomach or reflux of gastric contents into the esophagus.   

Non-esophageal manometry includes tests such as anorectal manometry, which evaluates disorders of the rectum and anal sphincter; and sphincter of Oddi manometry which assesses the muscle controlling bile flow from the bile ducts into the small intestine. The sphincter of Oddi is a muscular valve located where the bile duct and pancreatic duct empty into the duodenum, which is the first part of the small intestine. 

Esophageal manometry is primarily indicated for evaluating symptoms of esophageal dysfunction such as difficulty swallowing (i.e., dysphagia) or pain when swallowing (i.e., odynophagia). It is also indicated for heartburn, chest pain, and frequent regurgitation of food. It may also be performed before a fundoplication surgery, also known as anti-reflux surgery,  which is done to treat symptoms of gastroesophageal reflux disease (GERD). Esophageal manometry may also be used to assess motility disorders of the esophagus, such as achalasia, which is a swallowing disorder where esophageal muscles fail to contract properly; diffuse esophageal spasm, which is when the esophagus muscles contract in an uncoordinated manner; or scleroderma, an autoimmune disease resulting in the smooth muscle of the esophagus being replaced with fibrous scar tissue.  

In contrast, anorectal manometry may be performed in an individual with chronic constipation or fecal incontinence (i.e., the inability to hold stool). It can be used to diagnose conditions such as Hirschsprung disease, which is a congenital defect resulting in loss of nerves in the large intestine; injury to the anus or rectum; and irritable bowel syndrome, a condition associated with altered bowel movements. Sphincter of Oddi manometry is indicated when an individual experiences abdominal pain that is thought to be related to the bile duct due to either stenosis (i.e., narrowing) or dyskinesia (i.e., abnormal contraction) of the sphincter of Oddi.  

The test results of esophageal manometry help identify abnormal patterns of muscle contraction and relaxation in the esophagus. For example, if an individual has gastroesophageal reflux disease, their lower esophageal sphincter may be weak resulting in stomach acid flowing backward. If they have achalasia, the manometry may show high pressure in the lower esophageal sphincter at rest, failure of the lower esophageal sphincter to relax after swallowing, and an absence of peristaltic contractions in the lower esophagus. Alternatively, if an individual has diffuse esophageal spasms, manometry typically shows simultaneous contractions of the esophagus with greater than 30% of swallows and normal peristalsis. Lastly, those with scleroderma may have decreased lower esophageal sphincter pressure and absent or ineffective peristalsis of the distal esophagus.  

Non-esophageal manometry may show decreased anal sphincter tone in those with injuries to the anus or rectum affecting the nerves and/or muscles. If the rectal muscles and sphincter are not able to relax when the balloon is inflated, the individual may have Hirschsprung disease resulting in paralysis of the muscles. Those with irritable bowel syndrome may be either more or less sensitive to changes in pressure from the balloon, or have a more stiff rectum requiring higher pressures to inflate the balloon on manometry. If there is a sphincter of Oddi dysfunction, manometry may show higher pressures on average compared to those without dysfunction.