While the use of anorectal manometry to evaluate bowel function is well-established,1 the evolution of high-resolution and 3-dimensional (3D) devices has increased the detail these tools can uncover about functional abnormalities. For gastroenterology fellows learning these techniques, the emerging question is whether training should still be performed using the conventional method.

“Realistically, the degree of expertise needed with either conventional or high-resolution devices will be influenced by interest in motility and bowel function disorders, but I think it is important for fellows to understand how these studies are performed and how to interpret the results,” said Joseph M. Croffie, MD, pediatric gastroenterologist at Riley Hospital for Children, Indiana University School of Medicine in Indianapolis.

Three-dimensional anorectal manometry display.
Image courtesy of Given Imaging, Inc.

Often coupled with other diagnostic tools, such as the balloon expulsion test, anorectal manometry helps diagnose causes of constipation, incontinence, and pain with defecation when initial treatment strategies fail.2,3 The major advantage of high-resolution over conventional devices is that they employ circumferential and proximal sensors, and provide more complete information about muscle function.

High-resolution devices can range from 10 sensors up to 256 sensors in 3D devices2; 3D models are useful when information about the internal and external anal sphincter pressures may underlie symptomatic complaints. High-resolution manometry also allows sphincter pressure to be understood within a spatial relationship to sensation, compliance, and reflexes. This more comprehensive information can identify a broader array of, and provide information about, complex abnormalities.

In a study on the utility of high-resolution manometry, 7 phenotypes were identified by using manometry to evaluate patterns of anal and rectal pressure abnormalities at rest and during evacuation.4 The phenotypes included local rectal pressure alone, low rectal pressure and impaired anal relaxation during evacuation, and short high-pressure zones in the anus. These phenotypes may be relevant to understanding the pathophysiology of constipation and for tailoring interventions.4


An editorial co-authored by Satish S.C. Rao, MD, PhD, chief of the Section of Gastroenterology/Hepatology at Georgia Regents University in Augusta, Georgia, cautioned that these phenotypes were identified using a strict protocol that is not necessarily relevant to routine patient practice, but that high-resolution manometry reveals a neuromuscular complexity in defecation not fully appreciated with previously available tools.5

“By providing pressure readings in a topographical format, one can obtain substantially greater detail about muscle function and sensation, particularly when individuals perform defecatory maneuvers,” Dr. Rao said in an interview with GI Fellow Advisor.

For pediatric patients, a major advantage of high-resolution manometry is that it requires no manipulation of the probes once they are in position, according to Dr. Croffie. This advantage may eliminate the need to perform studies under sedation—a benefit as patients can perform defecatory maneuvers to recreate symptoms during the procedure. Dr. Croffie added that greater data obtained with high-resolution manometry reduces the likelihood that artifacts can confuse the clinical picture.

“In children, we most often employ anorectal manometry to rule out Hirschprung’s disease and other abnormalities, but we find functional disease in most children; so pressure readings along with information about sensation help us recommend the appropriate treatment for these children, but also may raise suspicion about the presence of myopathies or neuropathies causing pelvic floor dysfunction,” Dr. Croffie said.

Studies have suggested that pressure readings using high-resolution and conventional water-perfused anorectal manometry correlate, but one comparison found that high-resolution devices provided greater detail for relating symptomatic complaints to the anatomy.6 The study, which included patients with constipation, incontinence, or fecal soilage, was performed with a 36-channel catheter with sensors at 1-cm intervals. Results showed that the high-resolution device was associated with a shorter study duration time: an advantage for patient comfort and staff resource allotment.6

For fellows learning both high-resolution and conventional manometry, Anish Sheth, MD, director of the Esophageal Program at University Medical Center of Princeton at Plainsboro in New Jersey, noted that there is a learning curve for becoming proficient with either type of device; however, proficiency is not more difficult to acquire with a more sophisticated method. “High-resolution anorectal manometry is easier to interpret and the studies are performed more quickly and comfortably for patients,” Dr. Sheth said. “Moving forward, it makes more sense to train fellows solely on high-resolution devices.”

Although anorectal manometry is used to gain information on sphincter strength and rectal sensation, other tests may be critical for a complete understanding of the underlying disorder. Following an accurate diagnosis, high-resolution manometry can provide highly reproducible information about bowel function that may help pinpoint better therapeutic interventions.

“High-resolution manometry changed our capabilities in identifying the underlying factors in disturbed bowel function overnight,” Dr. Rao noted. “With better objective information, our ability to intervene effectively has been greatly improved.”


  1. Kim JH. How to interpret conventional anorectal manometry. J Neurogastroenterol Motil. 2010;16(4):437-439.
  2. Rao SS. Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation. Clin Gastroenterol Hepatol. 2010;8(11):910-919.
  3. Raza N, Bielefeldt K. Discriminative value of anorectal manometry in clinical practice. Dig Dis Sci. 2009;54(11):2503-2511.
  4. Ratuapli SK, Bharucha AE, Noelting J, et al. Phenotypic identification and classification of functional defecatory disorders using high-resolution anorectal manometry. Gastroenterology. 2013;144(2):314-322.
  5. Rao SS, Hasler WL. Can high-resolution anorectal manometry shed new light on defecatory disorders? Gastroenterology. 2013;144(2):263-269.
  6. Jones MP, Post J, Crowell MD. High-resolution manometry in the evaluation of anorectal disorders: a simultaneous comparison with water-perfused manometry. Am J Gastroenterol. 2007;102(4):850-855.

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