Rectal Sensation Testing: Four Questions to Ask

Rectal sensation testing checks how you notice the rectum filling. A small balloon on a probe is inflated inside the rectum, and you describe what you feel. It may be included in anorectal physiology investigations for constipation or bowel leakage. Leeds Teaching Hospitals describes this alongside tests of anal muscle function and structure.¹

1. Which sensations should I report?

The International Anorectal Physiology Working Group² recommends recording the balloon volume at three points: the first sensation that persists, the desire to open your bowels, and the maximum you can tolerate. These are separate measurements, recorded in milliliters.²

Ask the physiologist to explain each cue before inflation begins. The protocol’s final cue is the point when the sensation becomes too uncomfortable and you need inflation to stop.² You can say, “I feel something now, but I am not sure which sensation you mean.” Reporting uncertainty gives the person doing the test a chance to clarify the instruction.

2. What should I do before the appointment?

Read the letter from your own service before fasting, taking an enema or changing medicines. Leeds says its patients can eat, drink and take prescribed medicines normally, without laxative or enema preparation. It allows about an hour in the department, including changing and discussion, although testing usually takes around forty minutes.¹

UCLH also says no preparation is required for its service. Its leaflet specifically says menstruation, wearing continence pads or not having opened your bowels does not prevent testing.³ Those are useful details to confirm if your letter leaves you unsure whether to attend.

Tell the team beforehand if the anal area is already sore. UCLH notes that existing soreness can make the examination uncomfortable and asks patients to discuss it.³ Ask about a chaperone, privacy and how to request a pause before the probe is inserted.

3. Which reference range will interpret my volumes?

Ask for the measured volumes beside the laboratory’s reference ranges. The working group did not specify a universal set of normal values: equipment and methods vary. Continuous inflation and inflation in separate steps produce results that are not interchangeable.²

Also check the test name beside each number. Sensation testing records balloon volumes; balloon expulsion testing records how long it takes to push a balloon out.² A time in seconds and a volume in milliliters answer different questions.

4. Who will explain what this changes in my care?

UCLH describes anorectal physiology as one part of an assessment that may also include imaging or a transit study. Its service gives a preliminary indication after testing, then prepares a report for consultant review and discussion with the referring doctor.³

Ask whether your service follows that sequence, who receives the report and when the treatment discussion happens. Request an explanation of which finding fits your symptoms and which question still needs another investigation. Keep that explanation with the report.

Chapter 8 of Bloated by Dinner suggests adding straining, incomplete emptying and any manual help to your Belly Clock notes before a bowel appointment. Bring those observations with your test letter. They give the results discussion a specific problem to address, such as soft stool that still feels difficult to pass.