Most patients describe the endorectal coil as uncomfortable rather than truly painful. The sensation during insertion is commonly compared to a digital rectal exam, with pressure rather than sharp pain. The coil stays in place for 45 to 60 minutes, and while that sustained presence can feel awkward, the majority of discomfort comes from the initial insertion and the inflation of a small balloon that holds the device in position.
What the Insertion Feels Like
Before the coil goes in, a nurse or doctor covers it with a disposable sheath and applies lubricant. The coil is inserted a short distance into the rectum. Once positioned, a small circular balloon around the coil is inflated to keep it from shifting during the scan. That inflation is the moment most patients notice the most pressure. It’s not a sharp or stinging sensation. It feels like fullness, similar to the urge you might associate with a bowel movement.
People who have had a digital rectal exam during a prostate check will recognize the feeling. The key difference is duration: a rectal exam lasts seconds, while the coil remains inflated for the entire scan, typically 45 to 60 minutes. Lying still with that persistent internal pressure is what most patients find challenging. Some people adapt to it within 10 to 15 minutes as the sensation fades into the background. Others remain aware of it the whole time.
Factors That Affect Your Comfort
Several things influence how tolerable the experience is. If you have hemorrhoids, anal fissures, or any rectal sensitivity, the insertion and sustained pressure will likely feel more noticeable. Prior radiation therapy to the pelvic area can also increase sensitivity. Anxiety plays a significant role: tension in the pelvic floor muscles makes insertion harder and the pressure more pronounced. Slow, deliberate breathing during insertion genuinely helps relax those muscles.
Bowel preparation matters too. Johns Hopkins recommends light meals the day before, a light or liquid diet (no carbonated drinks) the day of the exam, and a fleet enema either the night before or the morning of your appointment, depending on your scan time. Following these steps reduces rectal contents, which makes the coil sit more comfortably and produces better images. Skipping the prep can mean more cramping and a less useful scan.
What the Rest of the Scan Is Like
Once the coil is placed, you lie on your back on the MRI table. Straps and bolsters may be positioned around you to help you stay still. You’ll need to remain as motionless as possible while images are captured, sometimes holding your breath for short intervals. Between imaging sequences, you can relax slightly, but you’ll be asked to hold your general position.
MRI scanners are loud. The rhythmic banging and buzzing can be startling if you’re not expecting it, and earplugs or headphones are typically offered. You’ll also be given a squeeze ball that alerts the technologist immediately if you need help. If the pressure from the coil becomes genuinely intolerable, you can signal at any time. Technologists can sometimes deflate the balloon slightly to relieve pressure, though this may affect image quality.
The combination of lying still, loud noise, the enclosed MRI bore, and rectal pressure makes the experience more mentally taxing than physically painful for most people. If you tend toward claustrophobia, mention it beforehand. Some facilities offer mild sedation or anti-anxiety medication.
Why Some Scans Still Use the Coil
You might wonder why the coil is used at all if it’s uncomfortable. Many imaging centers with modern 3-Tesla (3T) MRI machines have moved away from endorectal coils entirely, since image quality scores show no statistically significant difference with or without the coil on these stronger scanners. For aggressive, higher-grade prostate cancers, both approaches perform similarly well.
The coil still has a clear advantage in one specific situation: detecting lower-grade cancers that are harder to spot. In a study published in the American Journal of Roentgenology, all 13 intermediate-grade tumors in the study were visible with the endorectal coil, while four of those same tumors were missed without it. Sensitivity for clinically significant cancers reached 93% with the coil compared to 77% without it for one radiologist in the study. If your urologist or radiologist is looking for a subtle or early-stage cancer, the coil can catch things that an external coil alone might miss.
If your facility gives you a choice, it’s worth asking whether the added diagnostic value applies to your specific situation. For surveillance of known cancer or restaging, the coil may be less necessary on a high-field scanner. For an initial diagnostic workup where catching smaller tumors matters, the temporary discomfort may be a worthwhile trade-off.
How to Make It More Tolerable
- Follow the prep instructions carefully. A clean, empty rectum reduces cramping and pressure during the scan.
- Practice slow breathing. Relaxing your pelvic muscles before and during insertion makes the biggest physical difference.
- Ask about anti-spasm medication. Some facilities administer a muscle relaxant to reduce involuntary rectal contractions during the scan.
- Bring music or a podcast. Many MRI-compatible headphone systems let you listen to audio, which helps distract from both the noise and the pressure.
- Avoid caffeine the morning of. It can increase bowel motility and make the coil’s presence more noticeable.
On a 1-to-10 pain scale, most patients place the endorectal coil somewhere between 2 and 4. It registers as pressure and mild discomfort rather than pain for the large majority of people. The experience is temporary, and the sensation resolves immediately once the balloon is deflated and the coil is removed at the end of the scan.