Constipated? Can’t Poo? GI Issues? Yes, There Are Special Tests to Investigate This.

There are many causes of constipation or difficulty evacuating stool  even when it is “locked and loaded” in the rectum. Sometimes, the solution is as easy as changing diet and other lifestyle habits. Other times, there are medical causes involving colonic transit, tight pelvic floor muscles, rectal wall prolapse or a combination of all of these. It can be complicated and frustrating to figure out how to poo regularly!

There are a variety of medical tests used to assess this (and other GI issues) further. Patients are often nervous and not sure what to expect. Here’s some general information about the tests. In the future, we’ll cover some of these tests in depth with pros and cons.

From Cake Hour Cackle

From Cake Hour Cackle



(per NDDIC) Flexible sigmoidoscopy is a procedure used to see inside the sigmoid colon and rectum. Flexible sigmoidoscopy can detect inflamed tissue, abnormal growths, and ulcers. The procedure is used to look for early signs of cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus, and weight loss


More extensive than above. Examines the entire colon with a flexible four foot long, flexible tube about the thickness of a finger with a camera and a source of light at its tip. The tip of the colonoscope is inserted into the anus and then is advanced slowly, under visual control, into the rectum and through the colon usually as far as the cecum.

“Colonoscopy may be done for a variety of reasons. Most often it is done to investigate the cause of blood in the stoolabdominal paindiarrhea, a change in bowel habit, or an abnormality found on colonic X-rays or a computerized axial tomography (CT) scan. Individuals with a previous history of polyps or colon cancer and certain individuals with a family history of some types of non-colonic cancers or colonic problems that may be associated with colon cancer (such as ulcerative colitisand colonic polyps) may be advised to have periodic colonoscopies because their risks are greater for polyps or colon cancer” (

** Dr. Vikas Shah added: 

It would be worth mentioning CT colonography as an alternative test to colonoscopy: far less invasive, equal performance for finding cancers and can evaluate extracolonic structures. I am happy to write a short summary for you if you want.

Sitzmark Studies (Colon Transit Study):

In this procedure, a capsule is swallowed containing markers that show up on X-rays taken over several days. Looking for signs of intestinal muscle dysfunction and how well food moves through your colon.

There are modifications to the original testing, but here are sample directions given to patients:

The colon transit study will take 6 days to complete. You will begin the test after you have a bowel movement. You will take 1 Sitzmark capsule every day for 5 days. On the sixth day you will come to National Jewish Health for an x-ray of your abdomen”

SitzMark Test Results  via link

SitzMark Test Results via link

Colon Transit Test: Pelvic Floor Dysfunction All radio-opaque markers were sitting in the rectum 6 days after ingestion.

Colon Transit Test: Pelvic Floor Dysfunction
All radio-opaque markers were sitting in the rectum 6 days after ingestion.

Anorectal Manometry and Balloon Expulsion Test:

Manometry is a test used to measure and assess pressure, reflexes and sensation in the rectum. The test also evaluates the efficiency of the anal sphincter.  Balloon Expulsion can be done during the same testing period: a measurement of the time it takes to expel a balloon from the rectum.

Patient information: “While lying on your left side, a thin flexible catheter with a small uninflated balloon at the tip is passed through the anus and into the rectum. The catheter is slowly withdrawn while numerous pressure measurements are recorded. You will also be asked to push and squeeze your anal muscles at certain times. You will also be asked to indicate when you experience a feeling of fullness or distension in the rectum, upon inflation of a small balloon at the end of the catheter.”

CME (March 2007) Monthly Self-Study Series Management of Constipation Dr. Wong Sau Wai, Grace

CME (March 2007)
Monthly Self-Study Series
Management of Constipation
Dr. Wong Sau Wai, Grace

Anal Sphincter Electromyography:

Anal sphincter EMG is recorded with a small sponge electrode in the anal canal. The person relaxes, squeezes and pushes. A computer records sphincter muscle electrical activity.

Anal sphincter electromyography confirms the proper muscle contractions during squeeze and muscle relaxation during push. In people with non-relaxing puborectalis, the tracing of electrical activity gets bigger, instead of smaller, during a push.

** The exact testing procedure for EMG can be different in a physician vs. pelvic floor physical therapist office.


Defecograms (also known as fluoroscopic or xray proctograms, evacuation proctograms and defecating proctograms) can differentiate between anterior and posterior rectocele. Also, in external rectal prolapse that was not directly visualized during examination, this radiographic projection will demonstrate its presence. The position is relatively functional, with the patient sitting on a toilet.

“The technique itself involves insertion of a caulk gun device into the rectum with subsequent manual infusion of barium paste…. The patient is then transferred to a portable plastic commode which is situated next to a fluoroscope which records the defecation. Positioning of the x-ray camera is of paramount importance as visualization of the buttocks, rectal vault, and lower pelvis is critical.”

** Dr. Vikas Shah added: 
I don’t use a caulk gun, the whole idea sounds horrible! I simply use two 50 ml bladder syringes which have nozzles just the right size for easy insertion into the anal canal, and the whole thing is far cleaner as they are simply disposed afterwards.

** Full article about myths of defecography coming up soon from Dr. Shah!

With regards to your other questions; the jury is still out on how good MR proctography really is. My concerns are over the fact that it is done supine, and in my experience, if you see something that’s great but if you don’t then you should be wondering whether something has been missed because of how the test has been done. There are very few open MRI scanners where an upright test can be done, so access is an issue.

rectocoele trapping WM

Dynamic MRI Defecography (Dynamic Pelvic MRI)

For optimal MRI evaluation in the sagittal plane, the patient is placed in the supine position. Static images are frst obtained, with subsequent series of images performed during resting and straining in the midsagittal plane. Selected midline sagittal T2W images at rest and on the Valsalva maneuver and/or sagittal 2D GRE images in real-time at rest and on Valsalva are used to assess the degree of pelvic floor descent and pelvic organ prolapse. Some authors advocate the use of intraluminal contrast”


1. “the development of fast MRI sequences has allowed for the quick evaluation of pelvic organ prolapse and pelvic floor relaxation with increased patient comfort, decreased complexity, and decreased invasiveness and radiation exposure. The intrinsic soft tissue contrast capability of MRI allows for detailed visualization of the pelvic floor, and the faster techniques now allow for dynamic evaluation of pelvic support structures. Studies have shown that dynamic MRI has greater sensitivity than physical examination and has led to changes in the initial surgical plan in 41% of patients. It has become clear that MRI has an important role in the preoperative planning in patients with pelvic floor dysfunction” (Imaging the Female Pelvis: When Should MRI be Considered?)

2. The test also reveals anterior prolapses (not just rectocele, enterocele, rectal prolpase) such as cysteceles (bladder), uterine prolapse, vaginal vault.

Disadvantage: Expensive test and not functional (lying down), but still valuable.

My favorite dynamic pelvic MRI showing a rectocele:

Endoanal Ultrasound

Endoanal ultrasounds is a medical test to check the muscles of the anus (sphincters). This test can identify abnormalities such as tears, fistulas, and masses in the area.

Additional website Citations: 

The Evaluation of Constipation – PubMed Central

Diseases and Conditions – Constipation: Tests and Diagnoses – Mayo Clinic

Tracy Sher, MPT, CSCS  Private Practice Owner in Orlando, FL; International Speaker/Faculty. Passionate about treating pelvic pain and all pelvic floor disorders – bowel, bladder, sexual function. Secretly hoping to be a circus clown or rock, paper, scissors champion some day. Connect with Tracy on LinkedinCheck out Pelvic Guru on Facebook or Twitter @pelvicguru1

11 thoughts on “Constipated? Can’t Poo? GI Issues? Yes, There Are Special Tests to Investigate This.

  1. Thanks Tracy, seems everyone lately is plagued with constipation. The Herman and Wallace course Bowel Pathology by Lila Abbate was great, and has helped my patients. She gave out tons of clinical pearls of treatment

    • Thanks for your comment! Constipation is definitely an issue for many, particularly with pelvic floor dysfunction or due to medications and/or poor diet!

      • Hi very interesting blog tracy and everyone. I have ‘bowel issues’ too, but only cause i have opiate meds in my system due to PN like pain… (I can’ sit at all etc) . My PT recently diagnosed me with severe anal spasm and NOT PN thankfully. So we are working on my trigger pts ..
        But meanwhile I can’t poop withouttaking strong laxative (Dulcolax)! due to the pain meds.
        Duloclax is like a bomb..causes explosive runs next day and practically empties entire colon!..Not good ! If I take a milder laxative..then no action and feeling of stool pressure occurs on my painful area..(painful too) I also take Colace(stool softener and eat fibery foods, drink water, take magnesium (when I remember!). etc..
        Any other ideas on how to help folks on pain medicaition to Poop normally without using strong laxatives? I
        have tried many things, with no “luck” so am forced to take dulcolax so I don’t get backed up..
        Any advice appreicated !! Thanks so much1

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  3. Pingback: So, You Need Defecography Testing for Bowel Issues? Dispelling the Top 5 Myths. | Pelvic Guru ™

  4. Simply desire to say your article is as amazing. The clearness in your post is just spectacular
    and i can assume you’re an expert on this subject.

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  5. How do you deal with removal of redundant colon, 3 inches above navel, left with infection; packed for 6 weeks and then had a hernia which required another surgery? Now I have huge issues with pain where colon was removed and voiding takes almost an act of congress. Connected to side of rectum where, when matter is in holding pattern, pressure is so great, I have pain and the pressure causes me to walk to protect issue. And then be told, if I did PT, I didn’t need surgery. Is this today’s health care? I question whether or not I even had a prolapse, but now I have n o life.

  6. Pingback: So, You Need Defecography Testing for Bowel Issues? Dispelling the Top 5 Myths – The Pelvic Guru

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