Blocked Rectum – Causes and Symptoms of Rectal Blockage

The rectum lies towards the end of the colon where it plays an important role is temporarily holding feces before a bowel movement. Like any part of the bowels, the rectum may become blocked. As a result the movement of stool is hampered and a person may experience this blockage as constipation. Without intervention, a blocked rectum can become a serious condition and even lead to tearing of the bowel walls.

Symptoms of a Blocked Rectum

Usually a blockage is partial and develops gradually. A complete blockage is uncommon. Therefore symptoms become evident over a period of time and may be missed in the early stages. Some of the symptoms of a blocked rectum includes:

  • Constipation – difficulty passing stools that are often hard and dry.
  • Tenesmus – urging to pass stool despite having emptied the bowel.
  • Pain,  discomfort and burning rectum.
  • Fecal incontinence.
  • Blood and/or mucus in the stool.
  • Pencil thin stools.

In addition there may be other signs and symptoms specific to the causative condition.

Is constipation due to a blockage in the rectum?

Constipation is one of the symptoms that may occur in a rectal blockage. However, most cases of constipation are not due to a blockage and often the cause of constipation is unknown. Often constipation is linked to dietary and lifestyle factors such as low fiber intake, insufficient water consumption and a sedentary lifestyle. There are various other conditions where constipation may occur as a symptom and often these conditions are not due to any blockage.

colon and rectum

Causes of Rectal Blockage

There are many possible ways that the rectum may become blocked. This includes growths, foreign bodies, strictures and more commonly, feces. This blockage can be partial or complete. As a result, it may impair movement of feces through the rectum and out of the anus to varying degrees. Since the rectum is continous with the colon, causes of colon obstruction may also contribute to a blocked rectum.

Read more on blocked colon.

Fecal Impaction

Fecal impaction is a condition where the stool forms a hard dry mass in the bowels and causes an obstruction since it cannot be evacuated. It is more likely to occur in people who are constipated. Sometimes people with fecal impaction may experience small volume of watery stools as some feces seeps around the mass. Without proper treatment, the pass can compress the bowel tissue and affect blood flow to the bowel wall,.


Intestinal polyps are abnormal growths that can occur in any body cavity. Large intestine polyps are common and are more frequently found in the latter parts of the large intestine, such as the sigmoid colon and rectum. Large polyps and/or multiple polyps can cause an obstruction within the colon and rectum. Although most polyps are benign (non-cancerous) there is always the risk of some of these polyps becoming malignant (cancerous).

Foreign Bodies

Foreign bodies are any object from the outside environment that may enter the body. In the rectum this may include suppositories that do not dissolve as expected or even objects that may be intentionally inserted through the anus. If the foreign body is not expelled during a bowel movement, it can cause an obstruction within the rectum. This may be further complicated by impacted feces.


Inflamed and swollen rectal veins is a common condition. It is also known as hemorrhoids (piles). Sometimes these veins can be enlarged to the point where it may cause partial rectal obstruction and exacerbate any blockage due to other causes. In addition, the pain and discomfort may cause anxiety about having a bowel movement which in turn can contribute to constipation and thereby lead to complications such as fecal impaction.


Compression of the rectum may occur from neighboring organs and structures. This may include the prostate in men and uterus in women. An enlarged prostate (benign prostatic hypertrophy) and uterine fibroids are two possible causes of external pressure on the rectum. Sometimes cancer of these organs can also push against the rectum resulting a blocked rectum, which is usually partial.


Strictures refer to any narrowing of a passage in the body. Anorectal strictures occur where there is narrowing at the point where the rectum meets the anusa and thereby cause a blockage in the anus and/or rectum. Apart from neighboring organs compressing on the rectum as discussed above, anatomical abnormalities and scar tissue can also cause a narrowing which may result in a blockage.

Trapped and Twisted Bowels

Any abnormality in position and orientation of the bowels can lead to a partial or complete bowel blockage. This may not always involve the rectum only but needs to be considered as possible causes. Firstly, a portion of the bowel can become trapped in an abdominal wall hernia which impairs movement through this position. Another possibility is that there can be twisting of the bowels where one segment becomes “pinched” together as is seen in a volvulus.

“False” Obstruction

A pseudo-obstruction is not an actual blockage by any mass, growth or object. Instead it is where muscles or nerves in a portion of the bowel malfunction and a portion of the bowel becomes very wide, thereby preventing movement through it. This is known as acute pseudo-obstruction (ACPO) or Ogilvie syndrome. If left untreated it can lead to a tear in the bowel wall and complications may even result in death.

Colorectal Cancer

Colorectal cancer is one of the most common and deadly cancers in the world. Depending on the size of the malignancy, it can cause a blockage in the rectum. If colorectal cancer is not diagnosed and treated promptly then it can become life threatening within a short period of time. Any change in bowel habit, rectal bleeding, unintentional weight loss and fatigue for no known reason should raise the concern about colorectal cancer.

Diagnosis and Treatment

It is imperative that any blockage in the rectum is medically diagnosed by a health care professional. The signs and symptoms alone may be misleading as several conditions may present in a similar manner despite there being no obstruction in the rectum or elsewhere in the colon.

The following diagnostic investigations may be considered to diagnose a blocked rectum:

  • Colonoscopy
  • Abdominal x-ray
  • Barium x-ray

Other investigations that may also be considered include a CT scan or an MRI. A biopsy of any growth may also be collected and sent for histologic examination. The appropriate treatments will then be considered based on teh findings of these diagnostic investigations.

Last updated on Septembe 4, 2018.

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