Rectal diverticulosis

Last revised by Dr Daniel J Bell on 12 Dec 2021

Rectal diverticulosis (plural: diverticuloses) or the presence of diverticula in the rectum is very rare.

Rectal diverticula are very rare with only scattered case reports in the global medical corpus, and symptomatic cases, e.g. rectal diverticulitis, are even rarer 1. It has been stated that diverticula of the rectum are seen with an incidence of only one-thousandth of colonic diverticula 5.

No age predominance has been seen, although they seem to be more common in male patients.

Weakening of the rectum/supporting structures is thought to be the primary risk factor for development of rectal diverticula 1,10.

  • anorectal surgery: iatrogenic rectal diverticula have also been called rectal pocket syndrome (RPS), which tend to occur at suture sites 2,4-6
  • rectal muscle weakness 1
    • congenital
    • primary atrophy of the muscle
  • absence/underdevelopment of coccyx
  • serially-impacted feces: causes rectal dilatation  1
  • weakening of the rectal wall 1
    • trauma
    • infection
  • obesity 4

In general, rectal diverticulosis is an incidental diagnosis, and symptomatic disease, usually rectal diverticulitis is very rare, most commonly presenting as 1:

Other described presentations have included:

  • stricture 4
  • rectovesical fistula 4
  • ileus 4
  • rectal prolapse of an inverted diverticulum 1
  • retrorectal cyst/abscess 4
  • renal tract obstruction: single case 4
  • carcinoma within a diverticulum: one case from 1911 8

The pathogenesis of rectal diverticula is poorly understood, not helped by the rarity of the condition.

Most of the reported rectal diverticula, are found arising from the lateral walls; it is thought that this is due to a thinner longitudinal muscle layer than is seen at the anterior or posterior walls. The majority of diverticula arising in the rectum are true diverticula, i.e. involving all three layers of the wall (cf. colonic diverticula which are actually pseudo or false diverticula) 1. Although pseudodiverticula of the rectum have been reported 4.

In contradistinction to colonic diverticulosis, rectal diverticula tend to be low in number, usually one to three, and usually larger than 2 cm in size. Conversely in the colon diverticula are usually smaller than 1.5 cm 1,4.

Characteristically have been described as large outpouchings of the rectum. Early reports were on barium enema studies only. More recently the CT and MRI appearances have also been described 2-4. Transrectal ultrasound (TRUS) demonstrates an outpouching of the rectum 3. Interestingly, endoscopy may miss a rectal diverticulum 3.

In general, as rectal diverticula are asymptomatic, they do not require treatment. Surgery is only usually required for those who present with complications 1.

The first description in the literature was in a report of two cases from 1911. The author, an American surgeon called Herbert Z Giffin, was himself surprised that he had not seen a prior case. He reviewed the literature from 1902 to 1911 and found no previously reported cases  8,9.

Rectal pocket syndrome (RPS) was first described in 2006 2.

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Cases and figures

  • Case 1: rectal diverticulum
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