Patients (and doctors!) are often embarrassed to present with rectal bleeding, usually preferring to ‘wait and see as it’s probably nothing’, Well it is something, and unfortunately not always the haemorrhoids which they have usually self-diagnosed. So some truths and myths about rectal bleeding.
The Big C
Patients and doctors really want to ensure rectal bleeding is not from a colorectal cancer. All other diagnoses don’t really matter, so long as you don’t miss a cancer. Actually not; colitis and polyps which present with rectal bleeding also (if ignored) can lead to colorectal cancers. Furthermore, without a firm diagnosis and treatment to abate the bleeding, there will always be an underlying psychological worry that there is an undiagnosed malignancy. If the bleeding is heralding a potentially much larger GI bleed, then clearly an earlier firm diagnosis is important.
Approximately 10% of UK adults will see some rectal bleeding each year, yet embarrassment or ‘being too busy’ means that far fewer present to their doctor, and only 57% of adults invited to return National screening faecal occult blood (FOB) tests actually do so, with women being marginally better responders than men, though men have higher rates of rectal cancer. With an annual UK incidence rate of 34,000 bowel cancers and an annual UK mortality rate of 16,000 from bowel cancer, then by simple calculation 47% of UK patients are late stage presenters. This is borne out by poor colorectal cancer survival figures in the UK in comparison to all other Western countries. For this reason the Government introduced the FOB screening programme and embarked upon a media campaign to encourage people with rectal bleeding to present earlier. However, not every patient who presents to their GP with rectal bleeding can be referred on for a Colorectal Specialist opinion, so who should be referred?
Who should be referred for a Specialist opinion?
The simplest answer is the National referral guidelines for bowel cancer:
- Rectal bleeding with a change of bowel habit greater than 3 weeks duration in over 40 year olds
- Rectal bleeding with no change in bowel habit greater than 3 weeks duration in over 50 year olds
- Anaemia, palpable rectal or abdominal mass, change of bowel habit of 3 weeks with no bleeding 50 years or more
Does this mean that a 38 year old with rectal bleeding and loose motion need not be referred? Of course not – these are purely guidelines, and you need to remain suspicious for unexpected or unexplained symptoms. We all know that the majority of patients with co-existent rectal bleeding and change in bowel habit are likely to be an irritable bowel syndrome aggravating piles but can we be sure? Well other parts of the history might help us:
- The quantity/ quality of the bleeding – large amounts which drip into the toilet post defaecation coating the stool (haemorrhoids) versus smaller amounts in association with a mucus discharge mixed with the stool (colitis/ cancers)
- The colour of the blood – bright blood of a local anorectal cause versus maroon mixed blood of a colonic cause (cancers and polyps/ diverticular bleeds/ colitis/ rarely angiodyplasia) and melena of an upper GI cause
- The association of other symptoms such as anorectal and abdominal pain, weight loss, symptoms of anaemia
- Pre-existing symptoms – longstanding bright rectal bleeding which has been repeatedly investigated or piles treated, longstanding proven diagnosis of IBS eg. beware making a new diagnosis of IBS in the elderly
- A family history of colorectal cancer, heavy smoker, anticoagulants
All patients must have a digital rectal examination unless there is severe anal pain in association with bleeding (fissures, abscesses, perianal haematomas but occasionally anal cancers), if the patient is a child or the patient will have a very soon/ urgent specialist appointment where the examination will be repeated along with a sigmoidoscopy in outpatients.
If there is doubt then I would advise specialist colorectal referral as no-one is going to criticize you – unless you fail to refer! If you are certain the patient’s symptoms are eg from an irritable bowel syndrome, then you might consider three FOBs to add reassurance to the diagnosis. Even if you feel the rectal bleeding is haemorrhoidal in nature, it’s not going to go away until treated (which in itself is a diagnostic test), and of course FOBs are of no use as they will definitely be positive. Not referring haemorrhoidal bleeding sends the wrong message to the patient – it’s OK to ignore bleeding when in the future this will mask bleeding from other causes, and patients will simply not re-present with bleeding in future.
Occult hidden rectal bleeding
All patients with positive FOBs or unexplained anaemia must be referred for specialist investigation. Although it might be from eg. haemorrhoids combined with warfarin usage, to ignore a positive (cancer screening) test sets a dangerous precedent. Similarly, to simply treat an un-investigated anaemia particularly in men and post-menopausal women, runs to risk of missing an ‘occult bleeding’ from a gastrointestinal cause. In pre-menopausal women without heavy periods again referral should be made for what is an unexplained anaemia, and in those with heavy periods, if treatment doesn’t solve the anaemia then they too require referral. Occasionally we see anaemia investigated only with a normal direct access gastroscopy, when these patients too must be referred for specialist full colonoscopy.
Faecal occult blood tests (FOBs) need to be performed on 3 separate days stools, since a single test is only 54% sensitive whereas 3 specimens increase sensitivity to 95% (but not 100%). Of all the FOBs, 2% will be positive (increased in men and increasing age) requiring colonoscopy in most instances, and 35% of these colonoscopies will show a significant adenomatous polyp (which if left would have lead to a colorectal cancer) with some polyps found completely coincidentally (no bleeding and producing a positive FOB). 10.9% of these colonoscopies will diagnose a cancer or malignant polyp. In the context of a National FOB screening programme, because these 10.9% (of 2% positive FOBs – therefore 0.2% of all FOB screened patients having a cancer diagnosis) are diagnosed without symptoms, these colorectal cancers are diagnosed at a much earlier and potentially curative stage; 17% malignant polyps and 72% early stage Dukes A & B tumours. This translates to a 15% reduction in mortality in the FOB screened patients at 5 years (remember 47% late stage symptomatic presentation), and hence the screening age group range has now been extended to 60 – 74 years with FOBs at 2 yearly intervals, and patients should be encouraged to participate (only 57% uptake currently).
Rectal bleeding diagnoses
The following common diagnoses include rectal bleeding:
Haemorrhoids – bright bleeding post defaecation coating the outside of the stool sometimes with significant quantity into the toilet pan and on the toilet paper. May be associated with pruritis ani from an increased production of potassium rich mucus irritating the perianal sensitive skin. Sometimes prolapse of piles will be noted by patients. Internal haemorrhoids are seldom painful. Referral allows injection sclerotherapy or banding treatment to hopefully stop the bleeding, rather as a diagnostic test.
Anal fissure – bright rectal bleeding but associated with pain on defaecation and thereafter. The anal sphincteric spasm (an attempt by the body to limit anal canal opening and resplitting of the fissure) is often perceived by patients as ‘piles blocking the outlet’. Examination is impossible and referral allows hopefully conservative treatment and then proper examination to confirm the diagnosis.
Perianal haematoma – smaller amounts of blood but characterized by a painful dome-shaped perianal lump (which is often mis-diagnosed as prolapsed internal piles with an attempt to painfully digitally reduce) which might follow heavy exertion (rising intra-abdominal back pressure and increased sphincteric tone causing haematoma formation). Early specialist referral is key allowing local anaesthetic drainage of the haematoma with immediate relief.
Diverticular bleeding – Diverticulae occur as mucosal herniations through the sigmoid colonic circular muscle at points of weakness where blood vessels penetrate to reach the colonic mucosa. Irritation of these diverticulae where blood vessels are present unsurprisingly can cause rectal bleeding. Characteristically this is fairly bright but may be mixed with the stool, and can be completely painless ie. not associated with diverticulitis. Radiological appearances of diverticulitis can be confused with simoid cancers and referral often results in colonocopic verification.
Colorectal Polyps – adenomatous polyps can grow to a considerable size before causing visible bleeding, but of course these are only in the distal colon since higher polyps might bleed small amounts but this will not be visible per rectum. Villous adenomata tend to grow more carpet-like with a mucus discharge which may simply present as perianal irritation. There may be a family history of colorectal polyps or cancers.
Colitis/ Proctitis – Rectal bleeding associated with mucus and usually loose motion with occasionally abdominal pain. Rarely this may be associated with extra-intestinal manifestations such as iritis, pyoderma gangrenosum, erythema nodosa, liver/ biliary disease etc. Patients often describe a pink mucus. Often early symptoms can be misdiagnosed as an irritable bowel syndrome but obviously there would be no blood with the latter.
Angiodysplasia – usually much darker bleeding as the angiodysplasia is based in the caecoascending colon. Sometimes may be large amounts of bleeding and can be treated with argon laser coagulation of the ectatic vessels.
Summary – Rectal Bleeding
Rectal bleeding should not be ignored. The majority of diagnoses will be completely innocent, yet these require a diagnosis and treatment to stop the bleeding rather as a diagnostic test, and to ensure that the patient leaves without rectal bleeding, such that if there are further episodes in the future, that these are not ignored and the patient re-presents. Hopefully this will result in an improvement in UK treatment results for colorectal cancers, and an increased awareness of the importance of rectal bleeding amongst patients and GPs.
