Abstract
Bleeding per rectum is defined as the passage of blood from the anus. It is a common presentation in adults of all ages and the majority of cases can be managed in primary care. This article will focus on the common causes of rectal bleeding, its assessment and management, including guidance for referral pathways to secondary care.
The GP curriculum and rectal bleeding
Know how to interpret common symptoms in general practice, including rectal bleeding Be aware that due to social and cultural factors some patients might find it embarrassing to discuss digestive problems Understand the National Institute for Health and Care Excellence referral guidelines for suspected cancer and the indications for urgent referral for suspected gastrointestinal cancer Be able to provide an appropriate environment for abdominal and rectal examination with dignity and under chaperoned conditions
Causes of rectal bleeding
Blood loss per rectum can be related to lesions in the upper and lower gastrointestinal tract, including the anorectal area. Rectal bleeding can clinically present as melaena, haematochezia or occult bleeding. Melaena is defined as the passage of black, tarry and foul-smelling stools and can be the result of bleeding from the upper gastrointestinal tract, the small intestine or even the right colon, whereas haematochezia is the passage of bright red blood per rectum originating from the left colon, rectal or anal region (Chait, 2010).
Causes of rectal bleeding.
Diverticular bleeding
Although bleeding from diverticulae is a rare event, diverticular disease is the leading cause of lower gastrointestinal bleeding and comprises 20–55% of all cases. It is rare in patients under the age of 40 years, however, it affects more than 65% of patients aged over 85 years (Strate, 2005).
Diverticulae are sac-like protrusions of the mucosa and submucosa through defects in the muscular layer of the bowel at sites weakened by penetration of the vasa recta. The exact mechanism of diverticular haemorrhage is not known, but it is postulated that the vasa recta are prone to injury over the dome of the colonic wall. Factors increasing the risk of bleeding are constipation and hard stools and the use of blood thinners such as non-steroidal anti-inflammatory drugs (NSAIDs) (Chait, 2010).
Although 90% of diverticulae are located in the left colon, 50–90% of diverticular bleeding occurs from right-sided colonic diverticula (Stollman & Raskin, 2004). Diverticular bleeding is painless and usually ceases spontaneously (Bokhari, Vernava, Ure, & Longo, 1996). However, the risk of a further bleeding event after an episode of bleeding is 25%, and can increase up to 50% in those patients who have had more than two episodes of diverticular bleeding (Finne, 1992).
Angiodysplasia
Angiodysplasia is a vascular abnormality of the gastrointestinal tract that predominantly occurs in the elderly (Strate, 2005). Its aetiology is not fully understood, but angiodysplasia is thought to occur as a result of degenerative lesions of the submucosal venules associated with increases in intraluminal pressures. Colonic lesions most commonly occur in the right colon.
Angiodysplasia accounts as a source of lower gastrointestinal bleeding in up to 40% of cases and bleeding is painless and can be subacute, chronic or recurrent (Chait, 2010).
Inflammatory diseases of the bowel
Inflammatory diseases of the bowel can present with lower gastrointestinal bleeding and include:
Inflammatory bowel disease (Crohn’s disease and ulcerative colitis) Ischaemic colitis Radiation proctitis
Crohn’s disease can affect any part of the gastrointestinal tract, but most commonly the terminal ileum. Per rectum (PR) bleeding mixed with diarrhoea can occur when the colon and the rectum are affected (Chait, 2010).
Ulcerative colitis starts in the rectum in form of proctitis and progresses proximally. When presenting to their GP, all patients suffering from ulcerative colitis display symptoms of bloody diarrhoea and bleeding from the rectum (Ghosh, Shand, & Ferguson, 2000).
Ischaemic colitis accounts for 3–9% of all cases of lower gastrointestinal bleeding; it is a result of impaired blood supply to the colon in patients with hypotension or embolic events. The regions mainly affected by impaired blood supply are the watershed areas, including the splenic-flexure and the recto-sigmoid junction, and patients can clinically present with cramping abdominal pain followed by haematochezia or bloody diarrhoea (Chait, 2010).
Radiation proctitis is an inflammation of the distal rectum, which occurs in patients treated for genitourinary or gynaecological malignancies. Symptoms include bloody diarrhoea and cramps that can develop within weeks to years after initiation of radiotherapy of the pelvic region (Mitra et al., 2015).
Neoplasm
Malignancies of the colon and rectum account for 10–20% of cases of lower gastrointestinal bleeding and can be the initial presenting symptom of colorectal malignancies in 26% of cases. Bleeding is painless and can be occult or mild (Chait, 2010).
Anorectal causes
Haemorrhoids are the most common anorectal cause of rectal bleeding. Haemorrhoidal bleeding can present with either fresh painless bleeding covering the stool or large bleeding into the toilet bowel during defecation (Kaidar-Person, Person, & Wexner, 2007).
Anal fissures are tears in the mucosa of the anal canal, which are localised in the midline anteriorly or posteriorly in 90% of cases.
Fissures affect mainly young adults, and are associated with constipation or repetitive trauma. The hallmark of fissures is a sharp pain on defecation associated with fresh bleeding on the toilet paper or mixed with the stool (Babakhanlou, 2016).
There are various other pathologies that can present with rectal bleeding. These are less common and include anal cancer, sexually transmitted diseases or dermatological conditions.
Diagnosis
The assessment of a patient presenting with rectal bleeding includes thorough history taking and physical examination. Examination requires suitable equipment and availability of a chaperone.
History
History should explore duration, frequency and colour of blood, and also the presence of associated symptoms, such as pruritus, weight loss, change in bowel habit and pain on defecation, as these may help in identifying the cause of bleeding. A detailed medication history should be obtained as well, as drugs such as aspirin, warfarin or NSAIDs can increase the risk of bleeding.
The past medical history should evaluate the presence of:
Diverticular disease Inflammatory bowel disease Peptic ulcers Previous pelvic radiation Recent removal of polyps Previous gastrointestinal (GI) malignancy Presence of cardiovascular problems including ischaemic heart disease
Examination
Examination includes inspection of the patient and both a general and a digital rectal examination (DRE). During inspection the examiner should pay attention to signs of weight loss, cachexia or muscle-wasting.
A general examination should assess vital signs (blood pressure, pulse) and check for signs of shock and haemodynamic stability. A more detailed physical examination should assess organomegaly in the abdomen, the presence of ascites or abdominal masses.
An inspection of the anal and perianal area should assess the presence of excoriation marks, fissures, visible haemorrhoids or papilloma.
Unless refused by the patient, all patients presenting with rectal bleeding should have a DRE to check for the presence of a mass and visible blood or pus on the examining finger. The examiner should provide an environment where DRE can be performed with dignity and under chaperoned conditions.
Investigation
Laboratory work-up depends on the age of the patient, the past medical history and the findings on clinical examination. Initial laboratory investigations in primary care should include full blood count, a full metabolic profile and clotting studies, if coagulopathy is suspected.
If there is suspicion of inflammatory bowel disease or inflammatory conditions, C-reactive protein and erythrocyte sedimentation rate should be checked.
If the patient reports a history of recent travel abroad, use of antibiotics or infectious colitis, then a stool sample should be sent off for stool culture and a stool assay in order to test for clostridium difficile toxin A and B.
Management
The management of rectal bleeding depends on the severity of the symptoms and the cause of the bleeding. Patients presenting with heavy rectal bleeding and signs of shock need an immediate referral to hospital for resuscitation and management.
It is estimated that 3–15% of patients with diverticulosis will experience bleeding (Adams & Margolin, 2009). The aetiology of diverticular bleeding is poorly understood, and since it has been attributed to repetitive trauma, the primary management of asymptomatic diverticulosis remains high-fibre diet, increased fluid intake and the use of bulk laxatives in order to avoid constipation (Aldoori & Ryan-Harshman, 2002).
In patients with diverticulitis, antibiotics are indicated to treat the inflammation.
In most patients, bleeding will stop spontaneously, but around 25% will need emergency intervention. In patients with severe bleeding, and those not responding to conservative treatment within 48 hours, hospital admission is indicated (Strate, 2005).
Routine referrals should also be considered for patient with highly symptomatic haemorrhoids or fissures, not responding to conservative management (Royal College of Surgeons, 2013).
Referral guidelines
Criteria for suspected lower GI cancer (2-week wait appointment).
Conclusion
Rectal bleeding is a common presentation in primary care. It is important to establish whether a patient with PR bleeding requires hospital admission or can be managed in primary care. Social and cultural factors may affect presentation in primary care.
KEY POINTS
Rectal bleeding is a common presentation to general practice Most cases are due to benign ano-rectal conditions A thorough history and physical examination, including a DRE will establish likely diagnosis and subsequent management Patients with red-flag symptoms require urgent referral to secondary care for further assessment and investigation