Rectal Bleeding

Etiology

Gastrointestinal bleeding is divided into the upper and lower gastrointestinal tract (GIT) bleeding based on whether the bleeding originates from above or below the ligament of Treitz (suspensory ligament of the duodenum). Rectal bleeding is mainly caused by pathology from the lower GI tract, which includes the small intestine beyond the duodenum, the colon, rectum, or anal canal.

• Colon cancer: The proliferating cancer cells form pathological vasculature to supply themselves for growth. This pathologic vasculature is extremely friable, which may lead to rectal bleeding, especially as cancer progresses. Although it is not a major contributor to the overall incidence of rectal bleeding, representing only approximately 3.4% of the cases, it is one of the more serious causes that should be ruled out, especially in older patients.[3]
• Inflammatory bowel disease: Chronic inflammation in the digestive tract, such as in ulcerative colitis and Crohn's disease, may present with rectal bleeding. This is often associated with diarrhea and abdominal pain.
• Diverticular diseases: Diverticula are small pouches in the wall of the colon, which usually occur at weak points where the vasa recta penetrate the muscular layer. Over time, the blood vessels in the wall of these pouches become friable, making them susceptible to rupture, which can cause bleeding.
• Hemorrhoids: Hemorrhoids are cushions of tissues found in the submucosa of the anal canal. They are found in the left lateral, right anterior, and right posterior positions. They are comprised of submucosal vessels and muscle fibers arising from the internal sphincter and the conjoined longitudinal muscle. It is a weakness in the muscle fibers that make the hemorrhoids symptomatic. The terminal branches of the superior hemorrhoidal artery are the primary blood supply, whereas the superior, middle, and inferior hemorrhoidal veins are responsible for the venous outflow. Hemorrhoids are further classified into internal (above the dentate line), external (below the dentate line), and mixed (both above and below the dentate line). Internal hemorrhoids cause 'painless bleeding.'[4] Goligher's classification is the most commonly used classification system and divides the hemorrhoids into 4 grades. Grade 1 hemorrhoids bleed but don't prolapse. Grade 2 hemorrhoids prolapse through the anus on straining but reduce spontaneously. Grade 3 hemorrhoids protrude and require digital reduction. Grade 4 hemorrhoids are irreducible after prolapse.[5]
• Anal fissures: a tear in the epithelial lining of the anal canal, which commonly occurs with constipation and the passage of hard stools (posterior anal fissures) or with childbirth (anterior anal fissures). It is associated with painful defecation with blood-streaked stools.
• Infections: Sexually transmitted infections (STI) and enteric pathogens can cause rectal bleeding. N. gonorrhoeae, C. trachomatis (including LGV serovars), HSV, and T. pallidum are the most common STI pathogens. Escherichia coli and Clostridium difficile are two of the more common infections that cause acute hemorrhagic colitis

Upper GIT bleeding: Upper GI bleeding can present with black tarry stools. As the blood passes through the GIT, gastric and duodenal secretions convert hemoglobin into acid hematin giving the stool its dark reddish-brown color. Hematochezia may result from upper GI bleeding if the bleeding is of large enough volume that the gastric and intestinal secretions are not sufficient to convert hemoglobin into acid hematin. Blood also acts as a cathartic, decreasing intestinal transit time and providing less time for the enzyme reaction to take place. If a patient is experiencing hematemesis associated with hematochezia, this would further suggest that the source of the bleed is coming from the upper GI tract, especially if these symptoms are associated with hemodynamic instability or shock. Examples of upper GI bleedings that may cause hematochezia include a Mallory Weiss tear, bleeding esophageal varices, or a perforated gastroduodenal artery. It's worth mentioning that in patients with insufficient secretion of gastric HCl, as in achlorhydria, an upper GI bleed may present with hematochezia as well. General causes of bleeding: When evaluating an individual for GI bleeding, it is also important to consider other underlying factors that may be contributing to the acute presentation. This includes bleeding diatheses such as vitamin K deficiency, hemophilia, thrombocytopenia, or anti-coagulant toxicity.

Epidemiology

There is a dearth of population-based studies to suggest the true incidence of rectal bleeding. However, many community-based studies have shown the prevalence of rectal bleeding to be between 13% to 34%.[6][7][8] There has been conflicting data regarding the incidence of rectal bleeding between genders. As per Eslick et al., no significant difference in incidence was found between men and women. Women had higher rates of rectal bleeding in the age groups of 18 to 39 and above 60 years, whereas men had a higher incidence of bleeding in the age group of 40 to 49 years.[6][7] 

It has also been noted that only 40% of patients with rectal bleeding seek medical care.[9] The most likely reason for those who did not seek medical consultation was that they thought the rectal bleeding wasn't serious enough to require medical attention. Moreover, most of these patients hail from the age group of more than 60 years.[1]

History and Physical

History

Detailed history taking and a thorough physical exam are essential to rule out the different causes of rectal bleeding, such as anal fissure, rectal prolapse, fistulas, inflammatory bowel disease, and neoplasia.[10] Direct questions regarding onset, duration, amount, frequency, and passage of clots should be foremost during the consultation. Differentiation between fresh (bright red) and old blood (maroon or tarry) is also an important distinction to make. Associated symptoms of abdominal pain, weight loss, change in bowel habits, and a previous history of any recent pelvic surgery or abdominal-pelvic radiation should be included as well. Patients should be asked about trauma, sexual activities, fever, discharge, or rashes.

A comprehensive review of the patient's comorbidities and medications is warranted. Special attention should be given to comorbidities that may contribute to bleeding tendencies or those that require the patient to take anticoagulants such as an artificial heart valve or atrial fibrillation. With regards to medications, special attention should be given to NSAIDs, anticoagulants, and antiplatelet agents as possible contributing factors to rectal bleeding.

Anal pain associated with defecation may suggest anal fissures. A change in bowel habits, as well as significant weight loss in older patients, may hint at a malignancy.

The most common cause of rectal bleeding in the middle-aged and older population is hemorrhoids, which are often asymptomatic. They may be described as soft, painless protrusions in the anal canal. In essence, there is a downward displacement of the hemorrhoidal cushions, which causes venous dilatation and, hence, symptoms.[11] Some of the common symptoms include bleeding with or without defecation, swelling, and mild discomfort or irritation. Other symptoms may include mucous discharge, pruritis, difficulties with hygiene, and a sense of incomplete evacuation. Internal hemorrhoids are only painful if they have thrombosed, have prolapsed with edema, and/or are strangulated. External hemorrhoids only cause pain when they become thrombosed.[5]

Physical Exam

The physical exam should begin with an assessment of hemodynamic status via the measurement of vital signs. Attention should be paid to low blood pressure, tachycardia, and/or a high respiratory rate, as these may indicate hemodynamic instability and necessitate rapid escalation of care.

A focused exam for lower GI bleeding should include an abdominal exam with assessment for pain, masses, distention, and signs of cirrhosis, which might hint toward rectal varices. Perineum inspection should be carried out with the patient lying in the left lateral decubitus position under a light source to evaluate for old blood, thrombosed vessels, prolapsing hemorrhoids, fissures, or protruding masses.

The rectal exam should follow inspection of the anus for any skin tags protruding, sentinel piles, fissures, protruding piles, or any other apparent abnormalities that could be causing the bleed. A rectal exam can be uncomfortable and painful for patients, particularly in the case of acute fissures. In this case, inspection, while gently spreading the buttocks, helps in visualizing most anal fissures and is sufficient for diagnosis. A digital rectal exam should be done to assess for masses and internal hemorrhoids and to obtain stool for a fecal occult blood test (FOBT). Gross blood may also be visible after the exam. The digital rectal exam is contraindicated in immunocompromised patients, given the possibility of introducing pathogens, which could potentially cause life-threatening infections.[12]

Evaluation

A complete blood count (CBC) should be ordered with any complaint of bleeding to assess the severity and help direct the management. Other important lab tests to obtain are the international normalized ratio (INR) and the partial thromboplastin time (PTT), which will help to assess for any bleeding tendencies. A cross-match test may be needed in order to reserve blood for transfusion in cases of severe bleeding to maintain the hemoglobin level above 7gm/dL.

In patients who practice anal receptive sex, testing should be done for STIs, including gonorrhea and chlamydia. Endoscopies are the gold standard for investigating rectal bleeding, which should be performed in patients who are older than 40 years of age regardless of other clinical symptoms.[13] An anoscope or rigid procto-sigmoidoscope can be used to evaluate for a distal source of bleeding, such as from internal hemorrhoids, proctitis, rectal ulcers, malignancies, or varices. A colonoscopy should be done if there is a concern for proximal lower GIT pathology.

CT angiography may be pursued if there is a large volume of bleeding or if the patient is too unstable to undergo anesthesia for endoscopic intervention. If there is a large volume of blood in the gut, it may be difficult to isolate the specific site of where the blood is coming from.

Tagged red blood cell scintigraphies are an accurate investigation for localizing the bleeding vessels and identifying the site into which they bleed. It can be utilized in recurrent and persistent rectal bleeding of an unknown cause.

Treatment / Management

Acute, severe rectal bleeding requires initial hemodynamic assessment and the initiation of hemostatic resuscitation if needed to control the patient's vital signs. This may be achieved with IV fluids or vasopressors in more severe cases. Rectal bleeding severe enough to compromise the hemodynamic system is rare and is usually due to severe upper GI bleeding such as bleeding varices, perforated ulcer, or an aortoenteric fistula, and may mandate an upper GI endoscopy. If the patient undergoes endoscopy, bleeding can be controlled by certain procedures such as endoscopic cauterization, ligation, or direct injection to the bleeding site with either epinephrine or sclerosing agents.

Cauterization involves thermally ablating the site of bleeding with a unipolar or bipolar electrical cautery. Sclerosing agents are tissue irritants that cause vascular thrombosis and thus can be injected during hemostatic endoscopy. The most commonly used agents are ethanolamine oleate and sodium tetradecyl sulfate. If the patient undergoes an angiography, arterial embolization may be performed, especially if the bleeding vessels have been previously clipped as this makes them easily identifiable in imaging. If the patient is hemodynamically stable, they can be investigated and treated on an outpatient basis.[14] Below are some of the main causes of rectal bleeding and their specific treatments. Hemorrhoids

Management of hemorrhoids can be divided into conservative, office-based, and surgical categories. Conservative management revolves around the incorporation of high fiber options in the diet to minimize the risk of constipation and hence straining while defecating. Daily consumption of 25 grams of fiber for women and 38 grams of fiber for men is advised.[15] It can take up to 6 weeks for fiber therapy to improve the hemorrhoids.[16] Increased fluid intake is also important to prevent constipation.[17] Stool softeners and hyperosmolar supplements, such as glycerin and sorbitol, which can be given as rectal suppositories, or oral milk of magnesia and polyethylene glycol 3350, can be used as adjuncts to a high fiber diet. Sitz baths help to decrease pain, burning, and itching following a bowel movement for active, symptomatic hemorrhoids.[18] Symptom relief can also be achieved by the use of various topical local anesthetics, corticosteroids, and anti-inflammatory drugs. One of the most commonly used drugs is 0.2% glyceryl trinitrate (GTN) rectal ointment (mostly in grade 1 or 2 hemorrhoids), which relieves symptoms of hemorrhoids associated with high resting anal canal pressures. The efficacy of topical steroids is currently unproven.[12] (A1)

Office-based management mainly involves rubber band ligation, and it is the most widely used office technique for internal hemorrhoids. The procedure involves the application of a rubber band at the apex of internal hemorrhoids. This will cause the fixation of hemorrhoids in the anal canal, correcting the prolapse, with the additional benefit of decreasing blood flow resulting in a decrease in size.[19] It is beneficial for grade 1-3 hemorrhoids and is considered the most effective non- excisional treatment in the literature.[20] However, 18% to 32% of patients will have recurrence requiring repeated treatment.[21] (A1)

Infrared coagulation is one of the most commonly used energy ablation methods for treating internal hemorrhoids. The heat generated from infrared radiation causes protein coagulation and local inflammation. Each hemorrhoidal complex is exposed to the radiation at 4 different locations, with the depth of the penetration being around 3 mm. This process causes tissue necrosis, eventually leading to fibrosis and scarring.[12] It is most effective for the treatment of first and second-degree hemorrhoids but is less effective for prolapsed hemorrhoids.[22] Another treatment option is injection sclerotherapy, which requires the injection of a sclerosing agent at the base of the internal hemorrhoidal complex. This causes scarring, fibrosis, and ultimately fixation of the hemorrhoidal complex.[12] Sclerotherapy is not as successful as rubber band ligation for grade 3 hemorrhoids.[23] Arterial embolization procedures of the superior and inferior rectal arteries have also proven effective in controlling severe and persistent bleeding.[16](A1)

Operative management is reserved for patients who fail medical management, continue to have symptoms despite undergoing office-based procedures, present with extensive thrombosed hemorrhoids, or have other manifestations of advanced disease. Moreover, strangulated or gangrenous hemorrhoids will require immediate operative intervention as well. Closed excisional hemorrhoidectomy is the most commonly performed operation for this problem in the United States.[24] An elliptical incision is made around the hemorrhoidal tissue, and it is dissected off the underlying muscle sphincter fibers. After complete dissection of the underlying tissue, it is ligated at its base. The defect is then closed with absorbable suture.[25] The Milligan-Morgan technique involves a similar dissection of the hemorrhoidal tissue. However, it does not require the closure of the defect as in the Ferguson technique.[12] (B2)

Stapled hemorrhoidectomy is another alternative to second and third-degree hemorrhoids. This technique involves placing a purse-string suture in a circumferential fashion into the submucosa above the transition zone. The tissue above the suture is then excised with the help of the transplant stapler. In women, a vaginal exam should be done before firing the stapler to ensure the purse-string suture has not incorporated the posterior vaginal wall.[12] Trans-arterial hemorrhoidal de-arterialization involves the use of a doppler to search for arterial inflow to the hemorrhoid above the dentate line and then ligating it.[4] Thrombosed external hemorrhoids, if present in the early phase, can be treated with enucleation.[26] 

Complications after hemorrhoidectomy include pain, urinary retention, hemorrhage, anal stenosis, infection, and fecal incontinence. Topical agents such as nitroglycerin and metronidazole have been shown to decrease post hemorrhoidectomy pain.[27][28] Urinary retention is another common complication that can increase morbidity in patients undergoing hemorrhoidectomy. Severe hemorrhoidal disease, the number of quadrants excised, and high analgesia requirements increase the risk of these complications.[29] Bleeding may occur as a complication after hemorrhoidectomy, either in the immediate postoperative period (primary hemorrhage) or 7 to 10 days after surgery (secondary hemorrhage).[30] Anal stenosis can occur if excessive anoderm is removed at the time of the procedure.[31] Postoperative infections are very rare after a hemorrhoidectomy. However, if cellulitis or an abscess develops, there is a need for antibiotics and drainage.[32](A1)

Anal Fissures

Conservative treatment includes stool softeners, nitroglycerin to loosen the anal sphincter, and warm baths. Surgical management may be an option in chronic or resistant cases where a sphincterotomy is performed.[24] Diverticular Bleeding(B2)

Diverticular bleeding may cause severe rectal bleeding. The bleeding is controlled by endoscopic procedures such as epinephrine injection, clip placement, or ligation. In severe cases where diverticula cause significant, persistent bleeding that can't be controlled with endoscopic procedures, partial colectomy may be performed.[33](A1)

Colon Cancer

Management is based on removing the tumor and the associated part of the colon. Depending on the stage of the tumor, radical excision, which involves removing the affected part of the colon, the associated mesocolon, and local lymph nodes, may be required. The treatment plan may also involve adjuvant chemotherapy and radiotherapy.[34][35]

Differential Diagnosis

The differential diagnosis of rectal bleeding should include consideration for more proximal sources of bleeding, especially the colon. Consideration should be given to colon cancer, angiodysplasia, adenomas, inflammatory bowel disease, infectious, and ischemic colitis. Once the colonic causes have been ruled out, other important etiologies to consider include hemorrhoids, anal fissures, rectal carcinoma, and radiation-induced proctitis.

Prognosis

The prognosis depends on the cause of rectal bleeding, the severity, and the patient's underlying health. Approximately 95% of rectal bleeding cases will regress spontaneously.

Complications

• External hemorrhoids may thrombose, causing extensive pain and discomfort.
• Acute anal fissures may develop into chronic fissures that are resistant to conservative treatment and may require surgery.
• Malignancies may metastasize to the draining lymph nodes and other organs if treatment is delayed.
• Ongoing, untreated bleeding may cause symptomatic anemia with fatigue, shortness of breath, or chest pain.