What is Lower Gastrointestinal Bleeding (GI Bleed)?
Gastrointestinal (GI) bleeding is a phrase used to describe any bleeding that happens in the digestive system, which extends from the mouth to the anus. This type of bleeding is divided into two main categories: upper and lower, based on where it’s happening. The point of distinction is typically the ligament of Treitz, a certain point within the digestive system. Bleeding that happens above this ligament is known as upper GI bleeding, while anything below is identified as lower GI bleeding. Understanding whether the bleeding is upper or lower is crucial as it influences how doctors assess and treat the patient.
What Causes Lower Gastrointestinal Bleeding (GI Bleed)?
Lower gastrointestinal (GI) bleeds can be grouped into three types: massive, moderate, and hidden, or “occult,” bleeding.
Massive bleeding typically happens in people over the age of 65 who have multiple health issues, and it shows up as bright red blood in the stool. These patients often have unstable vital signs, like blood pressure of 90 or less, heart rate of 100 or less, and a low rate of urine output. Blood tests might show that the amount of hemoglobin present is 6 g/dl or less. Most frequently, massive lower GI bleeds are a result of conditions like diverticulosis and angiodysplasias. Unfortunately, the death rate for these cases can be as high as 21%.
Moderate bleeding can happen at any age and also shows up as bright red blood in the stool, or as black, tarry stool. These patients usually have stable vital signs. This could be caused by a variety of diseases such as cancer, inflammation, infection, benign rectum conditions, and those present at birth.
Finally, hidden lower GI bleeds might occur in anyone, irrespective of age. Blood tests may reveal a type of anemia due to chronic blood loss. Possible reasons for this type of bleeding could be inflammation, cancer, and conditions present at birth. These patients generally appear healthy and have stable vital signs.
Risk Factors and Frequency for Lower Gastrointestinal Bleeding (GI Bleed)
Lower gastrointestinal (GI) bleeds are quite common, making up 20% to 30% of all serious GI bleeds. This condition is more common in older individuals and those taking multiple medications. About 80% to 85% of these bleeding episodes start beyond the ileocaecal valve (a valve between the small and large intestines), and only around 0.7% to 9% originate from the small intestine. The remaining cases usually start in the upper GI tract. Symptoms often include heavy bleeding, dark, sticky feces (melena), or passing bright red blood with stool.
- Lower gastrointestinal bleeds are relatively common, accounting for 20% to 30% of all serious gastrointestinal bleeds.
- This condition often occurs more in older individuals and those on multiple medications.
- Approximately 80% to 85% of these bleeds start after the ileocaecal valve; only about 0.7% to 9% start from the small intestine.
- Remaining cases usually begin in the upper gastrointestinal tract.
- Typical symptoms include heavy bleeding, dark sticky feces, or passing bright red blood with stool.
Signs and Symptoms of Lower Gastrointestinal Bleeding (GI Bleed)
When people have lower gastrointestinal bleeds, their symptoms can vary significantly. This can range from minor bleeding to severe hemorrhages. It’s important to take a detailed account of a patient’s medical history. This should highlight whether the bleeding happens over and over or sporadically, any related symptoms, and a comprehensive review of the patient’s medication including blood-thinning drugs, and non-steroidal anti-inflammatory drugs. The patient’s family history of colon cancer or inflammatory bowel disease should also be taken into account.
All patients experiencing lower gastrointestinal bleeding should have an abdominal examination and digital rectal examination. If possible, a proctoscopy (an examination of the rectum) should also be considered. The abdominal exam may reveal tenderness, bloating, or a mass depending on the cause. During the digital rectal exam, the doctor will look for bright red blood in the stool, or anorectal conditions like hemorrhoids. Research shows that bleeds from the left side of the colon usually result in bright red blood, while those from the right cause maroon-colored blood, sometimes accompanied by clots. But it’s important to note that severe and fast right-side bleeds can also produce bright red blood.
Testing for Lower Gastrointestinal Bleeding (GI Bleed)
If you come to the hospital with a lower gastrointestinal (GI) bleed, it’s imperative that the medical team evaluates you quickly. Patients with GI bleeding can worsen quite rapidly, so time is of the essence. The first thing doctors will check is your ability to breathe and maintain an open airway. If they are worried about your breathing, they’ll take steps to secure your airway straight away. If you’ve lost a lot of blood or are showing signs of shock, keep an airway setup close because your situation can decline very fast.
During your initial check-up, you’ll likely be given extra oxygen, have two large IV lines inserted, and be hooked up to a heart and lung monitor. Doctors will start an IV fluid called crystalloid right away to help stabilize your blood volume. Depending on how you are doing, they might also consider giving you a blood transfusion.
The team will also order several blood tests. These may include a complete blood count, a check of your electrolyte levels, liver function tests, lactate levels, and checks on your blood’s clotting ability, particularly if you are taking medications that may affect this.
To simplify the process, doctors use the BLEED criteria to evaluate any patient with a GI bleed. The criteria cover:
- Ongoing Bleeding: Vomiting blood or passing red/maroon liquid stool (not just dark, formed stool)
- Low Blood Pressure: Less than 100 mmHg not counting when you stand up
- Elevated Clotting Time: More than 1.2 times usual
- Erratic Mental Status: Any change in consciousness, whatever the reason
- Unstable Other Diseases: Another serious illness that would require ICU admission even without the presence of a GI bleed.
If you have one or more of these, you are considered high-risk and may have an increased chance of complications. Each criterion has specific definitions. For example, active or ongoing upper GI bleeding means you are vomiting blood, whereas active lower GI bleeding includes passing fresh or dark red liquid from the rectum. A low blood pressure reading doesn’t count if it’s only low when you stand up, and an erratic mental status can be due to any cause, even drugs. Lastly, an unstable comorbid disease is any other serious health problem that would justify an ICU admission even without a GI bleed.
Treatment Options for Lower Gastrointestinal Bleeding (GI Bleed)
Colonoscopy is a highly effective method for identifying the source of lower intestinal bleeding, with over 75% success rate. It can also be used to treat the identified issues. However, the best time to perform a colonoscopy remains a topic of debate. Most research suggests that it is best carried out within the first 24 hours after the patient is admitted to the hospital, following a bowel cleansing procedure. Diverticular bleeds, in particular, can be treated by injecting adrenaline directly at the bleeding site.
Not all patients will be in a condition stable enough to undergo a colonoscopy. In such cases, radiologic tests may be considered. CT angiography, which is quick and non-invasive, can detect bleeding rates of more than .3 to .5 mL per minute. However, it is not always accurate, with a sensitivity of only 85%. Catheter angiography is another test that is reserved for patients who cannot have a colonoscopy due to unstable body functions or recurrent bleeding.
Radionuclide imaging uses Technetium (99mTc)-based markers to label red blood cells and can help identify slow, intermittent bleeding. The Technetium has a long half-life, enabling the scan to be repeated multiple times in a 24-hour period for evaluations.
In some cases, if radiologic and endoscopic methods do not successfully treat the situation, the patient may need surgery. It is always a good idea to involve a colorectal surgeon early on when diagnosing a patient as conditions can deteriorate rapidly. For patients in critical condition, requiring more than six units of blood within 24 hours, or those not responding to resuscitation attempts, emergency surgical removal of the affected parts of the colon may be necessary.
What else can Lower Gastrointestinal Bleeding (GI Bleed) be?
When a doctor is trying to work out what’s causing someone’s symptoms, they may consider many different health conditions that have similar signs. In the case of certain digestive or abdominal symptoms, the doctor could be thinking about:
- Anorectal abscess
- Colitis (inflammation in the colon)
- Colon cancer
- Colonic polyps (small growths on the colon lining)
- Crohn’s disease (a type of inflammatory bowel disease)
- Diverticulitis (inflammation or infection in one or more small pouches in the digestive system)
- Endometriosis (a disorder where tissue from the uterus grows outside of the uterine cavity)
- Inflammatory bowel disease (a group of inflammatory conditions in the colon and small intestine)
- Intussusception (a problem with the intestine where one part folds into itself)
- Meckel’s diverticulitis (inflammation or infection of a pouch in the small intestine)
The doctor will carry out specific tests to determine which (if any) of these conditions are the cause of the symptoms.