Approach to hematochezia: Clinical sciences

Hematochezia refers to the passage of bright red blood or blood clots from the rectum. It is seen in patients with acute lower gastrointestinal bleeding that originates from a site distal to the Ligament of Treitz. Hematochezia might also occur in massive upper gastrointestinal bleeds.

When bleeding comes from the right side of the colon patients usually pass dark or maroon-colored stool while those with bleeding from the left side pass bright red blood or stool.

The first thing to do when assessing a patient with hematochezia is the ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, begin acute management by stabilizing the airway, breathing, and circulation. Next, obtain IV access and initiate IV fluids for immediate resuscitation. If your patient is actively hemorrhaging, you may need to transfuse your patient with blood products as well. Finally, start continuous vital sign monitoring, including pulse oximetry, blood pressure, and heart rate.

Once acute management is initiated, the next step is to obtain a focused history and physical exam, and order labs, such as blood type and crossmatch, CBC to monitor hemoglobin and hematocrit, coagulation studies, and CMP. Your patient may present with massive hemorrhage or have brisk bleeding. You should be on the lookout for signs of hemodynamic instability including hypotension and tachycardia. At times, the bleeding may cease, but you should always monitor for rapid rebleeding. Initial labs may show low hemoglobin and a normal blood urea nitrogen-to-creatinine ratio for a lower gi bleed. However, if the ratio is elevated, consider upper gastrointestinal bleeding.

Alright, now that history, physical, and labs are obtained, let’s move on to nasogastric lavage. Nasogastric lavage is performed by placing a nasogastric tube and instilling water or normal saline into the stomach. The liquid is then aspirated. If blood returns you have confirmed an upper gastrointestinal or GI bleed. On the other hand, if there is no blood, a lower GI bleed is more likely, so you’ll need to identify the source.

If this is the case, the next step involves a tagged RBC bleeding scan and angiography, as well as controlling the bleeding with interventional radiology embolization, endoscopic intervention, or in extreme situations emergent surgical intervention or resection. These procedures are both therapeutic and diagnostic, so besides treating the bleeding, you will be able to find the source and confirm your diagnosis of lower gi bleed.

Now that unstable patients are taken care of, let’s talk about stable patients. Your first step here is to obtain a focused history and physical exam, including a digital rectal exam, as well as labs like CBC for serial monitoring of hemoglobin and hematocrit, coagulation studies to assess the need to correct a coagulopathy, and blood type and crossmatch. In addition, you may want to order an abdominal and pelvic CT scan with oral contrast to look for pathologies that can cause GI bleed. Another important factor is to assess for rectal pain.

So, let’s first talk about cases where there is no rectal pain associated with the bleeding.Causes of painless hematochezia include colorectal cancer, Dieulafoy lesion, diverticular bleeding, and angiodysplasia.

Let's start with colon cancer. These patients typically report a low-grade, mild, or recurrent bleeding, as well as unintentional weight loss. CT scan typically shows a mass that protrudes from the colonic wall and narrows the lumen. In this case, you should consider a neoplasm of the lower gi tract, in either the colon or rectum and the patient should be set up for a colonoscopy with a biopsy. Findings might include overlying erosion or ulceration with a friable mass and low-grade bleeding. If biopsy results confirm cancer this is your diagnosis.

Alright, let’s move on to the Dieulafoy lesion. A patient may present with bleeding that can be self-limited but might recur and at times be profuse. History might also reveal some important risk factors like biologically male sex, cardiovascular disease, diabetes mellitus, hypertension, kidney disease, or alcohol use disorder. In this case, you should consider a Dieulafoy lesion and order a colonoscopy. Findings usually include a dilated aberrant submucosal vessel eroding the overlying epithelium without a primary ulcer, as well as mucosal atrophy or arterial spurting. If you see these, the diagnosis of the Dieulafoy lesion is confirmed.

Let’s switch gears and talk about diverticular bleeding. Diverticulosis refers to the presence of multiple diverticula in the colon. This is often asymptomatic or may present with painless bleeding, which can be massive and even life-threatening. Now, CT scan can support the diagnosis of diverticulosis by revealing multiple diverticula arising from the colonic wall. In this case, you should order a colonoscopy. If you see a penetrating vessel within the bowel lumen, diverticula with arterial vascular penetration, and active arterial bleeding, you can confirm the diagnosis of diverticular bleeding from diverticulosis.