Approach to constipation: Clinical sciences

Constipation is a common gastrointestinal condition characterized by infrequent bowel movements and difficulty passing stool. It happens when the intestines don't move waste to the rectum properly, and pelvic muscles and anal sphincter don't coordinate well to expel stool. Now, based on the cause, constipation can be classified as primary, also known as idiopathic or functional constipation; and secondary, which occurs as a side effect of some medications or due to another medical condition, such as malignancy.

Now, if your patient presents with constipation, first, you should obtain a focused history and physical exam. Always perform a digital rectal exam, including inspection, palpation at rest, and palpation during a simulated evacuation, which is performed by asking the patient to bear down on your finger as if they were having a bowel movement. Your patient will typically report a history of infrequent bowel movements, usually fewer than three stools per week, as well as straining, hard stools, and a feeling of incomplete evacuation. Additionally, history might reveal abdominal discomfort or bloating, and sometimes the patient might report the use of manual maneuvers to defecate.

Now, here’s a clinical pearl to keep in mind! Many patients find it embarrassing to discuss bowel habits, so they might not describe their symptoms in detail. So, be sure to ask direct questions about things like digital manipulation to defecate, and ask them to describe the appearance of their stools.

You can use tools like the Bristol stool chart, which lists seven categories of stool based on shape and texture, to help patients describe their stool.

Next, in patients with acute onset constipation, always ask about the ability to pass gas, as failure to pass gas can signal bowel obstruction. Other symptoms that point to obstruction include obstipation, which refers to severe or complete constipation with practically no stool passage and absence of flatus, and can be accompanied by abdominal pain, nausea, and vomiting.

Alright, moving on to the physical exam findings, which typically include fecal impaction and a palpable stool ball. Additionally, some patients may have anal fissures, hemorrhoids, or functional problems like pelvic floor dyssynergia. This is when the anal sphincter fails to relax or the perineum does not descend when the patient bears down during evacuation.

Based on these history and physical exam findings, you can make the diagnosis of constipation. Once you diagnose constipation, it's important to look for red flag features that could indicate underlying serious conditions like malignancy. These include hematochezia, unintentional weight loss, a family history of colorectal cancer, acute onset of constipation in an older adult, change in stool caliber, anemia, and the presence of a rectal mass.

If any of these red flag features are present, you should consider colorectal cancer and proceed with an endoscopy, such as colonoscopy or flexible sigmoidoscopy, with a biopsy to look for obstructive lesions. Endoscopy typically reveals an endoluminal, exophytic polypoid mass with or without bleeding and necrosis, while biopsy reveals malignancy. In this case, you can diagnose colorectal cancer.