Sigmoid Colon

• The sigmoid colon is the S-shaped final section of the large intestine before the rectum.
• Its primary function involves storing fecal matter and propelling it towards the rectum for elimination.
• Pain in the sigmoid colon area can indicate various conditions, including diverticulitis, inflammatory bowel disease, or irritable bowel syndrome.
• Common Sigmoid colon diseases and conditions range from benign issues like polyps to more serious concerns such as colorectal cancer.
• Early diagnosis and appropriate medical intervention are crucial for managing sigmoid colon-related health problems.

What is the Sigmoid Colon? Anatomy and Function

The Sigmoid Colon is the S-shaped terminal part of the large intestine, connecting the descending colon to the rectum. This segment is typically about 15 to 20 inches (38 to 50 cm) long and is characterized by its unique curvature, which allows it to store fecal matter temporarily before defecation. Its name, “sigmoid,” is derived from the Greek letter sigma (Σ), reflecting its distinctive shape. The sigmoid colon is a highly mobile section of the colon, suspended by a mesentery called the sigmoid mesocolon, which allows for significant movement within the pelvic cavity, adapting to the changing volume of its contents.

The primary Sigmoid colon function and anatomy are integral to the final stages of digestion and waste elimination. Anatomically, its muscular walls, composed of smooth muscle, contract rhythmically in a process called peristalsis, efficiently moving stool towards the rectum. Functionally, it plays a crucial role in absorbing residual water and electrolytes from the remaining indigestible food matter, which helps to solidify the stool before its final passage. Furthermore, it serves as a temporary storage site for feces, regulating the timing of bowel movements and contributing significantly to proper bowel control. The flexibility and strong muscular contractions of the sigmoid colon are essential for preventing premature defecation and ensuring efficient waste transport out of the body.

Sigmoid Colon Pain: Causes and Related Conditions

Pain originating from the sigmoid colon can manifest in the lower left abdomen and may range from mild discomfort to severe, acute pain. Understanding Sigmoid colon pain causes is crucial for accurate diagnosis and effective treatment. One of the most common causes is diverticulitis, an inflammation or infection of small, bulging pouches (diverticula) that can form in the lining of the colon, particularly in the sigmoid section due to increased pressure. When these pouches become inflamed or infected, they can cause significant pain, tenderness, fever, and changes in bowel habits, often requiring medical intervention.

Several Sigmoid colon diseases and conditions can lead to pain and other symptoms, necessitating a thorough medical evaluation. These include:

• Diverticular Disease: This encompasses both diverticulosis (the presence of diverticula) and diverticulitis (their inflammation or infection), which is a leading cause of lower left abdominal pain.
• Inflammatory Bowel Disease (IBD): Conditions such as Crohn’s disease and ulcerative colitis can affect the sigmoid colon, leading to chronic inflammation, ulcers, and persistent abdominal pain, along with other systemic symptoms.
• Irritable Bowel Syndrome (IBS): A common functional gastrointestinal disorder, IBS can cause recurrent abdominal pain, cramping, bloating, and altered bowel habits (diarrhea, constipation, or both), often localized to the lower abdomen.
• Colorectal Cancer: Malignant tumors developing in the sigmoid colon can cause persistent pain, changes in stool caliber or frequency, rectal bleeding, and unexplained weight loss. Early detection is vital for successful treatment.
• Ischemic Colitis: This condition arises from reduced blood flow to the sigmoid colon, leading to inflammation and damage. Symptoms typically include sudden onset of abdominal pain and bloody diarrhea.
• Colon Polyps: While often benign and asymptomatic, larger polyps can sometimes cause discomfort, bleeding, or, if precancerous, pose a risk for future malignancy.

Diagnosis typically involves a comprehensive physical examination, detailed patient history, and various diagnostic tests. These may include imaging studies like CT scans, MRI, or ultrasound, as well as endoscopic procedures such as a colonoscopy, which allows direct visualization of the colon lining. Blood tests and stool analyses may also be performed to identify inflammation, infection, or other markers of disease. Prompt medical evaluation is recommended for persistent, severe, or worsening sigmoid colon pain to ensure timely and appropriate management.