Back pain can be a symptom experienced during a flare-up of diverticulitis, though it is often considered an atypical presentation. Diverticulitis involves the inflammation of small, bulging pouches (diverticula) that form in the lining of the large intestine. When these pouches become infected or inflamed, the resulting discomfort, typically felt in the abdomen, can sometimes be perceived as pain in the lower back or flank area. This connection between an intestinal issue and distant back pain is explained by the body’s complex nervous system.
What Is Diverticulitis?
Diverticulosis is a common condition where small, balloon-like sacs develop in the wall of the colon. These pouches most frequently occur in the sigmoid colon, the lower, left-sided section of the large intestine. The presence of these pouches usually causes no symptoms and is often discovered incidentally during routine screenings.
Diverticulitis occurs when one or more of these diverticula become inflamed or infected, often due to a blockage in the pouch opening. This blockage is typically caused by hardened stool or undigested food particles, leading to bacterial overgrowth and subsequent inflammation.
How Diverticulitis Causes Back Pain
The pain from an inflamed section of the colon can be felt in the back through a process known as referred pain. This phenomenon happens because the internal organs and the skin and muscles of the lower back share nerve pathways that lead to the spinal cord. Inflammation of the sigmoid colon can irritate these nearby nerve fibers.
The nerve signals originating from the inflamed colon are interpreted by the brain as coming from the lower back or flank region, rather than the true source. The proximity of the colon to structures in the retroperitoneal space, which includes nerves that supply the lower back, facilitates this nerve signal confusion.
Pain is often localized to the left lower back, aligning with the typical location of the sigmoid colon. In some cases, the inflammation can be intense enough to cause muscle spasms in the surrounding abdominal and lower back muscles, contributing to the overall discomfort.
Recognizing Other Symptoms of Diverticulitis
Back pain rarely occurs in isolation with diverticulitis, making it a symptom that should be evaluated in context with other signs. The most common sign of a flare-up is abdominal pain, which is usually constant and often localized to the lower left quadrant of the abdomen. This abdominal discomfort may range from mild cramping to severe, acute pain.
Other typical gastrointestinal symptoms often accompany the pain, including changes in bowel habits such as new-onset constipation or diarrhea. Systemic signs of infection are also frequent, including nausea, vomiting, and a low-grade fever.
The presence of these accompanying symptoms helps distinguish diverticulitis from purely musculoskeletal back issues. Tenderness in the lower abdomen is another common finding that points toward an underlying inflammatory process in the colon.
When Back Pain Signals an Emergency
While back pain can be part of an uncomplicated diverticulitis episode, a sudden worsening of this pain, especially with other severe symptoms, can signal a serious complication. A sharp, constant, and rapidly intensifying back or abdominal pain may indicate a perforation, where the inflamed pouch tears and spills intestinal contents into the abdominal cavity, leading to peritonitis.
Signs of a life-threatening complication requiring immediate medical attention include:
- An inability to pass gas or stool.
- Persistent high fever above 101°F.
- Signs of shock like dizziness or a rapid heart rate.
- Excruciating back pain that radiates more broadly.
Excruciating pain may indicate a larger area of inflammation or the formation of an abscess. An abscess is a pocket of pus that forms outside the colon wall, and its expansion can place increasing pressure on surrounding structures, including nerves.
Resolving the Pain Through Treatment
Treating the back pain caused by diverticulitis requires addressing the underlying inflammation in the colon. For mild cases of uncomplicated diverticulitis, treatment often involves bowel rest and dietary modifications. A short period on a clear liquid diet allows the colon to rest, which helps reduce the irritation causing the pain.
Oral antibiotics are typically prescribed to clear up the infection, reducing the inflammatory process. Once the inflammation subsides, the irritation of the nearby nerves stops, and the referred back pain gradually resolves. Pain relievers like acetaminophen can be used to manage discomfort, though nonsteroidal anti-inflammatory drugs (NSAIDs) are generally avoided due to their potential to increase complication risks.
More severe episodes, particularly those involving an abscess or perforation, necessitate hospitalization and intravenous antibiotics. Surgical removal of the diseased section of the colon eliminates the source of the inflammation, stopping the nerve irritation and resolving the associated referred back and abdominal pain.