Diverticulitis is characterized by inflammation or infection within small pouches, called diverticula, that bulge out from the wall of the colon. The condition typically presents with acute, often intense, pain in the lower left quadrant of the abdomen, frequently accompanied by fever and an elevated white blood cell count. The abdominal cavity houses multiple organ systems, meaning many other conditions can produce closely mirrored symptoms, making diagnosis challenging. A precise diagnosis, often confirmed by a Computed Tomography (CT) scan, is necessary for effective treatment, as misidentification can lead to inappropriate management of a completely different ailment.
Digestive Tract Conditions That Mimic Diverticulitis
Conditions affecting the gastrointestinal tract frequently cause confusion due to anatomical overlap with the colon. Irritable Bowel Syndrome (IBS) flare-ups cause recurrent abdominal pain and changes in bowel habits, but they generally lack the systemic signs of acute infection seen in diverticulitis, such as fever and a significant rise in inflammatory markers. A distinguishing feature is that IBS pain is often relieved following a bowel movement, which is not typically the case with the inflammatory pain of diverticulitis.
Inflammatory Bowel Disease (IBD), including Crohn’s disease and Ulcerative Colitis (UC), can also present with localized abdominal pain and inflammation. IBD involves chronic, immune-mediated inflammation of the bowel lining, often presenting with diarrhea, weight loss, and blood in the stool. Unlike diverticulitis, which is an acute infection, IBD is a chronic condition.
Acute infectious colitis, caused by pathogens like C. difficile or other bacteria, creates inflammation that closely mimics diverticulitis. This condition shares symptoms like abdominal tenderness, fever, and changes in stool consistency. However, infectious colitis is usually diagnosed by stool testing to identify the specific pathogen, whereas diverticulitis is confirmed by imaging that shows wall thickening and fat stranding around a diverticulum.
Urinary System Conditions Presenting as Abdominal Pain
The proximity of the urinary system to the lower colon means problems originating in the kidneys, ureters, or bladder can cause pain mistaken for a digestive issue. The acute pain of a ureteral or kidney stone (renal colic) is a common mimic, especially when the stone is passing down the left ureter. While the pain from diverticulitis is usually steady, stone pain is typically characterized by waves of severe pain that can radiate from the flank down toward the groin.
Pyelonephritis, an infection of the kidney, also presents with fever and abdominal discomfort. Pyelonephritis often includes additional symptoms not present in uncomplicated diverticulitis, such as painful urination (dysuria), frequent urge to urinate, or blood in the urine (hematuria). The presence of these specific urinary symptoms and flank tenderness strongly suggests a urinary tract source over a colonic one.
Gynecological and Reproductive Sources of Lower Abdominal Pain
Gynecological issues frequently cause lower abdominal and pelvic pain that overlaps with the symptoms of diverticulitis. An ovarian cyst that ruptures or an ovary that twists on its blood supply (ovarian torsion) can cause sudden, severe, unilateral lower abdominal pain. Ovarian torsion is a surgical emergency that causes intense, abrupt pain due to the cutting off of blood flow.
Pelvic Inflammatory Disease (PID), an infection of the upper reproductive tract, also causes lower abdominal pain, often alongside fever and unusual vaginal discharge. PID pain can be bilateral or localized to one side, mimicking diverticulitis or appendicitis. Specific testing, including a pelvic examination and often a pelvic ultrasound, is necessary to differentiate these conditions from a colonic infection.
Ectopic pregnancy, where a fertilized egg implants outside the uterus, is a potentially life-threatening cause of acute lower abdominal pain. This medical emergency must be ruled out immediately in any person of childbearing age presenting with severe abdominal pain. A pregnancy test is the initial step in distinguishing an ectopic pregnancy from a non-gynecological cause like diverticulitis.
Less Common Structural and Vascular Mimics
Less common, but equally serious, conditions can also present with symptoms mimicking an acute diverticulitis flare. Ischemic colitis occurs when blood flow to a section of the large intestine is temporarily reduced, leading to inflammation. This typically causes abdominal pain and tenderness, often in the left lower quadrant, but is usually distinguished by the presence of bloody stool and a history of vascular risk factors.
Ischemic colitis shares abdominal pain and tenderness with diverticulitis, but it may also present with a sudden urge to move the bowels. Advanced imaging is often needed to confirm the diagnosis, as both conditions can show signs of bowel wall thickening.
Another possibility is an incarcerated or strangulated hernia, where a section of the intestine or other tissue becomes trapped in a weak spot of the abdominal wall. A strangulated hernia can present with localized pain, tenderness, and signs of obstruction, mimicking the localized nature of a diverticular abscess. An abdominal wall hematoma, a collection of clotted blood within the abdominal muscles, can also cause severe localized tenderness and pain, especially after trauma or in people on blood-thinning medication.