Left Lower Abdominal Pain With Fever: Could It Be Diverticulitis?

Left lower abdominal pain with fever is often caused by diverticulitis, inflammation or infection of small pouches in the colon wall, although several other conditions can look similar. Fever together with worsening pain, repeated vomiting, a hard belly or feeling faint makes it urgent, because an inflamed pouch can form an abscess or tear. This article explains how clinicians sort out the causes, what testing and treatment may involve, and which symptoms call for 911 or same-day care.

Left lower abdominal pain with fever: why diverticulitis comes to mind first

Many adults develop small pouches, called diverticula, in the wall of the large intestine as they get older. Having the pouches is called diverticulosis, and it often causes no symptoms at all. Diverticulitis is what happens when one or more of those pouches become inflamed or infected. According to MedlinePlus from the NIH, diverticulitis can cause abdominal pain, fever, nausea and a change in bowel habits.

The pouches are most often found in the sigmoid colon, the S-shaped last stretch of the large intestine that sits in the lower left abdomen. That anatomy is why the pain of diverticulitis frequently shows up on the left side, low down. It is also why left lower pain plus fever sends clinicians toward this diagnosis early.

The exact reason a pouch becomes inflamed is not fully understood. Several factors are thought to contribute, including pressure and stool trapped in a pouch, changes in gut bacteria and inflammation in the colon wall. A fever suggests the body is reacting to inflammation or infection, so it is one reason this combination deserves attention rather than waiting it out.

What diverticulitis usually feels like

The typical picture is pain in the lower left abdomen that builds over a day or more rather than coming and going in waves. It may be constant, may feel worse with movement or coughing, and may be tender when you press on the area. Not everyone fits this description, so a different pattern does not rule it out.

Other symptoms that may go along with it:

• A low-grade or higher fever, sometimes with chills
• Nausea, with or without vomiting
• Constipation, or less often diarrhea
• Bloating or a feeling of fullness
• Reduced appetite
• Urinary urgency or burning, if the inflamed colon sits against the bladder

Pain that is mild and short-lived without fever is more often a gas or constipation problem. The combination of persistent one-sided pain and fever is what raises concern.

Who is more likely to develop it

Diverticulitis is more often diagnosed in middle-aged and older adults, but younger adults can have it too. Factors associated with a higher chance include older age, excess body weight, smoking, low physical activity and a long-term pattern of low fiber intake. Some medicines have also been linked with complications, so it is worth telling your clinician or pharmacist about every prescription and over-the-counter pain reliever you take, especially anti-inflammatory pain relievers and steroids. Do not change a prescribed medicine on your own; ask the prescriber.

People with a weakened immune system, for example from chemotherapy, organ transplant medicines or long-term steroids, can have fewer warning signs even when the problem is serious. If you are in one of these groups, a fever with abdominal pain is a reason to be evaluated promptly.

Other causes of left lower abdominal pain with fever

Diverticulitis is a common cause of this combination, not the only one. Clinicians combine your history, an examination and testing to sort out the possibilities, which include:

• Infectious colitis or gastroenteritis. Bacteria such as Salmonella or Campylobacter, or viruses, can cause cramping, fever and diarrhea. MedlinePlus describes gastroenteritis and its usual symptoms. Diarrhea that is watery or frequent points more toward this than toward diverticulitis.
• Inflammatory bowel disease. Crohn's disease and ulcerative colitis can cause pain, fever, weight loss and bloody stools. We compare them in our article on Crohn's disease and ulcerative colitis.
• Urinary tract problems. A kidney infection or a kidney stone can cause one-sided pain and fever, often with burning urination, blood in the urine or pain that travels toward the back or groin.
• Gynecologic causes. An ovarian cyst, ovarian torsion, pelvic infection or an ectopic pregnancy can cause left lower pain. If pregnancy is possible, this needs to be considered early. Our article on pelvic pain with unusual discharge covers pelvic infection.
• Hernia or a problem in the groin or testicle. A tender bulge, or sudden severe testicular pain, can be mistaken for bowel pain.
• Appendicitis. Appendicitis is usually felt on the right, but pain can be vague at first. Appendiceal diverticulitis is described in the medical literature as an uncommon condition.
• Colon cancer or another colon problem. This is much less common than the everyday causes above, and one symptom alone does not establish it. A colon tumor can sometimes cause a blockage or perforation that looks like diverticulitis, which is one reason follow-up is often discussed. See our article on colorectal cancer symptoms in people under 50.

How clinicians evaluate it

Expect questions about when the pain began, whether it is constant, any change in bowel habits, urinary symptoms, blood in the stool, recent antibiotics, medicines you take and, if relevant, pregnancy. The examiner will usually check for tenderness and for signs that the lining of the abdominal cavity is irritated, such as pain when pressure is released or a rigid belly.

Testing commonly includes blood tests to look for signs of infection, a urine test, and a pregnancy test when relevant. A CT scan of the abdomen and pelvis is often used when the diagnosis is uncertain or complications are suspected, because it can show inflamed pouches and also an abscess or free air. A pictorial review of CT findings in acute diverticulitis shows how those findings appear on imaging. Some people with a typical history and mild symptoms are diagnosed without a scan, and the choice is the clinician's.

A colonoscopy is generally avoided during an active attack because of the risk to an inflamed colon. Clinicians may recommend one after recovery to look at the colon directly, especially if the picture was unusual or the person has never had one.

Treatment: mild episodes versus complicated ones

Treatment depends on how severe the attack is and whether there are complications. A review titled Outpatient diverticulitis: mild or myth? discusses how some people with uncomplicated disease are managed at home while others need the hospital. Your clinician decides which group you belong to.

Uncomplicated diverticulitis

If you are able to drink fluids, are not severely ill and have no signs of a complication, your clinician may treat you at home. That can include rest, a temporary clear-liquid or low-residue diet, and in some cases antibiotics. Whether antibiotics are needed in mild cases is something clinicians weigh case by case. If antibiotics are prescribed, take them as directed and ask the prescriber or pharmacist before stopping early or if side effects bother you.

Ask the clinician which pain reliever is appropriate for you. Some over-the-counter pain medicines can irritate the digestive tract or interact with other medicines, and the right choice depends on your health and other prescriptions.

Clinicians usually want to see improvement in pain and fever after treatment starts. If you are getting worse, or the fever continues, contact the clinician the same day rather than waiting for the planned follow-up.

Complicated diverticulitis

Hospital care may be needed when there is an abscess, a perforation, a blockage, a high fever with severe pain, trouble keeping fluids down, or when the person has other health problems. Treatment can include intravenous fluids and antibiotics, a drain placed through the skin to empty an abscess, or surgery. Surgery may involve removing the affected part of the colon, sometimes with a temporary or permanent opening for stool (ostomy), depending on the situation.

Complications and why they change the urgency

Most episodes are uncomplicated, but the complications explain the warning signs in the box on this page.

• Abscess. A pocket of pus forms next to the colon. It can cause persistent fever and growing pain, and may need drainage. Case reports describe abscesses from a colon perforation that spread into the space behind the abdominal cavity and produced less obvious signs, as in clinical signs of retroperitoneal abscess from colonic perforation.
• Perforation and peritonitis. If a pouch tears, stool and bacteria can spill into the abdominal cavity. This can cause severe pain, a rigid belly, rapid heartbeat and fever, and it is a surgical emergency.
• Blockage. Repeated inflammation can scar and narrow the colon. Signs include a swollen belly, vomiting and being unable to pass stool or gas.
• Fistula. An abnormal channel can form between the colon and another organ, such as the bladder. Air bubbles or stool in the urine, or repeated urinary infections, can be a sign.
• Bleeding. Diverticula can bleed, usually without pain, though bleeding is more typical of diverticulosis than of an inflamed attack. MedlinePlus has a page on gastrointestinal bleeding.
• Sepsis. Infection that spreads can cause a dangerous whole-body reaction. Our article on sepsis warning signs lists what to look for.

A fever is not a 911 line by itself. It becomes an emergency when paired with the symptoms above, such as confusion, fainting, a rigid belly or severe worsening pain.

After the attack: recovery and lowering the chance of another

Many people recover from a first episode without further problems, but some have it again. Your clinician may talk with you about follow-up and whether a colonoscopy is appropriate after you recover, particularly to look for other conditions that can mimic diverticulitis.

Habits that are generally associated with colon health, and that you can discuss with your clinician, include:

• Gradually returning to a diet with plenty of fiber from vegetables, fruits, beans and whole grains once you have recovered
• Drinking enough fluids
• Regular physical activity
• Quitting smoking
• Maintaining a healthy weight

Older advice to avoid nuts, seeds and popcorn is not well supported by evidence, so ask your clinician rather than cutting foods out on your own. Increase fiber slowly, since a sudden jump can cause gas and bloating, and do not start a high-fiber plan during an active flare unless your clinician says to.

What to do today if you have this pain and a fever

Check the emergency list on this page first. If any 911 item fits, call now rather than driving yourself. If not, but you have pain on one side of the abdomen along with a fever, contact a clinician the same day or go to urgent care. Writing down when it started, your temperature readings, your medicines and any bowel or urinary changes will help them decide quickly.

Until you are seen, avoid heavy meals, drink fluids if you can keep them down, and avoid taking new laxatives or leftover antibiotics. Ask a pharmacist or clinician before taking any pain reliever. This article is general information and cannot diagnose the cause of your pain.

When to Seek Medical Care