Abdominal Distention (Distended Abdomen)

Abdominal distention vs bloating

The two words are often used together, but they mean different things:

• Bloating is a feeling: pressure, fullness or tightness inside the belly. You can feel bloated without your belly looking bigger.
• Distention is a sign: the belly actually gets larger, measured by a tighter waistband, a visible swelling or a tape measure.

About half of people who feel bloated also have visible distention. In functional gut disorders such as IBS, distention often happens because the diaphragm drops and the belly wall muscles relax in response to normal amounts of gas, a reflex called abdomino-phrenic dyssynergia. This explains why the belly can balloon without much gas on an X-ray.

Causes of abdominal distention

Doctors learn the "six Fs" to remember the main causes: flatus (gas), feces, fluid, fat, fetus and fatal growth (tumor). A seventh, an enlarged organ, completes the list.

Gas and digestion (most common)

• Swallowed air: eating fast, chewing gum, fizzy drinks and drinking through straws.
• Gas-producing foods: beans, lentils, onions, cabbage family vegetables, and sugar alcohols such as sorbitol in sugar-free products.
• Irritable bowel syndrome: distention that builds through the day, with belly pain and changes in stool that improve after a bowel movement.
• Food intolerances: lactose intolerance causes gas, distention and diarrhea 30 minutes to 2 hours after dairy. Fructose malabsorption works similarly.
• Celiac disease: distention, diarrhea or constipation, fatigue and anemia after eating gluten.
• SIBO: excess bacteria in the small intestine ferment food early, causing distention soon after meals. It is more likely after bowel surgery or with diabetes.
• Gastroparesis: slow stomach emptying, with early fullness and nausea, common in long-standing diabetes.

Constipation

Hard stool sitting in the colon causes distention, discomfort and reduced appetite. Constipation is a frequent cause in older adults and in people taking opioids, iron or some antidepressants.

Fluid in the abdomen (ascites)

Ascites is fluid collecting in the space around the intestines. The belly swells evenly, the flanks bulge, and the belly button may flatten or push out. It develops over weeks. Causes include:

• cirrhosis, the cause in about 8 in 10 cases
• heart failure
• cancer spreading to the lining of the abdomen, especially ovarian, stomach, bowel and pancreatic cancer
• kidney disease with heavy protein loss
• tuberculosis and pancreatitis (less common)

Bowel obstruction and ileus

A bowel obstruction is a blockage, often from scar tissue (adhesions) after surgery, a hernia or a tumor. Gas and fluid build up behind it. Ileus is a similar picture where the bowel stops moving without a physical block, for example after surgery or with low potassium. Both cause rapid distention, cramping pain, vomiting and no passage of stool or gas.

Tumors and enlarged organs

• Ovarian cancer: persistent bloating and distention, early fullness, pelvic pain and needing to urinate often. These symptoms are easy to mistake for IBS in women over 50.
• Large fibroids or ovarian cysts: a firm swelling in the lower belly.
• Enlarged liver or spleen: from liver disease, blood disorders or infection.
• Other abdominal tumors: bowel, stomach or pancreatic cancer.

Other causes

• Weight gain: fat in and around the abdominal organs enlarges the belly gradually and does not fluctuate through the day.
• Pregnancy: always consider it in women of childbearing age with a growing belly.
• Hormonal changes: fluid retention before a period or during perimenopause.
• Weak belly wall: a separation of the abdominal muscles after pregnancy (diastasis recti) or a hernia.

Clues that point to the cause

Symptoms that often come with distention

• Pain that eases with gas or a bowel movement: points to IBS or trapped gas.
• Nausea and early fullness: gastroparesis, ulcers or a growth pressing on the stomach.
• Shortness of breath: large-volume ascites pushes up on the diaphragm. Heart failure can also cause both.
• Yellow skin or eyes: liver disease.
• Swollen ankles: heart, liver or kidney disease.
• Weight loss, night sweats or blood in stool: needs prompt investigation for cancer or inflammatory bowel disease.

How doctors find the cause

A doctor will ask when the swelling began, whether it goes down overnight, how it relates to meals and bowel movements, your alcohol intake, medicines, menstrual history and any weight change. Examination includes tapping the belly (gas sounds hollow, fluid sounds dull and shifts when you roll), feeling for an enlarged liver, spleen or mass, and listening for bowel sounds.

Tests are chosen according to the clues:

• Blood tests: blood count, liver and kidney function, celiac antibodies, and CA-125 in women with persistent symptoms.
• Pregnancy test when relevant.
• Abdominal and pelvic ultrasound: detects fluid, organ enlargement, cysts and fibroids.
• X-ray or CT scan: shows obstruction, tumors and the pattern of gas.
• Breath tests: for lactose or fructose malabsorption and SIBO.
• Paracentesis: a needle sample of ascites fluid to find its cause.
• Colonoscopy or endoscopy: for alarm features or age-appropriate screening.

Treatment for a distended abdomen

Treatment targets the cause.

Gas, IBS and food triggers

• Eat slowly, cut down on fizzy drinks and chewing gum.
• Try a short trial of reducing lactose, or a dietitian-led low-FODMAP diet, which helps many people with IBS.
• Increase fiber gradually, and prefer soluble fiber such as psyllium, which causes less gas than bran.
• Walking after meals helps move gas through the bowel.
• Simethicone and peppermint oil capsules help some people. Follow the label dose.
• For IBS with persistent distention, a doctor may prescribe medicines or refer you for biofeedback to retrain the belly wall reflex.

Constipation

More fluids, fiber and activity, and an osmotic laxative such as polyethylene glycol if needed.

Ascites

Limiting salt, water pills (diuretics), and draining large volumes of fluid with a needle. Treating the underlying liver, heart or cancer problem matters most.

Bowel obstruction

Hospital treatment with nothing by mouth, IV fluids and a tube through the nose to empty the stomach. Some blockages need surgery.

Frequently asked questions

What is the difference between abdominal distention and bloating?

Bloating is the feeling of pressure or fullness in the belly. Distention is a visible or measurable increase in belly size. They often happen together, but you can feel bloated without your belly getting bigger, and a belly swollen with fluid may not feel bloated.

What causes abdominal distention?

Most often gas, constipation, IBS and food intolerances such as lactose intolerance. Less commonly it is fluid in the abdomen (ascites) from liver disease, heart failure or cancer, a bowel obstruction, an enlarged organ, a large cyst or fibroid, or pregnancy.

When should I worry about a distended abdomen?

Get emergency care if distention comes with vomiting, severe pain or no stool or gas. See a doctor soon if your belly keeps growing over days to weeks, or you have yellow eyes, swollen legs, weight loss, blood in your stool, or daily bloating for 3 weeks or more.

Why does my stomach swell up through the day?

Belly swelling that is flat in the morning and grows after meals is typical of gas, IBS and food intolerance. Eating, swallowed air and fermentation of food add gas, and the belly wall relaxes in some people. It usually settles overnight. Persistent swelling all day is different and needs checking.

Can ovarian cancer cause a distended abdomen?

Yes. Persistent bloating and distention, feeling full quickly, pelvic or belly pain and needing to urinate often are recognized early symptoms. If these happen most days for 3 weeks or more, especially after age 50, ask your doctor about a CA-125 blood test and pelvic ultrasound.

How do you get rid of a distended stomach?

For gas-related distention: eat slowly, avoid fizzy drinks and gum, walk after meals, treat constipation and identify trigger foods. Simethicone or peppermint oil may help. Distention from fluid, blockage or a growth needs medical treatment of the cause.