Bloated Stomach – Causes of Abdominal Bloating

The term “bloated stomach” is used to describe a visible distention in any part of the abdomen. Many people use the term “stomach” to describe different parts of the abdomen. However, this is not accurate. The abdomen contains many different organs, and the stomach is only one of them. Therefore, the more accurate term to describe a visible enlargement of any region of the abdomen is “bloated abdomen”.


A bloated abdomen is usually caused by accumulation of fluid, gas, feces or fat. The swollen region of the abdomen may feel spongy, soft, or hard. The distention may either be a generalized swelling of the entire abdomen or a restricted bulge in a specific region of the abdomen. In some cases, growth of a solid mass within the abdomen (such as a tumor) could also cause a noticeable enlargement in one part of the abdomen. However, not all causes of bloated abdomen are pathological in nature. For example, pregnancy is a normal physiological cause of a distended abdomen.

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Causes of Bloated Abdomen

As mentioned, bloating may occur as a swelling that either encompasses the entire abdominal area or only a specific region of the abdomen. The entire abdomen can be divided into four distinct quadrants and the umbilical region. The following sections discuss the potential causes of abdominal bloating in different regions of the abdomen.

Causes of swelling in the RUQ abdomen

Swelling observed in the upper right quadrant of the abdomen may be caused by enlargement of the following abdominal organs.

Liver

An enlargement of the liver (technically referred to as hepatomegaly) can be caused by a variety of factors. Some common causes of hepatomegaly include biliary cirrhosis, alcoholic liver disease, primary hepatocellular carcinoma, viral hepatitis, autoimmune hepatitis, and cardiac failure.

Gallbladder

Expansion of gallbladder can be caused by gallstones, gallbladder cancer, or inflammation of the gallbladder (technically referred to as cholangitis).

Right kidney

Kidney stones can obstruct the flow of the urine from the kidneys, leading to enlargement of the kidney. This condition is technically referred to as hydronephrosis. Swelling of the right kidney can cause swelling of the right upper quadrant of the abdomen. Other causes of kidney enlargement include polycystic kidney disease and renal carcinoma.

Colon

Accumulation of feces in the colon can result in swelling of the abdomen. Other causes of colon enlargement include colitis, colon cancer, and diverticulosis.

Causes of swelling in the LUQ abdomen

Swelling observed in the upper left quadrant of the abdomen may be caused by enlargements of the following abdominal organs.

Liver

Moderate to significant enlargement of the liver (hepatomegaly) can be detected in the left upper quadrant of the abdomen.

Spleen

An enlargement of spleen (technically referred to as splenomegaly) can be caused by a variety of factors. Some possible causes of splenomegaly include blood-borne infections, hemolytic anemia, lymphatic leukemias, lymphoma, blood clot formation (thrombosis) in the splenic or portal vein, cirrhosis of the liver, myelofibrosis, polycythemia rubra vera, systemic lupus erythematosus, and rheumatoid arthritis. Enlargement of both liver and spleen is referred to as hepatosplenomegaly. Cirrhosis, myeloproliferative diseases, lymphoma and amyloidosis can cause hepatosplenomegaly.

Left kidney

The potential causes for swelling of the left kidney are the same as the causes for the swelling of the right kidney. Renal carcinoma, polycystic kidney disease, and hydronephrosis caused by kidney stones are the main potential causes for swelling of the left kidney.

Stomach

The stomach lies in the left upper quadrant of the abdomen. Therefore, distention of the stomach can result in abdominal distension in the left upper quadrant. Possible causes of stomach distention are delayed gastric emptying and stomach cancer. Delayed gastric emptying of food may be caused by gastroparesis and pyloric stenosis.

Pancreas

A major part of the pancreas lies just behind the stomach in the upper left abdominal quadrant. Increase in the size of the pancreas may be caused by conditions such as pancreatic cancer, pancreatitis, benign cystadenoma, pancreatic abscess and pancreatic pseudocyst.

Colon

Distension of the colon in the upper left quadrant can be caused by accumulation of feces, colitis, colon cancer, diverticulosis, and splenic flexure syndrome.

Aorta

Aortic aneurysm can also cause distension of the abdomen in the upper left quadrant. However, the distension caused by aortic aneurysm may be more prominent in the epigastric region of the abdomen.

Causes of swelling in the middle abdomen

The middle area of the abdomen may be further subdivided into epigastric, umbilical and hypogastric (or suprapubic) regions.

  • Distension of the epigastric region of the abdomen can be caused by swelling of the stomach, colon, pancreas, and aorta.
  • Distension of the umbilical region of the abdomen can be caused by swelling of the stomach, colon, liver and spleen. Significant swelling of the spleen and liver must occur before these organs can be felt in the umbilical region. Crohn’s disease, intestinal obstruction, and hernia are some of the probable causes of bloating or distention in the umbilical region.
  • Distention of the suprapubic or hypogastric region can be caused by swelling of the urinary bladder, prostate gland and uterus. Distension of urinary bladder occurs when there is an obstruction to the flow of urine. The presence of stones may cause such a condition. Bladder cancer is another potential cause of bladder distention.
    A variety of diseases affecting the prostate gland can cause swelling of the prostate gland. Examples include prostatic cancer, prostatitis, and benign prostatic hypertrophy. Distention of the prostate may also affect emptying of the bladder, thereby causing bladder distention. In women, uterine fibroids and uterine cancer can cause swelling of the uterus.

Causes of swelling in the LLQ and RLQ abdomen

Swelling observed in the lower left and right quadrants of the abdomen may be caused by enlargements of the following abdominal organs.

  • Appendix: Abscess in the appendix can cause swelling in the lower right quadrant of the abdomen.
  • Small intestine: Lipoma, intestinal obstruction, and Crohn’s disease can cause distention of the small intestine.
  • Colon: Accumulation of feces, colon cancer, colitis, and diverticulosis are some of the potential causes of distension of the colon.
  • Ovaries: Tumors or cysts in the ovary are frequent causes of swelling in the ovary. Ectopic pregnancy may also be responsible for some cases of distention in the lower left and right abdominal quadrants.

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Other causes of abdominal distention

Abdominal distention can also be caused by problems that are not related to the abdominal organs. Examples of such conditions include hernia, trauma to abdominal wall, lipoma, peritonitis, ascites and peritoneal abscess. These are related to problems in the abdominal wall and peritoneal cavity.

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