What is a distended stomach?
The stomach is a hollow organ that fills with food after eating. Its walls are able to stretch and the entire stomach can distend to several times its size when empty. This distention is usually not visible from the exterior as space within the abdominal cavity allows for the stomach to expand. The term ‘stomach’ is also commonly used, and quite incorrectly, to refer to the abdominal cavity as a whole. Yet the stomach only occupies a small portion of the abdominal cavity, mainly sitting in the left upper quadrant. The term ‘distended stomach’ is therefore often used to refer to a distended abdomen.
The abdominal cavity is covered by the abdominal wall comprising skin, subcutaneous tissue including variable amounts of fat, muscles and and inner abdominal lining known as the peritoneum. There is no skeletal system offering a rigid framework to protect the abdominal cavity. Therefore the abdomen can expand with accumulation of fluid, blood, gas or any mass within the cavity. The entire abdomen may distend with fluid and gas or there may be localized distension (protrusion) with masses.
Distension vs Bloating
There are several common terms to describe abdominal distension including :
Swelling indicates an enlargement usually due to fluid accumulation. Bloating is a non-specific term to describe enlargement as well due to any cause. However, bloating is a common term to describe a sensation of fullness. Stomach bloating therefore may also refer to fullness in the stomach area, often felt after overeating or with indigestion.
Causes of a Distended Stomach
Distension may be generalized or localized. Generalized distension of the abdomen means that the entire abdomens is enlarged. Localized distension means that the enlargement is more prominent in one part of the abdomen.The causes of localized distension may differ depending on the location – one of the four abdominal quadrants : right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ) or left lower quadrant (LLQ).
The main causes of generalized distention of the stomach (abdomen) includes :
- Ascites is fluid accumulation within the abdominal cavity.
- Peritonitis is an inflammation of the inner lining of the abdominal cavity.
- Intra-adominal abscess is an accumulation of pus within the abdominal cavity which causes generalized abdominal distension along with localized distension.
- Internal bleeding (intra-abdominal) may arise when there is a rupture of a blood vessel following trauma or related to an abdominal aortic aneurysm (AAA).
- Functional bloating is distension that occurs for no known reason. It can occur on its own or be a symptom of other functional bowel disorders like irritable bowel syndrome (IBS).
Certain causes may lead to localized distension in any quadrant of the abdomen. This includes :
- Trauma to the abdominal wall.
- Hernia is a weakening in the abdominal wall thereby allowing parts of organs to protrude through it.
Any of the causes discussed below can also cause generalized abdominal distension.
Abdominal distension due to cirrhosis (liver disease)
Picture from Wikimedia Commons
Right Upper Quadrant
Hepatomegaly is an enlargement of the liver. In massive hepatomegaly, the enlargement may extend to the left upper quadrant (LUQ). Causes include :
- Alcoholic liver disease
- Primary hepatocellular carcinoma (liver cancer)
- Autoimmune hepatitis
- Viral hepatitis
Heart failure is an inability of the heart to conduct its functions properly. Some of the cardiac-related causes include :
- High blood pressure (hypertension)
- Heart valve defects
- Coronary artery disease (CAD)
- Heart muscle inflammation (myocarditis) or damage (cardiomyopathy)
- Congenital heart defects
- Arrhythmias (irregular heart beat)
Gallbladder disease is any disorder affecting the gallbladder, its duct or the other bile ducts. Some of the causes include :
- Cholangitis – inflammation of the gallbladder
- Gallbladder cancer
Kidney disease involving the right kidney specifically for right upper quadrant (RUQ) distension may be caused by :
- Polycystic kidney
- Renal carcinoma (cancer of the kidney)
Colon disease involving the upper part of the ascending colon, hepatic flexure and first half of the transverse colon may cause right upper quadrant distension. Causes may include :
- Colonic obstruction (blocked colon)
- Colon cancer
Left Upper Quadrant
Hepatomegaly mainly causes distension most prominently in the right upper quadrant (RUQ) but if it is severe it may extend to the left upper quadrant (LUQ). Causes are the same as above.
Splenomegaly is an enlargement of the spleen which may be caused by :
- Infections, especially blood-borne infections
- Hemolytic anemia
- Polycythemia rubra vera
- Heart failure
- Cirrhosis (liver)
- Thromobosis in the portal or splenic vein.
Hepatosplenomegaly is a simultaneous enlargement of the liver and spleen which may be caused by :
- Myeloproliferative diseases
Kidney disease of the left kidney may occur for the same reasons as discussed above under the right kidney.
Stomach disease may be a cause of left upper quadrant distension. A large part of the stomach is tucked under the left rib cage but it does distend with eating and less commonly with drinking fluids. Some of the causes of left upper quadrant distension due to stomach problems includes :
- Delayed gastric emptying like pyloric stenosis or gastroparesis.
- Stomach cancer
- Stomach polyps
Pancreas problems may cause left upper abdominal quadrant distension but the head of the pancreas, which is the part most commonly affected with pancreatic diseases, sits in the middle of the abdomen. Some of the causes of pancreatic diseases include :
- Pancreatic cancer
- Pancreatic pseudocyst
- Pancreatic abscess
- Cystadenoma (benign)
Colon disease may cause left upper abdominal quadrant distension when the left half of the transverse colon, splenic flexure and/or the first part of the descending colon are affected. The causes are largely the same as colon disease causing right upper abdominal distension as discussed above. Splenic flexure syndrome which is believed to be caused by trapped gas is an additional causative factor to consider.
Aorta problems (abdominal aorta) are more likely to cause distension in the middle of the abdomen. The most likely cause is an aortic aneurysm. If the aneurysm ruptures then blood may accumulate within the abdomen (internal bleeding) thereby causing generalized distension.
This is the area immediately behind and around the belly button (navel). Some of the causes of distension in this region includes :
- Hernia, particularly a paraumbilical hernia.
- Crohn’s disease (small intestine) which is a type of inflammatory bowel disease (IBD).
- Intestinal obstruction (blocked bowel)
- Hepatomegaly (massive)
- Splenomegaly (massive)
This is the lower middle part of the abdomen, below the navel, and just above the external genitalia. Extra fat accumulation in the area is common particularly in women. Some of the causes of distension in this area includes :
- Bladder disease particularly where there is severe inflammation of the bladder, a mass in the bladder or overdistension as is seen with bladder outlet obstruction often caused by bladder stones, bladder cancer and cystitis.
- Prostate disease (men only) that may lead to suprapubic distension includes benign prostatic hypertrophy (enlarged prostate), prostatitis or prostate cancer.
- Uterus problems (women only) that may cause distension of the suprapubic region possibly extending up to umbilical region includes uterine fibroids or uterine cancer.
The causes of the right and left lower abdominal quadrant are discussed together although some causes may be isolated more to one side.
- Appendicitis is the inflammation of the vermiform appendix – the small outpouching from the cecum of the large intestine. It is more likely to cause lower right quadrant distension and generalized distension.
- Tumors – benign (non-cancerous) or malignant (cancerous)
- Small intestine – Crohn’s disease, intestinal obstruction.
- Large intestine – severe constipation, flatus (gas), impacted feces, colitis, colon cancer or diverticulosis.
- Gynecological disorders – ovarian cyst, ovarian tumor or ectopic pregnancy.