I. Problem/Condition.

Abdominal swelling is a general condition in which the abdomen is distended or enlarged. Abdominal swelling can be associated with a sensation of fullness, bloating, stretching, or pain and is usually associated with an increase in overall girth.

II. Diagnostic Approach

A. What is the differential diagnosis for this problem?

Broadly speaking, abdominal swelling can be due to ascites, organomegaly or constipation with retained air. These conditions can cause generalized abdominal distension or swelling.

Ascites can be caused by a number of underlying conditions that can be broadly categorized to include hepatic disorders like cirrhosis, cardiac disorders like congestive or right sided heart failure, malignancy like peritoneal carcinomatosis, and portal vein thrombosis. Pancreatic disease like pancreatitis, and infectious disorders like tuberculosis can also cause the formation of ascites. Finally ascites can also be associated with hemodialysis in patients with end stage renal disease.

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Constipation with associated abdominal distension can be caused by metabolic disorders including hypokalemia, hypocalcemia and other electrolyte disturbances, neurologic disorders including Hirschprung’s and Parkinson’s disease, and endocrine disorders including hypothyroidism.

Chronic use of medications including narcotic analgesics, sedatives and anticholinergics may also cause constipation with abdominal swelling.

Finally, malignancy, including colon cancer, generalized weakness and prolonged immobility and pregnancy can also result in abdominal distension.

B. Describe a diagnostic approach/method to the patient with this problem

In a patient with abdominal swelling the differential diagnosis is broad, so focus on obtaining a history that addresses the most common causes of ascites and chronic constipation. Ask the patient if there is any history of liver disease and heavy alcohol use. Take a detailed history of the type and quantity of alcohol the patient drinks per week. Ask the patient about acetaminophen use including dose and duration.

Ask about symptoms associated with heart failure including orthopnea and shortness of breath, and malignancy including weight loss and loss of appetite. Take note of the patient’s medications including narcotics, sedatives and anticholinergics. Take a detailed account of the patient’s bowel habits including movements per day, if there has been any recent change on quality or appearance of the stool and straining. Ask the patient if there is any history of thyroid disease, diabetes and neuropathy.

1. Historical information important in the diagnosis of this problem.

More specifically, to help determine the cause of a patient’s abdominal swelling, the following systematic approach to asking pertinent questions can be used.

In a patient who may have ascites as the cause of his/her abdominal swelling it is important to focus on:

Hepatic disease
  • Do you have a history of liver disease or cirrhosis? Is there a history of liver disease in your family?

  • Do you drink alcohol? If so, how much do you drink, and for how long have you been drinking?

  • Do you have a history of hepatitis C or B?

  • Do you have a history of an iron storage disease affecting the liver?

Congestive heart failure
  • Do you have a history of congestive heart failure or heart disease?

  • Do you get short of breath when lying flat? Do you wake up in the middle of the night gasping for air?

  • How many pillows do you sleep on?

Portal vein thrombosis
  • Do you have a history of blood clots, or a clotting disorder?

Renal failure
  • Do you have a history of recent kidney injury or chronic kidney disease?

  • Are you on hemodialysis?

  • Do you have a history of pancreatitis? Do you drink alcohol? How much?

  • Do you have a history of cancer? If yes, where? Has it spread?

  • Have you ever been diagnosed with tuberculosis, or have you recently travelled to a country endemic for tuberculosis (TB)?

  • Do you have a history of cancer? If yes, where? Has it spread?

  • Are you losing weight? If so, how much and over what time period? Have you lost your appetite?


In a patient who may be constipated withassociated abdominal swelling, assess the nature and duration of theirconstipation. It is important to ask about the following associatedcauses:

  • Do you take any medications that cause you to be constipated or feel bloated? Are you taking any opiates like morphine?

  • Do you use any illegal drugs?

  • Narcotics, iron supplements, anticholinergics, and some anti-hypertensives like calcium channel blockers are associated with constipation.

Endocrine disorders
  • Do you have a history of diabetes mellitus? If yes, what type? Is it well controlled?

  • Do you have a history of under-active thyroid? If yes, are you on any thyroid replacement medications?

  • Do you have normal sensation in your hands and feet?

  • Do you have any numbness, tingling or burning sensations?

  • Do you have a history of Parkinson’s disease, multiple sclerosis or spinal cord injury?

  • Do you have a history of Hirschprung’s disease?

Irritable bowel syndrome
  • Do you suffer from irritable bowel syndrome?

  • Do you notice a frequent change in the frequency or quality of your bowel movements?

  • Are you pregnant?

  • Do you use a regular form of contraception?

2. Physical Examination maneuvers that are likely to be useful in diagnosing the cause of this problem.

In patients with abdominal swelling, expose the abdomen and check for a fluid thrill and shifting dullness to help confirm the presence of free fluid. Once you have determined that there is ascites, systematically evaluate the patient for stigmata of liver disease including spider angiomata, gynecomastia and asterixis.

Examine for signs of heart failure including an elevated jugular venous distention (JVD), pitting edema and renal failure by looking for signs of anemia, bruising and hyperventilation (metabolic acidosis). Also look for signs associated with pancreatitis including Cullen’s or Grey-Turner’s sign and malignancy (is a sister Mary Joseph nodule present?). Signs associated with alcoholism or alcohol withdrawal can be helpful also.

In patients with suspected chronic constipation and abdominal swelling, the rectal examination is helpful. Perform a digital rectal exam and assess the rectal tone. In patients with dyssynergia of the rectum, deep palpation of the abdominal wall muscles (with the opposing hand) while checking the rectal tone will not produce the normal rectal sphincter relaxation expected. Instead, inappropriate contraction or diminished relaxation will result. The presence of anal fissures and external hemorrhoids can implicate voluntary constipation in order to avoid the pain of defecation as a possible cause.

3. Laboratory, radiographic and other tests that are likely to be useful in diagnosing the cause of this problem.

In evaluating the patient with abdominal swelling, a hepatic panel, complete blood count, basic metabolic panel, serum calcium and magnesium, and serum lipase should be routinely obtained to help rule out hepatic, pancreatic or electrolyte disorders. A serum thyroid-stimulating hormone (TSH) can help rule out underlying thyroid disease. A plain film x-ray of the abdomen can help identify significant stool burden in the colon or the presence of free air.

A colonoscopy may be considered in patients over the age of 50 with no prior screening for colon cancer or in those at increased risk for underlying malignancy with unexplained anemia, weight loss or abdominal pain. Defacography and anorectal manometry are available tools for diagnosing dyssynergic defecation and rectal sensation and compliance but are not widely available and are heavily operator dependent.

C. Criteria for Diagnosing Each Diagnosis in the Method Above.

To make the diagnosis of ascites, a combination of the physical examination and radiologic testing is most helpful. The presence of ascites can be confirmed with an abdominal ultrasound, demonstrating free fluid in the abdomen. If free fluid is found, abdominal paracentesis should then be performed to calculate the serum to ascites albumin gradient (SAAG) which will help you determine if the fluid is secondary to portal hypertension or not. A SAAG of greater than 1.1g/dL would indicate the presence of portal hypertension. Furthermore, a cell count with differential can help determine the presence or absence of spontaneous bacterial peritonitis.

In patients with constipation and retained air in the bowel causing abdominal swelling, a combination of the history, physical examination, laboratory testing, and radiology is useful. A history of three or fewer bowel movements per day with the passage of hard or lumpy stools and straining is strongly suggestive of constipation. Immobility, narcotic use, hypothyroidism, diabetes, and neuropathy associated with Hirshprung’s or Parkinson’s disease all predispose a patient to the development of constipation. Combining radiologic data and findings from defacography and anorectal manometry, the diagnosis of chronic constipation as the cause for a patient’s abdominal swelling may be found.

D. Over-utilized or “wasted” diagnostic tests associated with the evaluation of this problem.

Computed tomography (CT) scan of the abdomen may be unnecessary in the initial evaluation of a patient with abdominal swelling. Sending paracentesis fluid for potential hydrogen (pH), lactate and cholesterol is also unnecessary.

III. Management while the Diagnostic Process is Proceeding

A. Management of abdominal swelling.

In the patient with abdominal swelling, bowel obstruction and impending bowel wall perforation require urgent evaluation and management. In the patient with nausea, vomiting and abdominal swelling, place a nasogastric tube to suction in order to decompress the gastrointestinal tract. The patient should be strictly nil per os (NPO), and all electrolytes including calcium and magnesium and serum phosphorous should be aggressively repleted. Intravenous (IV) fluid hydration should be started immediately. Avoid narcotic analgesia, anticholinergics and sedatives.

Obtain a plain film x-ray of the abdomen and CT scan of the abdomen if perforation or megacolon is strongly suspected and obtain a surgical consultation early if necessary. Extreme colonic dilatation is entertained if the bowel diameter is 12cm or more. A rectal tube to gravity may be placed. The presence of fever, leukocytosis, tachycardia and significant abdominal pain make the diagnosis of toxic megacolon more likely. If colonic obstruction has been ruled out, IV neostigmine can be utilized for those patients who have not responded to conservative therapy.

B. Common Pitfalls and Side-Effects of Management of this Clinical Problem

Overuse of narcotic analgesia.

IV. What's the evidence?

Lasser, RB, Bond, JH, Levitt, MD. “The role of intestinal gas in functional abdominal pain”. N Engl J Med. vol. 293. 1975. pp. 524-526.

Runyon, BA. “Management of adult patients with ascites caused by cirrhosis”. Hepatology. vol. 27. 1998. pp. 264-272.

Eisen, GM, Baron, TH, Dominitz, JA. “Acute colonic pseudo-obstruction”. Gastrointest Endosc. vol. 56. 2002. pp. 789-792.