Lower GI Series

 National Digestive Diseases Information Clearinghouse 

U.S. Department 

of Health and 

Human Services 

NATIONAL 

INSTITUTES 

OF HEALTH 

What is a lower 

gastrointestinal (GI) series? 

A lower GI series uses x rays to help diagnose problems of the large intestine, which 

includes the colon and rectum. A lower 

GI series is sometimes called a barium 

enema because the large intestine is filled 

with barium liquid. The barium liquid 

coats the lining of the large intestine and 

makes signs of disease show up more clearly 

on x rays. 

Colon 

Anus 

Rectum 

A lower GI series uses x rays to help diagnose 

problems of the large intestine, which includes the 

colon and rectum. 

What problems can a lower 

GI series detect? 

A lower GI series can detect problems of the 

large intestine, including 

•	 polyps 

•	 diverticula—bulges in the intestinal wall 

•	 cancerous growths 

•	 ulcers 

•	 fistulae—abnormal openings in 

the intestinal wall that lead to the 

abdominal cavity, other organs, or the 

skin’s surface 

•	 inflammation 

When is a lower GI series 

used? 

A lower GI series can be used to help determine the cause of 

•	 chronic diarrhea 

•	 rectal bleeding 

•	 abdominal pain 

•	 changes in bowel habits 

•	 unexplained weight loss 
 

How to Prepare for a Lower 

GI Series 

To prepare for a lower GI series, patients 

must empty all solids from the GI tract during a “bowel prep,” which is usually done at 

home. The doctor provides written bowel 

prep instructions. Generally, patients follow 

a clear liquid diet for 1 to 3 days before the 

procedure. Acceptable liquids include 

•	 fat-free bouillon or broth 

•	 strained fruit juice 

•	 water 

•	 plain coffee 

•	 plain tea 

•	 sports drinks, such as Gatorade 

•	 gelatin 

A laxative or enema is usually used the 

evening before a lower GI series. A laxative 

is medicine that loosens stool and increases 

bowel movements. Laxatives are usually 

swallowed as a pill or as a powder dissolved 

in water. An enema involves flushing a liquid 

solution into the anus using a special squirt 

bottle. Enemas are sometimes repeated the 

morning of the test. 

Sometimes, especially when only the rectum or end of the colon is being evaluated, 

emptying all solids from the entire GI tract 

beforehand is not necessary. Instead, the 

patient undergoes one or more enemas the 

day of the procedure to remove solids from 

just the large intestine. 

Before starting the bowel prep, patients 

should tell their doctor about all health 

issues and medications. Women who may be 

pregnant should discuss getting an alternate 

test, such as colonoscopy, or taking precautions to minimize radiation exposure to their 

unborn child. 

How is a lower GI series 

performed? 

A lower GI series is conducted by a radiology 

technologist or a radiologist—a doctor who 

specializes in x-ray imaging—at a hospital or 

outpatient center. 

While the patient lies on an x-ray table, a 

lubricated tube is inserted into the anus and 

the large intestine is filled with barium liquid. 

Patients may experience some discomfort 

and will feel the urge to have a bowel movement. Leakage of barium liquid is prevented 

by an inflated balloon on the end of the tube. 

To evenly coat the inside of the large intestine with barium liquid, patients are asked to 

change positions several times. 

X-ray pictures and possibly x-ray video are 

taken while patients hold still in various 

positions, allowing the technologist or 

radiologist to see the large intestine at 

different angles. If a technologist conducts 

the lower GI series, a radiologist will later 

examine the images to look for problems. 

When the imaging is complete, the balloon 

on the tube is deflated and most of the 

barium liquid drains through the tube. The 

patient expels the remaining barium liquid 

into a bed pan or nearby toilet. An enema 

may be used to flush out the remaining 

barium liquid. The entire procedure takes 

30 to 60 minutes—longer if it includes a 

double contrast study. 

2 Lower GI Series 
 

What is a double contrast 

study? 

The double contrast study gets its name from 

the combination of air and barium liquid 

working together to create a more detailed 

view of the intestinal lining on x rays. If performed, a double contrast study takes place 

after the patient has expelled most of the 

barium liquid. What remains clings to the 

intestinal wall. The large intestine is inflated 

with air, expanding the barium-coated large 

intestine, and additional x rays are taken. 

Recovery from a Lower 

GI Series 

For an hour or so after the procedure, most 

patients experience bloating. Not eating 

before the test and the test itself may cause 

one to feel tired. Repeated bowel movements and enemas during the bowel prep 

may cause anal soreness. And for several 

days, traces of barium liquid in the large 

intestine cause stools to be white or light 

colored. Unless otherwise directed, patients 

may immediately resume their normal diet. 

What are the risks 

associated with a lower 

GI series? 

Mild constipation from the barium enema is 

the most common complication of a lower 

GI series. Rarely, a barium enema causes 

bowel obstruction, a life-threatening condition that blocks the intestines. Drinking 

plenty of liquids after a lower GI series 

flushes out the barium and reduces the risks 

of constipation and bowel obstruction. 

A 1 to 4 percent risk of acute kidney injury 

exists from sodium phosphate—a commonly 

used laxative for lower GI series bowel 

preps.1 Laxatives can also lead to temporary but potentially serious imbalances 

in electrolytes—salts and minerals in the 

body—possibly causing sluggishness, confusion, muscle cramps, and seizures. People 

with—or those at risk for—kidney disease 

should discuss options for minimizing bowel 

prep-related risks with their doctor. 

Rarely, barium liquid causes an allergic reaction, which is treated with antihistamines. 

Leakage of barium liquid into the abdomen 

through a tear in the lining of the large intestine is a rare but serious complication that 

usually requires emergency surgery to repair. 

The risk of radiation-related damage to 

cells or tissues from a lower GI series is low. 

People who have recently undergone other 

x-ray tests should talk with their doctor about 

potential risks. 

Patients who experience any of the following 

rare symptoms after a lower GI series should 

contact their doctor immediately: 

•	 severe abdominal pain 

•	 rectal bleeding 

•	 failure to have a bowel movement 


within 2 days after the procedure
 

•	 inability to pass gas 

•	 fever 

1Lien, YH. Is bowel preparation before colonoscopy a 

risky business for the kidney? Nature Clinical Practice 

Nephrology. 2008;4(11):606–614. 

3	 Lower GI Series 
 

Points to Remember 

•	 A lower gastrointestinal (GI) series uses 

x rays to help diagnose problems of the 

large intestine, which includes the colon 

and rectum. 

•	 A lower GI series can detect polyps, 


diverticula, cancerous growths, and 


other problems. 


•	 To prepare for a lower GI series, 

patients must empty all solids from the 

GI tract during a “bowel prep,” which is 

usually done at home. 

•	 A lower GI series is performed by a 

radiology technologist or a radiologist at 

a hospital or outpatient center. 

•	 During the procedure, the large intestine is filled with barium liquid and x-ray 

pictures and possibly x-ray video are 

taken. 

•	 After the procedure, patients may feel 

tired and bloated and may experience 

anal soreness from the bowel prep. 

•	 Possible risks of a lower GI series 

include mild constipation, bowel 

obstruction, kidney injury, electrolyte 

imbalances, an allergic reaction to 

barium liquid, leakage of barium into 

the abdomen, and cell or tissue damage 

from radiation exposure. 

Hope through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK) 

conducts and supports basic and clinical 

research into many digestive disorders. 

Participants in clinical trials can play a more 

active role in their own health care, gain 

access to new research treatments before 

they are widely available, and help others 

by contributing to medical research. For 

information about current studies, visit 

www.ClinicalTrials.gov. 

For More Information 

Fact sheets about other diagnostic tests 

are available from the National Digestive 

Diseases Information Clearinghouse at 

www.digestive.niddk.nih.gov, including 

•	 Colonoscopy 

•	 ERCP (Endoscopic Retrograde 


Cholangiopancreatography)
 

•	 Flexible Sigmoidoscopy 

•	 Liver Biopsy 

•	 Upper GI Endoscopy 

•	 Upper GI Series 

•	 Virtual Colonoscopy 

American College of Gastroenterology 

P.O. Box 342260 

Bethesda, MD 20827–2260 

Phone: 301–263–9000 

Fax: 301–263–9025 

Email: info@acg.gi.org 

Internet: www.acg.gi.org 

American Gastroenterological Association 

4930 Del Ray Avenue 

Bethesda, MD 20814 

Phone: 301–654–2055 

Fax: 301–654–5920 

Email: member@gastro.org 

Internet: www.gastro.org 

4	 Lower GI Series 
 

 

 

 

 

 

 

 

 

 

 

Acknowledgments 

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This publication 

was reviewed by M. Brian Fennerty, M.D., 

Oregon Health and Science University. 

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov. 

This publication may contain information about 

medications. When prepared, this publication 

included the most current information available. 

For updates or for questions about any medications, 

contact the U.S. Food and Drug Administration 

toll-free at 1–888–INFO–FDA (1–888–463–6332) 

or visit www.fda.gov. Consult your doctor for more 

information. 

The U.S. Government does not endorse or favor any 

specific commercial product or company. Trade, 

proprietary, or company names appearing in this 

document are used only because they are considered 

necessary in the context of the information provided. 

If a product is not mentioned, the omission does not 

mean or imply that the product is unsatisfactory. 

5 Lower GI Series 
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The National Digestive Diseases Information 

Clearinghouse (NDDIC) is a service of the 

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and Kidney Diseases (NIDDK). The 

NIDDK is part of the National Institutes of 

Health of the U.S. Department of Health 

and Human Services. Established in 1980, 

the Clearinghouse provides information 

about digestive diseases to people with 

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This publication is available at 

www.digestive.niddk.nih.gov. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 10–4334 

December 2009