Abdominal X-rays are one of the most commonly taken X-ray images used in hospitals and clinics today.
An abdominal X-ray is taken when a patient is suspected of having problems with his digestive organs, hepatobiliary and urinary systems, or other abdominal structures.
When an abdominal X-ray is taken, radiation is momentarily applied to the abdomen. The image that is produced is the result of passing X-rays through the abdomen, to the film. Structures like bone or calcification, which are dense and have a high atomic number, absorb a lot of radiation, so that fewer X-rays reach the film, and appear white. Structures like bowel gas, which are full of air and have a low atomic number and density, appear black because most X-rays pass through without being absorbed. Liver, fat, tumor, and fluid absorb less X-rays than bone, but absorb more than air, and consequently appear gray on the film.
In the case of kidney stones, calcified stone absorbs more X-rays than kidneys, so they appear as white spots in the middle of the gray-appearing kidney. When the bowel is perforated from traumatic injury or peptic ulcer, gas can pass through the hole and be seen as a dark area where it shouldn't appear. When there is blockage in the bowel -- as with cancer or inflammatory narrowing -- gas, fluid, and food cannot pass through, thereby causing the bowel to distend. By using X-ray imaging, the black air shadow can delineate the bowel distention and the obstruction.
Abdominal X-ray is less accurate than other special studies, such as ultrasound, intravenous pyelography (IVP), CAT scan, or MRI. But it is highly sensitive in detecting small stones and abnormal gas shadow. It is also helpful in providing a view of the entire abdomen, so that further specific examinations can proceed.
Abdominal distention, abdominal pain, vomiting, diarrhea, and abdominal traumatic injury are the most common reasons for taking abdominal X-rays.
In the case of a urinary disturbance, such as bloody urine (hematuria) or lack of urine, "plain" X-rays can be taken to find stones or calcification (i.e., this type of X-ray is called "KUB," as it is focused on evaluating Kidneys, Ureter and Bladder.)
Urinary stones: stones in kidney, ureter, bladder, or urethra
Gallstones: calcified stones appear white in X-ray, but cholesterol stones cannot be detected using this method of radiography.
Bowel obstruction: causes of bowel obstruction can be cancer, post-surgical adhesion, inflammation, or hernia.
Swallowing foreign bodies, such as coins, pins
Bowel perforations relating to traumatic injury, peptic ulcer, tumor, and inflammation
Enlarged abdominal organs, such as enlarged liver, spleen, gallbladder, or kidneys
Abdominal mass: usually the mass should be large enough to be detected on plain abdominal X-ray. But calcified mass can be easily found, even when it is very small.
Accumulation of abdominal fluid in the case of heart failure, liver failure, renal failure, peritonitis, or traumatic injury
Before being X-rayed, remove all clothing and accessories and change into a hospital gown.
Two views are usually taken:
1. Flat abdominal view. X-rays are taken with the patient flat on his or her back on
the X-ray table. An X-ray tube is positioned over the abdomen and X-rays are exposed to
this area. The X-rays that penetrate will be detected on the film under the table.
For the X-ray image to be clear without blurring, the patient must remain still and hold
his breath while the picture is being taken.
Exposed film is developed, washed, and dried. Then a radiologist (a physician specialist experienced in X-ray and other radiology exams) places the X-ray film over an illumination box and interprets it. When necessary, it is interpreted in comparison to past film.
2. Upright abdominal view. The patient stands with his/her back against the photographic
plate, so that any gas in the abdomen will float and move upward.
No special preparation is needed.
Remove all clothing and jewelry and change into an X-ray gown.
When the X-ray is being taken, stay still and hold your breath.
Women who are pregnant or suspect pregnancy should inform their doctors or X-ray technologists.
If you have taken a barium enema, an upper GI study, or a CAT scan recently, inform your X-ray technologist or doctor. The residual barium or contrast material can hide part of your abdomen or be mistaken for stones or calcifications.
A radiologist (a physician specialist trained to interpret X-ray images or other radiology exams, such as CAT scans, MRI, mammography, etc.) reviews the abdominal X-rays and reports the results to your personal doctor.
The physician's office informs patients when the results are in, and the nature of the results. The office uses the results as a reference in evaluating and treating patients.
Abdominal radiography uses X-rays, a type of ionizing radiation that can potentially change chemical and genetic structures in the human body.
Patients are exposed to far less radiation now than they were in the past because X-rays are collimated so that there is almost no X-ray exposure outside the area of examination, X-rays pass through a filter before being irradiated on the body, and high-speed film is used.
For the safety of patients, radiology technologists and radiologists conduct X-ray exams under guidelines set by national and international radiology protection councils.
To minimize radiation exposure to the reproductive organs, a lead apron/shield can be placed over the testicles (for women, over the pelvic region).
A patient is exposed to 20 miliroentgens of radiation during a typical abdominal X-ray procedure. But considering that one is exposed to 100 miliroentgens a year from ultraviolet rays and small traces of uranium in the soil, radiation exposure from such examinations is really very little.
Women should inform their doctor or X-ray technologist if they are pregnant or suspect pregnancy. Special care will be taken during X-ray exams; otherwise, alternative exams such as ultrasonography can be done instead of X-rays.
Plain abdominal X-rays can render important clues in evaluating one's condition. But in many cases, it does not provide any specific information, and only functions as a gateway examination to the next step.
It is sensitive in detecting stones or abnormal gas shadows. But even when they are found in the X-rays, other examinations such as intravenous pyelography (IVP) or CAT scan should be done to determine if the images finally diagnose kidney stones, or abnormal gas from a perforated peptic ulcer.
Tumors of abdominal organs can be detected earlier using abdominal ultrasonography, abdominal CAT scan, or abdominal MRI than by using plain abdominal x-ray.
In the case of abdominal trauma, abdominal CAT scan is the examination of choice because it can demonstrate internal bleeding, organ injury, or bowel perforation specifically, in an early stage.
If you suspect ulcer, diverticuli, polyp or tumor of the bowel (from stomach, duodenum, small bowel, colon to rectum), barium contrast studies (i.e., barium enema, small bowel series, enteroclysis, upper GI series) or endoscopy should be done, in addition to abdominal X-rays.