Which abdominal study to order, by complaint
- Choosing a study
The right first study depends on where it hurts and who the patient is: ultrasound for gallbladder, pelvis, children and pregnancy; CT for most adults.
What it is
Most abdominal complaints can be sorted with three questions: where is the pain, who is the patient (child, pregnant woman, young woman, older adult) and is the patient stable? Ultrasound is first for the right upper quadrant, the pelvis in women, the kidneys when obstruction is suspected, children and pregnancy, because it is fast, portable and free of radiation. CT with intravenous contrast is the workhorse for most adults with acute abdominal pain, suspected appendicitis, obstruction, perforation or abscess. Non-contrast low-dose CT is the best test for urinary stones in adults. Plain abdominal films have a small role: suspected obstruction, perforation (with an erect chest X-ray) or a swallowed or retained foreign body. MRI helps in pregnancy and for the bile ducts. A CT of the abdomen gives roughly what a person receives from natural background radiation in about three years, while a plain abdominal film is closer to a few months, so the choice should be worth it.
How to decide
- Do a pregnancy test in every woman of reproductive age before any study that uses X-rays.
- Ultrasound first: right upper quadrant pain, jaundice, pelvic pain in women, suspected urinary obstruction, children and pregnancy.
- CT with intravenous contrast first: undifferentiated acute abdominal pain in adults, suspected appendicitis, obstruction, perforation, abscess or diverticulitis.
- Non-contrast CT first: suspected kidney or ureteric stone in a non-pregnant adult.
- An unstable patient is assessed at the bedside (FAST, ultrasound); CT only once stable.
- Contrast is not withheld in a true emergency because of mild kidney impairment; weigh the risk with the radiologist.
| Complaint | First study | Next if needed |
|---|---|---|
| Right upper quadrant pain, suspected gallstones or cholecystitis | Ultrasound | HIDA scan if unclear; MRCP if a duct stone is suspected |
| Jaundice | Ultrasound (are the ducts dilated?) | MRCP or CT; ERCP for treatment |
| Epigastric pain, suspected pancreatitis | Lipase; ultrasound for gallstones | Contrast CT if the diagnosis is unclear or no improvement after 2 to 3 days |
| Right lower quadrant pain, adult | CT with IV contrast | Ultrasound first in young slim women |
| Right lower quadrant pain, child or pregnancy | Ultrasound | MRI in pregnancy; observation, repeat ultrasound or CT in children |
| Renal colic, adult | Non-contrast low-dose CT | Ultrasound for follow-up |
| Renal colic in pregnancy or a child | Ultrasound of the kidneys and bladder | MRI or low-dose CT if still unclear |
| Suspected obstruction | Plain abdominal film | CT with IV contrast to find the cause and level |
| Suspected perforation | Erect chest X-ray | CT if the film is normal and suspicion remains |
| Pelvic pain, woman of reproductive age | Pregnancy test, then pelvic (transvaginal) ultrasound | CT or MRI if ultrasound is normal |
| Acute kidney injury | Renal ultrasound to exclude obstruction | Further imaging guided by the result |
| Older adult, acute pain, or suspected aneurysm or mesenteric ischaemia | CT with IV contrast (CT angiography if vascular) | Bedside ultrasound and surgeon if unstable |
Common mistakes
- Ordering a plain abdominal film for non-specific pain: it is rarely diagnostic and delays the right test.
- Ordering CT for right upper quadrant pain before ultrasound: CT misses many gallstones.
- Forgetting the pregnancy test, or not telling the radiologist the patient may be pregnant.
- Asking for «CT abdomen» without the clinical question: the radiologist chooses the phases and contrast from the question.
- Repeating CT in young patients with recurrent stones when ultrasound would answer the question.
Next step
- Write the clinical question and the key findings on the request (site of pain, fever, lab results, pregnancy status, kidney function).
- If unsure which study or which contrast phase to use, call the radiologist before ordering.
- Unstable patient: bedside FAST or ultrasound and the surgeon, not the scanner.
- First study inconclusive and symptoms persist: escalate (ultrasound to CT or MRI) or re-examine, rather than discharge.
- Child or pregnant woman: ultrasound first and MRI next; use CT when the answer is needed and other tests cannot give it.
Test yourself
Think of the answer, then tap the question to see it.
What is the first imaging test for right upper quadrant pain?
Ultrasound: it is the best test for gallstones and acute cholecystitis and also shows the bile ducts.
Which study is preferred for suspected renal colic in a non-pregnant adult?
Non-contrast low-dose CT of the abdomen and pelvis.
Why is a plain abdominal film a poor test for non-specific abdominal pain?
It is rarely diagnostic, adds radiation and delays the test that answers the question, usually ultrasound or CT.
What must be done before any X-ray-based study in a woman of reproductive age?
A pregnancy test, and the result or the possibility of pregnancy should be written on the request.
Elsewhere in DurgiPedia
Connections
Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.
Sources: Urolithiasis (StatPearls (NCBI Bookshelf), 2023); Acute Cholecystitis (StatPearls (NCBI Bookshelf), 2025); Appendicitis (StatPearls (NCBI Bookshelf), 2024); Ultrasound of the Urinary Tract (StatPearls (NCBI Bookshelf), 2025); Radiation Safety in Medical Imaging (StatPearls (NCBI Bookshelf), 2023).
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Representative model, for educational purposes only.