A CT scan of the abdomen and pelvis (plain) is a diagnostic imaging test that uses X-rays and computer processing to create detailed, cross-sectional (“slice-like”) pictures of the organs, blood vessels, bones, and soft tissues in your belly (abdomen) and lower abdomen (pelvis). “Plain” means the scan is performed without contrast dye (no IV contrast and typically no oral contrast), which can be helpful in situations where contrast is not needed or not recommended.

This type of medical imaging is performed in the radiology department. During the scan, a CT machine rotates around you to capture many images quickly. A radiologist then interprets the images and sends a report to your clinician.

What it shows/assesses: A plain CT scan can evaluate the size, shape, and appearance of abdominal and pelvic organs (such as the liver, kidneys, pancreas, spleen, bladder, uterus/ovaries or prostate), the bowel, lymph nodes, and the bony pelvis/spine. It can help identify concerns such as internal injuries, certain types of tumors, bleeding, kidney stones, bowel obstruction, or fluid collections.

What the results may mean (in plain language): Your results generally fall into patterns like: (1) No acute abnormality—no urgent cause is seen for symptoms such as abdominal pain; (2) A specific finding is identified—for example, a kidney stone, bowel blockage, inflamed appendix, fluid/abscess, enlarged organs, swollen lymph nodes, or a suspicious mass; or (3) Incidental findings—unexpected findings that may not be related to your symptoms (such as benign cysts). A CT report often recommends next steps, such as follow-up imaging, blood/urine tests, or referral to a specialist, depending on what is found.

A CT scan abdomen & pelvis (plain) is commonly ordered to help quickly determine the cause of symptoms or to evaluate known conditions. Your doctor may request this CT scan when a detailed look is needed beyond what an X-ray or ultrasound can provide, especially in urgent or complex situations.

Symptoms that may prompt this test include:

• Sudden or severe abdominal pain or pelvic pain
• Flank pain (side/back pain), especially when kidney stones are suspected
• Nausea/vomiting with concern for bowel blockage
• Fever with concern for infection or an abscess (a collection of pus)
• Blood in the urine (hematuria) when stones or urinary tract causes are suspected
• Unexplained weight loss, abdominal swelling, or a new palpable lump

Common clinical reasons (why it’s done):

• Suspected kidney/ureter stones: Non-contrast (plain) CT is often the preferred imaging test for detecting many urinary stones.
• Trauma or internal injuries: Helps assess for bleeding, organ injury, or fractures in the abdomen/pelvis (the exact protocol depends on the situation).
• Possible bowel obstruction or perforation: Can identify dilated bowel loops, transition points, or free air.
• Evaluation of masses or tumors: A plain CT may detect a mass; in some cases, contrast CT, MRI, or ultrasound is then used for better characterization.
• Appendicitis or diverticulitis workup: CT is commonly used to evaluate these; whether contrast is used depends on clinical judgment, kidney function, allergy history, and local protocols.
• Pre-procedure planning or follow-up: Monitoring certain conditions over time, such as stone burden or known lesions.

Why “plain” (no contrast) may be chosen: It may be selected when contrast isn’t necessary for the clinical question (for example, stones), or when contrast should be avoided due to prior severe contrast reaction, certain kidney problems, or other individualized factors. Your clinician and radiology team decide the most appropriate CT protocol for your symptoms and medical history.

• Kidney stones (renal calculi) and ureteral stones
• Appendicitis
• Diverticulitis
• Bowel obstruction (small bowel obstruction or large bowel obstruction)
• Abdominal or pelvic tumors/masses (benign or malignant)
• Enlarged lymph nodes (lymphadenopathy)
• Internal bleeding (hemorrhage) or other internal injuries after trauma
• Abdominal or pelvic abscess and certain infections/inflammatory conditions
• Hernias (such as inguinal or ventral hernia) and related complications
• Urinary tract obstruction (hydronephrosis)
• Ovarian cysts or pelvic masses (often followed up with ultrasound/MRI as needed)

• Finding the cause of persistent or severe abdominal pain or pelvic pain
• Rapid evaluation after accidents to check for internal injuries and bleeding
• Detecting and monitoring kidney stones and preventing recurrence through targeted care
• Assessing suspected bowel problems (for example, obstruction) to guide timely treatment
• Supporting earlier detection and evaluation of possible tumors or abnormal growths
• Guiding next steps in care (follow-up imaging, specialist referral, or treatment planning) based on clear radiology findings
• Tracking known abdominal or pelvic conditions over time to monitor stability or progression