Abdomen/PelvisLive data

CT Abdomen/Pelvis with Contrast

Contrast-enhanced CT of the abdomen and pelvis is the workhorse study for acute and chronic abdominal complaints, providing comprehensive evaluation of solid organs, bowel, mesentery, vasculature, and the peritoneal cavity. Portal venous phase imaging optimizes enhancement of the liver, spleen, and bowel wall, making it sensitive for infection, inflammation, ischemia, obstruction, and malignancy. Protocol tailoring (phases, oral contrast) depends on the specific clinical question.

Indications

Acute abdominal or pelvic pain of uncertain cause
Suspected appendicitis, diverticulitis, or other intra-abdominal infection/abscess
Bowel obstruction, ischemia, or perforation evaluation
Staging, surveillance, and complication assessment of known or suspected malignancy
Blunt or penetrating abdominal trauma (typically portal venous, with arterial phase for active bleeding)
Unexplained sepsis, fever of unknown origin, or leukocytosis to seek an occult source
Postoperative complication assessment (collection, leak, ischemia)

Contraindications & Cautions

Iodinated contrast allergy: use premedication or an alternative modality; document prior reactions
Renal impairment: assess eGFR, weigh risk of contrast-associated nephropathy, and hydrate; avoid or reduce contrast when appropriate
Pregnancy: justify; use IV contrast only when essential and counsel on iodine and fetal considerations
Metformin: no need to stop before contrast in normal renal function; follow local policy in renal impairment
Severe uncorrected hypovolemia or unstable patient without resuscitation and monitoring
ALARA dose considerations, particularly in young patients requiring repeat imaging

Patient Preparation

Fasting typically 4-6 hours before IV contrast to reduce aspiration risk with reactions
Establish reliable IV access (18-20 G antecubital preferred) for power injection
Administer oral contrast (positive or neutral) over 45-90 minutes when bowel evaluation is required; omit for renal colic/trauma per protocol
Screen renal function, contrast allergy, and pregnancy status; obtain consent per local policy
Position supine, arms raised above the head to reduce streak artifact
Rehearse a single breath-hold to minimize respiratory motion

Technique & Parameters

Helical acquisition from the diaphragmatic domes to the pubic symphysis (include lung bases and ischial tuberosities)
IV contrast 90-120 mL of iodinated agent at 2.5-4 mL/s; portal venous phase at ~65-75 s delay
Add arterial (~30-35 s or bolus-tracked) and delayed phases for trauma, hypervascular tumors, or hematuria as indicated
120 kVp (lower kVp for slim patients / vascular studies) with automated tube-current modulation
Reconstruct 3-5 mm axial images with 1-2 mm thin sections for multiplanar and vascular reformats
Review on soft-tissue, lung (bases), and bone windows; coronal and sagittal reformats routinely

Systematic Review

Solid organs: liver, spleen, pancreas, adrenals, and kidneys for lesions, laceration, or enhancement abnormality
Hollow viscera: stomach and bowel for wall thickening, dilatation, transition point, and enhancement
Mesentery and peritoneum: fat stranding, free fluid, free air, nodules, and collections
Vasculature: aorta, mesenteric vessels, and portal/hepatic veins for aneurysm, thrombus, or active extravasation
Lymph nodes: mesenteric, retroperitoneal, and pelvic node size and morphology
Urinary tract and pelvic organs (bladder, uterus/ovaries or prostate), and hernial orifices
Skeleton and lung bases for metastases, fractures, and incidental thoracic findings

Key Findings & Significance

Dilated fluid-filled appendix >6 mm with periappendiceal fat stranding: acute appendicitis
Colonic wall thickening with pericolic stranding and diverticula: acute diverticulitis (assess for abscess/perforation)
Small-bowel dilatation with a transition point and collapsed distal loops: mechanical obstruction
Pneumoperitoneum or focal defect: perforation; extraluminal contrast indicates a leak
Reduced or absent bowel-wall enhancement, pneumatosis, and portal venous gas: bowel ischemia
Organ laceration, perisplenic/perihepatic blood, or a contrast blush: traumatic injury with active bleeding
Solid-organ or nodal masses, ascites, and peritoneal implants: malignancy or metastatic disease

Differential Considerations

Right lower quadrant pain: appendicitis vs mesenteric adenitis vs terminal ileitis vs ovarian pathology
Left lower quadrant pain: diverticulitis vs epiploic appendagitis vs colitis vs ureteric colic
Diffuse bowel-wall thickening: infectious/inflammatory colitis vs ischemia vs edema (low-albumin/heart failure)
Hypodense liver lesion: cyst vs metastasis vs hemangioma vs abscess (correlate phases)
Free fluid: physiologic/benign ascites vs hemoperitoneum vs infected/malignant fluid
Pancreatic changes: acute pancreatitis vs neoplasm; assess for necrosis and vascular complications

Pearls & Pitfalls

Always scrutinize the lung bases and hernial orifices, which are common sites of missed pathology
A closed-loop obstruction (U- or C-shaped loop, converging mesenteric vessels) mandates urgent flagging for strangulation
Portal venous timing can miss active arterial bleeding; add an arterial phase in trauma or GI hemorrhage
Under-opacified bowel can mimic wall thickening or a mass; use multiplanar review and water-density oral contrast when needed
Small-volume pneumoperitoneum is best seen on lung windows in the non-dependent abdomen
Do not overlook incidental but significant findings (adrenal, renal, and pancreatic lesions) requiring follow-up

Structured Report

State protocol, phase(s), oral/IV contrast, and comparison studies
Report the primary finding relevant to the clinical question first, with location and severity
Systematically document solid organs, bowel, vasculature, nodes, urinary/pelvic organs, and peritoneum
Quantify obstruction transition points, collection sizes, and free fluid/air
Note incidental findings and recommend appropriate follow-up (e.g., per ACR incidental findings guidance)
Impression: concise prioritized diagnosis, complications, and actionable recommendations

References

ACR Appropriateness Criteria: Acute Nonlocalized Abdominal Pain; Right Lower Quadrant Pain; Left Lower Quadrant Pain
ACR Manual on Contrast Media
ACR White Papers on Managing Incidental Findings
Federle et al., Diagnostic Imaging: Abdomen

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CT Abdomen/Pelvis with Contrast

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References