How to Dictate a CT Abdomen and Pelvis: Organ Order, Incidentaloma Routing, and the Appendix Sentence

The CT abdomen and pelvis is the workhorse of the emergency list and the easiest report to dictate badly, because it contains more organs than any other study and the clinical question usually concerns exactly one of them. The temptation is to answer the question and wave at the rest. The discipline is the opposite: a fixed organ-by-organ march, every study, every time — because the march is what catches the finding nobody asked about, and the finding nobody asked about is where this exam's lawsuits live.

The order is the checklist

Dictate the same sequence every time, and the sequence becomes a search pattern:

Lung bases → liver → gallbladder and biliary tree → pancreas → spleen → adrenals → kidneys and ureters → stomach and bowel → appendix → bladder → reproductive organs → lymph nodes → vessels → peritoneum and mesentery → abdominal wall → bones.

Each organ gets a line even when normal, because a named normal is evidence you looked and an unnamed organ is evidence of nothing. "Visualized lung bases are clear" is the first line for a reason: the bases are on every abdominal CT and basal nodules, effusions, and the occasional pulmonary embolus in the imaged segmental arteries are classic satisfaction-of-search misses once you've scrolled past the diaphragm.

Two habits make the march fast rather than tedious. First, normal lines are short and fixed — our normal CT abdomen/pelvis template is the scaffold. Second, pathology gets dictated within its organ's slot, not appended at the end; the reader hunting for the pancreas finds everything pancreatic in one place.

Incidentaloma routing: know the next test before you dictate

The abdominal CT is incidentaloma country, and the resident's job is not to characterize everything on a portal-venous single phase — it is to route each incidental finding to the correct characterizing study, using the white-paper logic the attendings apply reflexively.

Renal lesions. A homogeneous, water-density, non-enhancing lesion is a simple cyst; say benign and stop. Anything complex — septations, mural thickening, nodularity, hyperdensity — on a single-phase study is "incompletely characterized," and the routing sentence is: recommend renal-mass-protocol CT or MRI for Bosniak classification. Do not assign a Bosniak class from a portal-venous phase alone; the system is defined on dedicated pre- and post-contrast imaging, and a confident wrong class is worse than an honest deferral.

Adrenal nodules. The question is adenoma versus not. If an unenhanced series exists and the nodule measures ≤ 10 HU, it is a lipid-rich adenoma — say so and close the loop. On a contrast-only study, a nodule 1–4 cm with no priors routes to adrenal washout CT: the widely taught thresholds are absolute washout ≥ 60% or relative washout ≥ 40% for adenoma — arithmetic the adrenal washout calculator does from three ROI values. Under 1 cm with no cancer history generally needs nothing; ≥ 4 cm is surgical-consult territory regardless of washout. A prior CT showing the nodule stable for years outranks all of it — say "stable since 2021, benign" and spare the patient the workup.

The pattern generalizes: the single-phase CT's verb for an incidentaloma is rarely "is" and usually "route to" — the right protocol, the right interval, or the priors. The calculator hub exists because the thresholds are lookup values, not judgment; the judgment is knowing which lookup applies.

The appendix sentence

Every CT abdomen and pelvis contains exactly one sentence about the appendix, and it is one of three:

1. "The appendix is normal" — when you traced it, tip to base, and it is.
2. "Acute appendicitis" — with the caliber in millimeters, periappendiceal fat stranding, an appendicolith if present, and the complications line: no evidence of perforation, abscess, or extraluminal gas (or the evidence thereof).
3. "The appendix is not definitively visualized; no secondary signs of acute appendicitis" — the honest third option, which exists so that option one is never a bluff.

What is not allowed is silence. An appendicitis miss on a CT whose report never mentions the appendix is indefensible; the same miss after sentence three is a documented limitation. A normal appendix is conventionally 6 mm or less in caliber, but caliber alone neither makes nor breaks the diagnosis — a fluid-distended 7 mm appendix with clean fat is usually fine, and the sentence should weigh the fat stranding more than the ruler.

Free air and free fluid: wording that moves

Free intraperitoneal air is a phone call, and the report should read like one. Say where it is ("anti-dependent free air along the anterior liver margin"), how much, and the presumptive source ("adjacent to the gastric antrum, suspicious for perforated ulcer"). Two qualifiers keep you honest: recent surgery or instrumentation explains small-volume pneumoperitoneum for days — name the surgery and the date; and tiny locules need lung windows to find and to trust. "No free air" dictated from soft-tissue windows alone is a guess.

Free fluid gets a volume word (trace, small, moderate, large), a location, and — when it matters — a density. Simple fluid measures water; fluid in the 30–45 HU range in a trauma patient is blood until proven otherwise, and the word is "hemoperitoneum," not "fluid." Trace pelvic free fluid in a woman of reproductive age is commonly physiologic; the same finding in a 70-year-old man is not, and the report should know the difference. When free air and free fluid coexist, say so in the same sentence — the combination upgrades the urgency beyond either alone.

The phrases attendings correct

• "Unremarkable abdomen and pelvis" as a findings section. The march or nothing.
• "Cannot exclude" attached to an organ you never mentioned otherwise. If you can't exclude it, say what limits you.
• "Correlate clinically" as the entire plan for an incidentaloma. Route it: the protocol, the interval, or the priors.
• Burying free air in line nine. Emergencies lead the impression, numbered first, with the documentation of who was called and when.

A model report

EXAMINATION: CT abdomen and pelvis with IV contrast
HISTORY: 63-year-old male, right lower quadrant pain,
leukocytosis.
TECHNIQUE: Portal venous phase axial images from lung
bases through pubic symphysis following IV contrast.
Oral contrast administered.
COMPARISON: CT abdomen 2021-03-18.
FINDINGS:
Lung bases: Clear. No effusion.
Liver: Normal attenuation. No focal lesion.
Gallbladder/biliary: No stones or ductal dilation.
Pancreas: Normal. Spleen: Normal.
Adrenals: 1.8 cm left adrenal nodule, homogeneous,
unchanged from 2021 — benign.
Kidneys: 2.4 cm simple left renal cyst. No
hydronephrosis or stone.
Bowel: The appendix is dilated to 11 mm with an
appendicolith and periappendiceal fat stranding. No
extraluminal gas or organized fluid collection. Remaining
bowel normal caliber.
Bladder/prostate: Unremarkable.
Lymph nodes/vessels: No adenopathy. Atherosclerotic
aorta, normal caliber.
Peritoneum: No free air or free fluid.
Bones: Degenerative change, no aggressive lesion.
IMPRESSION:
1. Acute uncomplicated appendicitis — no perforation or
   abscess. Findings called to Dr. Lee at 14:32.
2. Left adrenal nodule stable since 2021, benign; no
   further workup.
3. Simple left renal cyst — benign.

The march answers the question, routes the incidentals, and documents the call. If you want to see a scratch dictation become this report with the organ order enforced and the white-paper routing applied automatically, run a CT case in the live demo — no signup, thirty seconds.