Ultrasound follow-up

• TR3: FNA if ≥2.5 cm, follow-up if ≥1.5 cm.
• TR4: FNA if ≥1.5 cm, follow-up if ≥1.0 cm.
• TR5: FNA if ≥1.0 cm, follow-up if ≥0.5 cm.

Source: ACR TI-RADS 2017

• Simple cyst: BI-RADS 2 — no follow-up.
• Complicated cyst: BI-RADS 3 — 6-month US follow-up.
• Complex cystic & solid mass: BI-RADS 4 — biopsy.

Source: ACR BI-RADS Atlas

• O-RADS 2 (almost certainly benign): minimal or no follow-up depending on type/size.
• O-RADS 3: US specialist or MRI follow-up.
• O-RADS 4–5: gyn-oncology referral and/or MRI.

Source: ACR O-RADS US 2020

• Solid intratesticular lesion: urology referral; consider tumor markers.
• Sub-centimeter non-palpable lesion: short-interval US (3 months) is reasonable.

Source: ESUR / consensus guidance

• Anechoic, thin-walled, posterior acoustic enhancement → simple cyst, no follow-up.
• Internal echoes, septations, or solid component → contrast-enhanced CT/MRI for Bosniak classification.

Source: Bosniak 2019 / ACR

• <6 mm, no risk factors: no follow-up.
• 6–9 mm: US at 6 months, then yearly to 5 years.
• ≥10 mm or rapid growth (≥2 mm/yr): cholecystectomy.

Source: ESGAR / SAGES 2022 update

• Simple anechoic cyst: no follow-up.
• Hyperechoic well-defined lesion <3 cm in non-cirrhotic, no malignancy history: presume hemangioma, no follow-up.
• Atypical features or known malignancy → MRI for characterization.

Source: ACR Incidental Findings white paper

• ICA PSV ≥125 cm/s or ICA/CCA ratio ≥2: ≥50% stenosis.
• ICA PSV ≥230 cm/s or ICA/CCA ratio ≥4 + EDV ≥100: ≥70% stenosis.
• Symptomatic ≥70% stenosis → vascular surgery referral for CEA/CAS.

Source: SRU consensus 2003 / NASCET

• Negative whole-leg US: DVT effectively excluded; no repeat needed.
• Negative proximal-only US in outpatient with moderate–high pretest probability: repeat US in 5–7 days or D-dimer-guided strategy.
• Isolated distal (calf) DVT: serial US vs. anticoagulation based on symptoms and risk.

Source: ACCP / ACR Appropriateness Criteria

• Discriminatory β-hCG ~3,500 mIU/mL without intrauterine pregnancy → consider ectopic.
• Yolk sac visible at mean sac diameter ≥10 mm; embryo at ≥25 mm with no cardiac activity → failed pregnancy.
• Hemodynamically unstable or adnexal mass with free fluid → emergent gyn consult.

Source: SRU 2013 consensus