The Level I Obstetrical Sonogram No disclosures. An Update on - PowerPoint PPT Presentation

The Level I Obstetrical Sonogram No disclosures. An Update on AIUM/ACR/ACOG/SRU Guidelines Lori Strachowski, MD Clinical Professor of Radiology University of California, San Francisco Chief of Ultrasound, Zuckerberg San Francisco General Lecture Goals Level I • Nomenclature, history of “Levels” • Standard • 2013 Practice Guidelines – General issues: • Routine • 2 nd or 3 rd tri exam • Practitioner training, equipment Highlight updates specifications, documentation, • “Screening” fetal safety, etc. Helpful tips and references – Trimester specific components

Level I Level II Level I Level II • Standard • Detailed • Standard • Detailed • Routine • Targeted • Routine • Targeted • 2 nd or 3 rd tri exam • 2 nd or 3 rd tri exam • Directed • Directed • “Screening” • “High-risk” • “Screening” • “High-risk” www.aium.org OB US Levels History of “Levels” • MS-AFP screening program • Level I US: to detect obstetric problems – Incorrect dates The “level” of exam is predicated by the – Multiple gestations INTENT of the examination. – Demise • Level II US: to detect fetal anomalies – Open NTD – Abdominal wall defects

History: OB US Practice Guidelines “AIUM” Guidelines • www. aium.org ACR and AIUM ACOG 1986 (rev. ‘90, ‘93, ’96) 1988 (rev. ’93) – Practice Guidelines • Obstetric ACR, AIUM, ACOG • Goal: 2003 (rev. 2007) – Provide a minimum standard for all SRU practitioners of obstetrical ultrasound ACR, AIUM, ACOG, SRU www.aium.org 2013 2013 additions and modifications in blue General Requirements General Requirements • Practitioner • Practitioner – Initial certification – Initial certification – MOC – MOC • Exam request • Exam request • Documentation and retention • Documentation and retention – Images – Images – Report – Report • Equipment specifications • Equipment specifications • Fetal safety • Fetal safety www.aium.org www.aium.org

General Requirements General Requirements • Practitioner • Practitioner – Initial certification – Initial certification – MOC - 170 exams/yr + 30 hrs Category 1 Credits /3 yrs – MOC - 170 exams/yr + 30 hrs Category 1 Credits /3 yrs • Exam request • Exam request • Documentation and retention • Documentation and retention – Images – Images – Report – Report • Equipment specifications • Equipment specifications • Fetal safety • Fetal safety www.aium.org www.aium.org Fetal Safety Fetal Safety • Generally considered safe, when: • In keeping with the ALARA principle”, to document – Performed for a valid medical embryonic/fetal heart rate: indication – M-mode should always – Using lowest possible exposure be used 1 st settings under ALARA principle – Only if unsuccessful, • Any pulsed Doppler (color, spectral may be briefly spectral or power) should be used (4-5 heart beats) used only when there is a clear benefit/risk advantage • Keeping TI < 1.0 Measure blip to blip AIUM Statement on Measurement of Fetal Heart Rate

Bioeffects of US Thermal Index • Two major categories: • Definition: – Mechanical: • Ratio of power used to that required to produce a 1°C increase • Energy imparted on gas particles to Not an issue create movement → cavita�on • For obstetrics, subdivided as: for OB – MI (mechanical index) – TIS (soft tissues) < 10 wks – Thermal: – TIB (bone) ≥ 10 wks BIG issue • Absorbed energy → heat • Value: should always be < 1.0 for OB – TI (thermal index) – Doppler exposure time < 5-10 min (never > 60 min) AIUM Statement on the Safe Use of Doppler Ultrasound Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011 During 11-14 week scans (or earlier in pregnancy) What can ( and should) you do to limit the Where is TI displayed? thermal energy imparted upon an embryo/fetus during an US exam? 90% A. Increase the dwell time B. Use a lower frequency transducer C. Increase use of zoom/resolution box D. Select the lowest energy scan mode 9% 2% 0% e m . . . . . . i . . . y t t s e g l y r r e l c / e NOTE : Not displayed if transducer/system n m n w e e d u o o t e q s e z e h t r f w f o e o incapable of exceeding an MI or TI of 1.0. s r e a e s l w u e e h r o c e t l s n a a c t I e e e r l s c e U n S I

What can ( and should) you do to limit the Factors to Consider thermal energy imparted upon an embryo/fetus during an US exam? • Increase dwell time • Use a lower frequency transducer • Increase of zoom/resolution box A. Increase the dwell time • Select the lowest energy scan mode B. Use a lower frequency transducer C. Increase use of zoom/resolution box D. Select the lowest energy scan mode Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011 Factors to Consider Factors to Consider • Decrease dwell time • Decrease dwell time • Use a lower frequency transducer • Use a higher frequency transducer • Increase of zoom/resolution box • Increase of zoom/resolution box • Select the lowest energy scan mode • Select the lowest energy scan mode Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011 Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011

Factors to Consider Factors to Consider • Decrease dwell time • Decrease dwell time • Use a higher frequency transducer • Use a higher frequency transducer • Limit use of zoom/resolution box • Limit use of zoom/resolution box • Select the lowest energy scan mode • Select the lowest energy scan mode Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011 Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011 Factors to Consider Classification of Fetal US Examinations • Decrease dwell time • 1 st Trimester • Use a higher frequency transducer • Standard 2 nd or 3 rd Trimester • Limit use of zoom/resolution box • Limited • Select the lowest energy scan mode • Specialized 34 x’s >er!!! Low High 34 mW/cm 2 1180 mW/cm 2 B-mode M-mode color Doppler spectral Doppler Abramowicz, J, Lewin, P, et al, Glob. libr. women's med.,(1756-2228) 2011

Limited Examination Specialized Examinations • Appropriate only when a complete exam is on record • A detailed anatomic examination when an anomaly is suspected based upon: • Specific question requires investigation – History – Cardiac activity in a bleeding pt – Biochemical abnormalities – Presentation in a laboring pt – Results of a standard or limited exam – Re-evaluation of fetal size or interval growth • Fetal Doppler – Re-evaluate abnormalities previously noted • Biophysical profile • Fetal echocardiogram • Additional biometric measurements 1 st Trimester: Indications • 12 indications, including: – Confirm IUP – Dating 1st Trimester US Examination – Suspected ectopic – Vaginal bleeding ( up to 13 weeks 6 days) – Assess for certain fetal anomalies, such as anencephaly, in high-risk patients – Nuchal translucency (NT) measurement when part of a screening program for aneuploidy …..and others* *see reference chart in syllabus

1 st Trimester: Technique 1 st Trimester: Technique • Overall Comment • Overall Comment – Scanning in the first trimester may be performed either – Scanning in the first trimester may be performed either transbdominally or transvaginally. If transabdominal transbdominally or transvaginally. If transabdominal examination is not definitive, a transvaginal scan or examination is not definitive, a transvaginal scan or transperineal scan should be performed whenever transperineal scan should be performed whenever possible. possible. 1 st Trimester: Components 1 st Trimester: Components 1. Gestational sac (presence/location), yolk sac, embryo 1. Gestational sac (presence/location), yolk sac, embryo and measurements and measurements 2. Cardiac activity 2. Cardiac activity Embryo = < 11 weeks Embryo = < 11 weeks 3. Embryonic/fetal number 3. Embryonic/fetal number Fetus = ≥ 11 weeks Fetus = ≥ 11 weeks 4. Embryonic/fetal anatomy 4. Embryonic/fetal anatomy 5. Nuchal region 5. Nuchal region 6. Uterus, adnexa, cul-de-sac (for abnormalities) 6. Uterus, adnexa, cul-de-sac (for abnormalities)

1. GS, YS, Embryo, Measurements 1. GS, YS, Embryo, Measurements • Uterus (cervix) and adnexa • Comments: evaluated for a gestational – Even w/o YS or embryo, any round/oval fluid sac, and location if identified collection is highly likely to represent an IUP (absent findings of an ectopic) • Comments: • Intradecidual sign may be helpful – Definitive dx requires a • CAUTION: Pseudo-gestational sac of EP yolk sac or embryo – In “pregnancies of undetermined location”, • Yolk sac recommend f/u US, +/- serum β-hCG “to avoid inappropriate intervention in a potentially viable early – Thin ring pregnancy.” – < 6 mm 1. GS, YS, Embryo, Measurements 1. GS, YS, Embryo, Measurements • Measurements: • Measurements: – MSD (no embryo) – CRL (with embryo) – MSD (no embryo) L+W+H Avg. of 2-3 3