Ultrasound in Pregnancy - Complete Guide for Final Year MBBS Exam

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  { text: "Fetal Biometry  ·  Doppler  ·  Soft Markers  ·  Cervical Length  ·  Third Trimester  ·  BPP", options: { color: "90CAF9", fontSize: 13, fontFace: "Calibri" } }
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// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 1 – PRINCIPLES
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 1", "Principles & Physics of Obstetric Ultrasound");

flashcard(
  "What is the physical principle behind obstetric ultrasound?",
  [
    "Uses high-frequency sound waves (2–10 MHz)",
    "Waves reflect differently from tissues with varying acoustic impedance",
    "No ionising radiation – safe throughout pregnancy",
    "Real-time B-mode imaging is standard",
    "Doppler mode measures frequency shift from moving red cells"
  ],
  "USG is the ONLY imaging modality that is safe at ALL gestational ages"
);

flashcard(
  "What is the ALARA principle in obstetric ultrasound?",
  [
    { key: "ALARA", value: "As Low As Reasonably Achievable" },
    "Use minimum exposure to obtain diagnostic information",
    "Doppler has HIGHER energy output than B-mode",
    "Use Doppler judiciously in the first trimester",
    "No proven teratogenic effects at standard diagnostic settings"
  ],
  "Doppler in 1st trimester: use only when clinically indicated (higher thermal index)"
);

flashcard(
  "What are the three main values delivered by the midtrimester anatomy scan?",
  [
    "1. Confirms/corrects gestational age by biometry",
    "2. Detects structural fetal abnormalities before viability",
    "3. Identifies maternal findings – fibroids, placenta previa/accreta"
  ],
  "Anatomy scan detects ~60% of major structural anomalies (Gagnon et al.)"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 2 – TYPES OF EXAMINATIONS
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 2", "Types of Obstetric Ultrasound Examinations");

flashcard(
  "Name the main types of obstetric ultrasound and their CPT codes.",
  [
    { key: "76801", value: "Standard 1st trimester (<14 wks) – single gestation" },
    { key: "76802", value: "Standard 1st trimester – each additional gestation" },
    { key: "76805", value: "Basic midtrimester anatomy scan (18–22 wks)" },
    { key: "76811", value: "Detailed Level II – known/suspected anomaly" },
    { key: "76816", value: "Follow-up / serial growth scans" },
    { key: "76815", value: "Limited – fetal position, heartbeat, fluid check" }
  ],
  "76811 (Level II) is NOT for routine scans – needs a specific indication (anomaly risk, diabetes, teratogen)"
);

flashcard(
  "What must every obstetric ultrasound report contain?",
  [
    "Patient identifying information & date",
    "Indication for the procedure",
    "Type of examination",
    "Gestational age by established dates",
    "Fetal number & chorionicity (if multifetal)",
    "Fetal biometry with predicted gestational age",
    "Principal findings – normal, abnormal, poorly visualised",
    "Differential diagnosis for any abnormality",
    "Recommendations for management or further scans"
  ],
  null
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 3 – FIRST TRIMESTER
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 3", "First Trimester Ultrasound (6–13 Weeks)");

flashcard(
  "What are the sequential sonographic milestones in the first trimester?",
  [
    { key: "~4.5–5 wks", value: "Gestational sac (first structure visible)" },
    { key: "~5–6 wks", value: "Yolk sac" },
    { key: "~6 wks", value: "Fetal pole + cardiac activity" },
    { key: "6–13 wks", value: "Crown-rump length (CRL) – gold standard dating" }
  ],
  "Cardiac activity visible from ~6 weeks (FHR 90–110 bpm at 6 wks → 150–180 at 8–10 wks)"
);

flashcard(
  "What is the most accurate parameter for gestational age in the first trimester, and what is its error margin?",
  [
    { key: "Parameter", value: "Crown-Rump Length (CRL)" },
    { key: "Error ≤10 wks", value: "± 5 days" },
    { key: "Error 10–13 wks", value: "± 7 days" },
    "CRL is SUPERIOR to LMP in irregular cycles",
    "Measured in strict mid-sagittal plane, maximum length of embryo",
    "After 13 wks, CRL loses accuracy – use biometry (BPD, HC, AC, FL)"
  ],
  "If CRL and LMP differ by >7 days before 10 wks, change EDD to CRL-based date"
);

flashcard(
  "What structural assessments are possible at 11–14 weeks?",
  [
    "Nuchal translucency (NT) measurement",
    "Nasal bone assessment",
    "Cardiac 4-chamber view (feasible early)",
    "Intracranial anatomy – posterior fossa, falx",
    "Major malformation screen: anencephaly, omphalocele, megacystis",
    "Chorionicity determination in multiple pregnancy (most accurate before 14 wks)"
  ],
  "Chorionicity: T-sign = monochorionic; Lambda (twin-peak) sign = dichorionic"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 4 – NUCHAL TRANSLUCENCY
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 4", "Nuchal Translucency (NT) Screening");

flashcard(
  "Define Nuchal Translucency (NT). When is it measured?",
  [
    "Collection of fluid under the skin behind the fetal neck",
    { key: "Gestational window", value: "11–14 weeks" },
    { key: "CRL range", value: "45–84 mm" },
    "Transabdominal approach successful in ~95% of cases",
    "Median NT increases with CRL – must convert to MoM or delta NT before risk calculation",
    "Reflects lymphatic fluid accumulation related to chromosomal/cardiac anomalies"
  ],
  "NT ≥3.5 mm is significant even if below 95th centile – warrants karyotyping"
);

flashcard(
  "List the 7 technical standards for NT measurement.",
  [
    "1. CRL must be 45–84 mm (success 98–100%)",
    "2. Transabdominal OR transvaginal (TA preferred)",
    "3. True mid-sagittal view – tip of nose visible, 3rd & 4th ventricle seen",
    "4. Fetal head, neck & upper thorax occupy >50% of image",
    "5. Clearly distinguish fetal skin from amniotic membrane",
    "6. Calipers on INNER borders of nuchal space; crossbar must NOT protrude into space",
    "7. Maximum measurement is recorded and used for risk calculation"
  ],
  "Calipers on INNER borders – most common exam question about NT technique"
);

flashcard(
  "What is the Down syndrome detection rate of NT alone vs combined first-trimester screening?",
  [
    { key: "NT alone", value: "77–82% detection at 5–8.3% FPR" },
    { key: "NT + age", value: "77% at 5% FPR (cutoff >1:300)" },
    { key: "Combined test (NT + PAPP-A + free β-hCG)", value: "~88% detection at 5% FPR" },
    { key: "With nasal bone added", value: "~93% detection at 5% FPR" },
    "Sample: >100,000 pregnancies; 326 trisomy 21 fetuses"
  ],
  "Combined 1st trimester test = NT + PAPP-A + free β-hCG → 88% detection"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 5 – NASAL BONE
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 5", "Nasal Bone – First Trimester Marker");

flashcard(
  "What is the clinical significance of absent nasal bone in the first trimester?",
  [
    "Based on flat nasal bridge – classic feature of Down syndrome",
    { key: "Absent NB in trisomy 21", value: "73% of cases" },
    { key: "Absent NB in euploid fetuses", value: "only 0.5%" },
    { key: "Sensitivity (absent NB alone)", value: "65% for trisomy 21" },
    { key: "FPR", value: "0.8%" },
    { key: "PPV", value: "54% – 1 in 2 fetuses with absent NB had trisomy 21" },
    { key: "Likelihood ratio increase", value: "87-fold for trisomy 21" }
  ],
  "Absent NB → 87× increase in trisomy 21 risk. Combined with NT + age → 93% detection"
);

flashcard(
  "What factors affect nasal bone visibility / absence in euploid fetuses?",
  [
    "Increasing NT measurement (more absent NB with higher NT)",
    "Ethnicity – African origin has higher rate of absent NB in euploids",
    "Gestational age / CRL – affects ossification timing",
    "Must be imaged in strict mid-sagittal plane at correct angle",
    "Absent NB in 2nd trimester (14–25 wks) found in 1/3 of Down syndrome (radiographic studies)"
  ],
  null
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 6 – ANATOMY SCAN
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 6", "Second Trimester Anatomy Scan (18–22 Weeks)");

flashcard(
  "What are the HEAD & FACE elements assessed in the standard midtrimester anatomy scan?",
  [
    "Cranial bones (integrity, shape – lemon sign in spina bifida)",
    "Falx cerebri",
    "Cavum septi pellucidi (CSP) – absent → agenesis of CC or HPE",
    "Thalami",
    "Lateral ventricles (atrial width ≤10 mm is normal)",
    "Cerebellum (banana sign in spina bifida; Chiari II)",
    "Cisterna magna (obliterated in Chiari II)",
    "Orbits",
    "Facial profile & nasal bone",
    "Upper lip (cleft lip screening)"
  ],
  "Absent CSP → think agenesis of corpus callosum or holoprosencephaly"
);

flashcard(
  "What are the THORAX elements in the midtrimester anatomy scan?",
  [
    "Four-chamber view of heart (detects most major CHD)",
    "Cardiac axis (normal = 45° ± 20° to left) – dextrocardia if deviated right",
    "Left ventricular outflow tract (LVOT) – aortic root",
    "Right ventricular outflow tract (RVOT) – pulmonary artery",
    "Lung parenchyma (echogenicity for CDH, CCAM)"
  ],
  "4-chamber + LVOT + RVOT views together detect >80% of significant CHD"
);

flashcard(
  "What are the ABDOMINAL elements in the midtrimester anatomy scan?",
  [
    "Stomach (fluid-filled gastric bubble; absent → esophageal atresia)",
    "Intestines (echogenic bowel = soft marker for aneuploidy, CF, CMV)",
    "Abdominal cord insertion (omphalocele: covered, cord at apex; gastroschisis: uncovered, to right of cord)",
    "Kidneys bilaterally (renal pelvis AP <10 mm)",
    "Bladder (distended = obstruction; absent = bilateral renal agenesis)",
    "Umbilical arteries around bladder (normal = 2 arteries; single UA = trisomy 18 risk)"
  ],
  "Omphalocele: liver-covered mass at cord base → high aneuploidy risk. Gastroschisis: bowel floating freely, to right of cord"
);

flashcard(
  "What are the SPINE & EXTREMITY elements in the midtrimester scan?",
  [
    "Spine in BOTH longitudinal and transverse planes (spina bifida, sacral agenesis)",
    "Upper long bones: humerus, radius/ulna – both sides",
    "Lower long bones: femur, tibia/fibula – both sides",
    "Hand and foot anatomy (clubfoot, polydactyly, rocker-bottom foot = trisomy 18)",
    "Posture of hands and feet",
    "Genitalia (gender determination)"
  ],
  "Clubfoot (talipes) is a soft marker for trisomy 18 (especially with other anomalies)"
);

flashcard(
  "What placenta, cord & amniotic fluid parameters are documented in the anatomy scan?",
  [
    { header: "PLACENTA" },
    "Location (previa if <2 cm from internal os on TVS)",
    "Appearance: cysts, lucencies, accessory lobe",
    "Cord insertion site into placenta (velamentous = risk of vasa previa)",
    { header: "AMNIOTIC FLUID VOLUME" },
    { key: "AFI (4-quadrant sum)", value: "Normal 8–25 cm" },
    { key: "MVP (max vertical pocket)", value: "Normal 2–8 cm" },
    { key: "Oligohydramnios", value: "AFI <5 cm  OR  MVP <2 cm" },
    { key: "Polyhydramnios", value: "AFI >25 cm  OR  MVP >8 cm" }
  ],
  "Placenta previa diagnosed if placental edge <2 cm from internal os on TVS at 32+ weeks"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 7 – FETAL BIOMETRY
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 7", "Fetal Biometry & Growth Assessment");

flashcard(
  "Name the four standard fetal biometric parameters and their measurement planes.",
  [
    { key: "BPD (Biparietal Diameter)", value: "Transventricular axial plane; outer-to-inner" },
    { key: "HC (Head Circumference)", value: "Same plane as BPD; ellipse method" },
    { key: "AC (Abdominal Circumference)", value: "Transverse plane at level of portal vein sinus & stomach" },
    { key: "FL (Femur Length)", value: "Long axis of femur diaphysis; ossified shaft only" },
    "EFW = derived from HC + AC + FL (Hadlock formula)",
    "AC is most sensitive for IUGR (reflects fetal liver glycogen stores)"
  ],
  "Most sensitive parameter for IUGR = AC (abdominal circumference)"
);

flashcard(
  "What defines fetal growth restriction (FGR) on ultrasound?",
  [
    { key: "Definition", value: "EFW or AC <10th percentile for gestational age" },
    { key: "Severe FGR", value: "EFW <3rd percentile" },
    "Serial growth scans every 3–4 weeks in high-risk pregnancy",
    "Most sensitive single marker: AC (reflects liver size / glycogen stores)",
    "Asymmetric FGR (head sparing): head growth maintained; AC falls first",
    "Symmetric FGR: all parameters equally reduced (early onset / chromosomal)"
  ],
  "Asymmetric FGR = uteroplacental insufficiency (AC↓ first). Symmetric FGR = chromosomal or early-onset"
);

flashcard(
  "Gestational age dating accuracy by trimester – what are the error margins?",
  [
    { key: "1st trimester (CRL)", value: "±5–7 days (most accurate)" },
    { key: "2nd trimester (18–22 wks)", value: "±10–14 days" },
    { key: "3rd trimester (>28 wks)", value: "±21–28 days (least accurate)" },
    "Never change EDD established by early ultrasound using later scans",
    "EDD based on 1st trimester CRL supersedes LMP if they differ by >7 days (before 10 wks)"
  ],
  "1st trimester CRL = most accurate dating (±5 days). 3rd trimester USG = ±3 weeks"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 8 – DOPPLER
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 8", "Doppler Ultrasound in Pregnancy");

flashcard(
  "What are the three key Doppler indices and their formulas?",
  [
    { key: "S/D ratio", value: "Peak systolic velocity ÷ End-diastolic velocity" },
    { key: "Resistance Index (RI)", value: "(S − D) ÷ S" },
    { key: "Pulsatility Index (PI)", value: "(S − D) ÷ mean velocity  (most comprehensive)" },
    "All three decrease through normal pregnancy as placental resistance falls",
    "PI is preferred in research; S/D ratio widely used clinically"
  ],
  "PI is NOT affected by absent/reversed diastolic flow (unlike S/D ratio which → infinity)"
);

flashcard(
  "Describe the progressive Doppler abnormalities in umbilical artery and their clinical significance.",
  [
    { header: "Umbilical Artery Doppler – Progressive Worsening" },
    { key: "1. Elevated S/D ratio", value: "Increased placental resistance → early IUGR" },
    { key: "2. Absent End-Diastolic Flow (AEDF)", value: "Severe placental insufficiency; ~70% of chorionic villi obliterated" },
    { key: "3. Reversed End-Diastolic Flow (REDF)", value: "Critical – fetal pH likely acidotic; expedite delivery" },
    "Normal: S/D falls progressively through pregnancy (diastolic flow increases)",
    "Correlates strongly with IUGR and adverse neonatal outcomes"
  ],
  "REDF = imminent fetal danger → consider immediate delivery regardless of gestational age"
);

flashcard(
  "What is the clinical significance of Middle Cerebral Artery (MCA) Doppler?",
  [
    { key: "Normal MCA", value: "LOW resistance (brain needs continuous high flow)" },
    { key: "Brain-sparing (IUGR)", value: "MCA PI falls (cerebrovascular vasodilation) as compensation" },
    { key: "MCA PSV >1.5 MoM", value: "Significant fetal anaemia (sensitivity ~88%)" },
    "MCA PSV >1.5 MoM has replaced amniocentesis for monitoring rhesus disease",
    "Cerebroplacental ratio (CPR) = MCA PI ÷ UA PI; CPR <1.0 = brain-sparing"
  ],
  "MCA PSV >1.5 MoM → fetal anaemia. Seen in Rh isoimmunisation, parvovirus B19 infection"
);

flashcard(
  "What is the significance of ductus venosus and uterine artery Doppler?",
  [
    { header: "DUCTUS VENOSUS" },
    "Reflects fetal cardiac preload / right heart function",
    { key: "Absent or reversed A-wave", value: "Imminent fetal cardiac decompensation" },
    "Used in combination with BPP for preterm IUGR surveillance",
    { header: "UTERINE ARTERY" },
    "Assessed at 20–24 weeks for preeclampsia / IUGR prediction",
    { key: "Persistent bilateral notching + elevated PI", value: "High risk for preeclampsia & placental insufficiency" }
  ],
  "Reversed DV A-wave = worst Doppler sign → imminent fetal death, delivery indicated"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 9 – SOFT MARKERS
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 9", "Second Trimester Soft Markers of Aneuploidy");

flashcard(
  "List the second trimester ultrasound soft markers and their aneuploidy associations.",
  [
    { key: "Nuchal fold ≥6 mm (16–20 wks)", value: "Trisomy 21 (strongest marker)" },
    { key: "Echogenic bowel", value: "Trisomy 21, cystic fibrosis, CMV, IUGR" },
    { key: "Echogenic intracardiac focus (EIF)", value: "Trisomy 21 (minor – isolated EIF in low-risk: reassure)" },
    { key: "Short femur / short humerus", value: "Trisomy 21" },
    { key: "Choroid plexus cysts (CPCs)", value: "Trisomy 18 (especially with other markers)" },
    { key: "Renal pyelectasis (>4 mm)", value: "Trisomy 21" },
    { key: "Single umbilical artery", value: "Trisomy 18, structural anomalies" },
    { key: "Absent / hypoplastic nasal bone", value: "Trisomy 21" }
  ],
  "Nuchal fold ≥6 mm at 16–20 wks = STRONGEST 2nd trimester soft marker for T21"
);

flashcard(
  "How do isolated soft markers change aneuploidy risk management?",
  [
    "Multiple soft markers: risk is multiplicative – offer invasive testing",
    "Single isolated minor marker (EIF, mild pyelectasis) in low-risk patient: does NOT require amniocentesis",
    "Nuchal fold ≥6 mm: significant even in isolation – offer genetic counselling",
    "CPCs with trisomy 18 features: hands (clenched/overlapping fingers), rocker-bottom foot, cardiac defect",
    "Integrated sequential screening uses soft markers + serum markers + NT for final risk"
  ],
  "Isolated EIF in low-risk patient – reassure. Multiple markers – offer amniocentesis"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 10 – CERVICAL LENGTH
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 10", "Cervical Ultrasound");

flashcard(
  "What is the role of cervical length ultrasound in predicting preterm birth?",
  [
    { key: "Method", value: "Transvaginal ultrasound (TVS) – gold standard" },
    { key: "Normal CL", value: "≥25 mm at 16–24 weeks" },
    { key: "Short cervix", value: "<25 mm – strongest predictor of spontaneous PTB" },
    { key: "Very short cervix", value: "<15 mm – very high risk" },
    "Short CL + fFN (fetal fibronectin) positive = highest risk combination",
    "Progesterone therapy indicated for short cervix in singleton pregnancy",
    "Cerclage indicated in history of preterm birth + short cervix"
  ],
  "CL <25 mm at 16–24 wks → offer vaginal progesterone (17-OHPC or micronised)"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 11 – THIRD TRIMESTER & BPP
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 11", "Third Trimester Ultrasound & BPP");

flashcard(
  "What are the main indications for third trimester ultrasound?",
  [
    "Serial fetal growth monitoring (IUGR, macrosomia)",
    "Fetal presentation (cephalic / breech / transverse) – ECV counselling before 36 wks",
    "Placental localisation (re-assess previa at 32–36 wks)",
    "Amniotic fluid assessment (post-dates, IUGR, PROM)",
    "Biophysical profile (BPP) for fetal wellbeing",
    "Doppler assessment in high-risk (IUGR, PET, Rh disease)",
    "Evaluate for placenta accreta spectrum if previa present"
  ],
  "Placenta previa found at 20 wks: 90% will migrate away from os by 36 wks (especially if posterior)"
);

flashcard(
  "Describe the 5 components of the Biophysical Profile (BPP) and scoring.",
  [
    { header: "Each parameter: 2 = present, 0 = absent (max 10/10)" },
    { key: "1. Fetal movement", value: "≥3 discrete body/limb movements in 30 min" },
    { key: "2. Fetal tone", value: "≥1 episode of extension + return to flexion (hand open/close counts)" },
    { key: "3. Fetal breathing", value: "≥1 episode of breathing ≥30 sec in 30 min" },
    { key: "4. Amniotic fluid", value: "MVP ≥2 cm in ≥1 pocket" },
    { key: "5. Non-stress test (NST)", value: "Reactive = ≥2 accelerations in 20 min" }
  ],
  "BPP 8–10 = normal; 6 = equivocal (repeat in 24h); ≤4 = abnormal → consider delivery"
);

flashcard(
  "Interpret BPP scores and their management.",
  [
    { key: "10/10 or 8/10 (normal AFV)", value: "Reassuring – routine management" },
    { key: "8/10 (abnormal AFV)", value: "Deliver if ≥36 wks; consider early delivery" },
    { key: "6/10", value: "Equivocal – repeat in 24 hours; deliver if ≥36 wks or mature lungs" },
    { key: "4/10", value: "Strongly consider immediate delivery" },
    { key: "2/10 or 0/10", value: "Deliver immediately (acute fetal distress)" },
    "Modified BPP = NST + AFI (widely used in US practice)",
    "Acute markers: movement, tone, breathing (reflect CNS function at time of scan)",
    "Chronic marker: AFI (reflects placental function over days)"
  ],
  "BPP ≤4/10 = deliver immediately regardless of gestational age (if viable)"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 12 – ADVANCED TECHNIQUES
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 12", "Advanced Techniques");

flashcard(
  "What are the uses and limitations of 3D/4D ultrasound in pregnancy?",
  [
    { header: "3D ULTRASOUND" },
    "Better surface anatomy: cleft lip/palate, skeletal dysplasias",
    "More accurate volume measurements (e.g., nuchal volume)",
    "Limitations: image quality limited by fetal position and AFV",
    { header: "4D ULTRASOUND (real-time 3D)" },
    "Fetal behaviour and facial expressions",
    "Cardiac morphology (spatiotemporal image correlation – STIC)",
    "NOT superior to 2D for routine anomaly screening"
  ],
  null
);

flashcard(
  "What is vasa previa and how is it detected on ultrasound?",
  [
    { key: "Definition", value: "Fetal vessels (umbilical or velamentous) overlying the internal cervical os" },
    "Detected with: colour Doppler + transvaginal ultrasound",
    { key: "Risk", value: "Vessel rupture with membrane rupture → fetal exsanguination (mortality ~60% if undiagnosed)" },
    "Associations: low-lying placenta, velamentous cord insertion, bilobed/succenturiate placenta",
    "Management: elective CS at 35–37 weeks, hospitalisation from 32 wks"
  ],
  "Vasa previa = fetal vessels over os → painless PV bleeding at ROM = fetal emergency"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 13 – SCANNING SCHEDULE
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 13", "Recommended Ultrasound Schedule in Pregnancy");

flashcard(
  "What is the recommended ultrasound schedule throughout pregnancy?",
  [
    { key: "6–9 wks", value: "Confirm IUP, viability, number, CRL dating, ectopic exclusion" },
    { key: "11–14 wks", value: "NT + nasal bone + aneuploidy screening + fetal survey" },
    { key: "18–22 wks", value: "Anatomy scan (CPT 76805) – biometry, anomalies, placenta, AFV" },
    { key: "22–24 wks", value: "Uterine artery Doppler (PET risk), cervical length (PTB risk)" },
    { key: "28–32 wks", value: "Fetal growth, presentation" },
    { key: "34–36 wks", value: "Presentation, placenta migration, AFV, BPP/Doppler if indicated" }
  ],
  "In LOW RISK pregnancy: minimum 2 scans (dating at 11–14 wks + anatomy at 18–22 wks)"
);

// ══════════════════════════════════════════════════════════════════════════════
//  SECTION 14 – HIGH-YIELD EXAM POINTS
// ══════════════════════════════════════════════════════════════════════════════
sectionDivider("SECTION 14", "High-Yield Exam Points");

flashcard(
  "What are the HIGH-YIELD number-based facts for the final exam?",
  [
    { key: "NT measurement window", value: "CRL 45–84 mm (11–14 weeks)" },
    { key: "NT clinical significance threshold", value: "≥3.5 mm warrants karyotyping" },
    { key: "Lateral ventricle width (normal)", value: "≤10 mm" },
    { key: "Cisterna magna (normal)", value: "2–10 mm" },
    { key: "Placenta previa threshold (TVS)", value: "Placental edge <2 cm from internal os" },
    { key: "Normal AFI", value: "8–25 cm; oligohydramnios <5 cm; polyhydramnios >25 cm" },
    { key: "Normal MVP", value: "2–8 cm" },
    { key: "Cervical length (short)", value: "<25 mm at 16–24 weeks" },
    { key: "MCA PSV threshold (anaemia)", value: ">1.5 MoM" },
    { key: "Nuchal fold ≥6 mm", value: "At 16–20 weeks (T21 soft marker)" }
  ],
  null
);

flashcard(
  "What are the key MNEMONICS and diagnostic clues to remember?",
  [
    { key: "Lemon sign + Banana sign", value: "Spina bifida (neural tube defect)" },
    { key: "Double bubble", value: "Duodenal atresia (T21 association)" },
    { key: "Snowstorm appearance", value: "Hydatidiform mole" },
    { key: "T-sign (1st tri)", value: "Monochorionic twins" },
    { key: "Lambda/Twin-peak sign", value: "Dichorionic twins" },
    { key: "Brain-sparing", value: "MCA PI↓ + UA PI↑ = IUGR compensation" },
    { key: "AEDF/REDF", value: "Absent/Reversed end-diastolic flow → imminent fetal compromise" },
    { key: "Absent nasal bone", value: "87× risk for Down syndrome" }
  ],
  "Lemon + Banana signs = Open spina bifida (Arnold-Chiari II malformation)"
);

flashcard(
  "What Doppler findings indicate the most serious fetal compromise and what is the management?",
  [
    { header: "MOST CRITICAL SIGNS (in order of severity)" },
    { key: "1. Elevated UA S/D ratio", value: "Watch + serial Doppler every 1–2 wks" },
    { key: "2. Absent end-diastolic flow (AEDF)", value: "Admit + steroids + daily Doppler; deliver at 34 wks" },
    { key: "3. Reversed end-diastolic flow (REDF)", value: "Deliver immediately if viable (>24 wks)" },
    { key: "4. Absent/reversed DV A-wave", value: "Imminent cardiac failure → deliver IMMEDIATELY" },
    "MCA PSV >1.5 MoM → intrauterine transfusion (IUT) if <34 wks"
  ],
  "REDF + reversed DV A-wave = DO NOT DELAY delivery (perinatal mortality very high)"
);

// ══════════════════════════════════════════════════════════════════════════════
//  BACK COVER
// ══════════════════════════════════════════════════════════════════════════════
const back = pres.addSlide();
back.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: 10, h: 5.625, fill: { color: "0A1045" } });
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back.addText(`Total Cards: ${cardNum}  ·  14 Sections`, {
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back.addText("Review daily. Cover the answer side first. Good luck in your finals!", {
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back.addText("Source: Creasy & Resnik's Maternal-Fetal Medicine  |  Orris AI", {
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  fontSize: 10, color: "5C6BC0", align: "center", fontFace: "Calibri"
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// ══════════════════════════════════════════════════════════════════════════════
//  SAVE
// ══════════════════════════════════════════════════════════════════════════════
pres.writeFile({ fileName: "/home/daytona/workspace/usg-flashcards/USG_Pregnancy_Flashcards.pptx" })
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