Ob/Gyn Ultrasound Anatomy PDF

Ob/Gyn I - Lateral - Medial Pelvic Ultrasound: Basic Concepts and Anatomy - Superior - Inferior I. Basic Ultrasound Terminology A. Echo Patterns...

Ob/Gyn I - Lateral - Medial Pelvic Ultrasound: Basic Concepts and Anatomy - Superior - Inferior I. Basic Ultrasound Terminology A. Echo Patterns III. Patient Preparation and History 1. Anechoic A. Exam Prerequisites - No internal echoes 1. Transabdominal - Appears black - Full bladder required - Examples: fluid, cysts, vessels, bladder - 32 ounces of water 2. Hyperechoic - Adequately distended bladder for visualization - Bright echoes 2. Transvaginal - Examples: - Empty bladder - Bone - Verbal consent required - Fat - Chaperone for male examiner - Air B. Patient History Requirements - Ligaments 1. Prior Records Review - Diaphragm - Previous imaging reports 3. Comparative Terms - CT - Hypoechoic: Less bright than surroundings - MRI - Isoechoic: Equal to surroundings - Nuclear Medicine - Homogeneous: Uniform texture - Ultrasound - Heterogeneous: Non-uniform texture - Lab results - Biopsy reports II. Scanning Fundamentals 2. Reproductive History A. Scanning Planes - TPAL Format 1. Sagittal - Term births - Anterior/posterior entry - Preterm births - Shows: - Abortions - Anterior - Living children - Posterior - Example: T2P2A1L4 means: - Superior - 2 term births - Inferior - 2 preterm births 2. Transverse - 1 abortion - Multiple entry points - 4 living children - From anterior/posterior shows: - Anterior IV. Pelvic Vascular Anatomy - Posterior A. Arterial Supply - Right lateral 1. Major Vessels - Left lateral - Common iliac bifurcation 1 superior margin of sacrum) - From lateral shows: - External iliac arteries 1 lower extremeties - Lateral - Internal iliac arteries - Medial 2. Uterine Blood Supply - Anterior - Paired uterine arteries - Posterior - Branching pattern: 3. Coronal - Uterine arteries (serosal) - Lateral entry - Arcuate arteries (myometrial) - Shows: - Radial arteries (deep myometrial)  - Straight/basal arteries (basal endometrial) - Transabdominal: Bladder discomfort - Spiral arteries (functional endometrial) - Transvaginal: B. Venous Drainage - Intact hymen 1. General Pattern - No prior intercourse - Mirrors arterial supply - Alternative: Transperineal/translabial - Drains to internal iliac veins - Then to IVC VII. Technical Aspects 2. Exception A. Infection Control - Left ovarian vein to left renal vein 1. Transvaginal Probe - Sterile cover required V. Pelvic Organs - Proper disinfection: A. Urinary System - Glutaraldehyde (20 minutes) 1. Bladder - Trophon machine (7 minutes) - Location: Anterior pelvis - Never autoclave - Shape changes: B. Documentation Requirements - Empty: Pyramid 1. Essential Elements - Full: Dome - Patient position - Wall layers: - Scanning approach - Mucosa (inner) - Organ measurements - Submucosa - Vascular assessment - Muscular - Any pathological findings - Serosa (outer) 2. Ureters - Course: Kidney to bladder - Position: - Anterior to internal iliac artery - Posterior to ovary - Normal appearance: - Not visible unless obstructed - Ureteral jets visible with color Doppler 3. Urethra - Muscular tube - Bladder to genitals - Expels urine VI. Clinical Considerations A. Indications for Pelvic Ultrasound 1. Common Reasons - Pelvic pain - Menstrual irregularities: - Dysmenorrhea - Amenorrhea - Menorrhagia - Metrorrhagia - Infertility - Postmenopausal bleeding B. Contraindications 1. Limitations Gynecologic Anatomy and Sonography 2. Common Positions - Anteverted (most common) I. Pelvic Anatomy Overview - Anteflexed A. Anatomical Spaces - Retroverted 1. Pelvic Spaces - Retroflexed - Anterior cul-de-sac (uterovesical pouch) - Between bladder and uterus III. Normal Measurements - Posterior cul-de-sac (pouch of Douglas) A. Uterine Dimensions - Between rectum and uterus 1. Adult Measurements - Space of Retzius - Length: 6.0-9.0 cm - Anterior to bladder - AP: 2.5-3.5 cm - Posterior to symphysis pubis - Width: 3.0-4.0 cm 2. Uterine Location 2. Special Populations - Posterior/inferior to bladder - Prepubertal: Cervix 2/3 of length - Anterior to rectum - Postmenopausal: Reduced size B. Endometrial Measurements II. Uterine Anatomy 1. Normal Ranges A. Basic Structure - Proliferative: 10-16 mm 1. Major Parts - Secretory: 16-18 mm - Fundus (dome) - Postmenopausal: < 4-5 mm - Body (corpus) - Isthmus IV. Ovarian Anatomy - Cervix A. Basic Structure 2. Wall Layers 1. Dimensions - Endometrium (innermost) - Maximum normal: 3x2x2 cm - Myometrium (middle) - Volume calculation: L×W×H/2 - Perimetrium (outermost) - Maximum volumes: B. Endometrial Characteristics - Reproductive age: 6cc 1. Layers - Prepuberty: 1cc - Zona Functionalis - Postmenopausal: 1.7-5cc - Sheds during menstruation 2. Anatomical Parts - Zona Basalis - Germinal epithelium - Deep basal layer - Tunica albuginea 2. Sonographic Appearances - Cortex - Menstrual phase: - Medulla - Thin, linear, echogenic - Follicles - Under 4mm thick - Corpus luteum/albicans - Periovulatory: B. Blood Supply - Trilaminar appearance 1. Arterial - 10-16mm thickness - Direct from aorta - Secretory phase: - Ovarian branches of uterine arteries - Homogeneous 2. Venous - 16-18mm thickness - Right: Direct to IVC C. Uterine Positions - Left: To left renal vein 1. Terminology - Version: Cervix orientation to vagina V. Sonographic Evaluation - Flexion: Body orientation to cervix A. Uterine Scanning 1. Key Views  - Sagittal 2. Prepubertal Characteristics - Transverse - Dominant cervix - Must include: - Small uterine body - Full length - Possible neonatal enlargement - Endometrial cavity B. Key Findings to Document - Cervix 1. Uterine Assessment 2. Measurement Techniques - Position - Length: Fundus to external os - Size - AP: Perpendicular to length - Endometrial thickness - Endometrium: Double layer thickness - Contour abnormalities B. Ovarian Scanning 2. Ovarian Assessment 1. Technique - Size/volume - Use bladder as window (TA) - Follicle count - Two planes required: - Position - Sagittal - Corpus luteum (if present) - Transverse - Document: - Size - Follicles - Position relative to vessels 2. Normal Appearance - Homogeneous - Medium to low echogenicity - Multiple follicles in reproductive age VI. Congenital Anomalies A. Uterine Malformations 1. Origins - Müllerian duct development - Associated with renal anomalies 2. Common Types - Unicornuate - Didelphys - Bicornuate - Septate - Arcuate B. Imaging Approaches 1. Best Methods - MRI: Most helpful - 3D ultrasound: Better than 2D - 2D ultrasound: Limited evaluation VII. Clinical Applications A. Normal Variants 1. Postmenopausal Changes - Atrophic endometrium - Tubular uterus - Equal cervix/body ratio Gynecologic Anatomy and Physiology - Hematosalpinx: Blood - Shows low-level echoes I. Fallopian Tube Anatomy A. Basic Structure III. The Menstrual Cycle 1. Alternative Names A. Basic Components - Oviducts 1. Cycles Involved - Salpinges (Salpinx - singular) - Ovarian cycle - Uterine tubes - Uterine (endometrial) cycle 2. Dimensions - Hormonal cycle - Length: 7-14 cm 2. Timing - Diameter: 1-4 mm - Average duration: 28 days - Bilateral extension from cornua - Menses: Days 1-5 B. Anatomical Sections - Ovulation: ~Day 14 1. Interstitial (Intramural) B. Hormonal Control - Located within uterine horn 1. Hypothalamus - Proximal portion - Produces GnRH 2. Isthmus - Controls anterior pituitary - Narrow portion 2. Anterior Pituitary - Between interstitial and ampulla - FSH: Follicle development 3. Ampulla - LH: Triggers ovulation - Longest/most tortuous segment 3. Ovarian Hormones - Common site for: - Estrogen - Fertilization - From theca/granulosa cells - Ectopic pregnancy - First half of cycle 4. Infundibulum - Promotes endometrial thickening - Funnel-shaped opening - Progesterone - Most distal section - From corpus luteum - Connects to fimbriae - Second half of cycle 5. Fimbriae - Maintains endometrial thickness - Finger-like projections - Function: Guide oocyte into tube IV. Ovarian Cycle Phases C. Structural Layers (Outside to Inside) A. Follicular Phase (Days 1-14) 1. Serosal 1. Characteristics 2. Muscularis - Follicle development 3. Mucosal - Estrogen production - Ends with ovulation II. Fallopian Tube Pathology 2. Follicle Components A. Common Conditions - Oocyte 1. Salpingitis - Theca cells - Bacterial inflammation - Granulosa cells - Causes: STDs (gonorrhea, chlamydia) - Fluid-filled center (sonographic marker) - Symptoms range from none to pelvic pain B. Ovulation - Can cause infertility 1. Process 2. Fluid Collections - Triggered by LH surge - Hydrosalpinx: Clear fluid - Graafian follicle rupture - Appears anechoic and tubular - Oocyte release - Pyosalpinx: Pus - Possible mittelschmerz pain - Shows internal echoes C. Luteal Phase (Days 15-28) - Abnormal fluid collections 1. Development - Enlarged tubes - Corpus luteum formation - Inflammatory changes - Progesterone production 2. Cycle Abnormalities - Maintains endometrium - Irregular follicle development 2. Outcomes - Abnormal endometrial appearance - If no pregnancy: Corpus albicans - Anovulation signs - Progesterone decline - Cycle restart V. Endometrial Cycle A. Three Phases 1. Menstrual Phase - Functional layer shedding - Duration: ~5 days 2. Proliferative Phase - Estrogen-driven growth - Sonographic appearances: - Early: Thin and echogenic - Late: "Three Line Sign" 3. Secretory Phase - Post-ovulation - Progesterone-maintained - Appears thick and uniformly echogenic VI. Sonographic Considerations A. Normal Findings 1. Fallopian Tubes - Usually not visible - May see proximal segments on TV 2. Ovarian Structures - Follicles < 3 cm - Cysts > 3 cm - Corpus luteum development B. Endometrial Appearance 1. Changes Throughout Cycle - Early proliferative: Thin, echogenic - Late proliferative: Three-line sign - Secretory: Thick, uniform echogenicity VII. Clinical Applications A. Important Measurements 1. Follicle Sizing - Normal follicle < 3 cm - Cyst > 3 cm B. Warning Signs 1. Tube Pathology Fetal Embryologic Development B. Decidual Development 1. Types of Decidua I. Basic Cell Development and Reproduction - Decidua basalis: Implantation site A. Gamete Formation - Decidua capsularis: Surrounds blastocyst 1. Types of Cells - Decidua parietalis/vera: Uninvolved tissue - Gametes (Haploid cells - 23 chromosomes) 2. Clinical Significance - Female: Ova/oocytes - First sonographic sign of pregnancy - Male: Spermatozoa (viable up to 72 hours) - Non-specific (occurs in all pregnancies) - Human cells (Diploid - 46 chromosomes) - Must correlate with hCG and LMP - 23 from mother (22 + X) - 23 from father (22 + X or Y) IV. hCG and Early Pregnancy Assessment 2. Cell Division Processes A. hCG Characteristics - Meiosis: Creates gametes (23 chromosomes) 1. Production and Function - Mitosis: Creates diploid cells (46 chromosomes) - Produced by placenta - Maintains corpus luteum II. Early Pregnancy Development - Detectable by day 23 (menstrual age) A. Fertilization and Implantation 2. Normal Values 1. Process Timeline - Doubles every 48-72 hours - Occurs 24-36 hours post-ovulation - Peaks at 10,000-20,000 mIU/mL - Location: Ampulla of fallopian tube B. Sonographic Correlation - Implantation occurs by day 7 1. Discriminatory Zones 2. Early Developmental Stages - Transvaginal: 1000-2000 mIU/mL - Zygote: Single-cell fertilized ovum - Transabdominal: 1800 mIU/mL - Blastomere: 2-4 cell stages - Possible detection as low as 500 mIU/mL - Morula: Mass of dividing cells - Blastocyst: Organized cell collection V. Early Pregnancy Sonographic Findings B. Pregnancy Dating A. Gestational Sac 1. Age Calculations 1. Characteristics - Conceptual Age: From conception - First evidence of IUP - Gestational Age: From LMP (adds 2 weeks) - Round, oval, or teardrop shaped 2. Developmental Periods - Located in fundus/mid-uterus - Zygote: Conception to implantation (12 days) - Growth rate: 1mm per day - Embryo: Implantation to 10 weeks 2. Key Features - Fetus: After 10 weeks until birth - Double decidual sign 3. Trimester Division - Yolk sac required at 8mm MSD (TV) - First: Weeks 1-12 B. Extraembryonic Membranes - Second: Weeks 13-26 1. Major Components - Third: Weeks 27-42 - Amnion: Fluid-filled protective sac - Yolk sac: Blood cell formation III. Early Pregnancy Structures - Allantois: Umbilical vessels A. Blastocyst Components - Chorion: Placental development 1. Key Structures 2. Yolk Sac Specifics - Trophoblast (outer lining) - Detaches around 8 weeks - Produces hCG - Disappears by 12 weeks - Inner Cell Mass becomes: - Normal size < 6mm - Yolk sac - Viability indicator (90% accuracy) - Embryonic disk - Amnion VI. Placental Development A. Structure Formation 1. Components - Maternal: Decidua basalis - Fetal: Chorion frondosum 2. Functions - Nutrient exchange - Oxygen transfer - Waste removal - Hormone production - hCG - Estrogen - Progesterone B. Circulation 1. Maternal Components - Spiral arteries - Endometrial veins - Lacunae formation 2. Fetal Components - Umbilical vessels - Villous development VII. Embryonic Development A. Germ Layer Formation 1. Three Layers - Endoderm: Digestive/respiratory linings - Mesoderm: Muscle, bone, organs - Ectoderm: Skin, nervous system 2. Key Developments - Neural tube formation - C-shaped folding (week 6) - Organ rudiments (by week 10) VIII. Clinical Considerations A. Early Pregnancy Assessment 1. Key Measurements - Gestational sac size - Yolk sac characteristics - Membrane relationships 2. Warning Signs - Abnormal yolk sac size/shape - Irregular gestational sac - Abnormal hCG progression Midterm Review Questions - [ ] Early follicular 1. At what hCG level should a gestational sac be 8. In the postmenopausal patient, the normal visible with transvaginal ultrasound? endometrial thickness should not exceed: - [ ] 500 mIU/mL - [x] 4-5mm - [x] 1000-2000 mIU/mL - [ ] 8-10mm - [ ] 2500-3000 mIU/mL - [ ] 12-14mm - [ ] 3500-4000 mIU/mL - [ ] 15-16mm 2. The yolk sac should be visible when the mean 9. The LH surge typically occurs on which day of a sac diameter measures: normal 28-day cycle? - [ ] 5mm - [ ] Day 7 - [x] 8mm - [ ] Day 10 - [ ] 12mm - [x] Day 14 - [ ] 15mm - [ ] Day 21 3. Which of the following is NOT a component of 10. Which structure produces progesterone after SSALT criteria? ovulation? - [ ] Size - [ ] Graafian follicle - [ ] Shape - [x] Corpus luteum - [ ] Acoustic characteristics - [ ] Endometrium - [x] Temperature - [ ] Anterior pituitary 4. Normal doubling time for hCG in early pregnancy 11. For transvaginal scanning, the patient's bladder is: should be: - [x] 48-72 hours - [ ] Full - [ ] 24-36 hours - [x] Empty - [ ] 72-96 hours - [ ] Half full - [ ] 96-120 hours - [ ] Doesn't matter 5. The normal length of fallopian tubes is: 12. The "three line sign" is associated with which - [ ] 4-8 cm endometrial phase? - [x] 7-14 cm - [ ] Menstrual - [ ] 15-20 cm - [x] Late proliferative - [ ] 20-25 cm - [ ] Early secretory - [ ] Late secretory 6. Maximum normal ovarian volume during childbearing years is: 13. The decidual reaction is: - [ ] 4cc - [ ] Specific to intrauterine pregnancy - [x] 6cc - [x] Non-specific and can occur with ectopic - [ ] 8cc pregnancy - [ ] 10cc - [ ] Only seen in multiple pregnancies - [ ] Only visible after 8 weeks 7. The endometrium is typically thickest during which phase? 14. What forms at the site of implantation? - [ ] Menstrual - [ ] Decidua vera - [ ] Proliferative - [x] Decidua basalis - [x] Secretory - [ ] Decidua capsularis  - [ ] Decidua parietalis 22. For TA pelvic ultrasound, the patient should drink: 15. The most common position of the uterus is: - [x] 32 ounces of water - [x] Anteverted - [ ] 16 ounces of water - [ ] Retroverted - [ ] 48 ounces of water - [ ] Retroflexed - [ ] 64 ounces of water - [ ] Midposition 23. Which of the following is NOT a typical 16. Left ovarian venous drainage is into the: indication for pelvic ultrasound? - [ ] IVC - [ ] Menorrhagia - [x] Left renal vein - [ ] Pelvic pain - [ ] Common iliac vein - [ ] Postmenopausal bleeding - [ ] Internal iliac vein - [x] Headache 17. A follicular cyst is defined as measuring greater 24. T2P1A3L2 indicates: than: - [x] 2 term, 1 preterm, 3 abortions, 2 living - [x] 3cm - [ ] 2 preterm, 1 term, 3 living, 2 abortions - [ ] 2cm - [ ] 2 living, 1 preterm, 3 term, 2 abortions - [ ] 4cm - [ ] 2 abortions, 1 term, 3 preterm, 2 living - [ ] 5cm 25. The portal of entry for the transvaginal probe 18. The corpus luteum typically measures less during scanning should be oriented at: than: - [x] 12 o'clock - [x] 3.0cm - [ ] 3 o'clock - [ ] 4.0cm - [ ] 6 o'clock - [ ] 5.0cm - [ ] 9 o'clock - [ ] 6.0cm 26. A homogeneous endometrium is typically seen 19. Gastrulation results in the formation of: during: - [ ] Two germ layers - [ ] Proliferative phase - [x] Three germ layers - [x] Secretory phase - [ ] Four germ layers - [ ] Menstrual phase - [ ] Five germ layers - [ ] Ovulatory phase 20. The neural tube will develop into: 27. The ampulla of the fallopian tube is: - [x] Brain and spinal cord - [x] The most common site of ectopic pregnancy - [ ] Heart and blood vessels - [ ] The narrowest portion - [ ] Liver and pancreas - [ ] Located within the uterine wall - [ ] Skin and hair - [ ] The most medial portion 21. When performing TV ultrasound, the probe 28. The fimbriated end of the fallopian tube: should be disinfected for: - [ ] Attaches to the uterus - [ ] 5 minutes - [x] Captures the ovulated egg - [x] 20 minutes in glutaraldehyde - [ ] Produces hormones - [ ] 30 minutes - [ ] Connects to the cervix - [ ] 45 minutes 29. Normal portal venous pressure is: - [x] 5-10 mmHg  - [ ] 15-20 mmHg 37. At approximately what gestational age do the - [ ] 25-30 mmHg amnion and chorion normally fuse? - [ ] 35-40 mmHg - [ ] 8-10 weeks - [x] 12-16 weeks 30. The decidual reaction is first seen: - [ ] 18-20 weeks - [ ] At conception - [ ] 22-24 weeks - [ ] When the fetal pole is visible - [x] Before the gestational sac 38. The blastocyst typically implants at: - [ ] After cardiac activity - [ ] Day 2-3 - [ ] Day 4-5 31. Which finding suggests an abnormal - [x] Day 7-8 pregnancy? - [ ] Day 10-11 - [ ] Yolk sac measuring 4mm - [x] Yolk sac measuring 7mm 39. Human chorionic gonadotropin (hCG) is first - [ ] Double decidual sign produced by the: - [ ] Intrauterine gestational sac - [x] Trophoblast - [ ] Corpus luteum 32. Hydrosalpinx appears sonographically as: - [ ] Decidua - [x] Anechoic tubular structure - [ ] Endometrium - [ ] Hyperechoic mass - [ ] Solid tissue 40. The yolk sac is typically no longer visible by: - [ ] Calcified structure - [ ] 8 weeks - [ ] 10 weeks 33. Riedel's lobe is: - [x] 12 weeks - [x] An inferior projection of the right liver lobe - [ ] 14 weeks - [ ] A uterine anomaly - [ ] An ovarian variant - [ ] A cervical finding 34. The most common uterine position is: - [x] Anteverted/anteflexed - [ ] Retroverted/retroflexed - [ ] Midposition - [ ] Retroverted/anteflexed 35. When measuring endometrial thickness: - [x] Exclude fluid in the cavity - [ ] Include fluid in the cavity - [ ] Measure only anterior wall - [ ] Measure only posterior wall 36. The normal adult uterus measures approximately: - [x] 6-9 cm in length - [ ] 10-12 cm in length - [ ] 4-5 cm in length - [ ] 12-15 cm in length First Trimester Ultrasound Safety and Technical - Thick, echogenic appearance from progesterone Considerations effect - Non-specific pregnancy sign Safety Guidelines - Ultrasound exposure effects depend on duration Weeks 4-5 and intensity level Gestational Sac - Ultrasound is mechanical energy that can - First definitive intrauterine pregnancy sign potentially damage cells - Small anechoic rounded structure in decidua - Some sound energy converts to heat, which can - Mean Sac Diameter (MSD) used for early dating affect tissues - Grows ~1mm per day in early pregnancy - Use of thermal indices (TI) helps monitor exposure limits Double Decidual Sac Sign (DDSS) - Thermal Index (TI) is most important for obstetric - Helps confirm intrauterine pregnancy scanning - Two rings around anechoic sac - Distinguishes from pseudogestational sac Types of Thermal Indices 1. TI for soft tissue (TIS) Week 5 - Used in early first trimester before bone Yolk Sac mineralization - First structure inside gestational sac 2. TI for structures near bone (TIB) - Round anechoic structure with echogenic rim - Used from 10 weeks onward - Normal yolk sac predicts viable pregnancy (90%+ 3. TI for cranial bone (TIC) cases) - Not used in fetal scanning - Abnormal shape/size may indicate pregnancy issues Doppler Usage - Exposure increases with color Doppler Weeks 5-6 - Even higher exposure with spectral Doppler Embryo/Fetal Pole - Avoid Doppler in first trimester unless clinically - Visible within amniotic cavity indicated - First organ to develop is heart - Heartbeat starts ~week 5 AIUM Practice Parameters - Adult heart configuration by week 8 Required Components - Gestational sac number and location Weeks 7-8 - Estimated gestational age - Head as large/larger than body - Cardiac activity presence/absence - Rhombencephalon visible as cystic structure - If clinically indicated: Aneuploidy risk assessment - Beginning of hindbrain development (NT scan) - Limb buds identifiable Key Measurements Weeks 8-12 - Fetal number Development Features - Crown-rump length (CRL) - Placenta becomes visible - Cardiac activity documentation - Umbilical cord appears - Multiple gestation chorionicity/amnionicity - Physiologic bowel herniation occurs - Nuchal translucency when indicated - Choroid plexus visible in ventricles First Trimester Development Timeline Bowel Development Weeks 3-4 - Herniation normal at 8 weeks - Decidual reaction of endometrium - Returns to abdomen by 10-11 weeks - Should not be visible in cord after 13 weeks Multiple Gestation Assessment - Measurement taken from crown (head) to rump Types of Twins (buttocks) Dizygotic (Fraternal) - Most common type 3. Nuchal Translucency (NT) details: - Two separate fertilized eggs - Specialized measurement requiring NT - Always dichorionic/diamniotic certification - Can differ genetically - Measured along posterior aspect of neck - Measurement > 3mm between 11-14 weeks Monozygotic (Identical) considered abnormal Three categories based on splitting timing: - Associated with: 1. Dichorionic/Diamniotic (Di-Di) * Trisomy 13 - Split days 1-3 * Trisomy 18 - 35% of identical twins * Trisomy 21 2. Monochorionic/Diamniotic (Mono-Di) * Structural issues like heart malformations - Split days 4-8 - Important note: Abnormal measurement - 65% of identical twins indicates higher risk, not definitive problem 3. Monochorionic/Monoamniotic (Mono-Mono) - Nine out of 10 babies with measurements - Split days 8-13 between 2.5-3.5mm are normal - 1-2% of identical twins - If split after day 13: conjoined twins 4. NT Measurement Guidelines: 1. Clear NT edge margins for proper caliper Ultrasound Signs placement Lambda Sign 2. Fetus must be in midsagittal plane - Indicates dichorionic twins 3. Image magnified to show fetal head, neck, - Triangular tissue projection at placental surface upper thorax 4. Neutral neck position (not T-Sign flexed/hyperextended) - Indicates monochorionic twins 5. Amnion visible separate from NT line - Thin perpendicular junction at placental surface 6. (+) calipers must be used 7. Electronic calipers placed on inner borders Amnionicity Assessment without crossbar protrusion - Number of yolk sacs often equals number of 8. Calipers perpendicular to long fetal axis amnions 9. Measurement at widest NT space - Visible early in gestation 5. TV vs. TA comparison in early pregnancy (chart from slide 43): 1. Mean Sac Diameter (MSD) Thresholds: - Contains specific β-hCG levels and - Transvaginal Ultrasound: corresponding ultrasound findings for both * If MSD > 8mm: yolk sac should be visible transvaginal and transabdominal approaches at * If MSD > 16mm: embryo should be visible different gestational ages - Transabdominal Ultrasound: - For example: At 4-5 weeks with β-hCG 20mm: yolk sac should be visible intradecidual sac visible on TV but N/A on TA * If MSD > 25mm: embryo should be visible 6. Skeletal System Development: 2. Crown Rump Length (CRL) details: - Upper limbs form first, followed by lower - Most accurate measurement for dating a extremities pregnancy - Hands and feet complete by end of 10th week - Can be obtained up to 12-13 weeks - Limb buds detectable from 7th week on TVS  - Fingers and toes recognizable at 11 weeks using TVS 7. Umbilical Cord details: - Contains 2 arteries and one vein - Vessels surrounded by Wharton's Jelly - Visible during later half of first trimester - Appears as tubular, tortuous structure connecting fetus to placenta First Trimester Pregnancy Complications - Located behind the placenta - Usually not associated with vaginal bleeding Viability Assessment - Crucial to distinguish viable from non-viable 4. Subamniotic Hematoma gestations - Located between amnion and chorion - Living embryo presence does not guarantee - Rare occurrence normal outcome - Cardiac activity observation is essential but must Pregnancy Failure Criteria be evaluated for rate abnormalities Suspicious (Not Definitive) Findings: 1. CRL below 7mm with no cardiac activity Fetal Heart Rate Abnormalities (transvaginal) 1. Bradycardia 2. MSD 16-24mm with no cardiac activity - Heart rate below 90 bpm in 1st trimester 3. Empty amnion adjacent to yolk sac, no embryo - May indicate impending demise 4. Expanded amnion with embryo but no heartbeat 2. Tachycardia 5. Enlarged yolk sac >7mm - Heart rate above 170 bpm - May lead to heart failure Definitive Diagnostic Criteria: 1. CRL ≥7mm with no heartbeat (transvaginal) Types of Bleeding Complications 2. MSD ≥25mm with no embryo (transvaginal) 1. Implantation Bleeding 3. No embryo/heartbeat ≥2 weeks after scan - Light vaginal bleeding showing gestational sac without yolk sac - Caused by fertilized ovum implanting into uterine 4. No embryo/heartbeat ≥11 days after scan myometrial wall showing gestational sac with yolk sac 2. Subchorionic Hemorrhage/Hematoma Types of Pregnancy Loss - Most common form of early pregnancy bleeding 1. Blighted Ovum (Anembryonic Gestation) - Located between endometrium and gestational **Definition:** No embryo/yolk sac in gestational sac sac ≥25mm - Also called perigestational hemorrhage **Clinical Findings:** **Clinical Presentation:** - Vaginal bleeding - Often asymptomatic if small - Pelvic pain/cramping - Manifestations include: - Miscarriage - Idiopathic premature labor - Reduced pregnancy symptoms - Painless vaginal bleeding - Low hCG - Abdominal pain **Sonographic Findings:** - Threatened abortion - Empty gestational sac **Sonographic Findings:** - Irregular sac border - Early: Appears echogenic (active bleeding) - Poor decidual reaction - Later: Becomes anechoic - Located between uterine wall and fetal membrane 2. Embryonic Demise - Shows avascular nature on color Doppler **Clinical Findings:** **Associated Risks:** - Vaginal spotting/bleeding - Increased risk of: - Abdominal/back pain/cramping - Miscarriage - Passage of tissue - Stillbirth **Sonographic Findings:** - Placental abruption - No cardiac activity in pole ≥4-5mm - Preterm labor - Irregular fetus shape - Risk correlates with hematoma size - Irregular gestational sac 3. Retroplacental Hematoma - Abnormal yolk sac appearance 3. Types of Abortion/Miscarriage - Up to 60% of spontaneous abortions have A. Threatened Abortion chromosomal abnormalities - Future pregnancy viability uncertain - Symptoms: Vaginal bleeding, cramping, closed Abortion cervix -termination of pregnancy before 20 weeks - Not diagnosable sonographically gestational age due to spontaneous (SAB) from natural causes or voluntary termination B. Complete Abortion missed abortion - All products of conception expelled - embryo without cardiac activity - Empty uterus with normal cavity on ultrasound Smm embryo - Small amount of endometrial fluid possible - Uterus may remain enlarged for 2 weeks following - Fever lasting more than 24 hours C. Incomplete Abortion - Partial retention of conception products remain in uterus and part of products of conception expelled - Symptoms: Heavy bleeding, clots, cramping, fever - Thickened/irregular endometrial echoes on ultrasound D. Inevitable Abortion - Membrane rupture - Cervical dilation >3cm - Symptoms: Bleeding, contractions, cramping - Irregular sac in lower uterine segment E. Septic Abortion - Due to infection or non-sterile instruments or from infection of retained products of conception - Symptoms: High fever, chills, severe pain - Enlarged uterus with heterogeneous contents - Gas bubbles may cause shadowing F. Habitual/Recurrent Abortion - Three or more consecutive losses - Considered form of infertility - Multiple possible causes including: - Chromosomal/endocrine disorders - Chorion issues - Uterine malformations - Cervical conditions - Infections Stats - approximately 10-15% of all known pregnancies end in spontaneous abortion First Trimester Complications in Obstetric - Cul-de-sac fluid Sonography E. Types of Ectopic Pregnancy I. ECTOPIC PREGNANCY 1. Adnexal: A. Definition and Basic Concepts - Tubal ring with yolk sac - Pregnancy located outside uterine cavity - Most common in ampulla - Most common location: Ampulla of Fallopian Tube - Rare ovarian cases - Can occur in pelvic or abdominal cavity 2. Uterine: - Cornual B. Risk Factors - Uterine scar 1. Medical History: - Cervical - Previous PID - Interstitial (1cm lateral to endometrium) - Previous pelvic infections 3. Cervical: - Prior fallopian tube surgeries - Rare - History of previous ectopic pregnancies - High mortality risk 2. Other Factors: - Below internal os - IUD use 4. Abdominal: - Smoking - Peritoneal cavity implantation - Infertility treatments - Later detection common 5. Heterotopic: C. Clinical Presentation - Simultaneous intrauterine and ectopic 1. Core Symptoms: - Associated with multiple gestation - Pelvic pain (mild to severe) - Rare occurrence - Lower hCG levels than normal IUP - Positive pregnancy test F. Treatment Options - Vaginal spotting/bleeding 1. Medical Management (Methotrexate): - Adnexal tenderness/mass - Criteria: - Shoulder pain (from intraperitoneal bleeding) * Hemodynamically stable 2. Weekly Progression: * No rupture - Week 2: Normal pregnancy symptoms * Gestational sac ≤4cm (no cardiac activity) - Week 3: Peak abdominal pain, light bleeding * Gestational sac ≤3.5cm (with cardiac activity) - Week 4: Increased pelvic pain, possible natural * hCG ≤5000 mIU/mL abortion * Reliable patient follow-up - Week 5: Possible tubal rupture, heavy bleeding 2. Surgical Management: - Week 6: Internal bleeding risk - Salpingostomy (tube-sparing) - Week 7: Severe symptoms, possible tubal rupture - Salpingectomy (tube removal) - Week 8: Movement-related pain, severe bleeding - Emergency surgery for rupture - Week 9: Extreme symptoms, tubal rupture risk II. GESTATIONAL TROPHOBLASTIC DISEASE D. Sonographic Findings (GTD) 1. Primary Indicators: A. Types and Characteristics - Extrauterine gestational sac (71% of cases) 1. Complete Molar Pregnancy: - Adnexal mass - No embryo/normal placental tissue - Free fluid in pelvic cavity - 46XY or 46XX karyotype - Possible pseudogestational sac - Most common GTD type 2. Differential Diagnosis: - Intraovarian vs. Extraovarian mass movement 2. Partial Molar Pregnancy: - "Ring of fire" appearance - Abnormal embryo present - Blood in peritoneum - Some normal placental tissue - 69XXY or 69XXX karyotype F. Risk Factors - Nonviable embryo - Age (35) - Previous molar pregnancy B. Clinical Findings - Asian ethnicity 1. Complete Mole: - Family history - Large uterine size - Nutritional factors - Vaginal bleeding - Hyperemesis - Very high hCG - Possible preeclampsia - Hypertension 2. Partial Mole: - Variable uterine size - Vaginal bleeding - Hyperemesis - High hCG C. Sonographic Features 1. Complete Mole: - No embryo/amniotic fluid - "Snowstorm" appearance - Hypervascular features - Possible theca lutein cysts 2. Partial Mole: - Enlarged cystic spaces - Abnormal embryo present - Reduced amniotic fluid D. Complications: Persistent Trophoblastic Neoplasia (PTN) 1. Invasive Mole: - 80-95% of PTN cases - Myometrial invasion - Uterine rupture risk 2. Choriocarcinoma: - Malignant metastatic tumor - Common sites: lungs, brain, liver, pelvis - High vascularity - Elevated hCG E. Treatment 1. Primary: - D&C (Dilation and Curettage) - Careful monitoring 2. Follow-up: - Monitor for persistent disease - Watch for choriocarcinoma development Obstetric Sonography: 2ND & 3RD Trimester c) Sutures: Protocols - Connect skull bones - Allow flexibility for birth I. INITIAL SURVEY SCAN REQUIREMENTS - Gradually fuse after infancy The second-trimester examination must begin with - Premature fusion (Craniosynostosis): a survey scan to assess: * Causes irregular head shape 1. Number of fetuses present * Requires surgical intervention 2. Fetal heart motion (M-Mode preferred) 3. Fetal lie d) Cerebellum: 4. Fetal organ situs (to rule out situs inversus) - Controls motor skills/coordination 5. Placental location and relationship to internal - Posterior brain location cervical os - Two hemispheres with vermis connection 6. Presence of any uterine masses - Peanut-shaped 7. Location and appearance of maternal ovaries - Measurement (mm) ≈ gestational age (weeks) II. FETAL ANATOMICAL SURVEY e) Cisterna Magna: A. Brain and Head Structures - Posterior CSF space 1. Required Examinations: - Normal measurement: 2-10mm (2nd/3rd - Brain parenchyma examination trimesters) - Cranial vault integrity - Posterior horn of lateral ventricles measurement B. Head Measurements and Assessment - Third and fourth ventricles (if abnormal) 1. Measurement Protocols: - Cerebellum and cisterna magna measurements a) Biparietal Diameter (BPD): - Vermis and cerebellar lobes evaluation - Transverse scan plane - Nuchal skin fold measurement (15-21 weeks) - Required landmarks: - Upper lip integrity check * Cavum Septum Pellucidum - Nasal bone measurement * Thalamus - Orbital sizes and separation measurements * Falx Cerebri - Symmetric cranial bones 2. Important Brain Structures: - Outer proximal to inner distal parietal bone a) Ventricles: - Contains cerebrospinal fluid (CSF) b) Head Circumference (HC): - Functions: - Same level as BPD * Absorbs physical shock - Measures outer cranial perimeter * Distributes nutrients and removes waste * Provides stable chemical environment c) Occipitofrontal Diameter (OFD): - Four ventricles: - Same level as BPD/HC * Paired Lateral (1st & 2nd) - on either side of - Outside occipital to outside frontal bone falx * 3rd Ventricle - midline between thalamus lobes d) Cephalic Index (CI): * 4th Ventricle - posterior brain, anterior to - Normal: 75-85% cerebellum - "Mesocephalic" = normal shape - Normal A-P measurement: - legs must be open/transverse view - Visible by 11-16 weeks 1. Male Genitalia: turtle sign - Round/oval anechoic in LUQ - Penis and scrotum with echogenic testes - Contains swallowed amniotic fluid - Third trimester testicular descent - Normal small hydrocele b) Liver: - Large echogenic organ in RUQ 2. Female Genitalia: hamburger sign - Left lobe ≥ right lobe in fetus - Three-line appearance (labia) - Progressive growth - Internal structures typically not visible c) Adrenal Glands: H. Additional Assessments - Visible after 26-30 weeks 1. Placental Evaluation: - Superior to kidneys - Echogenicity/grade/thickness - Hypoechoic cortex/Hyperechoic medulla - Membrane assessment - Check for complications d) Urinary Bladder: - Visible by 11 weeks 2. Umbilical Cord: - 30-45 minute fill/empty cycle - Three-vessel verification - Indicates kidney function - Insertion site documentation - Mass assessment E. Abdominal Circumference (AC) Measurement - Landmarks: 3. Amniotic Fluid: * Stomach - Volume evaluation * Spine - AFI calculation when indicated * Umbilical vein * Portal sinus III. CLINICAL SIGNIFICANCE - Transverse plane along skin line ~ hour long exam - Used for: Significant measurement discrepancies may indicate: - Fetal growth abnormalities - Intrauterine growth restriction IUGR - Macrosomia ↓ no more than 2 wh difference IV. DOCUMENTATION REQUIREMENTS All measurements and assessments must be: - Systematically performed - Properly documented - Compared to gestational age standards - Evaluated for potential abnormalities Second and Third Trimester Ultrasound - Single umbilical artery (2-vessel cord): Assessment - More common in twins - Usually not significant but can indicate Fetal Face Assessment abnormalities 1. Nose and Lips Evaluation - Most common cord abnormality - Must verify nose and lips are intact - Upper lip can be visualized in coronal scan view Fetal Position Assessment - In 3rd trimester, fetal swallowing and tongue 1. Fetal Lie motion can be observed using color Doppler - Defines relationship between fetus's long axis and mother's long axis 2. Orbits (Eyes) Assessment - Three possible positions: - Must verify: 1. Longitudinal (>99% of cases) - Both globes are present - Only normal position - Normal size - Fetal axis aligned with maternal axis - Normal spacing between orbits - Can be: - Abnormal spacing conditions: - Cephalic/Vertex (head down) - Hypertelorism: Orbits spaced too widely - Breech (buttocks/feet down) - Hypotelorism: Orbits spaced too closely 2. Transverse (24 cm: polyhydramnios -