Usg . Gynecological and Obstetrics. Explain me how to read them. Details on them. Give me usg picture on different types of Gynecological and obstetrical problems. Also give me normal usg pictures of fetus of first , second and third trimester. Take References from books like Williams Obstetrics and Gynecology, DC dutta etc.
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normal fetal ultrasound first second third trimester images labeled gynecological USG reading
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gynecological ultrasound fibroid placenta previa molar pregnancy uterus ovary USG images
Ultrasound (USG) in Gynecology and Obstetrics - A Complete Guide
References: Creasy & Resnik's Maternal-Fetal Medicine (Principles and Practice); Berek & Novak's Gynecology; Grainger & Allison's Diagnostic Radiology; ISUOG Practice Guidelines 2019; D.C. Dutta's Textbook of Obstetrics (cited by principle); Williams Obstetrics (cited by principle)
PART 1: FUNDAMENTALS - HOW TO READ A GYNECOLOGICAL/OBSTETRIC USG
The Ultrasound Report: What to Look For First
Every obstetric USG report must contain (per Creasy & Resnik's MFM, Chapter 16):
- Patient identifying information
- Date of examination
- Indication for the procedure
- Type of examination (transabdominal / transvaginal)
- Gestational age by established dates
- Number of fetuses and chorionicity (if multiple)
- Fetal biometry with predicted gestational age
- Principal findings (normal, abnormal, and poorly visualized structures)
- Differential diagnosis for any abnormalities
- Recommendations for management
Probe Types and Patient Preparation
| Approach | Probe | Bladder | Best Used For |
|---|---|---|---|
| Transabdominal (TAS) | Curvilinear (3-5 MHz) | Full | 2nd/3rd trimester, general pelvic survey |
| Transvaginal (TVS) | Endocavitary (5-10 MHz) | Empty | 1st trimester, cervical length, adnexa |
| Translabial | Curvilinear | Moderately full | Cervical os visualization |
Rule: TVS gives better resolution for early pregnancy (< 8 weeks), obese patients, and detailed adnexal assessment. TAS is preferred once the uterus rises above the pelvic brim (after ~12 weeks).
Basic Echogenicity Key (How structures appear on screen)
| Appearance | Term | Examples |
|---|---|---|
| Bright white | Hyperechoic / Echogenic | Bone, calcifications, gas |
| Mid-gray | Isoechoic | Normal myometrium, liver |
| Dark gray | Hypoechoic | Muscle, solid masses |
| Jet black | Anechoic | Fluid, blood, cysts |
| Mixed | Heterogeneous | Complex masses, fibroids with degeneration |
The "posterior acoustic enhancement" sign: seen behind purely fluid-filled cysts - the area behind a cyst appears brighter than surrounding tissue. This confirms a truly cystic (fluid-filled) structure.
PART 2: OBSTETRIC USG - THE THREE TRIMESTERS
OBSTETRIC USG POCKET REFERENCE
FIRST TRIMESTER USG (Weeks 4-13+6)
Goal: Confirm intrauterine pregnancy, gestational age, cardiac activity, number of fetuses, nuchal translucency.
What you see in sequence (using TVS):
| Gestational Age | Structure Visible | Size/Notes |
|---|---|---|
| 4-4.5 weeks | Gestational Sac (GS) | Anechoic, intradecidual sign |
| 5 weeks | Yolk Sac (YS) | Round, echogenic ring, 3-5 mm |
| 6 weeks | Fetal Pole (FP) | Adjacent to yolk sac |
| 6-7 weeks | Cardiac Activity | Must confirm when CRL ≥ 7 mm |
| 11-13+6 weeks | Nuchal Translucency (NT) | < 3 mm normal |
Key measurements:
- Mean Sac Diameter (MSD) = (Length + Width + Height) ÷ 3 - used before CRL is measurable
- Crown-Rump Length (CRL) = most accurate dating measurement in 1st trimester (±3-5 days)
- Nuchal Translucency (NT) - measured at 11-13+6 weeks; > 3 mm raises risk of aneuploidy
Discriminatory zone for hCG:
- TVS: Gestational sac should be visible when hCG > 1,000-2,000 mIU/mL
- TAS: Gestational sac visible when hCG > 3,000-5,000 mIU/mL
Diagnostic criteria for early pregnancy failure (Creasy & Resnik):
- CRL ≥ 7 mm with NO cardiac activity = missed abortion
- MSD ≥ 25 mm with NO embryo = anembryonic pregnancy (blighted ovum)
- No embryo with heartbeat ≥ 2 weeks after GS seen without yolk sac
- No embryo with heartbeat ≥ 11 days after GS seen with yolk sac
SECOND TRIMESTER USG - THE ANATOMY SCAN (Weeks 18-22)
This is the "standard" anatomy scan. Per Creasy & Resnik's MFM (Box 16.3), the mid-trimester anatomy scan (CPT 76805) must assess:
HEAD AND FACE:
- Cranial bones (should be bright, smooth)
- Falx cerebri (midline bright linear echo)
- Cavum septi pellucidi (CSP)
- Thalami
- Lateral ventricles (< 10 mm = normal)
- Cerebellum ("banana" shape = normal; "banana sign" absent = spina bifida suspect)
- Cisterna magna (2-10 mm = normal)
- Orbits, facial profile, upper lip, nasal bone
USG Image: Fetal BPD/HC Measurement (18 weeks)
USG Image: Posterior Fossa - Cerebellum, Cisterna Magna, Nuchal Fold
USG Image: Fetal Nose and Lips
THORAX:
- Four-chamber view of heart (heart apex should point LEFT at ~45° from spine)
- Cardiac axis
- Left ventricular outflow tract (LVOT) - aorta arising from LV
- Right ventricular outflow tract (RVOT) - pulmonary artery arising from RV
- Lung parenchyma (should be slightly echogenic)
USG Image: Fetal Four-Chamber Heart View
ABDOMEN:
- Stomach (anechoic bubble in left upper quadrant - confirms swallowing)
- Intestines
- Abdominal circumference (AC) - measured at level of umbilical vein
- Kidneys (bilateral, pelvis < 4 mm)
- Bladder
- Umbilical cord insertion (normal vs omphalocele/gastroschisis)
SPINE AND EXTREMITIES:
- Spine in longitudinal and transverse views
- All four long bones (femur, tibia, fibula, humerus, radius, ulna)
- Hands and feet posture
PLACENTA, CORD, FLUID:
- Placenta location (anterior, posterior, fundal - note if low-lying)
- Umbilical cord (should have 2 arteries + 1 vein = 3 vessels)
- Amniotic Fluid Index (AFI) or Maximum Vertical Pocket (MVP)
- Normal AFI: 8-24 cm; Normal MVP: 2-8 cm
Standard Biometry Parameters (2nd/3rd trimester):
| Measurement | Abbreviation | What to Measure | Clinical Use |
|---|---|---|---|
| Biparietal diameter | BPD | Outer to inner table of skull at thalami | Gestational age |
| Head circumference | HC | Circumference of skull at BPD level | Age + growth |
| Abdominal circumference | AC | Circumference at liver + umbilical vein | Growth, IUGR detection |
| Femur length | FL | Length of ossified diaphysis | Age + skeletal dysplasia |
| Estimated fetal weight | EFW | Calculated from BPD, HC, AC, FL | Growth assessment |
THIRD TRIMESTER USG (Weeks 28-40)
Primary goals: Fetal growth, presentation, placenta, amniotic fluid, Doppler.
- Fetal presentation: Cephalic (vertex), breech, transverse, or oblique
- Fetal lie: Longitudinal, oblique, or transverse
- Placenta: Grade (Grannum 0-III), position (distance from os if low-lying)
- Amniotic fluid: AFI (< 5 = oligohydramnios; > 24 = polyhydramnios)
- Doppler studies: Umbilical artery, middle cerebral artery (MCA), ductus venosus
- Normal umbilical artery: forward diastolic flow
- Absent/reversed end-diastolic flow = fetal compromise
Fetal weight estimation (Hadlock formula): Uses BPD, HC, AC, FL - accurate to ±15%.
PART 3: GYNECOLOGICAL USG - NORMAL ANATOMY
Normal Uterus on USG
Transabdominal (full bladder required):
- Pear-shaped organ in pelvis
- Uterus size: length 7-8 cm, width 4-5 cm, AP diameter 4 cm (nulliparous)
- Myometrium: homogenous, medium echogenicity
- Endometrium appears as a bright echogenic line (varies with cycle phase)
Endometrial thickness by cycle phase:
| Phase | Thickness | Appearance |
|---|---|---|
| Menstrual | 2-4 mm | Thin, bright line |
| Proliferative (early) | 4-8 mm | Thin, echogenic |
| Proliferative (late) | 8-12 mm | Multilayered / trilaminar pattern |
| Secretory | 10-14 mm | Thickened, bright, homogeneous |
| Postmenopausal (normal) | < 4-5 mm | Thin bright line |
Normal ovary:
- Size: 3 x 2 x 2 cm (volume ~8 cc in reproductive age)
- Contains developing follicles (anechoic, round, 2-20 mm)
- Dominant follicle at ovulation: 18-25 mm
- Corpus luteum: thick-walled, with peripheral vascularity ("ring of fire" on Doppler)
PART 4: GYNECOLOGICAL PATHOLOGIES ON USG
1. UTERINE FIBROIDS (Leiomyoma)
USG appearance:
- Well-defined, hypoechoic to heterogeneous, rounded masses in or around the uterus
- May contain calcifications (bright echoes with shadowing)
- Posterior acoustic shadowing is common
- Uterus is usually enlarged and irregular in contour
Types and location:
- Intramural: within myometrium (most common)
- Submucosal: bulges into endometrial cavity
- Subserosal: projects outward from uterine surface
- Pedunculated: on a stalk, may mimic adnexal mass
D.C. Dutta's Obstetrics principle: Fibroids causing submucosal distortion are most likely to cause abnormal uterine bleeding and should be carefully evaluated by TVS or sonohysterography.
2. OVARIAN CYSTS
The first image below is from a tubal ectopic pregnancy but illustrates the anechoic ring appearance of an adnexal cyst:
Classification of ovarian cysts on USG (Grainger & Allison's Diagnostic Radiology):
| Type | USG Appearance | Likely Diagnosis |
|---|---|---|
| Simple cyst | Anechoic, thin walls, posterior enhancement, no internal echoes | Follicular cyst, serous cystadenoma |
| Hemorrhagic cyst | Internal reticular ("fish-net") echoes, no flow on Doppler | Hemorrhagic corpus luteum |
| Complex cyst | Thick walls, internal septae, solid components | Endometrioma, dermoid, malignancy |
| Dermoid (teratoma) | Bright hyperechoic "tip-of-the-iceberg" appearance, shadowing, "Rokitansky nodule" | Benign mature teratoma |
| "Chocolate cyst" | Homogeneous, ground-glass low-level echoes | Endometrioma |
Risk of Malignancy Index (RMI) uses USG score (U), menopausal status (M), and CA-125:
- Multilocular cysts, bilateral masses, ascites, solid areas, metastases each raise the score
- RMI > 200 = high risk, refer to gynecologic oncologist
USG Image: Fetal Ovarian Cyst with Daughter Cyst (31 weeks)
3. ECTOPIC PREGNANCY
USG findings (Berek & Novak's Gynecology):
- Empty uterine cavity (no IUP visible)
- Adnexal mass separate from ovary ("tubal ring" sign)
- Free fluid in pouch of Douglas (hemoperitoneum)
- Live ectopic pregnancy: fetal cardiac activity outside uterus (pathognomonic)
Discriminatory zone: If hCG > 1,500-2,000 mIU/mL and TVS shows empty uterus = ectopic until proven otherwise.
Pseudogestational sac: Small central anechoic collection in uterus due to decidual reaction - does NOT have an echogenic ring (unlike true IUP); NO yolk sac inside.
4. MOLAR PREGNANCY (Hydatidiform Mole)
Complete mole:
- Classic "snowstorm" pattern - uterus filled with heterogeneous echogenic material with multiple small anechoic spaces (representing hydropic villi)
- No identifiable fetal parts or normal placenta
- Bilateral theca-lutein ovarian cysts (large, multi-septate)
- Markedly elevated hCG
Partial mole:
- Ratio of transverse to AP diameter of gestational sac > 1.5
- Abnormal fetal parts may be present (triploid fetus)
- Swiss cheese appearance of placenta
D.C. Dutta's principle: The snowstorm appearance on USG + markedly elevated hCG is pathognomonic of complete hydatidiform mole. TVS is more sensitive than TAS for early diagnosis.
5. PLACENTA PREVIA
Definition: Placenta implanted over or near the internal cervical os.
USG grading (per Creasy & Resnik/ISUOG):
- Complete previa: Placenta completely covers the internal os
- Partial previa: Placenta partially covers the os
- Marginal previa: Placental edge reaches the os
- Low-lying placenta: Placental edge within 2 cm of os but not covering it
How to assess:
- TAS first; always confirm with TVS (full bladder on TAS may give false previa)
- Measure distance from placental edge to internal os in mm
- < 2 cm from os = low-lying; 0 cm or overlap = previa
- Remember: "Placental migration" - most low-lying placentas at 20 weeks migrate away by 34 weeks as the lower segment develops
6. PLACENTAL ABRUPTION
USG findings:
- Retroplacental hematoma: hypoechoic/anechoic area between placenta and uterine wall
- Subchorionic hematoma: collection under the chorion
- Marginal hematoma: at placental edge
- Note: USG sensitivity for abruption is only ~50% - diagnosis is primarily clinical. A NEGATIVE scan does NOT rule out abruption.
7. POLYCYSTIC OVARIAN SYNDROME (PCOS)
Rotterdam criteria (USG component):
- Ovarian volume > 10 cc (calculated as 0.523 × L × W × H)
- ≥ 12 follicles per ovary measuring 2-9 mm in diameter ("string of pearls" sign)
- Follicles arranged peripherally around an echogenic stroma
8. ENDOMETRIAL PATHOLOGY
| Condition | USG Finding |
|---|---|
| Endometrial polyp | Focal hyperechoic intrauterine mass, often with central vascular stalk on Doppler |
| Endometrial hyperplasia | Diffusely thickened, bright endometrium (> 4-5 mm postmenopausal) |
| Endometrial carcinoma | Irregular, heterogeneous, thickened endometrium; may invade myometrium |
| Asherman's syndrome | Thin/absent endometrium, intrauterine synechiae |
9. ABNORMAL EARLY PREGNANCY / MISCARRIAGE
| Type | USG Finding |
|---|---|
| Threatened abortion | IUP present, cardiac activity present, small subchorionic hemorrhage may be seen |
| Incomplete abortion | Heterogeneous echogenic material in uterine cavity, open os |
| Complete abortion | Empty uterine cavity (endometrium < 15 mm) |
| Missed abortion | GS/embryo present, NO cardiac activity (CRL ≥ 7 mm) |
| Blighted ovum | GS present (MSD ≥ 25 mm), no embryo |
PART 5: KEY USG VIEWS IN SUMMARY
The Obstetric USG Pocket Reference
(As illustrated in the POCUS 101 reference card above)
1st Trimester Checklist:
- Confirm IUP (gestational sac in uterus)
- Gestational dating: MSD, then CRL
- Yolk sac and fetal pole
- Cardiac activity
- Nuchal translucency (at 11-13+6 wks)
2nd/3rd Trimester Checklist:
- Fetal heart rate
- Fetal lie and presentation
- Amniotic fluid volume (MVP/AFI)
- Fetal biometrics: BPD, HC, AC, femur length
- Evaluate placenta (location, appearance, cord insertion)
- Detailed anatomy (2nd trimester)
KEY REFERENCE SUMMARY
| Topic | Source |
|---|---|
| Types of obstetric USG examinations, documentation, anatomy scan elements | Creasy & Resnik's Maternal-Fetal Medicine, Chapter 16 (CPT codes 76801-76816) |
| Detailed fetal anatomy images (figs. 16.1-16.38) | Creasy & Resnik's MFM, pp. 319-330 |
| Fetal anomalies: ovarian cysts, renal cysts, abdominal masses | Creasy & Resnik's MFM, Chapter 24, pp. 507-510 |
| Ovarian cyst classification, hemorrhagic cysts, transvaginal imaging | Grainger & Allison's Diagnostic Radiology, Chapter 7 |
| Ectopic pregnancy USG criteria | Berek & Novak's Gynecology, Chapter 9 |
| Fetal heart four-chamber view, LVOT, RVOT | Creasy & Resnik's MFM, pp. 325-327 |
| Fibroid, molar pregnancy, PCOS | D.C. Dutta's Textbook of Obstetrics (clinical principles) |
| Placenta previa classification | Creasy & Resnik's MFM; Williams Obstetrics 26th ed. |
| ISUOG biometry guidelines | ISUOG Clinical Standards Committee, Ultrasound Obstet Gynecol 2019;53:715-723 |
Important clinical note: USG findings must always be interpreted together with the clinical history, examination, and laboratory results (hCG, CA-125, etc.). A single USG finding in isolation is rarely diagnostic. Serial scans and Doppler studies add significantly to the diagnostic accuracy in both gynecological and obstetric practice.
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USG Gynecology Obstetrics Reference Guide
PDF Document · PDF
What's inside (10 pages):
| Page | Content |
|---|---|
| Cover | Title page with structured table of contents |
| Part 1 | Probe types, echogenicity key, mandatory report elements |
| Part 2 | First trimester USG - sequential appearances, discriminatory zones, early pregnancy failure criteria |
| Part 3 | Fetal biometry with labeled USG images (BPD/HC at 18 wks, posterior fossa/cerebellum) |
| Part 4 | Detailed fetal anatomy - labeled images of cavum septi pellucidi, falx, lateral ventricles, nasal bone, orbits, nose/lips, four-chamber heart, LVOT, RVOT, M-mode HR |
| Part 5 | Normal uterus measurements, endometrial thickness by cycle phase, normal ovary, cervical length |
| Part 6 | Fibroids (all types), ovarian cyst classification with images, ectopic pregnancy with labeled USG, molar pregnancy, placenta previa, PCOS, endometrial pathology |
| Part 7 | Differential diagnosis tables (empty uterus, adnexal mass, PMB) |
| Part 8 | Normal biometry reference table (GA 12-40 wks), trimester checklist, Doppler quick reference |
| References | Creasy & Resnik MFM, Berek & Novak, Grainger & Allison, D.C. Dutta, Williams Obstetrics, ISUOG 2019 |
All USG images are from the actual textbook CDN (Creasy & Resnik MFM, Bailey & Love) with anatomical labels embedded beneath each image.
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