Basic Gyne OBS Ultrasound

 

Basic GYNE and Obstetrics Ultrasound: A Beginner's Guide

Ultrasound has revolutionized gynecology and obstetrics by offering a non-invasive, real-time, and safe imaging modality for diagnosis, monitoring, and management. Whether it’s confirming an early pregnancy or evaluating abnormal uterine bleeding, ultrasound is the frontline tool for most OB-GYN clinicians.

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📌 What is Ultrasound?

Ultrasound uses high-frequency sound waves to produce images of internal organs. It is:

• Safe: No radiation

• Painless

• Portable

• Cost-effective

In OB-GYN, it is performed transabdominally or transvaginally, depending on the indication.

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🟪 Types of Ultrasound Probes

1. Transabdominal (Convex Probe - 3.5–5 MHz)

   • Used in early pregnancy, pelvic mass assessment, fetal scans

   • Requires a full bladder for better visualization

2. Transvaginal (Endocavitary Probe - 5–9 MHz)

   • Better resolution; used in early pregnancy, infertility, endometrial studies

   • Empty bladder preferred

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🔴 Basic Obstetric Ultrasound

1️⃣ First Trimester (0–13 weeks)

Objectives:

• Confirm intrauterine pregnancy

• Assess gestational age

• Detect viability (fetal heartbeat)

• Count fetuses (single or multiple)

• Rule out ectopic/molar pregnancy

• Nuchal translucency scan (11–13.6 weeks)

Key Measurements:

• Gestational Sac (GS)

• Yolk Sac

• Crown-Rump Length (CRL) – most accurate for dating

• Cardiac Activity – seen by 6–7 weeks (TVS)

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2️⃣ Second Trimester (14–28 weeks)

Objectives:

• Detailed anatomy scan (Level II)

• Assess fetal growth and anomalies

• Placental location

• Amniotic fluid volume (AFI)

• Cervical length

• Fetal movements & well-being

Key Measurements (Biometry):

• BPD (Biparietal Diameter)

• HC (Head Circumference)

• AC (Abdominal Circumference)

• FL (Femur Length)

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3️⃣ Third Trimester (28+ weeks)

Objectives:

• Fetal growth & weight estimation

• Fetal position & presentation

• Placental grading

• Doppler studies (if required)

• Biophysical profile (BPP)

• Assessment of high-risk pregnancies

Doppler Ultrasound:

• Umbilical artery

• Middle cerebral artery (MCA)

• Uterine artery
  Used in cases of IUGR, preeclampsia, etc.

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🔵 Basic Gynecology Ultrasound

✳️ Indications:

• Abnormal uterine bleeding (AUB)

• Pelvic pain or mass

• Infertility evaluation

• PCOS screening

• Fibroids or adenomyosis

• Endometrial thickness & pathology

• Ovarian cysts or masses

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🔍 Key Structures Assessed:

1. Uterus

• Size, shape, echotexture

• Endometrial stripe (thickness varies with cycle)

• Look for fibroids, polyps, adenomyosis

2. Ovaries

• Size, volume, follicles (antral follicle count)

• Dominant follicle tracking (in fertility scans)

• Look for cysts, masses, torsion

3. Endometrium

• Measured in sagittal view

• <5 mm postmenopausal = normal

• Cyclic variation: thin (early proliferative) → thick (secretory)

4. Pouch of Douglas

• Look for free fluid (physiological or pathological)

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⚙️ Common Gynecologic Findings

Condition	Sonographic Appearance
Fibroids	Hypoechoic, well-circumscribed, shadowing masses in the myometrium
Adenomyosis	Heterogeneous myometrium, small cysts, asymmetric wall
PCOS	≥12 follicles <9mm, increased ovarian volume, "string of pearls"
Endometrial polyp	Focal thickening of endometrium, feeding vessel on Doppler
Ovarian cysts	Simple: thin-walled, anechoic. Hemorrhagic: internal echoes, reticular pattern

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🧪 Ultrasound in Infertility Work-up

• Baseline scan (Day 2/3)

• Follicular monitoring (Day 9 onwards)

• Ovulation check

• Endometrial thickness tracking

• Polycystic ovaries identification

• Hydrosalpinx / Tubal block suspicion

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💡 Tips for Beginners

• Always start with a general overview, then zoom into pathology.

• In obstetrics, confirm viability, number of fetuses, and dating before anything else.

• Be systematic: uterus → endometrium → ovaries → adnexa → POD.

• Use Doppler judiciously, especially in early pregnancy.

• Know normal variants vs abnormal findings.

• Keep in mind clinical history—it guides your focus.

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📚 Conclusion

Basic ultrasound in gynecology and obstetrics is a cornerstone of patient care. With practice, a structured approach, and clinical correlation, even a beginner can become proficient. Whether it's a routine antenatal checkup or an infertility evaluation, ultrasound helps decode the unseen with remarkable clarity.

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