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DMST 202: Ultrasound Scanning Fundamentals - Female Pelvis

DMST 202: Ultrasound Scanning Fundamentals, Female Pelvis
Patient Preparation

  • Full Bladder Required:

    • Approximately 4 glasses of water (1 L) one hour before the examination. This distension creates an acoustic window, displacing overlying bowel gas and pushing the uterus and ovaries superiorly into the focal zone for better visualization.

    • If the patient is dehydrated, this may not be sufficient. Recommendations include:

    • Drink 2L of water the day before, and more if engaging in physical activity.

    • Avoid coffee, tea, and alcohol the day prior to the exam. These are diuretics and can lead to dehydration, making it difficult to achieve adequate bladder distension.

    • Drink up to 6 glasses (1.5L) of water one hour prior to the exam.

Anatomy Location in Female Pelvis

  • Urinary Bladder:

    • Located posterior to pubic symphysis, anterior to the uterus. Its distension is critical for a transabdominal pelvic ultrasound.

  • Uterus, Cervix, and Vagina:

    • Positioned posterior to the distended bladder and anterior to the rectum. The uterus is typically anteverted and anteflexed but can vary.

  • Fundus of the Uterus:

    • Usually lies just to the right or left of midline, superior-most portion of the uterus.

  • Cervix and Vagina:

    • Typically lie in the midline of the pelvis, inferior to the uterine body. The cervix connects the uterus to the vagina.

  • Ovaries:

    • Lateral to the uterus, often positioned in the ovarian fossa, anterior to the internal iliac vessels and ureter. Size varies, but typically measure about 3-5\text{ cm} in length, 1.5-3\text{ cm} in width, and 1-2\text{ cm} in thickness in reproductive-aged women.

Sonographic Appearance

  • Uterine Myometrium:

    • Appears mid-grey with even texture; contour should be smooth. Heterogeneous texture or focal masses (e.g., fibroids) indicate pathology.

  • Endometrium:

    • An echogenic area within the middle of the body/fundus.

    • Varies in thickness and echogenicity based on menstrual phase and patient age:

    • Proliferative phase (days 1-14): Thin, echogenic line (typically 2-7\text{ mm}).

    • Secretory phase (days 15-28): Thick, hyperechoic, edematous (up to 14\text{ mm}).

    • Post-menopausal: Thin, usually less than 5\text{ mm}, unless on hormone replacement therapy.

  • Vagina:

    • Walls are mid-grey; vaginal canal is hyperechoic due to collapsed walls.

  • Ovaries:

    • Mid-grey with even texture, possibly showing follicles as anechoic areas. Follicles are fluid-filled structures that show as rounded, black (anechoic) cysts. The number and size of follicles vary with the menstrual cycle.

  • Bladder:

    • Distended bladder appears anechoic (black) with thin echogenic walls; hard to visualize when empty and does not provide an adequate acoustic window.

Scanning Windows and Breathing Techniques

  • Patient Position:

    • Supine.

  • Breathing:

    • Normal respiration during the examination. This helps maintain consistent transducer-patient contact and reduces imaging artifacts from excessive movement.

Indications for a Female Pelvis Sonogram

  • Pelvic Pain.

  • Infertility.

  • Intrauterine contraceptive device (IUCD) placement.

  • Irregular menstrual cycles.

  • Abnormal vaginal bleeding.

  • Evaluation of pelvic masses.

Scanning Protocol for Female Pelvis

  • Professionalism During Procedure:

    • Introduce yourself as a SAIT student.

    • Confirm patient's full name and date of birth.

    • Explain the examination process to the patient.

    • Request permission to start the examination.

  • Ultrasound Machine Setup:

    • Input patient ID: First and last name, SAIT ID number, and scan operator initials.

    • Select the SAIT GYNE Preset.

    • Use 5MHz curvilinear transducer. This transducer frequency provides a good balance of penetration for deeper pelvic structures and resolution for detailed visualization.

  • TGC Setup:

    • Apply gel above the pubic symphysis.

    • Place probe in the sagittal plane.

    • Adjust angle to capture the longest length of the patient’s bladder.

  • Ensure full visualization of the bladder and maintain appropriate depth for uterus and ovaries.

  • Adjust Focus and TGC settings for optimal image quality. TGC (Time Gain Compensation) allows for selective amplification of echoes from different depths, compensating for attenuation and ensuring uniform brightness throughout the image.

Required Sweeps of the Uterus

  • Transverse Interrogations:

    • Begin with probe in transverse position, ensuring perpendicular angle to patient’s skin at midline.

  • Sweep from vagina through cervix, uterus body, and fundus, then return. This methodical sweep ensures complete coverage of the uterus in the transverse plane, identifying any focal lesions or asymmetries.

  • Identify true transverse lie of the uterus before maintaining the angle. Use fanning and rocking motions to optimize views.

    • Sagittal Interrogations:

  • Rotate probe 90 degrees to display vagina, cervix, uterus body, and fundus.

  • Perform lateral sweeps to capture full view of the structures. This provides a comprehensive evaluation of the uterus in the sagittal plane, allowing for assessment of overall uterine size, shape, and endometrial stripe.

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Required for Checklist of the Female Pelvis

  • Sweeps must be complete:

    • Images required in both sagittal (SAG UTERUS) and transverse (TRV UTERUS) planes.

    • Anatomical structures to identify include:

    • Urinary Bladder

    • Vagina

    • Cervix

    • Uterus Body

    • Uterus Fundus

    • Myometrium

    • Endometrium Accurate identification and documentation of these structures are fundamental for a complete diagnostic examination and for detecting any abnormalities.

Anatomy and Landmark Requirements

  • Sagittal Uterus:

    • Midline uterus with endometrial stripe, anechoic bladder.

    • Optimal depth with some tissue displayed posterior to the uterus; focus should be posterior to uterus. Optimal depth ensures that all relevant structures are visible without excessive tissue clutter or insufficient penetration.

  • Transverse Uterus:

    • Probe must display vagina, cervix, and uterine body and fundus in same plane.

    • Ensure uniform grey tones throughout the image for clarity. Uniform grey tones indicate proper TGC adjustment, allowing for consistent assessment of tissue echogenicity across the image.