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ULTRASOUND IN OBSTETRICS & GYNECOLOGY

ULTRASOUND IN OBSTETRICS & GYNECOLOGY. Hidayat Wijayanegara Department of Obstetric & Gynecology School Medicine Padjadjaran University / Hasan Sadikin Hospital Bandung. Ultrasound examination : Reveals vital information Fetal anatomy Fetal environment Growth Well being

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ULTRASOUND IN OBSTETRICS & GYNECOLOGY

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  1. ULTRASOUND IN OBSTETRICS & GYNECOLOGY Hidayat Wijayanegara Department of Obstetric & Gynecology School Medicine Padjadjaran University / Hasan Sadikin Hospital Bandung

  2. Ultrasound examination : • Reveals vital information • Fetal anatomy • Fetal environment • Growth • Well being • No biological hazard • The first obstetrical application of USG imaging : Ian Donald (1958)

  3. Ultrasound • Sound waves of frequencies higher than the hearing limit of the human ear are called ultrasonic waves • The limit is by convention 20 KHz • Medical practice frequencies between 1-10 MHz are commonly used

  4. Technology : • Sound waves reflecting back from the fetus or image structure  displayed on the ultrasound screen • Alternating current is applied to a transducer made of piezoelectric material  intermittent high frequency sound waves exceeding 20,000 cps are generated

  5. The transducer emits a pulse of sound waves that passes through the layer of soft tissue  Interface between structures of different tissue densities  Some of the energy is reflected back to the transducer  A small electrical voltage  Display on a screen • Bone is dense (echogenic)  white on the screen • Fluid (anechoic)  black • Soft tissues  varying shade of gray

  6. 1.Operator control 6. Visual information 2.Transducer drive 5. Electric information 3.Ultrasound pulses 4. Acoustic information The diagnostic ultrasound visualization method Operator Instrument Transducer Tissue interaction

  7. Transabdominal Scanning : • Performed with 3.5 – 7 MHz • Safety : no confirmed biological effects in mammalian tissue have been demonstrated in the frequency range of medical ultrasound (AIUM, 1991)

  8. Choice of equipment : • Transabdominal scanning • Transvaginal scanning • Doppler and color flow imaging • 3D 2D

  9. Biophysical mechanism : • Are not fully understood • The effects of ultrasound on various biological entities may be due to one or a combination of any of the following : 1. Heating effects 2. Cavitational effects 3. Mechanical effects Are associated only with high average intensities and not found in diagnostic equipment

  10. Preparation of the patient • Ultrasound beam cannot penetrate gas • The interface created by gas  the sound beam totally reflected • Water  excellent transmission medium • The distension of bladder  displaces intestinal loop acoustic window to the pelvic structure • Patient should be scanned with a full bladder • The full bladder technique offer : 1. It displaces the fetal head upwards 2. It allow visualization of the cervix

  11. Coupling agents • A gel or an oil  eliminates the air interface between the transducer and the patient’s skin Scanning technique • The patient is on your right • The machine is on your left • Work in dim lighting to help reflection on the screen

  12. Indications for ultrasound examination • Gynecology : - Uterus, Ovaries, Adnexa - Abnormal bleeding, pelvic pain & discomfort - IUCD location and complications - Pelvic mass reveals mass or enlargement of pelvic organ - Evaluation of masses palpable - Ovulation induction therapy - Guidance for abscess drainage

  13. Uses of ultrasound in gynecology 1. Determine the size and location of lesions 2. Characteristics of the lesion: cystic, complex or solid 3. Determine if mass is uterine or extrauterine 4. Evaluate the extent of pelvic inflammatory disease or endometriosis and follow-up 5. Follow the course of a simple cyst: regression, etc. 6. Locate the position of an intrauterine device 7. Detection of ascites 8. Radiation therapy planning

  14. Obstetrics : • Routine obstetrical ultrasound scan: 18-20 weeks • 1st Trimester : • Confirm pregnancy, viability, gestational age • Rule out : • Ectopic pregnancy • Gestational trophoblastic disease • Foreign bodies • Large for dates – fibroid, uterine malformation, multiple gestation • Small for dates – missed abortion, blighted ova

  15. Ovaries, rule out adnexal lesions, uterine position, rule out uterine anomalies • Undetermined etiology of vaginal bleeding • Suspected complications, i.e subchorionic hematome

  16. 2nd and 3rd trimester : • Confirm viability, gestational age, fetal number • Evaluated fetal growth, anatomy, lie, position, follow up anomaly • Evaluate placenta, AFV, cord • Biophysical profile for fetal well being • Vaginal bleeding

  17. Components of basic ultrasound examination according to Trimester pregnancy 1st trimester • Gestational sac location • Embryo identification • Crown rump length (CRL) • Fetal heart rate motion • Fetal number • Uterus & adnexal evaluation 2nd and 3rd trimester • Fetal number • Presentation • Fetal heart motion • Placental location • Amniotic fluid volume • Gestational age • Survey of fetal anatomy • Evaluation for maternal pelvic mass

  18. Ultrasonic Landmark Occurence (weeks of gestation) • Gestational sac 5 – 6 weeks • Fetal embryonic pale 6 – 7 weeks • Detection of fetal life 7 – 8 weeks • Placenta 8 – 10 weeks • Loss of gestational sac 11 – 13 weeks • Fetal head 11 – 14 weeks (Biparietal diameter)

  19. Evaluation of ultrasound to determine gestational age • Crown Rump Length (CRL) • Biparietal diameter (BPD) • Femur Length (FL) • Head Circumference (HC) • Abdominal Circumference (AC)

  20. Accuracy of ultrasound measurement for different gestational groups Ultrasound parameter Accuracy • Gestational sac diameter + 7 days • Crown Rump Length + 3-5 days • BPD second trimester + 1 to 1.5 weeks • BPD third trimester + 2 to 4 weeks • FL second trimester + 1 to 1.5 weeks • FL third trimester + 3 to 3.5 weeks • Multiple parameter (2nd trimester) + 1.5 weeks • Multiple parameter (3rd trimester) + 2.5 weeks

  21. Summary 1. Physics of ultrasound The ultrasound used in clinical practice is limited to frequencies in the range of 1-10 cycles per second (1-10 MHz) In Obstetrics : 3.5 MHz and 5 MHz 2.Ultrasound Is produced when transmitted pulses of sound from the transducer cross body structures and reflect energy back to the transducer from the interfaces of organs

  22. 3. Ultrasound in Obstetrics • Confirmation of an intrauterine pregnancies • Exclusion of an ectopic pregnancies • Assessment of an intrauterine pregnancies • Determination of gestational age : • Are uncertain of the date of conception • Resolving discrepancies between gestational age and uterine size : • Large for dates • Small for dates

  23. Investigation of uterine bleeding • Visualization for high risk procedures • Amniocentesis • Chorionic villous sampling • Cordocentesis • Evaluation of fetal well-being • Distinguish congenital malformation • Biophysical profile • Doppler flow velocimetry • IUGR  60-80% of the time in cases where the umbilical artery waveforms are abnormal due to uteroplacental insufficiency

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