Obstetrical ultrasound

2D, 3D, 4D OBSTETRICAL USG FOR FETAL WELL BEING, ANOMALY SCANE, TVS FOR EARLY PREGNANCY, COLOUR DOPPLER STUDY ......

1. Obstetrical Ultrasound DR. YOGESH PATEL MBBS, DGO PG DIPLOMA IN ULTRASONOGRAPHY (D. USG ) FELLOWSHIP IN INFERTILITY (F. ART ) DIPLOMA IN LAPAROSCOPY (D. MAS) FELLOWSHIP IN LAPAROSCOPY (F. MAS) EMERGENCY MEDICINE SPECIALIST FORMER CONSULTANT AIIMS NEW DELHI MEMBER OF THE WORLD ASSOCIATION OF LAPROSCOPIC SURGEONS

2. Ultrasound in Ultrasonography In physics, the term "ultrasound" applies to all acoustic energy (longitudinal, mechanical wave) with a frequency above the audible range of human hearing. The audible range of sound is 20 hertz-20 kilohertz. Ultrasound is frequency greater than 20 kilohertz.

3. Ultrasound Technology Principle of SONAR, used by bats and ships Generation of high-frequency sound waves through a transducer Pulsed sound waves penetrate till structures of different tissues densities is reached Reflected energy to the transducer is amplified and displayed on a screen Detection of breathing, cardiac actions and vessel pulsations

4. Obstetrical Ultrasound Introduced in the late 1950’s ultrasonography is a safe, non-invasive, accurate and cost-effective means to investigate the fetus Computer generated system that uses sound waves integrated through real time scanners placed in contact with a gel medium to the maternal abdomen The information from different reflections are reconstructed to provide a continuous picture of the moving fetus on the monitor screen

5. Risks and Side-effects Ultrasonography is generally considered a "safe" imaging modality. However slight detrimental effects have been occasionally observed (see below). Diagnostic ultrasound studies of the fetus are generally considered to be safe during pregnancy. This diagnostic procedure should be performed only when there is a valid medical indication, and the lowest possible ultrasonic exposure setting should be used to gain the necessary diagnostic information under the "as low as reasonably achievable" or ALARA principle.

6. World Health Organizations technical report series 875(1998).supports that ultrasound is harmless: "Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion". Although there is no evidence ultrasound could be harmful for the fetus, US Food and Drug Administration views promotion, selling, or leasing of ultrasound equipment for making "keepsake fetal videos" to be an unapproved use of a medical device.

7. Studies on the safety of ultrasound A study at the Yale School of Medicine found a correlation between prolonged and frequent use of ultrasound and abnormal neuronal migration in mice. A meta-analysis of several ultrasonography studies found no statistically significant harmful effects from ultrasonography , but mentioned that there was a lack of data on long-term substantive outcomes such as neurodevelopment.

8. Obstetrical Ultrasound Indications: Unsure last menstrual period Vaginal bleeding during pregnancy Uterine size not equal to expected for dates Use of ovulation-inducing drugs confirm early pregnancy Obstetric complications in a prior pregnancy: ectopic, preterm delivery Screen for fetal anomaly: abnormal serum screens, certain drug exposure in early pregnancy, maternal diabetes. Rhisoimmunization Postdate fetus Twins (monochorionic) Intrauterine growth restriction (IUGR) RADIUS study (1993) did not support routine US screening

9. Obstetrical Ultrasound 1 st . Trimester (less than 12 weeks) Gestational sac location / size / shape Embryo Yolk sac Amnion Fetal cardiac activity Placental position/Umbilical cord Amnionitic fluid Fetal morphology >11 weeks) Cranium Heart Stomach/Bladder/Cord insertion/presence of limbs, hands and feet

10. Types of Ultrasonography Trans Abdominal Ultrasonography (TAS) Trans Vaginal Ultrasonography (TVS) Doppler Ultrasound Tissue Harmonic Imaging (THI) Three-dimensional Ultrasound (3-D USG

11. Trans Abdominal Ultrasound (TAS) Major technique for imaging in 2 nd and 3 rd trimester Patient to have full bladder because Pushes the uterus out of the pelvis Provides an acoustic window Displaces pelvic bowel loop superiorly Real-time ultrasound equipment includes: Sector transducers, when access is limited Linear curved array transducers, for less distortion and greater field of view

12. Trans Vaginal Ultrasound (TVS) Method of choice for Monitoring infertility disorders Diagnosis of ectopic pregnancy Differentiation of normal and abnormal 1 st trimester pregnancy Diagnosis of congenital anomalies in 2 nd trimester Patient to have empty bladder because Uterus will be pushed posteriorly out of the field of view of the transducer

13. Trans Vaginal Ultrasound (TVS) cont Specially designed high frequency transducers Higher resolution images Favorable for obese patients or in early stage of pregnancy Limitations include Reduced beam penetration More invasive nature of the technique

14. Doppler Ultrasonography Most widely employed for detection of: Fetal cardiac pulsation Pulsation in various fetal blood vessels Doppler waveform for useful information about intra-uterine growth retardation Use remains controversial due to increased power

15. Tissue Harmonic Imaging (THI) Processing of lower amplitude, higher frequency waveforms accompanying fundamental frequency Lesser clutter and scatter Better visualization of fetal structure

16. Three-dimensional USG (3-D) 3-Dimensional “cleaner” image of the scanning Transducer captures series of images 3-D processing done by Computer Significant improvement in identifying Cleft lips Spina bifida Polydactyl

17. Application of Ultrasound in Trimesters First Trimester Commonly performed at 9-12 weeks 2nd and 3rd Trimester Commonly performed at 18-20 weeks

18. Obstetrical Ultrasound Pre and peri-ovulation (1-2 weeks): ovarian follicle matures and ovulation Conceptus (3-5 weeks): Corpus luteum, fertilization, morula, blastocyst, bilaminar embryo Embryonic (6-10 weeks): Trilaminar C-shaped embryo Fetal Phase: (11-12 weeks):

19. Obstetrical Ultrasound (TVU) Gestational sac : seen at 4 weeks, fluid filled with echogenic border, grow at least 0.6 mm daily. 15 Yolk sac : 33 days (4.7 wk) Embryonic echoes: 38 days (5.4 w) with embryo at 6 wk In a normal pregnancy, the embryo should be visible if the gestational sac is 25 mm or larger in diameter.

20. Obstetrical Ultrasound An intrauterine gestational sac should be visualized by transvaginal ultrasound with β-hCG values between 1000 and 2000 IU and abdominal exam 5500-6500 IU Visible heart activity : 43 days (6.1w) Normal heart rate at 6 weeks: 90-110 bpm At 9 weeks:140-170 bpm. At 8-9 weeks if nl heartbeat: no bleeding 3%loss bleeding 13% loss At 5-8 weeks a bradycardia (<90 bpm) is associated with a high risk of miscarriage.

21. Obstetrical Ultrasound CRL(Crown Rump Length): Longest length excluding limbs and yolk sac Made between 7 to 13 weeks 3 days: 7-10 weeks 5 days: 10-14 weeks Fetal CRL in centimeters plus 6.5 equals gestational age in weeks

22. Obstetrical Ultrasound Ultrasound findings in a pregnancy destined to abort include: A poorly-defined, irregular gestational sac A large yolk sac (6 mm or greater in size) Low site of sac location in the uterus Empty gestational sac at 8 weeks' gestational age (the blighted ovum).

23. Obstetrical Ultrasound First Trimester Screening In 2007, the American College of Ob Gyn endorsed offering aneuploidy screening to all gravidas Performed between 11 and 13 weeks 6 days (fetal crown–rump length 42–79 mm). Fetal nuchal translucency and maternal blood, β-hCG and pregnancy-associated plasma protein A (PAPP-A). This test can detect approximately 60-85% of fetuses with Down syndrome, with a 5% false positive rate. 2 Abnormal screen can increase the risk of genetic, other aneuploidiesand other cardiac anomalies

24. Obstetrical Ultrasound Nuchal translucency: Translucent space between the back of the neck and the overlying skin The scan is obtained with the fetus in sagittal section and a neutral position . The fetal head (neither hyperflexed nor extended, either of which can influence the nuchal translucency thickness). The fetal image is enlarged to fill 75% of the screen, and the maximum thickness is measured, from leading edge to leading edge. (inner to inner measurement) It is important to distinguish the nuchallucency from the underlying amnionic membrane. > 6 mm considered abnormal

25. Measurement of Nuchal Translucency Nuchal Translucency

26. Two gestational sacs, each containing a yolk sac Identification and documenting the fetal number

27. Evaluation of Uterus and Adnexal structures Uterus and cervical plug

28. A) The following qualified persons may be considered eligible to perform USG for purposes and indications given under the provisions of the PCPNDT Act/ Rules. I . Radiologist having Post Graduate Qualification in Radiology / Imaging Sciences, as specified in the schedule I/II/III of the IMC Act of 1956. (Modified because of different PG degrees and their nomenclature in different states.)

29. II . Ob/ Gyn. having Post Graduate Qualification in Ob./ Gyn., as specified in the schedule I/II/III of the IMC Act of 1956. III. DNB qualification in Radiology / Obs / Gyn , as equated and as per provisions of the Medical Council of India for equivalence . IV. MBBS graduate from recognized University in India or any other foreign medical graduate qualification recognized by the Medical Council of India with Six (6) months of Obs / Gyn ultrasound training at any Govt. recognized teaching institute

30. DUTIES OF REGISTERED CENTRE Person conducting ultrasonography on a pregnant women shall keep complete record thereof in the clinic/centre in Form - F and any deficiency or inaccuracy found therein shall amount to contravention of provisions of section 5 or section 6 of the Act, unless contrary is proved by the person conducting such ultrasonography .

31. DUTIES OF REGISTERED CENTRE 1 Should not involve in fetal sex detection 2. Should keep copy of Bare act of PC-PNDT 3. Should display Board in local language also 4. Copy of Form D/E/F / Summary of these Forms must be submitted by 5 th of every month in the office of appropriate authority .

32. Take Home Message Performed with proper guidelines ROUTINE USG IN PREGNANCY can predict many problems and be a good watch dog for fetal and maternal wellbeing

33. Obstetrical Ultrasound 2 nd Trimester Ultrasound (13 weeks-24 weeks) Fetal survey : Fetal number Viability Presentation Fetal biometry Amnionitic fluid Placenta Cervix Fetal Anatomic screening

34. Obstetrical Ultrasound Cervical length Endovaginal probe, examine in dorsal lithotomy position with empty bladder Normal cervix should have a length of 2.5cm or more from 10 weeks gestation until 36 week The width of the cervical canal at the level of the internal os should be less than 4mm Document any evidence of funneling Optimal gestational age for cervical length assessment is after 16 to 20 weeks gestation Assessment 20-24 weeks best time evaluation PTD

35. Obstetrical Ultrasound Transvaginal probe Full bladder Cervical Length: internal os to external os

36. Obstetrical Ultrasound Funneling (percentage): internal os to end of funneling over total cervical length)

37. Obstetrical Ultrasound BPD: Greatest accuracy between 12-28 weeks (better>14 wks.) The plane for measurement of head circumference (HC) and bi-parietal diameter (BPD)must include: Cavum septum pellucidum Thalamus Choroid plexus in the atrium of the lateral ventricles. Measure outer table of the proximal skull to the inner table of the distal HC: Measure the longest AP length (BPD + OFD) X 1.62

38. Obstetrical Ultrasound Abdominalcircumference Determined on transverse view atthe level of thejunction of the umbilical vein, portal sinus,and fetal stomach Measured from the outer diameter to outer diameter Multiply mean diameter by 3.14 Assessing fetal weight/IUGR/macrosomia

39. Obstetrical Ultrasound Femur Length (FL): Aligning the transducer with the lower end of the fetal spine and rotating toward the ventral aspect of the fetus Can measure from 10 weeks onward Measurement origin to distal end of shaft and shows two blunted ends Do not include femoral head or distal epiphysis Femur image is at an angle of less than 30 degrees to the horizontal. It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. Humerus Measured similarly

40. Obstetrical Ultrasound Amnionitic Fluid AFI: measure four quadrants of largest verticle pocket 5-20 cm. nl, 6-8 cm. borderline,<5 cm oligohydramnios Polyhydramnios is defined as an amniotic fluid volume in excess of 2000 mL. A single pocket of fluid that is 8 cm or larger

41. Obstetrical Ultrasound Placenta: Determining its upper and lower edges r/o placenta previa With increasing gestational age, the placenta increases in echogenicity because of increased fibrosis and calcium content. This feature of placental maturation has led to a grading of placentas from immature (grade 0) to mature (grade 3). Placentolmegaly Diabetes, fetal hydrops, Rhisoimmunization Small placenta: Severe IUGR (symmetrical/asymmetrical) Grade 0 Grade 1 Grade 3

42. Obstetrical Ultrasound Abnormal placentas Placenta Previa found in approximately 5% of second-trimester scans If detected at 15–19 weeks, it persists in 12% of patients. If it is detected at 24–27 weeks, it may persist in up to 50%. VasaPrevia: membranous insertion of cord where exposed vessels cross internal os

43. Obstetrical Ultrasound Fetal anatomy: Head Atrium of lateral ventricles Choroid plexus assessment Cerebellum Cisterna magna Nuchal fold