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Presentation1.pptx, ultrasound examination of the 1st trimester pregnancy.

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Presentation1.pptx, ultrasound examination of the 1st trimester pregnancy.

  1. 1. ULTRASOUND EXAMINATION OF THE 1ST TRIMESTER. Dr/ ABD ALLAH NAZEER. MD.
  2. 2. FIRST TRIMESTER ULTRASOUND - Normal 1ST TRIMESTER ULTRASOUND PROTOCOL ROLE OF ULTRASOUND Ultrasound is essentially used for assessing gestational age, current viability and maternal wellbeing. Ultrasound is a valuable diagnostic tool in assessing the following indications; Unsure of Dates Vaginal Bleeding Pelvic Pain Exclude an ectopic pregnancy Maternal past history Threatened Miscarriage Nuchal Translucency (11-14 weeks : CRL 45-84mm) Patient History Gravidity Parity (Miscarriage, Termination of Pregnancy (T.O.P)) Fertility treatment Date of Last Menstrual Period Other pregnancy History Gynecological History
  3. 3. EQUIPMENT SELECTION AND TECHNIQUE Modern ultrasound unit Curved linear probe approx 3-7 MHz depending upon maternal factors Transvaginal probe approx 5-9 MHz (Use of non-latex cover if required) Ensure patient comfort and privacy. Warm gel, clean towels etc Select "Obstetric" preset for appropriate power levels and measurement packages Use a curvilinear probe (3.5-6MHZ) with low power to reduce risk of biological effects. use of Doppler should be avoided in the 1st trimester. SCANNING TECHNIQUE PATIENT PREPARATION 2 hours before the appointment time, empty your bladder. Over the next hour, drink at least 1 liter of water and do not go to the toilet until instructed.
  4. 4. <10 weeks Cervix - assess if closed and measure length between internal and external os Look for bright trophoblastic reaction around sac. Assess placental location and distance from internal os (may lie close to os at this stage) Check for retroplacental hemorrhages, placental masses etc Assess maternal ovaries, adnexae and Pouch Of Douglas (P.O.D) Confirm presence of intrauterine gestation, and number If multiple pregnancy, confirm number of fetuses, number of sacs, and number of placentas present to determine chorionicity. i.e. Monochorionic/Monoamnionic (MCMA),Monochorionic/Diamnionic (MCDA),Dichorionic /Diamnionic (DCDA) Confirm heart beat(s) & rate with M-Mode only (Use of Colour or Doppler traces is not recommended in the 1st trimester) Measure CRL to calculate gestational age and Estimated Date of Delivery(EDD). If too early to see the fetal pole measure the average sac diameter.
  5. 5. A 1st trimester series should include the following minimum images; Uterus - long, trans Both ovaries Adnexae Cervix and Pouch-Of-Douglas Gestational sac - Long & Trans Yolk sac if visible Fetal pole M mode fetal heart Document the normal anatomy. Any pathology found in 2 planes, including measurements.
  6. 6. GESTATIONAL SAC The gestational sac(GS) is the earliest sonographic finding in pregnancy. It will be difficult to see if the mother has a retroverted uterus or fibroids. The GS is an echogenic ring surrounding an anechoic centre. An ectopic pregnancy will appear the same but it will not be within the endometrial cavity. The GS is not identifiable until approximately 4 1/2 weeks with a transvaginal scan. Gestational sac size should be determined by measuring the mean of three diameters. These differences rarely effect gestational age dating by more than a day or two. The following image is using a transvaginal approach the gestational sac can be seen during week 4-5.
  7. 7. 5 week gestation. Yolk Sac Only seen. The yolk sac will be visible before a clearly definable embryonic pole. Mean Sac Diameter measurement is used to determine gestational age before a Crown Rump length can be clearly measured. The average sac diameter is determined by measuring the length, width and height then dividing by 3
  8. 8. The very early embryonic heart will be a subtle flicker. This may be measured using M-Mode(avoid Doppler in the first trimester due to risks of bioeffects).Initially the heart rate may be slow. The Crown Rump Length (CRL) measurement in a 6 week gestation. A mass of fetal cells, separate from the yolk sac, first becomes apparent on transvaginal ultrasound just after the 6th week of gestation. This mass of cells is known as the fetal pole.
  9. 9. YOLK SAC The yolk sac appears during the 5th week. It is the second structure to appear after the GS. It should be round with an anechoic centre. It should not be calcified, misshapen or >5mm from the inner to inner diameter. Yolk sacs larger than 6 mm are usually indicative of an abnormal pregnancy. Failure to identify (with transvaginal ultrasound) a yolk sac when the gestational sac has grown to 12 mm is also usually indicative of a failed pregnancy.
  10. 10. HEART BEAT Using a transvaginal approach the fetal heart beat can be seen flickering before the fetal pole is even identified. It will be seen alongside the yolk sac. It may be below 100 beats per minute but this will increase to between 120- 180 beats per minute by 7 weeks. In the early scans at 5-6 weeks just visualizing a heart beating is the important thing. Failure to identify fetal cardiac activity in a fetus whose overall length is greater than 4 mm is an ominous sign. Sometimes there is difficulty distinguishing between the maternal pulse and fetal heart beat. Often technicians will take the mothers pulse at the same time to check if it is the fetus or the mothers .
  11. 11. CROWN RUMP LENGTH (CRL) The CRL is a reproducible and accurate method for measuring and dating a fetus. Early ultrasonographers used this term (CRL) because early fetuses also adopted the sitting in the chair posture in early pregnancy. After 12 weeks, the accuracy of CRL in predicting gestational age diminishes and is replaced by measurement of the fetal biparietal diameter. In at least some respects, the term "crown rump length" is misleading: There is no fetal crown and no fetal rump to measure for most of the first trimester. Until 53 days from the LMP, the most caudad portion of the fetal cell mass is the caudal neurospone, followed by the tail. Only after 53 days is the fetal rump the most caudal portion of the fetus. Until 60 days from the LMP, the most cephalad portion of the fetal cell mass is initially the rostral neurospore, and later the cervical flexure. After 60 days, the fetal head becomes the most cephalad portion of the fetal cell mass. What is really measured during this early development of the fetus is the longest fetal diameter. From 6 weeks to 9 1/2 weeks gestational age, the fetal CRL grows at a rate of about 1 mm per day.
  12. 12. Measure the crown rump length (CRL) to estimate gestational age. At 10 weeks, visualize 4 jointed limbs, feet and hands.
  13. 13. NUCHAL TRANSLUCENCY From 12 weeks the basic morphology of the fetus is visible The Nuchal Translucency is used to provide a risk assessment for chromosomal abnormalities, specifically Trisomies 13,18 and 21 (Down's Syndrome).
  14. 14. The legs are usually crossed at the ankles. Confirm the presence and symmetry of the long bones. The correct angle the feet to legs can be confirmed. They should be at 90 degrees i.e. perpendicular or Talipes should be suspected.
  15. 15. The humerus, radius and ulna and the presence of hands are imaged from 11 weeks. 12 week choroids take up most of the space within the ventricles.
  16. 16. TWINS Initially twins may be identified as 2 separate gestational sacs (i.e. diamniotic, dichorionic) They may be 2 fetal poles within the same gestational sac (monochorionic). It is easier to determine chorionicity earlier in the pregnancy depending on the chorionicity and amnionicity. It is a sad situation when a "vanishing twin" occurs, which is about 20% of twin pregnancies. In these cases, one of the twins fails to grow and thrive. Instead, its development arrests and it is reabsorbed, with no evidence at delivery of the twin pregnancy. Monoamniotic Twins. Dichorionic diamniotic Twins.
  17. 17. TRIPLETS. Triplets with 2 sacs. Monoamniotic, monochorionic twins and a normal single.
  18. 18. GRAPHS TO DETERMINE GESTATIONAL AGE Depending on the age of the gestation, these graphs can be used to determine the correct EDD. Mean Sac Diameter measurement is used to determine gestational age before a Crown Rump length can be clearly measured. The average sac diameter is determined by measuring the length, width and height then dividing by 3. Once a fetal Pole can be visualized the CRL measurement is the most accurate method for dating the pregnancy.
  19. 19. COMMON PATHOLOGY: Thickened Nuchal Translucency(NL). Partial Ovular Detachment. Retained products of conception. Anembryonic Gestation. Gestational trophoblastic disease. Miscarriage. Ectopic Pregnancy. Subchorionic hemorrhage. Conjoined Twins. Antepartum Hemorrhage. Check heart beat. Check causes of bleeding.
  20. 20. Thickened Nuchal Translucency (NT): • One of the parameters used in sequential screening (SS) for Down’s syndrome in first trimester – SS: Pregnancy associated plasma protein levels, hCG levels, NT thickness • Measured during 11-14 wks gestational age • Seen on sagittal image as increased subcutaneous non-septated fluid in posterior fetal neck • Measurement >3mm usually considered abnormal, however exact cut off measurements are dependent on maternal age/gestational age • Detection rate of screening for Down’s Syndrome in first trimester: – sequential screening with NT: 82-87% – NT alone: 64-70%.
  21. 21. Thickened Nuchal Translucency (NT):
  22. 22. Thickened Nuchal Translucency
  23. 23. PARTIAL OVULAR DETACHMENT The maternal circulation inside the placenta starts peripherally (in the placental margins) and is associated to physiological oxidative phenomena that may lead to membranes rupture and formation. The abnormal development of such membranes may result in subchorionic hemorrhage, enhancing the predisposition to an adverse gestational outcome at the third trimester (PPROM and PTL). Such abnormality is common and also denominated as subchorionic hemorrhage or trophoblastic hematoma, being visualized in more than 18% of cases of threatened miscarriage. The presence of fetal heart activity confers an excellent prognosis. Clinically, subchorionic hemorrhage may course with vaginal bleeding. At ultrasonography, a crescent-shaped shadow is observed adjacent to the gestational sac, with debris. Gestational sac compression and consequential deformation may occur. In most of cases, a two-week follow-up evaluation confirms the hematoma resorption.
  24. 24. Retained products of conception are characterized by a thickened, disorganized and heterogeneous endometrium, with ill- defined mucosal layers and cavitary line, either with or without the presence of gestational sac. Clinically, the women presents abdominal pain and relative vaginal bleeding(1,4). In the presence of an intact gestational sac and closed cervix, the difficulty in a spontaneous resolution will be higher, requiring surgical evacuation
  25. 25. Retained products of conception.
  26. 26. Transvaginal sonography without (A) and with (B) color Doppler imaging in a case of RPC with endometrial expansion (arrows).
  27. 27. Images retained products conception.
  28. 28. EARLY EMBRYO DEATH Some sonographic findings characterize an embryo death in the first half of the first trimester in early phases, before the crown-rump length can be measured. The following aspects are highlighted: small, hyperechoic yolk sac, or hydropic yolk sac increased in volume with diameter > 7 mm, or even small amniotic cavity disproportionate to the gestational sac size. Before the 9th week, small gestational sac may be associated with aneuploidy.
  29. 29. Failed early pregnancy.
  30. 30. ANEMBRYONIC GESTATION At transvaginal ultrasonography, the yolk sac should be visualized in a gestational sac with mean diameter > 10 mm. The absence of a yolk sac within the gestational sac with > 10 mm in mean diameter, or the absence of a yolk sac within the gestational sac with > 16 mm in diameter characterize anembryonic gestation
  31. 31. IMAGES FOR ANEMBRYONIC PREGNANCY (BLIGHTED OVUM PREGNANCY).
  32. 32. IMAGES FOR ANEMBRYONIC PREGNANCY (BLIGHTED OVUM PREGNANCY).
  33. 33. GESTATIONAL TROPHOBLASTIC DISEASE The typical sonographic finding in most of cases of complete hydatidiform mole is a echogenic, intracavitary solid mass with intermingled, small cystic loci resembling a "snow storm", corresponding to the vesicles that macroscopically characterize this condition. The higher the gestational age, the larger the vesicles visualized as homogeneous anechoic images, increasing the method specificity. The ultrasonography sensitivity will depend on the gestational age at the moment of the diagnosis. Ultrasonography can detect vesicles with > 2 mm in diameter. In early pregnancies with trophoblastic disease, the sonographic method accuracy is limited, hindering the differentiation of gestational trophoblastic disease from other conditions involving the endometrial cavity. Partial hydatidiform mole offers higher diagnostic difficulty by ultrasonography. In a reasonable number of cases, this disease presents as an empty gestational sac corresponding to anembryonic gestation, or as early embryo death. However, two criteria have been described in the literature: gestational sac transverse/anteroposterior diameter ratio > 1,5 and cystic changes, irregularity of increase in echogenicity of decidual/placenta or myometrial reaction
  34. 34. ECTOPIC PREGNANCY Sonographic findings of ectopic pregnancy will vary as a function of the gestational age and site. Classically, the following sonographic findings are described: tubal ring sign, adnexal disorganized mass molded to the adnexa and/or cul de sac, solid, organized mass with regular margins mimicking a pediculated myomatous nodule, clinically progressing with low β-hCG levels, and presence of a live extrauterine conceptus. Uncommon gestational sites may be observed such as abdominal ectopic pregnancy, cervical ectopic pregnancy and ectopic pregnancy in a previous Cesarean section pregnancy.
  35. 35. Subchorionic hemorrhage (SCH) occurs when there is perigestational haemorrhage and blood collects between the uterine wall and the chorionic membrane in pregnancy. It is a frequent cause of first and second trimester bleeding. Epidemiology It typically occurs within the first 20 weeks of gestation. If seen in the first 10-14 days of gestation, they are also sometimes termed implantation bleeds. Radiographic features Ultrasound crescentic collection with elevation of the chorionic membrane depending on the time elapsed since bleeding, the collection will have variable echotexture acute: hyperechoic and may be difficult to differentiate from adjacent chorion subacute-chronic: decreasing echogenicity with time in almost all cases there is extension of the hematoma towards the margin of the placenta.
  36. 36. First trimester SCH (subchorionic bleed).
  37. 37. First trimester SCH (subchorionic bleed).
  38. 38. Extensive hematoma in a woman with chronic bleeding.
  39. 39. Subchorionic hemorrhage.
  40. 40. Conjoined twins are a rare and complex complication of monozygotic twinning, which is associated with high perinatal mortality. Early prenatal diagnosis of conjoined twins allows better counselling of the parents regarding the management options, including continuation of pregnancy with post-natal surgery, termination of pregnancy or selective fetocide in case of a triplet pregnancy. With the introduction of high- resolution and transvaginal ultrasound imaging, accurate prenatal diagnosis of conjoined twins is possible early in pregnancy. Although first- trimester diagnosis of conjoined twins is feasible, false-positive cases are common before 10 weeks because, earlier in gestation, fetal movements are limited and monoamniotic twins may appear conjoined. As most parents opt for immediate termination of pregnancy at confirmation of the diagnosis, there are limited data on the prenatal follow-up of conjoined twins. detailed analysis of case reports where 3D imaging was used indicates that this modality does not improve on the diagnosis made by 2D ultrasound. Overall, very early prenatal diagnosis and first-trimester 3D imaging provide very little additional practical medical information compared to the 11-14 weeks' ultrasound examination.
  41. 41. Images of the conjoined twins, there are two heads with conjoined body.
  42. 42. Images of the conjoined twins.
  43. 43. Conjoined twins. Ultrasound images of fetuses joined at the pelvis and chest, with separate heads.
  44. 44. Three-dimensional sonogram showing the conjoined twins of the thoraco-omphalopagus type.
  45. 45. First Trimester: Bleeding/Miscarriage, Molar Changes. Miscarriage is defined as the loss of a pregnancy prior to the completion of 24 weeks gestation and the main maternal symptoms are bleeding and pain. If a fetal HR has been detected, the risk of spontaneous miscarriage in singletons is 12.2%. Threatened Pregnancy Failure.
  46. 46. Threatened Pregnancy Failure.
  47. 47. An incomplete miscarriage.
  48. 48. CONCLUSION First trimester obstetric abnormalities are identified by screening studies or in cases of abnormal vaginal bleeding with the objective of determining the gestation viability. Transvaginal ultrasonography is the method of choice in the evaluation of first trimester pregnancy. In the presence of vaginal bleeding, this method is highly specific in the determination of the conceptus viability, most of times clearly defining the etiological process involved in the clinical condition. The knowledge of the sonographic findings that characterize each condition is essential for determining an appropriate clinical approach in these cases.
  49. 49. Thank You.

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