OBSTETRICAL ULTRASOUND By Dr/ Dina Metwaly

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)

FIRST TRIMESTER ULTRASOUND

ROLE OF ULTRASOUND 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) EQUIPMENT SELECTION AND TECHNIQUE 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. Transvaginal probe approx 5-9 MHz

SCANNING TECHNIQUE PATIENT PREPARATION Confirm presence of intrauterine gestation, and number Look for bright trophoblastic reaction around sac. Assess maternal ovaries, adnexae and Pouch Of Douglas (P.O.D) Cervix = assess if closed and measure length between internal and external os If multiple pregnancy, confirm number of foetuses, number of sacs, and number of placentas present to determine chorionicity. ie Monochorionic/Monoamnionic(MCMA),Monochorionic/Diamni onic(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 foetal pole measure the average sac diameter.

Items must be examined in 1st. Trimester (less than 12 weeks) Gestational sac location / size / shape Yolk sac & Amnion Crown rumple length (CRL) & Embryo Fetal cardiac activity (heart beat) Amnionitic fluid Fetal morphology>11 weeks) Cranium Heart Stomach/Bladder/Cord insertion/presence of limbs, hands and feet

GESTATIONAL SAC The gestational sac(GS) is the earliest sonographic finding in pregnancy. 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. The GS grow at least 0.6 mm daily. Gestational sac: seen at 4 weeks, fluid filled with echogenic border

YOLK SAC &Amnion 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 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.

a transvaginal approach the gestational sac can be seen during week 4-5. 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 . 5 week gestation. Yolk Sac Only seen.The yolk sac will be visible before a clearly definable embryonic pole. 

CROWN RUMP LENGTH (CRL) & Embryo CRL(Crown Rump Length): Longest length excluding limbs and yolk sac Made between 7 to 13 weeks Fetal CRL in centimeters plus 6.5 equals gestational age in weeks

HEART BEAT 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.

The very early embryonic heart measured using M-Mode The Crown Rump Length (CRL) measurement in a 6 week gestation.

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 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) > 6 mm considered abnormal

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).

2nd trimester ULTRASOUND 18-20 WEEKS - (MORPHOLOGY SCAN)

2nd TRIMESTER ULTRASOUND PROTOCOL ROLE OF ULTRASOUND In the 2nd trimester, ultrasound is essential for assessing the Current viability Structural integrity of the foetus Placental position and condition This scan must not be done before 18weeks. 19weeks is optimal.  EQUIPMENT SELECTION AND TECHNIQUE Warm gel, clean towels Use a curvilinear probe (3.5-6MHZ) with low power to reduce RISK of bio effects. 

SCANNING TECHNIQUE PATIENT PREPARATION Ensure the patient presents with a full bladder. This will aid in the cervical measurement and placental position and measurement in relation to the cervix. Start from the cervix then placenta then baby head, heart, abdomen, limbs and spine as a rough guide Have your worksheet with you and mark off as you go so you will not forget anything.

WHAT TO CHECK WHEN BABY IS SUPINE WHEN BABY IS DECUBITUS Profile ,nasal bone, nose/lips, mandible, palate, orbits. Head, BPD, HC Heart Humerus, rad/ulna, hands, fingers Diaphragm, liver, GB, bowel AC measurement, stomach, umbilical vein, Heart,4chamber & heart beat Chest cavity Spine coronal, trans Cord insertion,2 umblical arteries FL, femora, tib/fib, feet WHEN BABY IS LYING PRONE Bladder, gender Spine Kidneys Diaphragm Head, choroids

Cervical length Transvaginal probe Full bladder Cervical Length: internal os to external os

Biparietal Diameter and Head Circumference (BPD AND HC): 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

Abdominal circumference Determined on transverse view atthe level of the junction of the umbilical vein, portal sinus,and fetal stomach NO KIDNEYS in the view Assessing fetal weight/IUGR/macrosomia

Femur Length (FL): Aligning the transducer with the lower end of the fetal spine and rotating toward the ventral aspect of the fetus Measurement origin to distal end of shaft and shows two blunted ends Do not include femoral head or distal epiphysis It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. Humerus Measured similarly

Amnionitic Fluid AFI: measure four quadrants of largest verticle pocket normal, 6-8 cm. borderline,<5 cm less than 5 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

Grade 0 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 Small placenta: Severe IUGR (symmetrical/asymmetrical) Grade 1 Grade 3

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

Obstetrical Ultrasound The atrium of lateral ventricles should be less than 10mm in diameter (best measured at the occipital horn). The choroid plexii should be homogenous.

Obstetrical Ultrasound The cerebellar diameter should approximately equal the weeks of gestation. (Ex: 19weeks=19mm) Cisterna magna: < 10mm Nuchal fold: (outer edge of occipital bone to skin surface ) <6mm (between 17-20weeks).

Face: Profile Nasal bone Nose Lips

Obstetrical Ultrasound Thorax Lung volumes Diaphphram

Obstetrical Ultrasound Abdomen/Stomach (presence, size, and situs) Liver

Cord Insertion: Ensure the abdominal wall around the cord insertion is intact No bowel has herniated into the cord. 3-vessel

Kidneys/Bladder Kidneys: Confirm the presence and position of both kidneys. Look for the anechoic renal pelvis. The renal pelvis TS diameter should be less than 5mm.

Obstetrical Ultrasound Spine: Coronal or Sagital of entire spine: cervical Thoracic Lumbar Sacral Transverse assessment of entire spine

Upper Extremities Normal Abnormal Fist clenched Phocomelia

Obstetrical Ultrasound Lower Extremities:

3rd trimester ultrasound>26 WEEKS

3rd Trimester Ultrasound - Protocol Role of Ultrasound Ultrasound is a valuable diagnostic tool in assessing the following indications: Follow up of previously identified, or suspected, abnormality. Suspected or known low placental position Bleeding, fluid loss or pain Altered maternal health (eg hypertension or proteinuria) Decreased foetal movements Small for dates (SFD)or Small for Gestational Age (SGA) or Large for dates (LFD) or Large for Gestational Age (LGA) Patient Preparation The patient does not need to drink a lot of water at this stage.

Scanning Technique Cervix - assess if closed and measure length between internal and external os Assess placental location and distance from internal os. Check for retroplacental haemorrhages, placental masses etc Maternal adnexae (if indicated, also maternal kidneys) Confirm heart beat & rate Foetal lie: ( eg cephalic, spine to maternal left) If breech, describe the 'type' of breech. Frank Complete Footling Head: Shape Symmetry/falx Cerebellum Cavum septum pellucidum Ventricles

Chest: Heart~ rate (check for arrhythmia) position & orientation (4 chambers, outflow tracts) Diaphragm Lungs (homogenous & echogenic relative to liver) Abdo      stomach kidneys bladder anterior abdo wall & cord insertion Limbs: 12 long bones Position of hands/feet Movement & tone Spine: Symmetry from C spine to the sacral taper and an intact posterior skin edge

BIOPHYSICAL PROFILE ASSESSMENT (For utero-placental vascular insufficiency) Look for foetal movements such as leg, hand flexing and diaphragmatic movements. Assess foetal tone and posture. Biophysical Score is a combination of the following assessments giving them a mark out of 8 in total. Foetal breathing 2/2 Foetal limb/body movements 2/2 Foetal posture 2/2 AFI 2/2 If the score is below 7 then this is a concern which will need close follow up. The assessment must span a minimum of a 30minute period before a negative report is suggested.

Obstetrical Ultrasound Three-Dimensional Ultrasound3D Display multiple longitudinal, transverse, and coronal images. Images may improve the accuracy of anomaly detection of the fetal face, ears, and distal extremities

Obstetrical Ultrasound Abnormal 3D Images Cleft lip Cyclopia

Obstetrical Ultrasound 4D Ultrasounds that adds the element of time to the 3D process. Offers live images Fetal changes like movement, kicking, reach with hands and facial expressions can be seen

Obstetrical Ultrasound