1. In the name
of God

2. DR. Mojibina
Obstetrician & Gynecologist

3. Preparation to scan:
1-Orientation
2-Magnification
3-Gain

5. First trimester overview

6. 11 weeks-13weeks+6days Or
CRL mm

13. THE WEEKS SCAN
Ideally all women should be routinely offered a scan at 18 – 23 weeks of gestation.

14. Prior to starting the scan, confirm if the patient has had Down syndrome screening. If screening declined, discuss with the patient if they wish to be notified about the presence of markers of aneuploidy.

15. Objectives of the scan • To confirm fetal growth (and gestational age)
• To check for major structural anomalies
• To check for markers of chromosomal abnormality
• To determine the risk of preterm labour (cervical length)
Number of fetuses, fetal presentation, fetal heart action
• Placental localisation, amniotic fluid volume, number of cord vessels

16. Measurements: Biparietal diameter (BPD)
Occipito frontal diameter (OFD)
Posterior horn of lateral ventricle
Transverse cerebellar diameter (TCD)
Cisterna magna (CM)
Nuchal fold thickness
Nasal bone length
Abdominal circumference (AC)
Femur length
Humerus length

22. The following views of the fetus should be obtained:

23. Head & Brain

24. BPD view to demonstrate the septum cavum pellucidum (otherwise suspect absent corpus callosum) and examine both lateral ventricles

25. Sub-occipitobregmatic view to examine cerebellum and vermis

30. Face
• Mid-sagittal view of face (profile) to confirm presence of the nasal bone and exclude micrognathia • Transverse view of the orbits to exclude microphthalmia • Transverse view of the upper lip with anterior palate to exclude cleft lip Mid-sagittal view of face (profile) to confirm presence of the nasal bone and exclude micrognathia

37. Views of spine: sagittal, coronal and transverse (all vertebrae)

39. Thorax
• Transverse sweep through chest and down to fetal stomach to exclude mediastinal
shift and cystic lung lesions and establish situs of heart and stomach

41. Heart
Sweep through heart in transverse plane to include 4-chamber view, outflow tracts,
3-vessel view

46. Abdomen Transverse view of the abdomen to demonstrate normal stomach
• Longitudinal view of the abdomen to examine the cord insertion and demonstrate the bladder
• Transverse view of the abdomen with spine up to demonstrate both kidneys and renal pelvises

50. Extremities
Upper limbs – follow both limbs from shoulder to hand noting length and normality of long bones and digits. At least one hand should be seen unclenched and middle
phalanx of 5th digit seen

51. Extremities
Lower limbs – again follow both limbs from hips to feet to confirm symmetry in long
bone length and joint positions. A coronal or sagittal view of both ankles should be
seen to exclude talipes. A ‘sole-print’ view of each foot should be obtained.

57. placenta
If the placenta covers the internal cervical os or the lower border of the placenta is within 2 cm of the os the placental position should be determined transvaginally at 32 weeks.

60. Two vessel cord
If this is an isolated finding reassure parents that this is found in 1 in 200 normal pregnancies. In about 10% of cases there is poor fetal growth in the third trimester (compared to 5% for the average population). These patients will have the routine weeks scan and a growth scan at 36 weeks.

61. Cervical length of 15 mm or less
• In the sub group with cervical length of <15 mm the women should be offered prophylactic administration of progesterone (vaginal pessary of 200 mg/night) from 22 to 34 weeks, which reduces the rate of early preterm delivery by about 25%.

66. THE WEEKS SCAN
Ideally all women should be routinely offered a scan at 31+0 – 32+6 weeks of gestation.

67. Objectives of the scan To check for major structural anomalies
To asses fetal growth and wellbeing
To check for major structural anomalies
To check placental position
To check number of umbilical arteries

68. Assessment
The fetal anomaly screen should be completed in all cases. Fetal parts that cannot be examined should be recorded as ‘not examined’.
Assess growth velocity by reviewing HC, AC, FL and EFW charts
Measure the deepest vertical pool of amniotic fluid or AFI

69. Scans after 32 weeks
SGA, LGA, oligo and polyhydramnios, SUA at the weeks scan
Suspected SGA, LGA, oligo and poly from clinical examination after 34 weeks
Diabetes mellitus pre and gestational: 36 weeks. In addition to HC, AC, FL and Amniotic fluid (deepest pool) record the thickness of the fat layer in the standard AC view and note any obvious thickening of the interventricular septum of the heart.

70. Indications for cardiac scan

71. Suspicion of cardiac malformation on scan
Referral to HBR specifically for suspected heart defect
Increased NT (above 95th centile) or tricuspid regurgitation at wks
Fetal hydrops
Monochorionic twins
Family history (mother, father, child/fetus) of heart defect
Maternal insulin dependent diabetes mellitus
Maternal epilepsy currently on anti-epileptic medication
Maternal anti-Ro antibodies

73. Thank
You
Very
much
For
Your
attention

74. Trisomy 13:
Holoprosencephaly, microcephaly, facial abnormalities, cardiac abnormalities, enlarged and echogenic kidneys, exomphalos and post axial polydactyly

75. Triploidy
When there is double paternal contribution there is a molar placenta and the pregnancy rarely persists beyond 20 weeks. When there is a double maternal contribution the placenta is thin but of normal consistency and the pregnancy may persist into the third trimester. The fetus demonstrates severe asymmetrical growth restriction, mild ventriculomegaly, micrognathia, cardiac abnormalities, myelomeningocoele, syndactyly, and 'hitch-hiker' toe deformity

76. Turner syndrome:
Large cystic hygromas, generalised edema, mild pleural effusions and ascites, cardiac abnormalities and horseshoe kidneys, which are suspected by the ultrasonographic appearance of bilateral mild hydronephrosis

77. Markers of aneuploidy
Screening for chromosomal abnormalities is primarily by the first trimester combined test and in those who book late by the second-trimester quadruple test. However, a series of major or minor abnormalities detected at the weeks scan may modify the risk derived from the previous screening test.

78. In the second trimester scan each chromosomal defect has its own syndromal pattern of detectable abnormalities. Therefore, when an abnormality is detected a thorough check should be made for the other features of the chromosomal defect known to be associated with that marker:

79. Trisomy 21:
Nasal hypoplasia, nuchal fold thickness, cardiac defects, intracardiac echogenic foci, duodenal atresia and echogenic bowel, mild hydronephrosis, shortening of the femur, sandal gap and clinodactyly or mid-phalanx hypoplasia of the fifth finger

80. Trisomy 18:
Strawberry-shaped head, choroid plexus cysts, absent corpus callosum, enlarged cisterna magna, facial cleft, micrognathia, nuchal edema, heart defects, diaphragmatic hernia, esophageal atresia, exomphalos, single umbilical artery, renal abnormalities, echogenic bowel, myelomeningocoele, growth restriction and shortening of the limbs, radial aplasia, overlapping fingers and talipes or rocker bottom feet