obstetrics and gynecology imaging pregnancy ultrasound mbbs

1. Imaging techniques in
pregnancy
16/03/24

2. SLO
• Indications of USG in first trimester of pregnancy
• To know how to perform USG evaluation of the fetus in the second
and third trimesters of pregnancy
• To know how to assess the cervix by USG for cervical insufficiency

3. ULTRASOUND
• Piezoelectric crystals excited by an electric pulse generate
ultrasonographic waves that pass from transducer in to the tissues in
their path.
• When these waves meet the tissue interface –converted to electric
signal and digitalised as an usg image
• Obstetric usg 2-12 mhz
• Transvaginal 5-10mhz
• Transabdominal 2-6.5 mhz

5. TIMING OF USG
• First 11-13 weeks +6 days
• Second 18-20 weeks
• Third trimester growth scan and well being placenta evaluation

6. FIRST TRIMESTER
Indications
1.Confirmation of intrauterine pregnancy
2.Gestational age(dating)
3.Viability of pregnancy
4.Multiple pregnancy
5.Miscarriage
6.Ectopic pregnancy

7. CRL

8. FHR

9. MULTIPLE PREGNANCY

10. ECTOPIC

11. MISSED ABORTION

12. CONTD..
7.Hydatidiform mole
8.Screening for down syndrome by nuchal translucency
9.Cervical incompetence
10.Usg in prenatal procedures
11.Evaluation of uterine and adnexal pathology
12.Early identification of c section scar pregnancy

13. NT SCAN

14. CERVICAL INCOMPETENCE

15. MOLAR PREGNANCY

16. USG IN DIAGNOSIS OF CONGENTIAL
MALFORMATIONS
• 1.ANENCEPHALY
• 2.OTHER ANOMALIES

17. SECOND AND THIRD TRIMESTER USG
INDICATIONS
• FETAL ANOMALY
• ASSESSMENT OF FETUS:
• FETAL GROWTH
• FETAL WEIGHT
• GESTATIONAL AGE
• FETAL WELL BEING-BIOPHYSICAL PROFILE
• FETAL ANOMALY FOLLOW UP
• FETAL PRESENTATION
• FETAL DEMISE CONFIRMATION

18. CONTD..
• PLACENTAL LOCALISATION AND ABNORMALITIES
• FOR INTERVENTIONS –AMNIOCENTESIS,FETAL BLOOD SAMPLING

19. SECOND TRIMESTER
• Systematic examination for fetal anomalies
• Timing 18-20 weeks
• Components:
• General survey-fetal number, viability and location of placenta
• Fetal biometry
• Placenta, umblical cord and amniotic fluid
• Associated uterine and adnexal pathology, cervical length
• Structural anomalies of fetus

20. FETAL BIOMETRY
• BIPARIETAL DIAMETER
• FEMUR LENGTH
• ABDOMINAL CIRCUMFERENCE
• HEAD CIRCUMFERENCE
• TRANSVERSE DIAMETER OF CEREBELLUM(14-24) WEEKS

21. MEASUREMENT USED GESTATIONAL AGE AT
ASSESSMENT
ACCURACY
MEAN G SAC DIAMETER 5 WEEKS +- 5-7 DAYS
CRL 7-10 WEEKS +- 3 DAYS
CRL 11-14 WEEKS +-5 DAYS
BPD,HC,AC,FL 14-24 WEEKS +-7-10 DAYS
BPD,HC,AC,FL AFTER 26 WEEKS 14-21 DAYS

22. Fetal growth
• Abdominal circumference
at the level of intrahepatic portion of umblical vein of fetal liver
including stomach
• Biparietal diameter
• Associated with high false negative rates due to brain sparing effect
• In cases of IUGR use both head and abdominal circumference not only serial
bpd measurements
• HC:AC ratio better for SGA at risk babies if large assymetrical iugr
• If normal symmetrical iugr or sga
• AC >90th centile: accelerated growth large baby-maternal diabetes
mellitus

23. FETAL BIOMETRY

24. Estimation of fetal weight
• Using BPD and AC
• If engaged or in breech or dolicocephalic bpd unreliable
• Then use HC,AC,FL

25. BIOPHYSICAL PROFILE

26. Assessment of fetal environment
Placenta
• Recognised by stronger echo pattern than underlying myometrium
• Week 8
• Grannums grading system-texture and pattern grading
• In iugr and pih early maturation of placenta
• Placenta previa-distance between placental margin and internal os
2cm or less
• Adherent placenta
• Infarctions and calcifications

27. PLACENTA PREVIA AND PLACENTA ACRETA
SYNDROME

28. GRANNUM CLASSIFICATION

29. Estimation of amniotic fluid
• Maximum vertical pocket-single deep pocket=2-8 cm normal
• Amniotic fluid index
• Add the vertical depths of the largest pocket in each of the four quadrants
• Normal value-5 and 24 cm
• If <5cm oligohydramnios
• If >25 polyhydramnios

30. AFI

31. causes
oligohydramnios polyhydramnios
Rupture of membranes anencephaly
IUGR Duodenal atresia
Anomalies of urinary tract-renal agenesis,urethral
stenosis
Hydrops fetalis
Postdated pregnancy Maternal diabetes mellitus

32. Umblical cord
• Single umblical artery
• Nuchal cord
• Abnormal cord insertions-battledore placenta
• Umblical cord entry in to abdomen should be evaluated to rule out
abdominal wall defects and omphalocele

33. SINGLE UMBLICAL ARTERY

34. NUCHAL CORD

36. Structural defects in fetus
• Anomaly >70% of major anomalies and 50% of minor anomalies detected
• Anencephaly
• Hydrocephalus
• Duodenal atresia
• Jejunal atresia
• Diaphragmatic hernia
• Club foot
• Single umblical artery
• Hydrops fetalis

37. HYDROCEPHALUS

38. CONGENITAL DIAPHRAGMATIC HERNIA

39. DUODENAL ATRESIA

40. CLUB FOOT/CTEV

41. Markers of chromosomal abnormalities
• Cystic hygroma turner/trisomy 21
• Duodenal atresia trisomy 21
• Omphalocele trisomy 13/18
• Hyperechogenic bowel - fetal aneuploidy and cystic fibrosis

42. CYSTIC HYGROMA

43. OMPHALOCOELE

44. Third trimester usg
• Fetal growth
• IUGR-AC <3rd centile
• SGA/IUGR -BPD/FL/AC <10

45. FETAL WELLBEING
• BIOPHYSICAL PROFILE
• ANTEPARTUM FETAL SURVEILLANCE

46. OTHER THIRD TRIMESTER USG USES
• APH
• PPROM
• ANOMALIES-CARDIAC/HYDROCEPHALUS
• FETAL DEATH
• PRESENTATION IN OBESE
• MONITORING EXTERNAL CEPHALIC VERSION
• GUIDE DURING FETOSCOPY AND CORDOCENTESIS
• GUIDE DURING FETAL THERAPY-INTRAUTERINE TRANSFUSION/TWIN TO
TWIN TRANSFUSION
• FETAL GROWTH,WELL BEING,MULTIPLE GESTATION,ESTIMATED FETAL
WEIGHT

47. DOPPLER VELOCIMETRY
• Doppler shift principle
• Waveforms of uterine,middle cerebral and fetal umblical
arteries,ductus venosus blood flow
Uses: high risk pregnancy-
• Pre eclampsia
• Gdm
• Fetal growth restriction
• Fetal anemia

48. Umblical artery doppler
• Normal-low resistance blood flow-even during diastole-good flow to
the fetus
• If high resistance-flow is either absent or reversed
• Reversed flow-immediate termination of pregnancy irrespective
gestational age
• PERINATAL MORTALITY-reversed flow-33%,absent flow-10%

49. UMBLICAL ARTERY DOPPLER

50. DOPPLER INDICES
S/D RATIO:
• Ratio of maximum systolic to minimum diastolic blood flow
Resistance index:
• (Peak sys velocity-end diastolic velocity)/systolic velocity
Pulsatality index:
• (Peak systolic velocity-end diastolic velocity)/mean velocity

51. • S/D RATIO:
• Most commonly used
• Value decreases with fetal age
• 20 weeks-50th centile for s/d ratio is 4
• 30 weeks 2.83
• 40 weeks 2.18
• If resistance increases in umblical artery-s/d ratio increases
• Abnormal if >95th centile

52. Middle cerebral artery blood flow
• Normal-diastolic flow in cerebral artery < umblical arteries
• Cerebrovascular resistance >placental resistance
• Pusatality ratio of (MCA/UA)-cerebroplacental ratio(CPR) >1
• IF <1 FLOW FAVOURS BRAIN –PATHOLOGICAL –BRAIN SPARING

53. MCA DOPPLER

54. Indications of doppler velocimetry
• Screening of anomalies-cardiac
• Vascular malformations
• Diaphragmatic hernia/renal anomalies
Clinical indications:
Pre eclampsia 1st and 2nd trimester
Fetal anemia
Growth restricted fetus

55. • 3D ultrasound-facial defects
• 4D ultrasound-3D IN REAL TIME-cardiac activity
• Fetal ECHO-cardiac defects

56. X rays
• Restricted usage
• Abdomen shield
• If exposed in pre implantation stage-lethal to fertilised ova and
embryo-miscarriage
• Organogenesis stage-teratogenesis
• Fetal period exposure-growth restriction, microcephaly, mental
retardation

57. MRI
• Uses powerful magnets to produce radiofrequencies-no ionising
radiation
• Advantage over CT scan
• No harmful human effects
• Not recommended in first trimester

58. Indications:
• Intrabdominal malignancies: lymphoma, renal cell carcinoma
• Retroperitoneal space tumors: pheochromocytoma
• Characterise ovarian and uterine masses
• Assess fetal anatomy if usg is equivocal due to reduced liquor and
movements
• Road traffic accidents

59. • Thankyou