Obstetrics ultrasound Fetal growth retardation.pptx

Obstetrics usg topics placneta, FGR

1. IMAGING IN Obstetrics emergencies MODERATOR DR.RAVIKUMAR ASSOCIATE PROFESSOR DEPT OF RADIOLOGY BY DR.VAISHNAVI JR 1 DEPT OF RADIOLOGY PRESENTATION II

2. FETAL GROWTH RESTRICTION AND ABNORMAL DOPPLER INDICES

3. TERMINOLOGIES APPROPRIATE FOR GESTAIONAL AGE (AGA): An AGA fetus has biometric parameters and /or estimated fetal weight(EFW)between 10 th and 90 th percentile. LARGE FOR GESTAIONAL AGE(LGA): EFW or AC above the 90 th percentile. SMALL FOR GESTATIONAL AGE(SGA): A fetus typically having EFW or AC below the 10 th percentile. FETAL GROWTH RESTRICTION(FGR): AC or EFW below 3 rd centile is sole criteria to diagnose FGR

4. Umbilical artery doppler The umbilical arterial circulation is normally a low-impedance circulation, with an increase in the amount of end-diastolic flow with advancing gestation. Umbilical arterial Doppler waveforms reflect the status of the placental circulation, and the increase in end-diastolic flow that is seen with advancing gestation is a direct result of an increase in the number of tertiary stem villi that takes place with placental maturation. Diseases that obliterate small muscular arteries in placental tertiary stem villi result in a progressive decrease in end-diastolic flow in the umbilical arterial Doppler waveforms until absent, and then reverse flow during diastole is noted . Reversed diastolic flow in the umbilical arterial circulation represents an advanced stage of placental compromise and is associated with more than 70% of placental arterial obliteration. The notation of absent or reversed end-diastolic flow in the umbilical artery is commonly associated with FGR and oligohydramnios.

5. Doppler indices commonly used in obstetric imaging. c, constant related to the medium in which the sound is traversing; D, diastole; M, mean; PI, pulsatility index; RI, resistance index; S, systole. Doppler waveforms of the umbilical artery in a normal fetus in the third trimester of pregnancy. Note the increased end-diastolic velocity (D), consistent with a low impedance circulation. S, peak systole.

6. Abnormal umbilical artery Doppler waveforms; A.D ecreased end-diastolic velocity, B. absent end-diastolic velocity ( B ), reversed end-diastolic velocity ( C ).

7. Middle cerebral artery doppler The MCA is the most accessible cerebral vessel to ultrasound imaging in the fetus , and it carries more than 80% of cerebral blood flow. The cerebral circulation is normally a high-impedance circulation with continuous forward flow throughout the cardiac cycle. BRAIN SPARING EFFECT In the presence of fetal hypoxemia, central redistribution of blood flow occurs, resulting in increased blood flow to the brain , heart, and adrenals and a reduction in flow to the peripheral and placental circulations. This blood flow redistribution is known as the brain-sparing effect and plays a major role in fetal adaptation to oxygen deprivation.

8. Circle of Willis shown on color Doppler imaging. ACA, anterior cerebral artery; MCA, middle cerebral artery; PCA, posterior cerebral artery. ( A ) Doppler waveforms of the middle cerebral artery in a normal fetus ( B ). Hypoxemic fetus . Note the increase in end-diastolic velocity in fetus B resulting from a low-impedance cerebral circulation as part of the brain-sparing reflex.

9. DUCTUS VENOSUS DOPPLER Doppler flow studies of the inferior vena cava and ductus venosus in the fetus . Doppler waveforms obtained from the central venous circulation in the fetus reflect the physiologic status of the right ventricle. Specific information with regard to right ventricular preload, myocardial compliance, and right ventricular end-diastolic pressure can be derived from IVC and DV.

10. T hree-dimensional B flow image from a 17-week fetus illustrating the relationships of the venous system, heart, and aorta. C olor doppler sonogram of a coronal plane of the fetal abdomen and chest showing the inferior vena cava (IVC), joined by the ductus venosus (DV) and the left hepatic vein (LHV) as it enters the right atrium (RA).

11. Color Doppler sonogram of a transverse plane of the fetal abdomen showing the umbilical vein (UV) and the ductus venosus (DV). Note the presence of turbulence (with aliasing) on color Doppler in the ductus venosus. High scale settings best reveal high-velocity flow with aliasing in the ductus venosus ( arrow ) on this transaxial color Doppler ultrasound image through the fetal upper abdomen.

12. Uterine artery DOPPLER NON PREGNANT STATE (HIGH IMPEDENCE) LOW IMPEDENCE HIGH FLOW Initial fall (24-26weeks): Trophoblastic invasion of spiral arteries >26 weeks hormonal effect Uterine artery DOPPLER

13. Color Doppler imaging in the lateral lower uterine segment showing the main uterine artery as it crosses over the hypogastric iliac vessels before it enters the uterus and then divides into a uterine branch and a cervical branch. Doppler waveforms of the uterine artery obtained in the late second trimester of pregnancy S howing normal uterine circulation with increased end-diastolic velocity implying low-impedance circulation. B) A bnormal uterine artery circulation with a waveform notch ( top arrow ) and low end-diastolic velocity (high impedance) ( lower arrow ).

14. WHAT CAUSES THE DOPPLER CHANGES IN FGR? F ailure of normal development of maternal placental arteries into low resistance vessels and therefore reduced oxygenation( Changes in uterine arteries ). Reduction in number of placental terminal capillaries and muscular arteries in tertiary system villi and therefore impaired maternal fetal transfer( Changes in UA ). As a result of there REDISTRIBUTION of blood flow to the brain ( Reflected in MCA ) and to the heart ( Reflected in ductus venosus )

15. How is the abnormality reflected on doppler? ABNORMAL WAVE FORMS ABNORMAL INDICES: Abnormal PI,RI,PSV ,S/D (NOTE: Normally indices of MCA should always be greater than the indices of UA) ABNORMAL CEREBROPLACENTAL RATIO: MCA PI/ UA PI (NOTE: normally this ratio should be more than 1.1)

16. Grades of fetal growth restriction

17. Thank you