Ist trimester ultrasound

G Sac seen within the thickened decidua .
Eccentric location within endometrium
Should abut the endometrial canal ( to differentiate it from decidual cyst )
On TVS -4& half -5 weeks
Thresold level – identifies the earliest one can expect to see a sac -4w3d
Discriminatory level – identifies when one should always see the sac- 5w 2d .

1. IST TRIMESTER ULTRASOUND

2. EARLY PREGNANCY ULTRASOUND GESTATIONAL SAC YOLK SAC FETAL POLE

3. G SAC DOUBLE DECIDUAL SAC SIGN INTRADECIDUAL SAC SIGN MEAN SAC DIAMETER EMPTY G SAC PSEUDOGESTATIONAL SAC

4. INTRADECIDUAL SAC SIGN G Sac seen within the thickened decidua . Eccentric location within endometrium Should abut the endometrial canal ( to differentiate it from decidual cyst ) On TVS -4& half -5 weeks Thresold level – identifies the earliest one can expect to see a sac -4w3d Discriminatory level – identifies when one should always see the sac- 5w 2d .

5. Beta HCG AND G SAC B HCG becomes positive shortly after implantation long before Gsac visualised by usg 1800 mIU /ml –TAS > 1000 mIU /ml – TVS

6. DOUBLE DECIDUAL SAC SIGN DOUBLE DECIDUA – 1) decidua vera / parietalis lining the uterine cavity 2) decidua capsularis –lining the G SAC These 2 deciduas seen as 2 concentric rings surrounding the anechoic G sac Where the 2 adhere is the decidua basalis –the site of future placental formation seen as eccentric echogenic thickening . differentiate intrauterine pregnancy from pseudogestational sac . Identified by 5.5 -6 wks of GA ( same time when yolk sac becomes visible by TVS )

7. MSD

8. YOLK SAC Ist structure to seen normally within the G SAC . TAS MSD OF 10-15mm TVS MSD OF 8mm

9. Y sac should always be visualised at MSD Of 20mm on TAS & 8 mm on TVS . CONFIRMS IUP ( double decidual sac sign is not 100% specific ) Size – grows at a rate of 0.1mm /mm of MSD until 15mm of MSD after that growth slows down to 0.03 mm . Upper limit of size between 5-10 wks – 5.6mm Number of yolk sac = amniocity of a multifetal pregnancy

10. EMBRYO / FETUS CROWN RUMP LENGTH FETAL HEART RATE PHSIOLOGIC GUT HERNIATION EMBRYONIC RHOMBENCEPHALON

11. CONFIRMING INTRAUTERINE GESTATION Double decidual sac sign Intradecidual sac sign double bleb sign

12. FIRST TRIMESTER VAGINAL BLEEDING ECTOPIC PREGNANCY FAILED EARLY PREGNANCY GESTATIONAL TROPHOBLASTIC DISEASE SUBCHORIONIC HAEMORRHAGE DEMISE OF A TWIN IMPLANTATION BLEEDING

13. ANEUPLOIDY TESTING ANTENATAL SCREENING NUCHAL TRANS LUCENCY