This document summarizes methods for determining the age of a fetus or embryo. It discusses the difference between a fetus and embryo, noting an embryo is the developing pregnancy until 8 weeks of gestation, while a fetus develops after 8 weeks until birth. Two main methods for age determination are described: ultrasound examination and rectal examination. Rectal examination focuses on measurements of the amniotic vesicle, placentomes, uterine horn diameter, fetal fluid amount, fetal weight, and uterine artery diameter to estimate gestational age. The relationship between gestational age and fetal age is also clarified.

2. AGE DETERMINATION OF
FETUS AND EMBRYO
14-Arid-2022 FAISAL SHAHZAD
SOMROO
PRESENTED TO:
.Dr. Riaz husain Pasha .Dr. Mujeeb-ur-Rehman Sohoo
PRESENTED

3. Contents
 Difference between fetus and embryo
 Stages of development
 Methods of age determination
 Different statics
 Fetal and gestational age

4. Difference between fetus and embryo
 The embryo is defined as the developing
pregnancy from the time of fertilization until the
end of the eighth week of gestation.
 While the fetus a developing mammal or other
viviparous vertebrate after the embryonic
stage and before birth.

5. Fetus
Embryo

6. Stages of Development
Week 1:
 Zygote
 Morula
 Blastocyst

7. Cont…
Week 2:
 Trophoblast-outer cell layer
 Embryoblast-inner cell mass
 Implantation
 Bilaminar embryo

8. Cont…
Week 3:
 Gastrulation
 Notochord formation
 Trilaminar embryo
 Mesoderm
 Somitogenesis
 Neurogenesis

9. Cont…
Week 4:
 Heart
 Placodes
 Pharygeal arches

10. Cont…
 Week 5-7:
 Early face development
 WEEK 8 last week of embryonic development

12. IMPLANTATION OF EMBRYO

13. Stage Days Size
(mm)
1 1 0.1 - 0.15
2 2-3 0.1 - 0.2
3 4-5 0.1 - 0.2
4 5-6 0.1 - 0.2
5 7-12 0.1 - 0.2
6 13-15 0.2
7 15 - 17 0.4

14. Stage Days Size
(mm)
8 17-19 1.0 - 1.5
9 19-21 1.5 - 2.5
10 22-23 2 - 3.5
11 23-26 2.5 - 4.5
12 26-30 3 - 5
13 28-32 4 - 6
14 31-35 5 - 7

15. Stage Days Size
(mm)
14
31 - 35 5 - 7
15 35 - 38 7 - 9
16 37 - 42 8 - 11
17 42 – 44 11 - 14
18 44 - 48 13 - 17
19 48 – 51 16 - 18

16. WHY TO DO IT?
 For the comparison between normal and
abnormal structure.
 For diagnosing some inherited disease
 Cheking there functioning.

17. EMBRYO STAGES

18. Methods of determination of age
Ultrasound Method
Rectal Examination Method

19. Ultrasound Method
 It is a method used for the determination of
fetus and embryo
 This method is used for the diagnosis of
disease

20. ULTRASOUND METHOD

21. Rectal Examination Method
 It is a method which is used to determine the
age of embryo or fetus with the help of hand.
 During rectal examination of animal we focus
on the following points in order to determine
the exact age of embryo or fetus
 Diameter of Amniotic Vesicle
 Diameter of Placentomes
 Diameter of Horn containing the fetus
 Amount of Fetal Fluid
 Weight of Fetus
 Diameter of uterine Artery

24. Cont…
 Following are the points we will prefer more
 Diameter of Amniotic Vesicle
 Diameter of Placentomes

25. Diameter of Amniotic Vesicle
 A thin, tough, membranous sac that encloses
the embryo or fetus of a mammal, bird, or
reptile is called Amniotic Vesicle.
 It is filled with a serous fluid in which the
embryo or fetus is suspended.
 In this method we determine the diameter of
amniotic vesicle by using our hands.

26. Diameter of Placentomes
 The whole group of fetal and maternal tissues
that are involved in placentation is called
Placentomes.
 In this method we determine the diameter of
placentomes by using our hand.

27. Days of Gestation Diameter of Amniotic Vesicle
30 1.0 cm (Pea Size)
40 2.5-3.0 cm (Size of Plum)
50 3.5-5.0 cm
60 6-7.5 cm

28. Day of Gestation Diameter of
Placentomes
70 0.5-0.75 cm
80 0.5-1.0 cm
90 1.0-1.5 cm
120 1.5-2.5 cm
150 2.5-4.0 cm
180 4.0-5.0 cm
210 5.0-7.5 cm
240 6.0-9.0 cm
270 8.0-12 cm

29. Days of Gestation Diameter of Horn Containing
the fetus
30 2-4 cm
40 3-6 cm
50 5-7 cm
60 6-9 cm
70 7-10 cm
80 9-12 cm
90 10-13 cm
120 12.5-18 cm
150 18-23 cm
180
210
240
270
Diameter of Horn containing
Fetus

30. Day of Gestation Amount of Fetal Fluid
30 30-60 ml
40 75-100 ml
50 90-200 ml
60 200-450 ml
70 350-650 ml
80 500-800 ml
90 750-1400 ml
120 2000-3500 ml
150 4000-5000 ml
180 4000-7500 ml
210 6300-10,000 ml
240 8000-12000 ml
270 12,000-20,000 ml
Amount of Fetal Fluid

31. Day of Gestation Weight of Fetus
30 0.3-0.5 gm
40 1-1.5 gm
50 3-6 gm
60 8-30 gm
70 25-100 gm
80 120-200 gm
90 200-400 gm
120 1000-2000 gm
150 3000-4000 gm
180 5-10 kg
210 8-18 kg
240 15-25 kg
270 20-25 kg
Weight of Fetus

32. Days of Gestation Diameter of Uterine Artery
30
40
50
60
70
80
90 0.3-0.5 cm
120 0.5-0.8 cm
150 0.6-1.0 cm
180 0.9-1.25 cm
210 1.25-1.5 cm
240 1.25-1.7 cm
270 1.5-1.9 cm
Diameter of Uterine Artery

33. GESTATIONAL AND FETAL AGE
 Gestational or menstrual age is measure of
age of pregnancy where the origin is the
females last estrous cycle.
 Fetal age is the term that refers to the actual
age of baby starting at the time of conception.
 Fetal age is two weeks less than the
gestational age.

34. MATHODS FOR THE ESTEMATION
Method Variability Gestational age
Days from estimated
ovulation
±3 days +14days
Days from artificial
insemination
±3 days +14 days
Days from known single
sexual intercourse
±3 days …
First trimester physical
examination
±2 weeks …
Second trimester
physical examination
±4 weeks …
Third trimester physical
examination
±6 weeks …
…

35. ANY QUESTION?