1. Yolk sac diameter as a predictor of pregnancy outcome
Keerthana Anand, Shakila Shetty, Chaitanya Ganne
Department of Obstetrics and Gynaecology,
M.S. Ramaiah Medical college

2. BACKGROUND ABORTION USG
Spontaneous abortion is common in about 15% of recognizable pregnancies. [1]
Threatened abortion presents as vaginal bleeding and occurs in 21% of pregnancies before 20 weeks.
50% of these pregnancies will eventually abort[2]
USG
There is great difficulty in reliably anticipating which pregnancies will terminate in abortion
Various ultrasound markers are used to aid us in predicting the outcome of pregnancy:
Trophoblastic reaction
Appearance and size of gestational sac
Appearance and size of yolk sac
Size of the embryo (CRL)
Presence of cardiac activity
BACKGROUND

3. YOLK SAC
The secondary yolk sac is the first extra-embryonic structure that can be detected with TVS in the chorionic cavity
5th week – 3-4 mm
9th week- 5-6 mm
By 12th week – disappears
Yolk sac has nutritive, endocrine, metabolic, immunologic, secretory, excretory and hematopoietic functions.
Many studies on the prognostic significance of the YS for pregnancy outcome have been performed with conventional sonography and more recently with TVS. The results are conflicting.

4. To evaluate the size of secondary yolk sac as a predictor of pregnancy outcome
AIM

5. To study the biometry of the yolk sac and its co-relation with menstrual age and crown rump length.
To assess the predictive value of abnormal yolk sac size at endovaginal ultrasonogram for abnormal pregnancy outcome.
OBJECTIVES

6. MATERIAL AND METHODS Study Design Descriptive study Study setting
Department of Obstetrics and Gynaecology, M.S. Ramaiah Medical College
Study setting
22 months : Oct 2011 to July 2013
Study duration
MATERIAL AND METHODS

7. MATERIAL AND METHODS Study population Exclusion criteria Sample size
Pregnant women with menstrual age less than 10 weeks
Study population
Molar pregnancy
Ectopic pregnancy
Women with structural anomalies of uterus and cervix
Multiple gestation
Endocrine disorders – hypothyroidism, diabetes mellitus
Exclusion criteria
202
Above sample size was estimated based on study by Daniel J et al [3]
Relative precision of 20% and confidence level of 95%.
Sample size
MATERIAL AND METHODS

8. MATERIAL AND METHODS PROCEDURE Informed consent taken
A 7.7 MHz transducer was used to perform TVS
The following parameters were measured
Yolk sac diameter (YSD)
CRL
Gestational sac diameter
YSD was measured from outer to outer rim of the yolk sac
MATERIAL AND METHODS

9. PREGNANCYOUTCOME Normal outcome: Abnormal outcome:
Pregnancy continued beyond 24 weeks
Abnormal outcome:
Pregnancy had a spontaneous abortion or missed abortion or demonstrable foetal anomaly
PREGNANCYOUTCOME

10. STATISTICAL ANALYSIS Data was analysed using software SPPS version 20
All the quantitative parameters such as yolk sac diameter, gestational age, CRL, mean gestational sac diameter, age of women, etc. are described in terms of descriptive statistics such as mean and standard deviation
Upper and lower 95% confidence limits were estimated for yolk sac diameter based on normal pregnancy outcomes, for particular gestational age, which was grouped in weeks.
STATISTICAL ANALYSIS

11. An abnormal yolk sac diameter was defined as being more than 2 SD above or below the mean for particular gestational age.
Sensitivity, specificity, positive predictive value and negative predictive value were calculated for abnormal yolk sac diameter in predicting abnormal pregnancy outcome.
A p value of < 0.05 was considered as significant
STATISTICAL ANALYSIS

12. RESULTS 202 enrolled 173 women studied and analyzed
14 : loss for follow up
15: elective termination of pregnancy
173 women studied and analyzed

13. PREGNANCY OUTCOME
RESULTS
NORMAL
82.1%
ABNORMAL
17.9%

14. Linear regression of yolk sac diameter with CRL and gestational age
P < 0.001
r = 0.553
P < 0.001
r = co-relation co efficient

15. Distribution of yolk sac diameter in normal and abnormal pregnancy
RESULTS

16. RESULTS Yolk sac diameter for pregnancies with normal outcome
Gestational Age N
Mean
( cm ) SD
Range (cm)
( Mean ± 2SD )
6th week 17
0.366
0.094
7th week 49
0.382
0.067
8th week 45
0.430
0.068
9th week
0.513
0.077
10th week 14
0.491
0.075
RESULTS

17. RESULTS PREGNANCY OUTCOME SENSITIVITY: 61.29 % SPECIFICITY: 96.48 %
GESTATIONAL AGE:
OUTCOME
Total χ2 P
Abnormal
Normal
YOLK SAC DIAMETER 19 5 24
71.071
<0.001 12
137
149 31
142
173
RESULTS
SENSITIVITY: %
SPECIFICITY: %
PPV: 79.17%
NPV: 91.95%

18. RESULTS P value 0.144 <0.001 0.005 0.002 SENSITIVITY(%)
SENSITIVITY(%)
SPECIFICITY (%)
PPV (%)
NPV (%)
P value
6th week
33.33
94.11 50
88.89
0.144
7th week
97.96 75
94.12
<0.001
8th week 80
95.56
9th week
57.14
84.21
0.005
10th week 60
100
87.50
0.002
OVERALL
61.29
96.48
79.17
91.95
RESULTS

19. TVS at 68 days menstrual age showing abnormally small yolk sac of 0
TVS at 68 days menstrual age showing abnormally small yolk sac of 0.13 cm

20. A TVS showing an abnormally large yolk sac (YSD = 1
A TVS showing an abnormally large yolk sac (YSD = 1.96 cm) with a CRL of 0.38 cm corresponding to a GA of 5 weeks 4 days, at menstrual age of 70 days (10weeks). Cardiac activity was absent.

21. DISCUSSION Author Year n Abnormal outcome (%) Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
Lindsay et al. [3]
1992
486
32.7
26.9
92.7
51.1 -
Kucuk et al. [4]
1999
250
12.4 65 97 71 95
Our study
2013
173
17.9
61.29
96.48
78.17
91.95

22. YSD measurement 6th-10th week POG : Valuable tool to predict pregnancy outcome
YSD: Mode of early prediction of pregnancy outcome even before detection of embryo
CONCLUSION
Counseling patients regarding risk of abortion and need for follow up USG

23. 1. Roth, D. B. , The frequency of spontaneous abortion
1. Roth, D.B., The frequency of spontaneous abortion. Int J Fertil, : p
2. Everett, C., Incidence and outcome of bleeding before the 20th week of pregnancy: prospective study from general practice. BMJ, (7099): p
3. Lindsay, D.J., et al., Yolk sac diameter and shape at endovaginal US: predictors of pregnancy outcome in the first trimester. Radiology, (1): p
4. Kucuk, T., et al., Yolk sac size and shape as predictors of poor pregnancy outcome. Journal of Perinatal Medicine, (4): p
REFERENCES

24. THANK YOU