1. Dr U S SABITHA Assistant professor Dept of OBGyn PESIMSR, KUPPAM
FETAL BLOOD SAMPLING
Dr U S SABITHA
Assistant professor
Dept of OBGyn
PESIMSR, KUPPAM

2. INTRODUCTION
Originally introduced by Saling in 1967

3. AIM
to identify fetuses at risk for severe adverse outcome to be able to intervene before damage has occurred
To prevent and not predict adverse outcomes !!

4. Indications
Suspected fetal compromise suggested by an abnormal CTG pattern

5. In cases with bradycardia, FBS has no place.
Prolonged bradycardia, expedite delivery
If it recovers, observation for at least 20 minutes is recommended as transient acidaemia is likely shortly after a bradycardic event

6. Contraindications
• Clear evidence on continuous EFM of serious, sustained fetal compromise • Fetal bleeding disorders ( suspected fetal Thrombocytopaenia, haemophilia) • Face or brow presentation or uncertain presenting part • Maternal infection (eg HIV, hepatitis virus, and herpes simplex virus and suspected intrauterine sepsis) • Gestation less than 34 weeks gestation • Active second stage of labor Relative contraindications (discuss with Consultant Obstetrician) • Gestation range 34 weeks to 36 weeks and 6 days • Maternal pyrexia above 38 degree C

7. Minimum criteria Term baby Membranes ruptured Atleast 3 cm dilated
Verbal consent

8. 4 P’s
Prepare
Positioning
Procedure
Processing

9. Position
Left lateral position better
CTG to be connected.

10. FBS KIT

11. Capillary holder
Capillary tube

12. Procedure

13. RESULT INTERPRETATION
Fetal blood sample Lactate (mmol/L) pH Normal ≤ 4.1 ≥ 7.25 Pre-acidotic range Acidotic range > 4.8 ≤ 7.20 Which is better of the two: lactate or pH??

14. LACTATE Marker for increased dependancy on anerobic metabolism
Indicator of tissue perfusion (O2 levels at tissue level)
Lactate levels raise before pH falls in hypoxia
Also buffering capacity helps maintain pH- therefore fall in pH indicates prolonged hypoxia
Hence, lactate is a better predictor of depressed newborn.

15. Scalp lactate better than scalp pH sampling
easier
affordable
smaller volume needed – 5 microlitre
higher sampling success rate
more likely to be successful
the result is quick
can be performed at the bedside – point of care testing!!
Better predictor of long term neonatal condition
Larger volume – 50 microlitres
lower sampling success rate
Less likely to be successful
Failure rate- 20%
Takes around 20 min

16. What does NICE say?
Since December 2014, lactate has been recommended by the National Institute for Health and Care Excellence, provided that trained staff and the relevant equipment are available

17. What does Cochrane metanalysis say?
found no differences in fetal/neonatal outcome or operative interventions
a significantly higher success rate with lactate compared with pH (risk ratio 1.10; 95% CI 1.08–1.12).
East CE, Leader LR, Sheehan P, Henshall NE, Colditz PB. Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace. Cochrane Database Syst Rev 2010;(3):CD

18. Fetal scalp blood lactate as predictor of HIE?pH
LACTATE
Kruger K, Hallberg B, Blennow M, Kublickas M, Westgren M. Predictive value of fetal scalp blood lactate concentration and pH as markers of neurologic disability. Am J Obstet Gynecol 1999;181:1072–8.
sensitivity
67%
49%
specificity
93%

19. RESULT INTERPRETATION
Fetal blood sample Lactate (mmol/L) pH Normal ≤ 4.1 ≥ 7.25

20. Normal range • If CTG returns to normal there is no need to repeat the fetal scalp lactate • If abnormalities continue the fetal scalp lactate should be repeated in one hour • If abnormalities worsen then repeat sooner than an hour. What if the second fbs is normal and FHR trace remains unchanged ? Role of a third/further sample? When a third FBS is considered necessary, Consultant Obstetric opinion must be sought

21. RESULT INTERPRETATION
Fetal blood sample Lactate (mmol/L) pH Pre-acidotic range
Repeat within 30 minutes to establish a trend in results or deliver if there is significant deterioration from the previous result

22. RESULT INTERPRETATION
Fetal blood sample Lactate (mmol/L) pH Acidotic range > 4.8 ≤ 7.20
• The fetus should be delivered immediately by either instrumental delivery or urgent CS
• Stop oxytocin infusion if in progress

23. POINTS TO REMEMBER: Do women undergoing FBS experience pain?
Every lactate measurement device needs it own reference values.
Lactate analysis of a blood in a glass capillary should be carried out within ten minutes of sampling because lactate increases linearly with time.
Record the report on the case sheet of mother, baby and ctg
Do women undergoing FBS experience pain?
The median pain score was 3.5 out of 10

24. All fetal scalp lactate measurements should be interpreted taking into account: • clinical history • gestation • parity • onset of the labour • progress of the labour • presence of meconium stained liquor • number and type of CTG abnormalities • previous fetal scalp lactate measurement

25. Complications very rare haemorrhage: infection breakage of the blade
If significant bleeding persists the baby should be delivered.
Postnatal examination of the baby should include examination of the sampling site.
infection
breakage of the blade
Post Birth
Ensure that paired arterial and venous cord blood samples are collected following the birth of the baby and sent to the laboratory for blood gas analysis.
These results need to be reviewed and added to the clinical notes.

26. What if there is no facitlity for FBS?
Fetal scalp stimulation
Fetal acoustic stimulation

27. Thank you