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

INTRODUCTION Originally introduced by Saling in 1967

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 !!

Indications Suspected fetal compromise suggested by an abnormal CTG pattern

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

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

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

4 P’s Prepare Positioning Procedure Processing

Position Left lateral position better CTG to be connected.

FBS KIT

Capillary holder Capillary tube

Procedure

RESULT INTERPRETATION Fetal blood sample Lactate (mmol/L) pH Normal ≤ 4.1 ≥ 7.25 Pre-acidotic range 4.2 - 4.8 7.21 - 7.24 Acidotic range > 4.8 ≤ 7.20 Which is better of the two: lactate or pH??

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.

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

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

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):CD006174.

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%

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

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

RESULT INTERPRETATION Fetal blood sample Lactate (mmol/L) pH Pre-acidotic range 4.2 - 4.8 7.21 - 7.24 Repeat within 30 minutes to establish a trend in results or deliver if there is significant deterioration from the previous result

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

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

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

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.

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

Thank you