1. Obstetrics for Anaesthestists
Miss Julia Montgomery
15th September 2009

2. Overview Fetal monitoring - CTGs and Fetal Blood Sampling
Placenta praevia / accreta
Abruptio placentae
Uterine atony
Ruptured uterus
Vasa Praevia

3. Cardiotocograph CTG
Continuous print out of fetal heart rate and contractions
Abdominal ultrasound
detects cardiac movements and hence heart rate
FSE (clip applied to the fetal scalp)
detects the R-R wave of the fetal ECG
STAN (PR interval)

4. Features of a CTG Normal heart rate 110-160 bpm Baseline variability
Reduced variability - hypoxia/fetal anaemia
Accelerations
>15 bpm lasting 15s
Decelerations
early
Occur with contractions
late
Nadir of the deceleration occurs well after the peak of the contraction
variable
No relationship with contractions vary in shape as well

5. Significance of Decelerations
early
Normal vagal response
Intracranial pressure increases with contractions either head compression or cord compression
late
Suggestive of fetal hypoxia
variable
May mean cord compression - acc before and after the deceleration may indicate that the fetus is coping well
May indicate hypoxia

6. Meconium stained liquor
Present in 15% of term labours
Present in 40% of labours at 42 weeks
Mechanism:
vagal stimulation causing gut contraction & anal sphincter relaxation
Maybe associated with hypoxia
If CTG normal ignore (let paediatrician know)

7. Fetal Blood Sampling Why?
CTG is highly sensitive eg if normal, baby OK
But poorly specific eg if abnormal only a few babies are hypoxia
Use of CTG only leads to a 4 fold increase in Caesareans Sections for fetal distress
Need to check the CTG findings with FBS

8. Fetal Blood Sampling Tiny stab on the fetal scalp
Blood collected via a glass pipette
pH and base excess result
Contraindications
Infection such as HIV, Hepatitis B & Group B streptococci
Fetal bleeding disorder
Prematurity less than 32 weeks

9. Fetal Blood sampling pH > 7.25 normal No action pH 7.20-7.25
pH reflects the status of the baby at that moment of time
Base excess reflects a change over a longer period of time
pH > 7.25
normal
No action pH
borderline
Repeat in 30 mins
pH <7.20
abnormal
Deliver baby
<-6 mEq/L
normal
mEq/L
borderline
>-8mEq/L

10. Case 1

11. Case 9

12. Case 5

13. Case 8

14. Fetal bradycardia Turn off syntocinon
VE to exclude cord compression and assess cervical dilation
Turn on left
Fluid bolus
More than 3 minutes then immediate delivery
Can re-assess in theatre if fetal heart recovers

15. Prevalence of Placenta Previa
Occurs in 1/200 pregnancies that reach 3rd trimester
Placenta located in the lower segment of the uterus (ie after 24 weeks)
Low-lying placenta seen in 50% of ultrasound scans at weeks
90% will have normal implantation when scan repeated at >30 weeks
Repeat scan at 36 weeks

17. Risk Factors for Placenta Praevia
Previous caesarean delivery
Previous uterine instrumentation/surgery
High parity
Advanced maternal age
Smoking
Multiple gestation

18. Morbidity with Placenta Praevia
Maternal haemorrhage
Delivery of baby through placenta
Failure of contraction of placental bed
Excessive uterine bleeding
DIC
Operative delivery complications
Transfusion
Prematurity (bleeding in early pregnancy)
Placenta accreta, increta, or percreta

19. Placental Implantation

21. Abruptio placentae

22. Epidemiology of Abruption
Occurs in 1-2% of pregnancies
Risk factors
Hypertensive diseases of pregnancy
Smoking or substance abuse (e.g. cocaine)
Trauma
Over distention of the uterus (twins/polyhydramnios)
History of previous abruption
Unexplained elevation of MSAFP
Placental insufficiency
Maternal thrombophilia/metabolic abnormalities

23. Bleeding from Abruption
Externalized hemorrhage
Bloody amniotic fluid
Retroplacental clot
20% occult
“uteroplacental apoplexy” or “Couvelaire” uterus
Look for consumptive coagulopathy

24. Patient History - Abruption
Pain = hallmark symptom painful bleeding
Varies from mild cramping to severe pain
Back pain – think posterior abruption
Bleeding
May not reflect amount of blood loss
Differentiate from exuberant bloody show
Trauma (RTA)
Other risk factors (e.g. hypertension)

25. Physical Exam - Abruption
Signs of circulatory instability
Mild tachycardia normal
Signs and symptoms of shock
Maternal abdomen
Tender uterus
Continuous pain
Hard uterus
“woody feel”
Fetal death/abnormal CTG

26. Abruption & DIC 20% of abruptions will have DIC
Release of Fibrin Split Products causing uterine atony & bleeding
Release of thromboplastin causing fibrinogen conversion to fibrin (in all organs)
Stimulation of extrinsic pathway (fall in Factors 1,11,V, V11 and platelets)
Also secondary fibrinolysis by plasminogen
 PT, PTT and FDPs
 fibrinogen and platelets

27. Abruptio treatment Cyroprecipate (more fibrinogen than FFP) FFP
Packed RBCs
? platelets
? Factor V11a
Uterine atony:
Syntocinon (50iu in 500mls), ergometrine,
Misprostol ( PG ug pr) or haemobate (PGF2alpha) 250ug im every 15mins max dose 2gm)

28. Uterine Atony Drugs Aortic compression Balloon tamponade
B-Lynch suture
Ligation of uterine arteries (not v helpful)
Ligation of internal iliacs
Embolisation of internal iliacs
Hysterectomy

29. B-Lynch Brace suture

30. Epidemiology of Uterine Rupture
Occult dehiscence vs. symptomatic rupture
0.03 – 0.08% of all women
0.3 – 2.5% of women with uterine scar
Previous caesarean incision most common reason for scar disruption (any uterine incision)
Previous uterine curettage or perforation,
Oxytocin usage
Use of prostaglandin pessary
Trauma

31. Morbidity with Uterine Rupture
Maternal
Hemorrhage
Bladder rupture
Hysterectomy
Maternal death
Fetal
Respiratory distress
Hypoxia
Acidaemia
Neonatal death

32. Uterine Rupture
Sudden deterioration of FHR pattern is most frequent finding
Vaginal bleeding
Constant lower abdominal pain
Treatment
emergency caesarean delivery
can repair scar
maybe hysterectomy

33. Vasa Praevia Rarest cause of haemorrhage Onset with membrane rupture
Blood loss is fetal, with 50% mortality
Seen with placenta praevia, velamentous insertion of the cord or succenturiate lobe
Antepartum diagnosis
Color doppler ultrasound

34. Diagnostic Tests – Vasa Praevia
Apt test
based on colorimetric response of fetal hemoglobin (HbF) to alkali
Wright stain of vaginal blood
for nucleated RBCs
Kleihauer-Betke test
response to acid
can quantify amount of fetal blood in maternal circulation
used to determine fetal-maternal haemorrhage
used to quantify amount of Anti-D to be given

35. Management – Vasa Praevia
Immediate caesarean delivery if fetal heart rate is non-reassuring
Administer normal saline ? Maternal blood 10 – 20 cc/kg bolus to newborn, if found to be in shock after delivery