8A) Antenatal Care: Bleeding-related Flashcards
Definition of vasa praevia
Fetal vessels running in free placenta membrane (within 2cm of internal os)
Incidence of vasa praevia
1/1200-1/5000
Types of vasa praevia
Type 1: Vessels associated with velamentous card
Type 2: Vessels joining placenta to subcenturiate/accessory lobe
Type of bleeding seen with vasa praevia
Fetal blood.
Dark red. “Benckisers haemorrhage”.
Associated with feral distress.
What is average circulating fetal volume?
80-100mL
Mortality associated with vasa praevia
> 60% if diagnosed in labour due to bleeding + fetal distress.
<5% if diagnosed antenatally.
Treatment of vasa praevia if detected antenatally
- Confirm diagnosis in third trimester
- Consider admission 30-32 weeks
- Steroids 32 weeks
- ELCS 34-36 weeks
Percentage of vasa praevia which resolve by 30-32 weeks.
20%
Definition of placenta praevia
“Low lying” placenta has edge < 20mm from internal os.
“Praevia” has placenta lying directly over internal os.
After 16 weeks.
Incidence of placenta praevia
1 in 200
Risk factors for placenta praevia
Previous placenta praevia Previous CS Maternal age Multiparity Multiple pregnancy ART Scarred uterus - fibroid, infection, TOP, MROP. Smoking. Second pregnancy within 1 year.
Risk of placenta praevia with increasing number of CS
0 CS: 1 in 400 1 CS: 1 in 100 2 CS: 1 in 60 3 CS: 1 in 35 4 CS: 1 in 10
How to investigate low placenta?
If noted to be low on trans abdominal scan at 20 weeks then for TVS at 32 weeks and f still low then TVS 36 weeks.
What percentage of cases of low lying placentas will resolve before term?
5% of placentas will be low lying at 20 weeks and 90% of these will resolve by term.
What percentage of cases of low lying placentas resolve in twin pregnancies?
Majority resolve by 32/40. After 32/40 then a further 50% will resolve. No further change after 36/40.
What increases the risk of emergency Caesarean in cases of placenta praevia?
- Short cervical length on TVS before 34/40
- Recurrent APH
- Antenatal blood transfusion
- Previous CS
Management of placenta praevia
- Steroids 34-36 weeks.
- Weekly G&S for high risk women
- If symptomatic, delivery 34-36 weeks.
- If asymptomatic, delivery 36-37 weeks.
Risk of bleeding with placenta praevia at different gestation
5% by 35/40
15% by 36/40
30% by 37/40
60% by 38/40
Risk of requiring emergency hysterectomy at CS for placenta praevia
11 in 100 if isolated praevia
27 in 100 if praevia and previous CS
90 in 100 if abnormally invasive placenta
(Compared to 7-8/1000 if no praevia)
Risk of major obstetric haemorrhage at time of CS for placenta praevia
21 in 100
Risk of further laparotomy during recovery from CS for placenta praevia
7.5 in 100
Risk of bladder/ureteric injury at CS for placenta praevia
6 in 100
Risk of future placenta praevia after CS for placenta praevia
23 in 1000
Risk of VTE after CS for placenta praevia
3 in 100
Definition of placenta accreta/increta/percreta
Accreta: Villi adhere superficially to mayo myometrium without interposing decidua
Increta: Villi penetrate deeply into myometrium down to serosa
Percreta: Villi perforate through entire uterine wall and may invade surrounding pelvic organs.
Incidence of placenta accreta spectrum disorders
1/300-1/2000
Risk factors for placenta accretion
Previous CS Placenta praevia Maternal age ART Uterine scarring
Risk of placenta accreta in patient with placenta praevia and previous CS
\+1 CS: 3% \+2 CS: 11% \+3 CS: 40% \+4 CS: 61% \+5 CS: 67%
Diagnosis of placenta accreta
Diagnostic value of USS and MRI similar but MRI useful for depth of invasion and lateral extension of myometrial invasion.
When to deliver placenta accreta?
34-35 weeks (and 20% still require emergency delivery before this)
Definition of antepartum haemorrhage
Bleeding from, or in to, the genital tract between 24+0 weeks and delivery of baby.
Incidence of antepartum haemorrhage
3-5% of pregnancies
Categorisation of APH
Spotting
Minor (<50 mL)
Major (50-1000mL with no evidence of shock)
Massive (>1000mL or shock)
Incidence of placental abruption after previous abruption
4.4% after one abruption
19-25% after two abruptions
Risk factors for placental abruption
Previous history:
Previous abruption
Multiparity
Maternal characteristics: Maternal age Low BMI Smoking and drug use Thrombophilia - factor V Leiden, prothrombin mutation
Pregnancy features: Fetal growth restriction Polyhydramnios Malpresentation Assisted reproduction PET Trauma 1st trimester bleeding (particularly if haematoma present OR 6) Intrauterine infection PROM
Rates of cervical cancer per 100,000 deliveries
7.5 per 100,000 deliveries
Percentage of abruptions in low risk pregnancies
70%
Percentage of premature births associated with APH
20%
Risks associated with unexplained APH
Stillbirth Preterm birth PPROM Oligohydramnios Small gestational age Fetal anomalies
Role of tocolysis in APH
Contraindicated in abruption and “relatively contraindicated” in mild haemorrhage due to praevia.
Blood tests required with APH
Minor: FBC, G&S
Major: FBC, UE/LFT, Clotting, 4 unit XMatch
When to deliver APH?
- If compromise, via CS at the time.
- If no compromise and <37 weeks no evidence for preterm delivery.
- If no compromise but >37 weeks then consider IOL.
When should anti-D be given?
After any presentation with APH.
If recurrent, at least 6 weekly intervals.
Cannula required for APH
Minor: 1 x 14 gauge
Major: 2 x 14 gauge
Fluid therapy and blood product transfusion for massive APH
Until blood available:
- up to 2 units Hartmann’s
- up to 1-2 litres colloid
- RBC (cross-matched if possible, if not uncrossmatched group-specific or O Neg)
- 4 units of FFP (12-15ml/kg or total 1 litre) for every 4 units of RBC or if PT/APTT >1.5 x mean.
- Platelets if platelet count < 75
- Cryoprecipitate if fibrinogen <2
How much FFP/cryo can be given with continuing massive haemorrhage and awaiting coagulation studies?
4 units FFP and 10 units of cryogenic.
Target blood values during massive APH
Hb > 80
Platelets > 50
PT/APTT >< 1.5
Fibrinogen > 2
Definition of anaemia in pregnancy
1st trimester: Hb < 110
2nd/3rd trimester: Hb <105
Postpartum: Hb <100
What age should G&S samples be for provision of blood?
< 3 days old
What compatibility of blood should be used?
ABO, RhD and Kell compatible red cell units. And negative for any clinically significant antibodies.
CMV negative blood and platelets during pregnancy (not necessary during delivery or postpartum)
When is cell salvage recommended?
Anticipated blood loss great enough to induce anaemia or expected to exceed 20% of estimated blood volume.
What anti-D is required after cell salvage?
Minimum of 1500 units followed by Kleihauer 30-40 minutes post transfusion.
What compatibility of FFP/Cryo is required?
Ideally same group as recipient but ca have FFP of different ABO group if required provided doesn’t have high titre anti-A or anti-B.
What anti-D is required after FFP/Cryo?
None!
What anti-D is required after platelets?
250 units anti-D covers 5 adult therapeutic doses of platelets within 6 week period.
Thrombosis risk associated with factor VIIa
2.5%
How does TXA work?
Reversible binds plasminogen and prevents activation to plasmin. Reduces bleeding without increasing VTE risk.
Definition of primary PPH
Loss of >500mL of blood from the genital tract within 24 hour of the birth of a baby.
Categories of primary PPH
Minor: 500-1000mL
Major: >1000mL (Split into Moderate 1000-2000mL and Severe >2000mL)
Definition of secondary PPH
Abnormal/excessive bleeding from birth canal between 24 hours and 12 weeks postnatal.
Most common cause of PPH
Atony
Benefits of active management of third stage
2/3 reduction in risk of major PPH
Drugs for active management of third stage
Vaginal delivery: 10 units IM synt or syntometrine (5 units synt + 500 microgram ergometrine)
CS: 5 units IV syntocinon
At what EBL are physiological signs of hypovolaemia usually seen?
Pulse and BP maintained whilst EBL <1000mL.
If BP slightly low (and increased HR and RR) then EBL 1000-1500mL
If systolic BP < 80mmHg, usually > 1500mL
Management of PPH
- Stimulate uterine contractions
- Foley’s catheter
- Synt 5 units IV
- Ergometrine 0.5mg IM/IV
- Synt infusion
- Carboprost 250 microgram IM every 15 minutes for 8 doses (but f no improvement after 3 doses consider transfer to theatre)
- Misoprostol 800 micro gram
- Surgical options
How long does misoprostol take to take effect?
1.5-2 hours
Surgical options for management of PPH
- Uterine balloon tamponade
- B Lynch suture
- Stepwise devascularisation
- Interventional radiology embolisation
- Hysterectomy