Placental abruption Flashcards
Define placental abruption.
The premature separation of a normally located placenta from the uterine wall that occurs before delivery of the fetus.
What are the types of placental abruption?
Abruption may be:
- (A) REVEALED, when blood escapes through the vagina, or
- (B) CONCEALED, when the bleeding occurs behind the placenta, with no evidence of bleeding from the vagina.
Abruption may be partial, affecting only part of the placenta, or total, involving the entire placenta.
How common is placental abruption?
Affects 1 in 200 pregnancies
What is the aetiology of placental abruption?
- Direct trauma - causing separation
- Indirect trauma - shearing the placental off uterine wall
- Cocaine use - causing vasospasm that may lead to placental separation
However, some studies show chronic inflammation which may suggest abruption is part of a long-standing chronic process.
Pathophysiology is currently unknown.
42-year-old smoker presented to labour and delivery at 28 weeks of gestation with worsening abdominal pain of a few hours’ duration. She had also had some vaginal bleeding within the past hour. She was found to have low-amplitude, high-frequency uterine contractions, and the fetal heart rate tracing showed recurrent late decelerations and reduced variability. Her uterus was tender and firm to palpation.
What is the diagnosis?
Placental abruption
What are the clinical features of placental abruption?
- shock out of keeping with visible loss
- pain constant + lower back pain
- uterine contractions - thrombin is a powerful utero-tonic agent
- tender, tense uterus - “woody” uterus
- normal lie and presentation
- fetal heart: absent/distressed
- coagulation problems
- beware pre-eclampsia, DIC, anuria
What are the risk factors for placental abruption?
- Chronic HTN and pre-eclampsia
- Smoking
- Cocaine use
- Trauma
- Chorioamnionitis
- Uterine malformations
- Oligohydramnios
What investigations are used in diagnosis of placental abruption?
Conservative:
- Fetal monitoring - abnormal e.g. late decelerations, loss of variability, variable decelerations, a sinusoidal fetal heart rate tracing, and fetal bradycardia
Laboratory:
- Hb and Hct - normal or low
- Coagulation - abnormal e.g.PT, PTT, fibrinogen, and fibrinogen breakdown products
- K-B test (Kleinhauer-Betke test) - check presense of fetal RBCs in maternal blood; helps quantify size of FMH
Imaging:
- US - may show area of abruption
What is the use of the K-B test?
Blood test used during pregnancy to screen maternal blood for the presence of fetal red blood cells to assess the severity of fetal-maternal haemorrhage + used to calculate dosage of anti-D required to prevent sensitisation
Interpretation involves acid elution - here fetal cells appear bright and saturated and maternal RBCs appear pale
What is a simple test for DIC (can be done at bedside)?
Take some blood in a plain tube (without anticoagulation), and then invert the tube at 1-minute intervals.
The blood should clot within 8 to10 minutes; failure to do so may be taken as evidence of DIC
US findings in placental abruption:
Findings may include:
- retroplacental haematoma (hyperechoic, isoechoic, hypoechoic);
- pre-placental haematoma (jiggling appearance with a shimmering effect of the chorionic plate with fetal movement);
- increased placental thickness and echogenicity; sub-chorionic collection or marginal collection
What are differentials for placental abruption?
- Preterm labour
- Placenta praevia
- Chorioamnionitis
Others with no PV bleeding:
- UTI/acute pyelonephritis
- Acute appendicitis
- Degeneration of uterine fibroids
What is the management of placental abruption?
<37 weeks - fetus alive
- fetal distress: immediate caesarean
- no fetal distress: observe closely, steroids, no tocolysis, threshold to deliver depends on gestation
>37 weeks fetus alive
- fetal distress: immediate caesarean
- no fetal distress: deliver vaginally
Fetus dead
- induce vaginal delivery
All:
- Stabilisation of mother + monitoring - IV wide bore cannula; continuous monitoring; keep Hb over 100g/L
- Anti-D Ig to Rh -ve patients
- Monitoring fetus +/-delivery
- Corticosteroids if less than 34 +6 weeks
(timings in keeping with RCOG guidelines)
Why may haemorrhage in placental abruption post-placental delivery be difficult to control? What is the management of this?
Uterus may not contract adequately in these cases –> difficult to control haemorrhage. See PPH notes.
Management:
- Oxytocin 10U IM once
- +/- Methylergometrine 0.2mg IV/IM after delivery of shoulder and then every 2-4 hrs PRN
- +/- Misoprostol 800mcg PR/PV once
- +/- Carboprost tromethamine 250mcg IM once
What are the complications of placental abruption?
Mother:
- PPH –> hypovolaemic shock
- DIC
- Surgery - risks of surgery and anaesthetic
- Acute renal failure due to shock
Fetus:
- Preterm birth
- Perinatal death
- IUGR
- hypoxia
