Obstetrics 2 Flashcards
A 28-year-old woman is 34 weeks pregnant. She attends the maternity assessment unit as she felt a gush of fluid down her leg and can now feel something in her vagina. The foetus is in a transverse lie and deep decelerations are seen on the cardiotocograph (CTG). Possible diagnosis?
Cord prolapse
Why is cord prolapse an obstetric emergency?
- Cord prolapse → leads to cord compression + umbilical artery vasospasm → preventing venous + arterial blood flow to and from the foetus → leading to birth asphyxia
Risk factors for cord prolapse
General:
* Multiparity
* Low birth weight (<2.5kg)
* Preterm labour (< 37 weeks)
* Breech presentation
* Transverse, oblique or unstable lie
Procedure-related:
* Artificial rupture of membranes (ARM) with high presenting part
* Vaginal manipulation of foetus with ruptured membranes
* External cephalic version (ECV)
Clinicals features of cord prolapse
Symptoms:
* Cord felt in the vagina
Signs:
* Cord seen in the vagina
* Abnormal foetal heart rate pattern
* There may be no clinical signs or symptoms and a normal foetal heart rate pattern
Ix for cord prolapse
- Vaginal/speculum examination (visualisation of the prolapsed cord)
- Foetal heart ausculation
- Cardiotocography (abnormal heart rate) (non-specific to cord prolapse)
Management of cord prolapse
Management of cord prolapse = immediate delivery of the foetus
Pre-dlivery:
* Minimal handling of loops of cord lying outside of the vagina
* Elevate presenting foetal part
* Mother in knee-chest or left lateral position
* Tocolysis
Delivery: Caesarean section (if vaginal delivery is not imminent)
* Cat 1 (delivery witin 30 mins)
* Cat 2 (delivery within 75 mins)
* Vaginal (normally operative, forceps or vacuum extraction)
Complications of cord prolapse
Maternal:
* Caesarean section
* Operative vaginal delivery
Foetal:
* Low Apgar scores: babies with low Apgar scores at delivery are more likely to require resuscitation
* Birth asphyxia
* Hypoxic brain injury
* Cerebral palsy
* Perinatal death
A 35-year-old woman presents with painless vaginal bleeding. She is currently 32 weeks pregnant, with an uneventful antenatal period so far. She is G3P2 and has had two prior caesarean sections. Possible diagnosis?
Placenta accreta
What is placenta accreta?
- Normally, the placenta attaches to the endometrium.
- Placenta accreta = an obstetric complication where the** placenta abnormally adheres to the myometrium** (the smooth muscle middle layer of the uterine wall)
- This occurs due to a defect in the endometrial decidua basalis, often as a result of previous uterine surgery e.g. cesarean section or curettage procedure
Info: Placenta accreta is part of the following spectrum of abnormal placental attachment
Placenta accreta is part of the following spectrum of abnormal placental attachment:
- Placenta accreta: the placenta attaches to the myometrium
- Placenta increta: the placenta invades deeply into the myometrium
- Placenta percreta: the placenta penetrates the myometrium, reaching the uterine serosa (perimetrium) and potentially adjacent organs
Placenta accreta → ‘creeping’
Placenta increta → ‘invading’
Placenta perceta → ‘perimetrium’
Risk factors for placenta accreta
- Previous placenta accreta
- Previous caesarean section
- Previous endometrial curettage procedures
- Placenta praevia or low-lying placenta
- Uterine structural abnormality: examples include fibroids or a bicornuate uterus
- Advanced maternal age: >35
- Multiparity
- IVF
How does placenta accreta clinically present?
Placenta accreta = typically presents with painless vaginal bleeding - usualy occurring in the third trimester
(May be asymptomatic)
Ix for placenta accreta
First line: Transvaginal ultrasound
Investigations to consider:
* FBC: to assess Hb in acute bleeding
* Coagulation screen
* Crossmatch: perform if considering transfusion in a bleeding patient
* MRI: this can be used if ultrasound findings are inconclusive.
Management of placenta accreta
- Delivery at 35 to 36+6 weeks gestation: this reduces the risk of spontaneous labour and delivery, reducing the risk of haemorrhage
- Hysterectomy: the uterus is removed after delivery of the baby, reducing the risk of severe haemorrhage
- Uterine preserving surgery: this involves the resection of the placenta and part of the myometrium
- Expectant management: In selective cases, if future fertility is desired, the placenta may be left in situ to resorb over time. However, this carries significant risk of bleeding and infection and requires careful monitoring
Maternal and foetal complications of placenta accreta
Maternal:
* Postpartum haemorrhage: this is because the deeper penetration of the placenta past the endometrium makes separation very difficult during delivery. This can be life-threatening
* Disseminated intravascular coagulation (DIC): bleeding can lead to consumption of clotting factors, with subsequent DIC
* Hysterectomy
Foetal:
* Preterm birth: increased risk of prematurity
* Foetal death
A woman is pregnant with her first child. She is rhesus-D negative. What will happen if the she is not given IM Anti-D injections?
The sensitisation process
(If the child is rhesus positive)
- It is likely at some point in the pregnancy (i.e. childbirth) that the blood from the baby will find a way into the mother’s bloodstream.
- When this happens, the baby’s red blood cells display the rhesus-D antigen.
- The mother’s immune system will recognise this rhesus-D antigen as foreign, and produce antibodies to the rhesus-D antigen.
- The mother has then become sensitised to rhesus-D antigens.
The sensitisation process = usually doesn’t cause problems in the first pregnancy
What will happen if a mother has a second baby (rhesus positive) after the first (with no Anti-D treatment)?
Haemolytic disease of the newborn
- During subsequent pregnancies, the mother’s anti-rhesus-D antibodies can cross the placenta into the fetus.
- If that fetus is rhesus-D positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack them, causing the destruction of the red blood cells (haemolysis).
- The red blood cell destruction caused by antibodies from the mother is called haemolytic disease of the newborn.
What is management for rhesus incompatibility?
Prevention of sensitisation = mainstay of management → IM anti-D injections to rhesus-D negative women
Anti-D injections are given routinely on two occasions:
* 28 weeks gestation
* Birth (if the baby’s blood group is found to be rhesus-positive)
Anti-D injections should also be given at any time where sensitisation may occur, such as:
* Antepartum haemorrhage
* Amniocentesis procedures
* Abdominal trauma
(The anti-D medication works by attaching itself to the rhesus-D antigens on the fetal red blood cells in the mothers circulation, causing them to be destroyed. This prevents the mother’s immune system recognising the antigen and creating it’s own antibodies to the antigen. It acts as a prevention for the mother becoming sensitised to the rhesus-D antigen.)
Rhesus incompatibility: What test is performed after 20 weeks gestation to see how much fetal blood has passed into the mother’s blood, to determine whether further doses of anti-D are required?
Kleihauer Test
Kleihauer test = checks how much fetal blood has passed into the mother’s blood during a sensitisation event.
* This test is used after any sensitising event past 20 weeks gestation, to assess whether further doses of anti-D is required.
(The Kleihauer test involves adding acid to a sample of the mother’s blood. Fetal haemoglobin is naturally more resistant to acid, so that they are protected against the acidosis that occurs around childbirth. Therefore, fetal haemoglobin persists in response to the added acid, while the mothers haemoglobin is destroyed. The number of cells still containing haemoglobin (the remaining fetal cells) can then be calculated.)
