Preterm Delivery, Haemorrhage and Fetal Growth Flashcards
Preterm Labour
- Defined as labour at 24-37 weeks gestation.
- 5-8% of deliveries are preterm and a further 6% present preterm with contractions but deliver at term.
- In some cases preterm labour can be iatrogenic e.g. in pre-eclampsia
Preterm Labour - Risk Factors
60% caused by maternal infection, previous preterm labour, lower socioeconomic class, extremes of maternal age, a short inter-pregnancy interval, maternal illness e.g. DM or RF, male fetal gender
- Too much in tummy - multiple pregnancy or polyhydroamnios.
- Fetal survival response - in pre-eclampsia, IUGR, placental abruption.
- Cervical incompetence - following surgery, cancer, multple TOPs,
Predicting Preterm Labour
- Pregnancies with risk factores should be investigated by transvagainal ultrasound.
- Cervical length - <15mm at 23 weeks predicts 85% of perterm deliveries before 28 weeks
Prevention of Preterm Labour
- Cervical cerclage to strengthen cervix.
- Regular screening for infections and STIs.
- Reduction of higher order multiples at 10-14 wks.
- Needle aspiration of polyhydroamnios.
- Progesterone supplementation.
Preterm Labour - Investigations
- Abdominal palpation to assess lie and presentation of the fetus and VE to assess cervix - is it effaced or dilated.
- USS and CTG to assess health of the fetus.
- Fetal fibronection and transvaginal USS - if negative and length >15mm delivery is unlikely.
Preterm Labour - Management
- Steroids are given between 24-34 weeks to promote pulmonary maturity - take 24 hours to have an effect so delivery is artifically delayed (tocolysis) with nifidipine or atosiban.
- Vaginal delivery is preferred as reduces the risk of respiratory distress syndrome.
Spontaneous Rupture of Membranes
- Before 37 weeks - occurs in third of pregnancies.
- A gush of clear fluid followed by further leakage with pool of fluid in posterior fornix on speculum.
- In 50% labour follows within 48 hours.
Risks of SROM
- Infection of the fetus, placenta (chorioamnionitis) or the cord (funisitis) is common.
- Chorioamnionitis - abdo pain, fever, tachycardia, uterine tenderness and offensive liquor.
SROM - Investigations
- Bloods for FBC and CRP, high vagainal swabs and an ultrasound - can show reduced liquor but fetus still producing urine so can be normal amount.
- CTG to monitor fetus - tachy in infections.
SROM - Management
- Admit for steroids, investigate for infection and continuous fetal surveillance.
- If 36 weeks is reached women are induced.
APH - Definition and Causes
- Bleeding from the genital tract after 24 weeks.
- Common causes - undetermined orgin, placental abruption or placental previa.
- Uncommon causes - incidental genital tract pathology, uterine rupture or vasa previa.
Placenta Previa - Definition and Risk Factors
- When the placenta is implanted at the lower segment of the uterus - in 0.4% of pregnancies.
- At 20 weeks the placenta is often low lying but moves upwards during the pregnancy.
- Risk factors - multiple pregnancies, older maternal age and a scarred cervix.
Placenta Previa - Classification
- Marginal (previously 1-2) - placenta is located in the lower segment but not over the os.
- Major (previously 3-4) - the placenta is partially or completely covering the cervical os.
Placenta Previa - Complications
- Engagement is obstructed so lie is transverse and caesarean section is indicated.
- Haemorrhage can occur during or after pregnancy and can be severe. The lower segment is less able to constract and constrict the maternal blood supply.
Placenta Previa - Clinical Features
- History - intermittant, painless bleeding which increases in frequency and intensity over weeks. However a third of women have no bleeding.
- Examination - transverse lie and breech presentation are common. The fetal head is not engaged and high. VE can provoke massive bleeding and should not be performed.
Placenta Previa - Investigations
Can be detected on USS. If low lying placenta at 20 week scan should be repeated at 34 weeks to exclude placenta previa.
Placenta Previa - Management
- If asymptomatic women can stay out of hospital until 37 weeks. Ideally they should be able to quickly access the hospital.
- If there is bleeding women should be inpatients with blood available in case of haemorrhage.
- Ideally delivery should be at 39 weeks by Caesarean by senior surgeon.
Placenta Accreta and Pecreta
- Placenta accreta - the placenta implants in a previous Caesarean scar - it may implant so deeply as to prevent placental seperation.
- Placenta Pecreta - the placenta can penetrate the uterus and implant in e.g. the bladder.
- The risk is haemorrhage at delivery due to only partial seperation - management involves compression with a ballon or hysterectomy.
Placental Abruption
- Part or all of the placenta separates before delivery - occurs in 1% of pregnancies.
- Can be a revealed abruption where there is maternal bleeding or concealed where blood enters the myometrium so bleeding is absent.
Placental Abruption - Risk Factors
Hx of placental abruption, multiple pregnancy, high maternal parity, pre-existing hypertension, pre-eclampsia, IUGR, maternal smoking or cocaine use or intrauterine growth restriction.
Placental Abruption - Clinical Features
- History - painful vaginal bleeding (pain is due to blood behind placenta and in myometrium).
- Examination - tachycardia and hypotension suggest significant blood loss. The uterus is tender and often contracting as labout ensues.
Placental Abruption - Investigations
- Fetus - monitor well being with a CTG.
- Mother - catheterisation to monitoir urine output, central venous pressure, bloods for FBC, coag screen, group and save and U+Es.
Placental Abruption - Mangement
- Resuscitation - IV fluids, blood transfusion, steroids if gestation <34 weeks and analgesia.
- Delivery - once the mother is stabilised consider C section if fetal distress or induction of labour if no fetal distress and >37 weeks. Women can be monitored in hospital if stable and <37 weeks.
Ruptured Vasa Previa
- Occurs in 1 in 5000 pregnancies.
- When membranes rupture fetal blood vessel may also rupture and cause massive fetal bleeding.
- Presents with painless vaginal bleeding at amniotomy or SROM with fetal distress.
- Mx - C section but often not performed early enough in order to save the fetus.
Intrauterine Growth Restriction
Describes a fetus that has failed to reasch their own growth potential. Growth in utero is slowed and many are small for dates but not all.
Small For Dates
- The weight of the fetus is less than the 10th centile for its gestation - below 2.7kg at term.
- Most are constitutionally small, have grown consistently and are not compromised.
Small For Dates - Causes
- Genetics, nulliparity, Asian ethnicity and female fetal gender result in small babies.
- Pathology - pre-existing maternal disease e.g. renal or AI disease, pregnancy complications e.g. pre-eclampsia, multiple pregnancy, smoking, drug use, infection e.g. CMV or congenital abnormalities.
Small For Dates - Complications
Increased risk of being stillborn, cerebral palsy, preterm delivery, pre-eclampsia and C section.
Small for Dates - Management
- Growth is rechecked fortnightly - a consistently growing fetus with normal umbilical doppler values does not need intervention.
- If umbilical doppler is abnormal the fetus is delivered as long as post 36 weeks.
The Prolonged Pregnancy
A pregnancy that goes beyond 42 weeks - occurs in 10% of pregnancies.
Prolonged Pregnancy - Risks
Increased risk of stillbirth, neonatal illness, encephalopathy, meconium passgae and diagnosis of fetal distress.
Prolonged Pregnancy - Management
Induction between 41-42 weeks prevents 1 in 500 fetal deaths and is associated with fewer C sections. Induction before 41 weeks does not have this effect.
