Preterm Delivery, Haemorrhage and Fetal Growth

Question 1

Preterm Labour

Answer 1

• 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

Question 2

Preterm Labour - Risk Factors

Answer 2

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,

Question 3

Predicting Preterm Labour

Answer 3

• Pregnancies with risk factores should be investigated by transvagainal ultrasound.
• Cervical length - <15mm at 23 weeks predicts 85% of perterm deliveries before 28 weeks

Question 4

Prevention of Preterm Labour

Answer 4

• 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.

Question 5

Preterm Labour - Investigations

Answer 5

• 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.

Question 6

Preterm Labour - Management

Answer 6

• 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.

Question 7

Spontaneous Rupture of Membranes

Answer 7

• 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.

Question 8

Risks of SROM

Answer 8

• Infection of the fetus, placenta (chorioamnionitis) or the cord (funisitis) is common.
• Chorioamnionitis - abdo pain, fever, tachycardia, uterine tenderness and offensive liquor.

Question 9

SROM - Investigations

Answer 9

• 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.

Question 10

SROM - Management

Answer 10

• Admit for steroids, investigate for infection and continuous fetal surveillance.
• If 36 weeks is reached women are induced.

Question 11

APH - Definition and Causes

Answer 11

• 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.

Question 12

Placenta Previa - Definition and Risk Factors

Answer 12

• 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.

Question 13

Placenta Previa - Classification

Answer 13

• 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.

Question 14

Placenta Previa - Complications

Answer 14

• 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.

Question 15

Placenta Previa - Clinical Features

Answer 15

• 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.

Question 16

Placenta Previa - Investigations

Answer 16

Can be detected on USS. If low lying placenta at 20 week scan should be repeated at 34 weeks to exclude placenta previa.

Question 17

Placenta Previa - Management

Answer 17

• 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.

Question 18

Placenta Accreta and Pecreta

Answer 18

• 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.

Question 19

Placental Abruption

Answer 19

• 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.

Question 20

Placental Abruption - Risk Factors

Answer 20

Hx of placental abruption, multiple pregnancy, high maternal parity, pre-existing hypertension, pre-eclampsia, IUGR, maternal smoking or cocaine use or intrauterine growth restriction.

Question 21

Placental Abruption - Clinical Features

Answer 21

• 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.

Question 22

Placental Abruption - Investigations

Answer 22

• 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.

Question 23

Placental Abruption - Mangement

Answer 23

• 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.

Question 24

Ruptured Vasa Previa

Answer 24

• 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.

Question 25

Intrauterine Growth Restriction

Answer 25

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.

Question 26

Small For Dates

Answer 26

• 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.

Question 27

Small For Dates - Causes

Answer 27

• 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.

Question 28

Small For Dates - Complications

Answer 28

Increased risk of being stillborn, cerebral palsy, preterm delivery, pre-eclampsia and C section.

Question 29

Small for Dates - Management

Answer 29

• 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.

Question 30

The Prolonged Pregnancy

Answer 30

A pregnancy that goes beyond 42 weeks - occurs in 10% of pregnancies.

Question 31

Prolonged Pregnancy - Risks

Answer 31

Increased risk of stillbirth, neonatal illness, encephalopathy, meconium passgae and diagnosis of fetal distress.

Question 32

Prolonged Pregnancy - Management

Answer 32

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.