preterm birth

Question 1

what is fetal fibronectin

Answer 1

done for intact membranes
test giving predictive value of whether there will be a birth within 24 hours to 2 weeks

Question 2

what three things have to be present for it to be preterm labour

Answer 2

strong regular contractions (at least 1 per 10 minutes)
dilation of cervix
engagement of the presenting part
without these three things its not preterm labour

Question 3

management for threatened preterm labour

Answer 3

feel for contractions, do a spec
fetal fibronectin
send to tertiary centre, contact recieving hospital, contact patient family
?RFDS
?neonatal emergency transfer service
tocolysis
analgesia: panadiene forte, morphine IM, phernergen (antiemetic and seddation effect)

Question 4

what are you looking for on spec exam for the suspected preterm labour patient

Answer 4

full aseptic technique and not touching the cervix with the speculum
cervical swabs should be taken for immediate bacteriological assessment
if the cervix is closed and there is no bloo or amniotic fluid, do a fFN test
avoid digital examination due to infection risk

Question 5

is antibiotics used for preterm labour

Answer 5

of no use if the membranes are in tact
but you do need to do a HVS to exclude GBS and MSU to exclude UTI

Question 6

tocolysis

Answer 6

20mg nifedipine IR orally is first line (calcium channel blocker)
saalbutamol second line
be careful in the diabetic patient nifedipine and slbutaol can cause DKA on arrival

Question 7

dosage of nifedipine

Answer 7

20mg nifedipine IR orally (crush or chew)
after 30 minutes, if the contractions persist, give another 20mg
repeat every 3 hours until contractions cease or labour is established
maintenance dose is 20mg three times per day
max 160mg per day

Question 8

can you give nifedipine and salbutamol at the same time

Answer 8

no

Question 9

how long can tocolytics delay preterm birth

Answer 9

do not stop preterm birth
may delay for up to 48 hours to enable transfer to a tertiary perinatal centre to allow time to give corticosteroids for lung maturation

Question 10

antenatal corticosteroids

Answer 10

11.4mg betamethasone IM repeated after 24 hours
48 hours to achieve maximum effect
halves the rate of respiratory distress syndrome and death
matures all organs, especially the lung

Question 11

what gestations is antenatal corticosteorids necessary

Answer 11

given from 23+ to 34 weeks

Question 12

how to prevent preterm birth

Answer 12

1. no pregnancy should be need before 39 weeks unless there is a medical or obstetric justification
2. measurement of the length of the cervix at all mid-pregnancy scans
3. use of natural vaginal progesterone (200mg each evening) if the length of the cervix is less than 25mm
4. if the length of the cervix continues to shorten despite progesterone treatment, consider surgical cerclage
5. use vaginal progesterone if you have a prior history of spontaaneous preterm birth
6. women who smoke should be identified and offred support
7. to access continuity of care from a known midwife during pregnancy where possible

Question 13

define preterm birth

Answer 13

birth before 37 nd after 20 weeks

Question 14

causes of preterm birth

Answer 14

spontaneous preterm labour
preterm pre-labour rupture of membranes
medical conditions (preeclampsia, diabetes)
antepartum haemorrhage
multiple pregnancies
iatrogenic (late preterm birth)
infections (pyelonephritis, any fever, viral)
uterine anomalies (uncommon)

Question 15

risk factors for preterm birth

Answer 15

previous preterm birth
smoking
family history
extremes of reproductive age
socioeconomic conditions
stress/anxiety
previous second trimester abortion/loss
previous LLETZ or cone biopsy
previous first trimester TOP or repeated losses

Question 16

what is Amnisure

Answer 16

rapid test that detects if the membranes have been ruptured

Question 17

investigations for suspected preterm labour

Answer 17

bedside obs, urinlysis, vaginal loss, uterine activity/pain , FHR
HHVS/LVS for MC&S, fFN
speculum examination for any cervical changes
CTG
MSU
US to exclude low lying placenta
TVCL
proceed based on fFN and cervical change

Question 18

investigations for suspected rupture of membranes

Answer 18

bedside:
CTG
amniotic fluid special tests eg. amnisure
GBS swabs
urinalysis + MSU for UTI
first pass urine
STI swabs (HVS, EC)
bloods:
gain IV access
FBC + G+H
CRP
any missing antenatal bloods
imaging:
obstetric USS to assess presentation, gestation, fetal weight, fetal normality possibility/advisabilty of amniocentesis

Question 19

when might amniocentesis be necessary

Answer 19

this Ix may be appropriate to assess the presence or absence of intra-amniotic sepsis, or to asses fetal lung maturity
the use of this investigation should only be done by a consultant

Question 20

first thing you need to know in PROM

Answer 20

are they GBS positive
if so, start antibiotics and advise active management
if negative, engage in SDM for active/expectant management

Question 21

when should you probably not use tocolytic therapy

Answer 21

> 34 weeks gestation
for longer than 48 hours
once corticosteroids have been given and are current

Question 22

if there is negative fFN test

Answer 22

low risk of birth within the next 7-14 days
false negative result may occur due to
- use of lubricant with speculum examination (you should only use sterile water)
- intravaginal disinfectants

Question 23

if there is a positive fFN test

Answer 23

false positive result may occur due to coitus, DVE, transvaginal US, bleeding

Question 24

when to do screening TVCL

Answer 24

if the cervical length is <35mm on transabdominal US

Question 25

interpreting TVCL results for symptomatic women above 24 weeks

Answer 25

for symptomatic women >24 weeks:
a cervical length of <15mm is associated with an increased risk of spontaneous preterm birth, due to the distances required for transfer from WA regional centres a cut off of 20mm is appropriate

Question 26

interpreting TVCL results for asymptomatic women less than 24 weeks

Answer 26

for screening TVCL:
a cervical length of less than 25mm is associates with an increased risk of spontaneous preterm birth
the shorter the cervical length, the greater the risk of preterm birth

Question 27

if there is a negative fFN and no evidence of cervical change

Answer 27

TVCL > 20mm
there is low risk of birth within the next 7 dys
discharge home with outpatient follow up
admit for observation if contractions are frequent/painful

Question 28

if there is positive fFN and/or evidence of cervical change

Answer 28

there is an increased risk of birth within the next 7 days
admit and offer analgesia
administer steroids and commence tocolysis
CTG

Question 29

MgSO4 infusion

Answer 29

1. MgSO4 is only given to women who are at imminent risk of delivery of a preterm
   infant of less than 30 weeks gestation and birth is planned or definitely expected
   within 24 hours. Ideally it should be commenced 4 hours prior to delivery.
2. Urgent delivery for fetal or maternal indications should not be delayed in order to
   achieve MgSO4 administration.
3. Calcium gluconate 1g in 10 mL must be available at all times for treatment of
   MgSO4 toxicity. Resuscitation equipment should be readily available.
4. Apply continuous fetal monitoring.

Question 30

what is MgSO4 infusion used for

Answer 30

preterm birth for neuroprotection to reduce the incidence of cerebral palsy

Question 31

progesterone for prevention of preterm birth

Answer 31

use for women with short TVU CL <25mm
or with prior preterm birth
if CL<15mm, cervical cerclage is preferred