preterm birth Flashcards
what is fetal fibronectin
done for intact membranes
test giving predictive value of whether there will be a birth within 24 hours to 2 weeks
what three things have to be present for it to be preterm labour
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
management for threatened preterm labour
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)
what are you looking for on spec exam for the suspected preterm labour patient
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
is antibiotics used for preterm labour
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
tocolysis
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
dosage of nifedipine
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
can you give nifedipine and salbutamol at the same time
no
how long can tocolytics delay preterm birth
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
antenatal corticosteroids
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
what gestations is antenatal corticosteorids necessary
given from 23+ to 34 weeks
how to prevent preterm birth
- no pregnancy should be need before 39 weeks unless there is a medical or obstetric justification
- measurement of the length of the cervix at all mid-pregnancy scans
- use of natural vaginal progesterone (200mg each evening) if the length of the cervix is less than 25mm
- if the length of the cervix continues to shorten despite progesterone treatment, consider surgical cerclage
- use vaginal progesterone if you have a prior history of spontaaneous preterm birth
- women who smoke should be identified and offred support
- to access continuity of care from a known midwife during pregnancy where possible
define preterm birth
birth before 37 nd after 20 weeks
causes of preterm birth
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)
risk factors for preterm birth
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
what is Amnisure
rapid test that detects if the membranes have been ruptured
investigations for suspected preterm labour
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
investigations for suspected rupture of membranes
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
when might amniocentesis be necessary
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
first thing you need to know in PROM
are they GBS positive
if so, start antibiotics and advise active management
if negative, engage in SDM for active/expectant management
when should you probably not use tocolytic therapy
> 34 weeks gestation
for longer than 48 hours
once corticosteroids have been given and are current
if there is negative fFN test
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
if there is a positive fFN test
false positive result may occur due to coitus, DVE, transvaginal US, bleeding
when to do screening TVCL
if the cervical length is <35mm on transabdominal US
interpreting TVCL results for symptomatic women above 24 weeks
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
interpreting TVCL results for asymptomatic women less than 24 weeks
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
if there is a negative fFN and no evidence of cervical change
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
if there is positive fFN and/or evidence of cervical change
there is an increased risk of birth within the next 7 days
admit and offer analgesia
administer steroids and commence tocolysis
CTG
MgSO4 infusion
- 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. - Urgent delivery for fetal or maternal indications should not be delayed in order to
achieve MgSO4 administration. - Calcium gluconate 1g in 10 mL must be available at all times for treatment of
MgSO4 toxicity. Resuscitation equipment should be readily available. - Apply continuous fetal monitoring.
what is MgSO4 infusion used for
preterm birth for neuroprotection to reduce the incidence of cerebral palsy
progesterone for prevention of preterm birth
use for women with short TVU CL <25mm
or with prior preterm birth
if CL<15mm, cervical cerclage is preferred
