2nd trimester miscarriage

Introduction

whilst 1 in 5 pregnancies do result in miscarriage, the vast majority of these occur in the 1st trimester
only 0.5-1% of pregnancies will result in a miscarriage in the 2nd trimester between 13-20 weeks
unfortunately these generally cannot be prevented although some measures may reduce the risk in some people

for most people the cause will not be found, although in those with recurrent 2nd TM miscarriages, the cause may become evident such as cervical incompetence
fetal structural abnormalities
chromosomal abnormalities
maternal uterine abnormalities
maternal drugs, especially illicit drugs such as cocaine
poorly controlled maternal conditions like thyroid disease, diabetes or hypertension
autoimmune disease such as systemic lupus erythematosus (SLE)
thrombophilia such as antiphospholipid syndrome
cervical insufficiency or incompetence
- risk is ~1.5% after cervical surgery procedures such as cone biopsy
- there is currently no satisfactory objective test that can identify women with cervical weakness in the non-pregnant state.
- diagnosis is usually based on a history of second-trimester miscarriage preceded by spontaneous rupture of membranes or painless cervical dilatation
uterine infection, cervicitis and chorioamnionitis may account for 10-25% of cases
- bacterial vaginosis in 1st TM may be a risk factor
- however, there is no evidence that antibiotic therapy will prevent miscarriage
major trauma
rarely, very early pre-eclampsia and eclampsia

supplemental folate medications starting 2 months prior to pregnancy
avoidance of cigarette smoking or illicit drugs
ensuring maternal conditions as above are controlled
regular exercise
pregnant women with antiphospholipid syndrome should be considered for treatment with low-dose aspirin plus heparin to prevent further miscarriage ¹⁾
in those with known cervical incompetence, consideration for elective or rescue cerclage
- there is no clear improvement in neonatal mortality or morbidity with “rescue cerclage” although it may delay delivery by an average of 4 weeks ²⁾
- elective cervical cerclage is associated with potential hazards and should only be considered for those who are likely to benefit (eg. 3 or more 2nd TM miscarriages or pre-term deliveries) but it may not increase perinatal survival
- those with a history of incompetence who have not undergone cerclage, should be considered for serial sonographic surveillance
  - those with singleton pregnancies and history of 2nd TM loss due to presumed incompetence should be offered an US-indicated cerclage if cervical length is 25mm or less on TV USS done before 24 weeks gestation

resuscitate if heavy bleeding or sepsis as per usual
deliver fetus if this is imminent
- call gynae reg and admit to hospital
check Rh status and give Rh Anti-D if indicated (consider Kleihauer test to determine amount of Anti D to give)
FBE, U&E, CRP (and blood cultures if suspect sepsis)
for those with mild bleeding only, or suspected liquor loss:
- same day USS if possible to confirm viability and discuss with gynae registrar as may warrant admission for observation or further investigation to exclude sepsis
- in the absence of ruptured membranes, gynae reg may consider performing a gentle vaginal examination to assess the cervix and the extent of any vaginal bleeding
- even if fetal heart is present, induction of labour may be indicated if pre-eclampsia or high risk of sepsis (dilated cervix, membranes ruptured or uterine contents protruding through cervix).
- if fetal demise is detected:
  - expectant Mx can be considered if low risk for sepsis (closed cervix), well, healthy and without preeclampsia under guidance of the gynae team
    - 85% will spontaneously deliver within 3 wks
    - 10% risk of maternal coagulopathy if not delivered within 4 wks of fetal demise
  - induction of labour or surgical management can be considered
  - antiphospholipid antibody screening (positive diagnosis requires two positive tests at least 12 weeks apart)
  - thrombophilia screening

a viable pregnancy on USS in the 2nd trimester does NOT necessarily mean a miscarriage will not occur in the next 24hrs - discuss with gynae registrar and consider admission for observation
unless induction of labour is to occur, avoid vaginal examination in those patients where rupture of membranes is evident as this may increase risk of ascending infection, although a vaginal swab should be sent for culture

RANZCOG - recurrent miscarriage 2011 (pdf)
pelvic USS to assess uterine anatomy and further investigate suspected anomalies (eg. hysteroscopy)
antiphospholipid antibody screening if one of more 2nd TM miscarriage
thrombophilia screening if one of more 2nd TM miscarriage
cytogenetic analysis on POC for 3rd and subsequent miscarriages and referral to a clinical geneticist if a abnormal parental karyotype is found
referral to specialist clinic

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