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2nd trimester miscarriage


  • 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

Indicators of poor outcome in those with a dilated cervix

  • prolapsed membranes
  • evidence of intra-amniotic or systematic infection
  • symptomatic presentation
  • cervical dilatation > 3cms
  • cerclage after 22 weeks gestation

ED Mx of the patient with PV bleeding or liquor loss in 2nd TM

  • 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

  • post-partum haemorrhage risk can be high

Ix of those with recurrent 2nd TM miscarriage

  • 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
miscarriage2ndtm.txt · Last modified: 2019/04/15 13:22 by wh