Preterm labor: Difference between revisions

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==Background==
==Background==
*Defined as labor before 37 weeks (uterine ctx and cervical change)
*Defined as labor before 37 weeks (uterine contraction and cervical change)
*Increased risks to child depending on age of fetus
*Increased risks to child depending on age of fetus
**Cerebral palsy, poor lung development, cognitive delay, etc
**Cerebral palsy, poor lung development, cognitive delay, etc
*Can be triggered by maternal infx, stress, HTN, uncontrolled DM
*Can be triggered by infections, stress, hypertension, uncontrolled DM
 
==Clinical Presentation==


==Clinical Features==
*Similar to term labor
*Similar to term labor
**Uterine contractions q 10 min (may be irregular)
*Uterine contractions q 10 min (may be irregular)
**New onset of vaginal mucus, blood, pink discharge, amniotic fluid
*New onset of vaginal mucus, blood, pink discharge, amniotic fluid
**Low back ache, vaginal pressure
*Low back ache, vaginal pressure


==Differential Diagnosis==
==Differential Diagnosis==
{{VB DDX greater than 20}}


*[[Preterm Labor]]
==Evaluation==
*[[Placental abruption]]
*[[Placenta previa]]
*[[Vasa previa]]
*[[Uterine rupture]]
*[[Vaginal trauma]]
 
==Diagnosis==
 
*Do NOT perform digital exam in patients who present with vaginal bleeding when >20 weeks pregnant
*Do NOT perform digital exam in patients who present with vaginal bleeding when >20 weeks pregnant
*Start with ultrasound to assess position of cervix and r/o placenta previa
*Start with ultrasound to assess position of cervix and rule out placenta previa
*Swabs for fetal fibernectin, Group B strep should also precede digital exam
*Swabs for nitrazine, fetal fibronectin (FFN), GBS culture should also precede digital exam
**Some lubricants can affect FFN and amniotic fluid pH strip
**Nitrazine test (5% FP rate, 1% FN rate) - pH swab turns blue, indicating alkalotic amniotic fluid (pH 6.5 - 7.5 positive test); do not touch to mucous plug in cervix<ref>Nitrazine Test. https://www.pathology.med.umich.edu/poc/onsite/pH-amniotic.html</Ref>
*Proceed with digital exam if placental previa unlikely, and digital exam is urgently needed to assist patient care, such as in fetal HR decels
*Proceed with digital exam if placental previa unlikely, and digital exam is urgently needed to assist patient care, such as in fetal HR decels


==Management==
==Management==
 
*IV access, ABCs
*Fetal Heart Monitor
*Fetal Heart Monitor
*U/S to assess placental position / fetal position
*U/S to assess placental position / fetal position
*Digital exam to assess cervical thickness, effacement, rupture of membranes
*Digital exam to assess cervical thickness, effacement, rupture of membranes
*CBC, Chem, Coags, U/A w/ culture, Utox (cocaine increases risk of abruption)
*Type and Screen, CBC, Chem 10, Coags, U/A with culture, Utox (cocaine increases risk of abruption)


*Cervical length >30mm - Labor less likely
===Cervical length===
*>30mm - Labor less likely
**Observation of 6 hours might be appropriate
**Observation of 6 hours might be appropriate
 
*20-30mm - Increased risk for preterm labor
*Cervical length 20-30mm - Increased risk for preterm labor
**Fetal fibernetin result can assist, if over 50ng/ml manage labor actively
**Fetal fibernetin result can assist, if over 50ng/ml manage labor actively
 
*<20mm - labor very likely
*Cervical length <20mm - labor very likely
**Manage actively
**Manage actively


===Management by Weeks===
*24-32 weeks
**Mag sulfate (neuroprotection against cerebral palsy)
*<34 weeks
*<34 weeks
**Betamethasone, and hospitalization
**Hospitalization
**Tocolytics
**Betamethasone 12mg IM q24hrs x2 doses
**Tocolytics (see below for options/dosages)
**Antibiotics for GBS prophylaxis if status unknown
**Antibiotics for GBS prophylaxis if status unknown
**Other abx only indicated in setting of active infx
**Other antibiotics only indicated in setting of active infection


*24-32 weeks
===Tocolysis===
**Mag sulfate (neuroprotection against cerebral palsy)
 
==Tocolysis==
*Indications
*Indications
**Only if fetus would benefit from delay in delivery of 48 hrs
**Only if fetus would benefit from delay in delivery of 48 hrs
**Gestational age 22wks - 34 wks
**Gestational age 22wks - 34 wks
**Transport to facility for definitive delivery
**Transport to facility for definitive delivery
**Delay in delivery of reversible condition possibly triggering labor (UTI/pyelo)
**Delay in delivery for treatment of reversible condition possibly triggering labor (UTI/pyelo)
***Betamethasone requires approx 48 hrs for maximal benefit for lung maturity, reducing intraventricular hemorrhage, NEC, and death
***Betamethasone requires approximately 48 hrs for maximal benefit for lung maturity, reducing intraventricular hemorrhage, NEC, and death
***Tocolysis rarely effective for longer than 48 hrs
***Tocolysis rarely effective for longer than 48 hrs
***Does not remove underlying cause for tocolysis
***Does not remove underlying cause for tocolysis
*Contraindications  
*Contraindications  
**Intratuterine fetal demise / lethal anomaly
**Intratuterine fetal demise / lethal anomaly
**Maternal hemorrhage or instability
**Maternal hemorrhage or instability
**Intraamniotic infx
**Intraamniotic infection
**Severe preeclampsia or eclampsia
**Severe preeclampsia or eclampsia
**Nonreassuring fetal status
**Nonreassuring fetal status
**Contraindications to the drugs
**Contraindications to the drugs
*Medications
**[[Indomethacin]] 50-100mg loading dose, 25mg q4-6 hrs for 48 hrs
**[[Nifedipine]] 20mg x1, additional 20mg dose in 90min if ctx persist, followed by 20mg q3-8 hrs PRN ctx
**[[Terbutaline]] 0.25mg sq q20-30 min up to 4 doses PRN ctx


==Disposition==
==Disposition==
*Admission to OB floor for delivery, or transfer to facility to manage delivery
*If cervix >30mm, contractions have stopped, consider 6 hours of obs


==See Also==
==See Also==
*[[Vaginal Bleeding (Main)]]
*[[Pregnancy (main)]]


==External Links==
==External Links==


==References==
==References==
<references/>
<references/>
*UpToDate "Overview of preterm labor and birth"
*UpToDate "Inhibition of acute preterm labor"


UpToDate "Overview of preterm labor and birth"
[[Category:OBGYN]]
 
UpToDate "Inhibition of acute preterm labor"

Revision as of 07:53, 7 July 2017

Background

  • Defined as labor before 37 weeks (uterine contraction and cervical change)
  • Increased risks to child depending on age of fetus
    • Cerebral palsy, poor lung development, cognitive delay, etc
  • Can be triggered by infections, stress, hypertension, uncontrolled DM

Clinical Features

  • Similar to term labor
  • Uterine contractions q 10 min (may be irregular)
  • New onset of vaginal mucus, blood, pink discharge, amniotic fluid
  • Low back ache, vaginal pressure

Differential Diagnosis

Vaginal Bleeding in Pregnancy (>20wks)

Evaluation

  • Do NOT perform digital exam in patients who present with vaginal bleeding when >20 weeks pregnant
  • Start with ultrasound to assess position of cervix and rule out placenta previa
  • Swabs for nitrazine, fetal fibronectin (FFN), GBS culture should also precede digital exam
    • Some lubricants can affect FFN and amniotic fluid pH strip
    • Nitrazine test (5% FP rate, 1% FN rate) - pH swab turns blue, indicating alkalotic amniotic fluid (pH 6.5 - 7.5 positive test); do not touch to mucous plug in cervix[1]
  • Proceed with digital exam if placental previa unlikely, and digital exam is urgently needed to assist patient care, such as in fetal HR decels

Management

  • IV access, ABCs
  • Fetal Heart Monitor
  • U/S to assess placental position / fetal position
  • Digital exam to assess cervical thickness, effacement, rupture of membranes
  • Type and Screen, CBC, Chem 10, Coags, U/A with culture, Utox (cocaine increases risk of abruption)

Cervical length

  • >30mm - Labor less likely
    • Observation of 6 hours might be appropriate
  • 20-30mm - Increased risk for preterm labor
    • Fetal fibernetin result can assist, if over 50ng/ml manage labor actively
  • <20mm - labor very likely
    • Manage actively

Management by Weeks

  • 24-32 weeks
    • Mag sulfate (neuroprotection against cerebral palsy)
  • <34 weeks
    • Hospitalization
    • Betamethasone 12mg IM q24hrs x2 doses
    • Tocolytics (see below for options/dosages)
    • Antibiotics for GBS prophylaxis if status unknown
    • Other antibiotics only indicated in setting of active infection

Tocolysis

  • Indications
    • Only if fetus would benefit from delay in delivery of 48 hrs
    • Gestational age 22wks - 34 wks
    • Transport to facility for definitive delivery
    • Delay in delivery for treatment of reversible condition possibly triggering labor (UTI/pyelo)
      • Betamethasone requires approximately 48 hrs for maximal benefit for lung maturity, reducing intraventricular hemorrhage, NEC, and death
      • Tocolysis rarely effective for longer than 48 hrs
      • Does not remove underlying cause for tocolysis
  • Contraindications
    • Intratuterine fetal demise / lethal anomaly
    • Maternal hemorrhage or instability
    • Intraamniotic infection
    • Severe preeclampsia or eclampsia
    • Nonreassuring fetal status
    • Contraindications to the drugs
  • Medications
    • Indomethacin 50-100mg loading dose, 25mg q4-6 hrs for 48 hrs
    • Nifedipine 20mg x1, additional 20mg dose in 90min if ctx persist, followed by 20mg q3-8 hrs PRN ctx
    • Terbutaline 0.25mg sq q20-30 min up to 4 doses PRN ctx

Disposition

  • Admission to OB floor for delivery, or transfer to facility to manage delivery
  • If cervix >30mm, contractions have stopped, consider 6 hours of obs

See Also

External Links

References

  • UpToDate "Overview of preterm labor and birth"
  • UpToDate "Inhibition of acute preterm labor"