Obstructed Labour

last authored: Aug 2011, David LaPierre
last reviewed: March 2012, Kristen Fife




Obstructed labour, also know as dystocia, is the most common problem in labour, affecting primarily nulliparous women. Dystocia comes from the Greek, where dys refers to abnormal, and tocos describes labour.

Dystocia is defined as:

Increased concern should be present if a nulliparous woman is in the second stage of labour for three hours with epidural analgesia, or two hours without.

Multiparous women warrant consideration of options if the second stage has lasted more than two hours with epidural anagesia, or one hour without. However, if maternal and fetal monitoring do not reveal any worrying findings, the second stage can persist for up to 6 hours without negative consequence (Menticoglou et al, 1995).


Dystocia can be associated with a number of negative consequences, including stress and anxiety, infection, postpartum hemorrhage, Caesarean section, and most seriously fetal demise, if surgical intervention is not available.




The Case of Laura W.

Laura is a 24 year-old woman pregnant for the first time. She begins having regular contractions that gradually become stronger, and comes to the hospital to deliver her baby. However, 12 hours afer arriving, her nurse performs a vaginal examination and states she is only 3 cm dilated.

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Differential Diagnosis

The causes of dystocia may be grouped in the four P's: power, passenger, passage, and psyche.


  • contractions weak, infrequent, or poorly coordinated; may follow epidural analgesia
  • maternal effort inadequate



  • pain
  • stress/anxiety, mediated by stress hormones; these reduce uterine contractility
  • fatigue
  • sadness
  • frustration
  • absence of continuous support person


  • fetal position: lack of head flexion, asynclytism
  • fetal size: ie macrosomia
  • fetal anomalies, eg hydrocephalus


  • inadequate pelvic structure
  • full bladder or rectum
  • female genital mutilation
  • vaginal septum
  • tumour

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History and Physical Exam

  • history
  • physical exam


An accurate description of active labour is required to diagnose dystocia.

Adequate contractions are at most five minutes apart, last for one minute, and take place for at least one hour.

Physical Exam

Perform Leopold's maneuvers to assess fetal position and presentation.

The active phase of labour must be demonstrated before beginning timing the length of labour. This is defined by a cervix which is 3-4 cm dialation and demonstrating progressive change. Cervical assessment should be performed every few hours, or if changes are noted.

Assess the strength and quality of uterine contractions via abdominal palpation. Recognize that this has subjective limitations.

Vaginal exam can provide information about the bony pelvis or mass.

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  • lab investigations
  • diagnostic imaging

Lab Investigations

Lab investigations are not indicated for assessment of dystocia.

Diagnostic Imaging

Fetal monitoring should be carried out to ensure well-being.

Radiology does not predict or assist with assessment of dystocia.

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There are proven ways of reducing the risk of dystocia:

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Options depend on stage and on rupture of membranes.

It is important to not blame the mother, saying 'the baby is not coming down' rather than 'you're not pushing hard enough.'


First stage

In the first stage, consider the following:


Second stage

Women should not be encouraged to push unless they feel the urge. If no urge to push is present after one hour of second stage, consider the use of oxytocin.


Again, consider:

Episiotomy does not appear to effectively shorten the second stage of labour, though can be helpful if imminent birth is prevented by the perineum.


Instrumental delivery

  • background
  • vacuum
  • forceps


With a properly trained provider, vacuum and forceps are considered safe and reliable. While considering instrumentation, it is important to weigh:

  • maternal and fetal risks of instrumentation
  • risks associated with intrapartum Caesarean section
  • likelihood of success


Prerequisites for instrumentation include:

  • informed consent
  • reasonable chance of success
  • absence of fetal contraindications
  • ongoing fetal and maternal assessment
  • anaesthesia
  • membranes ruptured
  • cervix fully dilated
  • bladder is empty
  • head engaged
  • knowledge of the station of the skull, not the caput (swelling or molding of the soft tissues of the head)
  • adequate uterine contractions
  • experienced operator in an adequate facility
  • clinically adequate pelvis
  • backup plan

Some providers will perform instrumental delivery in the OR suite, so that a failed attempt, or fetal distress, may lead directly to C-section.


Regarding station, the options are considered:


  • head is engaged (station between 0 and +2)



  • skull is at station +2 or greater, and not on the pelvic floor


  • the scalp is visible without separating the labia
  • fetal skull has reached pelvic floor
  • saggital suture is in the AP diameter, or is ROA, LOA, or OP
  • rotation does not exceed 45 degrees


Vacuum is an assisted delivery device designed for traction, not rotation. It has risks, and should not be regarded as an easier alternative to forceps.


They may be considered if:

  • full dilation
  • low enough for it to be safe (+2 or +3)
  • >35 weeks
  • multiparous
  • good progress
  • good maternal effort


  • atypical or abnormal FHR pattern
  • medical conditions precluding valsava
  • poor effort


  • face or brow presentation
  • fetal conditions
  • contrandications to vaginal delivery
  • less than 34 weeks gestation
  • need for rotation


  • 3 pulls, over 3 contractions, with no progress
  • pop-off: three is the limit
  • 20 minutes of total elapsed time, with a delivery that is not imminent
  • hematoma
  • subgaleal bleed

If unsuccessful, proceed to Caesarean section.


Forceps may be used for traction, rotation, flexion, and extension.


Forceps may be considered if:

  • fully dilated
  • station +1 - +3
  • position is known
  • ++ Caput
  • analgesia (epidural or pudendal block)
  • Casearean section capability is present



  • arrest in 2nd stage
  • poor maternal effort
  • < 35 weeks gestational age (vs vacuum)


Potential complications

  • lacerations
  • malplacement
  • hematoma
  • shoulder dystocia
  • fracture

Stop when

  • failure of proper application
  • insufficent descent

If unsuccessful, proceed to Caesarean section.

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Resources and References

Menticoglou SM et al. 1995. Perinatal outcomes in relation to second stage duration. Am J. Obstet. Gynceol. 173:906.

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Topic Development



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