Obstructed Labour
last authored: Aug 2011, David LaPierre
last reviewed: March 2012, Kristen Fife
Introduction
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:
- dilation of less than 0.5cm/hour over four hours in the first stage
- descent of less than 1cm/hour in the second stage
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.
- how would you describe Laura's situation? Do you want any further information?
- how do you manage her situation?
Differential Diagnosis
The causes of dystocia may be grouped in the four P's: power, passenger, passage, and psyche.
Powers
Psyche
|
Passenger
Passage
|
History and Physical Exam
- history
- physical exam
History
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.
Investigations
- 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.
Prevention
There are proven ways of reducing the risk of dystocia:
- adequate preparation for labour
- effective identification of labour
- continuous labour support
- ambulation and upright posture
- appropriate anagesia
- amniotomy and augmentation if warranted during epidural anagesia
Management
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:
- repositioning the mother
- rest and analgesia
- amniotomy
- augmentation
- Cesarean section, if other treatments have failed
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:
- rest and analgesia
- repositioning the mother; for example, a hands and knees position can help if the baby is in a OP (occiput posterior) presentation
- augmentation
- instrumentation (described below)
- Cesarean section
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
Background
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:
Mid
Low
|
Outlet
|
Vacuum
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
Indications
- atypical or abnormal FHR pattern
- medical conditions precluding valsava
- poor effort
Contraindications
- face or brow presentation
- fetal conditions
- contrandications to vaginal delivery
- less than 34 weeks gestation
- need for rotation
Complications
- 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
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
Indications:
- 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.
Resources and References
Menticoglou SM et al. 1995. Perinatal outcomes in relation to second stage duration. Am J. Obstet. Gynceol. 173:906.
Topic Development
authors:
reviewers:
 |