Protraction and arrest disorders: Clinical sciences

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Introduction0:00–0:21

Protraction refers to labor progressing at a slower rate than expected, while arrest refers to the complete cessation of labor progress.
Given the increased morbidity with prolonged labor and the need for C-section with labor arrests, it’s important to promptly recognize these disorders.Your first step in evaluating patients for protracted or arrested labor is a focused history and physical.

Focused History and Physical0:21–2:08

This includes evaluation of the 4 Ps: passage, meaning pelvis; passenger, meaning fetal size and position; power, meaning strength of contractions and maternal pushing efforts; and psyche, referring to the patient’s mental state and social support.
Risk factors for abnormal labor will influence these 4 Ps in a number of ways. Nulliparity can affect ‘passage’, since having a previous birth can open the pelvis for subsequent deliveries.
Nulliparity may also affect the patient’s ‘psyche’ if they have insufficient support. Post-term pregnancy or gestational diabetes may result in a larger than average ‘passenger’, while intraamniotic infection and epidural analgesia can affect the ‘power’ of contractions and pushing efforts.
Physical exam findings may reveal risk factors like obesity, which increases the risk of a macrosomic ‘passenger’; or short stature, which is associated with a smaller pelvis.
You may also note that the ‘passage’ space feels narrow, possibly from a prior pelvic fracture or simply because of genetic variation.
Additionally, the ‘passenger’ can impact labor if the fetus is macrosomic or in a non-occiput anterior position. A non-reassuring fetal heart rate pattern also raises the risk of protracted or arrested labor, because it limits your ability to target ‘power’ with labor augmentation using a uterotonic agent like oxytocin.Once your history and physical are complete, assess the phase and stage of labor.

First Stage - Latent phase2:08–4:55

Patients in the first stage, from the onset of labor until 10 centimeters dilation, can be further separated by labor phase.
Patients are in the latent phase when cervical dilation is less than 6 centimeters. Now’s a good time to check how much time has passed since the onset of labor.
If more than 20 hours passed in a nulliparous patient, or 14 hours in a multiparous patient, then we are talking about prolonged latent phase of labor.
There’s actually minimal risk during this time. If you do nothing, contractions usually either stop on their own or pick up and transition to active labor.
Therefore, consider expectant management if there are no signs of maternal or fetal distress. You could send the patient walking for a few hours before rechecking the cervical dilation.
Alternatively, you may let the patient go home after a single exam with instructions to return when contractions get stronger or if their water breaks.Sometimes, the patient prefers or requires intervention.
Latent labor can be quite painful, so you can offer therapeutic rest, which involves administering a narcotic or benzodiazepine.
Usually, the patient can rest, and when they wake up, the contractions have either resolved, or the labor has progressed.
Alternatively, you can augment the labor using oxytocin, or by performing an amniotomy to rupture their membranes. Remember that a prolonged latent phase is not an indication for a C-section!
Here are a couple of clinical pearls! When given correctly, oxytocin is very safe.
Contraindications include drug hypersensitivity, a non-reassuring fetal status, and any contraindication to labor. Oxytocin should be titrated to the goal of at least moderate contractions every 2 to 3 minutes, depending on fetal tolerance.
Avoid tachysystole, which is a contraction frequency of more than 5 in 10 minutes, or contractions lasting longer than 2 minutes, as there’s a risk of fetal distress, uterine rupture, and abruption.
Another important clinical pearl to know is that the latent phase can last 24 hours, or even longer if maternal and fetal status allow.
To allow the best chance of vaginal delivery, be sure to administer oxytocin for at least 12 to 18 hours after membrane rupture before diagnosing a failed labor induction or augmentation.
Okay, let’s talk about patients in the active phase of the first stage, meaning between 6 and 10 centimeters of dilation.

First Stage - Active phase4:55–7:52

First, assess their rate of cervical change. Historically, labor progress was considered normal if the cervix dilated at least 1.2 centimeters per hour in nulliparous patients, and 1.5 centimeters per hour in multiparous patients.
However, newer data shows that slower progress can occur without maternal or fetal harm. So, for patients with very little to no cervical change beyond 6 centimeters of dilation, your diagnosis is a protracted first stage of labor.
This doesn’t necessarily mean something is wrong, but you can consider intervening to increase the power and frequency of contractions.Treatments require a reassuring maternal and fetal status because, if there’s fetal distress, intensifying contractions will worsen it.
You might place an intrauterine pressure catheter, or IUPC, which helps you determine the strength of each contraction so you can titrate oxytocin augmentation to maximize contractions.
Here's a high-yield fact! IUPC is used to calculate Montevideo units, or MVUs, by adding together the change in pressure during each contraction over a 10-minute period.
If the sum is less than 200 MVUs, you can increase the ‘power’ by titrating oxytocin to achieve adequate contractions.Another option to increase contractions is amniotomy.
Also, repositioning the patient through the Miles circuit or utilizing a peanut ball are low-risk interventions that might help move the ‘passenger’ and pelvis into positions that facilitate labor progression.
The Miles circuit is a series of 3 positions, each lasting 30 minutes. First, the patient is positioned on their hands and knees with the knees wide apart and their chest below the level of the bottom.
Then, they should lay on one side and have the leg on that side stretched out, while the other leg is lifted with pillows.
The final position involves some exercises like lunges or walking up or down the stairs.Next, assess the patient’s response.
If the cervix is changing in dilation, continue with a trial of labor. However, if there’s no further dilation in patients with ruptured membranes, despite 4 hours of adequate contractions, or 6 hours of inadequate contractions, that’s abnormal.
With no further dilation expected, diagnose an arrested first stage of labor, also called an arrest of dilation, and proceed with a C-section.Let’s move on to the second stage, which goes from 10 centimeters dilation until delivery.

Second Stage7:52–11:47

First, assess the progression of fetal descent. In nulliparous patients, you will note minimal to no fetal descent after 3 hours without an epidural, or after 4 hours with one.
Although the second stage starts when the patient is 10 centimeters, they should be allowed to actively push for at least 3 hours before diagnosing abnormal labor progress.Similarly, in multiparous patients, you can see minimal to no descent after 2 hours without an epidural, or after 3 hours with an epidural.
Keep in mind that they should spend at least 2 hours pushing. With these findings, you can diagnose a protracted second stage of labor.
Just like before, maternal and fetal status must be reassuring to intervene. An occiput anterior vertex allows the narrowest part of the fetal head to pass through the narrowest part of the pelvis.
If the occiput isn’t anterior, try manually rotating the fetus’s head to optimize the ‘passenger’. Additionally, consider oxytocin or amniotomy, if not yet done, to increase the ‘power’.
Also, try repositioning the patient with hands and knee position or closed knee pushing to adjust the ‘pelvis’ and make more space.
After trying these maneuvers, assess the response. If it’s adequate, meaning there’s fetal descent, continue with a trial of labor.
However, an inadequate response, meaning no fetal descent, is also possible. There isn’t an exact amount of time that defines an inadequate response here, as the descent is a continuum.
You can continue pushing if there’s any gradual progress and a reassuring status. But, if you’ve tried all your options and the fetus is still not making clear progress, go to the next steps.
Assess for an operative vaginal delivery with either a vacuum or forceps, depending on the clinical situation, provider experience, and preference.
You must evaluate the fetal station, which generally needs to be at least plus-2 to proceed. You must also know the orientation of the fetal vertex to apply the device safely.
Assess if the pelvis feels adequate, taking into consideration the estimated fetal weight and the pelvic space appreciated on the exam.
Don’t forget to review risks and benefits, and obtain maternal consent. The gestational age is important, as a vacuum cannot be used before 34 weeks due to the risk of fetal intracranial hemorrhage.If an operative vaginal delivery isn’t appropriate at this point, diagnose an arrested second stage of labor, also called an arrest of descent, and proceed with a C-section.
Otherwise, proceed with operative vaginal delivery. When successful, a vaginal delivery occurs!
However, even with your best efforts, the device sometimes can’t be applied or the fetus doesn’t descend with traction, which is an inadequate response.
At this point, diagnose an arrest of the second stage of labor and proceed to a C-section. Here’s a final high-yield fact!
The third stage of labor starts after delivery of the fetus and ends with delivery of the placenta. During vaginal delivery, this usually happens within the first few minutes, but it may take up to 30 minutes in some patients.
A protracted third stage is a significant risk factor for postpartum hemorrhage, so active management using uterine massage and uterotonic medications, such as oxytocin or misoprostol, can help reduce this risk.Alright, as a quick recap… Protraction and arrest disorders refer to abnormal lengths of labor, which can be diagnosed by cervical exam.

Review11:47–12:38

When a protracted first stage is noted, consider placing an IUPC, augmenting with oxytocin or amniotomy, and position changes.
A complete failure to progress is an arrest of labor in the first stage and requires a C-section. When a protracted second stage of labor is noted, consider manually rotating the fetus to the occiput anterior, augmenting with oxytocin or amniotomy, and position changes.
If those don’t work, assess for an operative vaginal delivery. If there’s no further descent, diagnose an arrest of labor in the second stage and perform a C-section.