New Labor Guidance, Part 2

Welcome back! Last time, we talked the new Clinical Practice Guideline #8 and the first stage of labor. While there were some new things, many of the recommendations were unchanged.

Today we’re going to talk second stage – time from complete dilation to fetal delivery. There are some big differences here versus the previous Obstetric Care Consensus, and we’ll try to point them out as we go!

What is a normal length of second stage?

• ACOG defines a prolonged second stage as:

• Three hours or more in nulliparas

• Two hours or more in multiparas

• Furthermore, they recommend an individualized approach to diagnose second stage arrest, “incorporating factors regarding progress, clinical factors that may affect the likelihood of vaginal delivery, discussion of risks and benefits of available interventions, and individual patient preference” if planning to extend beyond these parameters.

• Additionally, ACOG states that “second stage arrest can be diagnosed earlier if there is lack of fetal rotation or descent despite adequate contractions, pushing efforts, and time.”

• This is a more open, individualized, and less time-focused than the prior “4/3/3/2” recommendations in the Obstetric Care Consensus.

• The OCC also stated that there was no maximum amount of time in the second stage identified.

• The recommendation to consider diagnosis prior to reaching these time points is based on some concerns that developed in the literature that providers were failing to recognize issues in the second stage altogether by focusing on the “4/3/3/2” time, and that the “4/3/3/2” recommendations were not based in evidence supporting safety.

• CPG 8 takes an attempt at establishing some evidence:

• Observational study of over 53,000 laboring patients:

• Probability of vaginal delivery decreased with prolonged pushing time, but:

• At 4 hours, chance of vaginal delivery in nullipara remained 78%

• At 2 hours, chance of vaginal delivery in multipara remained 81%

• Longer pushing duration resulted in statistically significant rise in composite neonatal morbidity

• However, the absolute risk difference was small – less than 1%.

• Other studies have been mixed about neonatal outcomes with respect to prolonged second stage.

• Longer pushing duration resulted in rise in maternal risk:

• 3rd/4th degree laceration

• Operative vaginal delivery

• Postpartum hemorrhage

• Cesarean delivery

• If you remember the Obstetric Care Consensus, you might remember that the “additional hour of pushing time” was allotted for patients who had epidurals. Is that the same?

• They do note in the text that, based on Consortium for Safe Labor data, second stage was prolonged by about one additional hour in patients with an epidural.

• The additional clinical factors to consider include things like position (i.e., OP), maternal BMI, fetal weight, and the fetal station at time of complete dilation.

• However, studies performed since then demonstrated that, while prolonging the second stage by an additional hour resulted in more vaginal deliveries, it also increased risk of neonatal acidemia, NICU admission, and 3rd/4th degree lacerations.

• Thus, individualized discussions and management are highly encouraged. Keep the following in mind:

• Ongoing management of the second stage presumes continued demonstration of fetal descent. The limits written are total expected times for second stage – so if you’re not seeing anything, that’s cause for concern.

• 95% of patients are at 0 station or lower (on -5 to +5 scale) at complete dilation – so if patients are higher than this, that is also concerning.

How do I manage a prolonged second stage?

• Pushing timing

• ACOG recommends commencing pushing when complete cervical dilation is achieved.

• ACOG discusses the controversy surrounding “delayed pushing” or “passive descent” in this document, raising the findings of a recent high-profile RCT as well as a meta-analysis of 12 trials on the subject.

• The arguments go that delayed pushing minimizes patient exertion with pushing efforts, while immediate pushing more closely mimics the physiology of unanesthetized patients, whose pain makes them push earlier.

• Among high-quality studies, delayed pushing does not improve vaginal delivery rates.

• Additionally, delayed pushing prolongs time in labor; and in the high-profile RCT, the study was stopped early because of increased rates of chorioamnionitis, postpartum hemorrhage, and neonatal acidemia in the delayed pushing arm.

• So get to pushing!

• Manual rotation

• Positions such as OT or OP can be difficult to achieve vaginal delivery due to the mechanics of the fetal head within the pelvis.

• Using a hand to rotate the head into an OA position has been demonstrated in observational studies to be successful about 70% of the time, while reducing cesarean and operative delivery rates, and not causing infant harm.

• However, an RCT comparing a sham rotation to true rotation did not demonstrate any benefit, but was not powered to determine any risk of harm.

• Knowing position of the fetal spine may help influence success, as has been demonstrated in one RCT – so don’t be afraid to have an ultrasound to 1) confirm position before rotation, and 2) help know which way to rotate!

• Timing of manual rotation has not been adequately studied, so it can be performed at any point in the second stage.

• Operative delivery

• ACOG suggests an assessment for operative vaginal delivery before performing cesarean for second stage arrest.

• Outcome comparisons of operative vaginal delivery and unplanned cesarean delivery demonstrate reduced maternal morbidity after successful operative delivery, with similar rates of serious neonatal morbidity.

• This is no surprise to our listeners who have tuned in to our operative vaginal delivery podcast!

• Check out that podcast for more details – but the rates of intracranial hemorrhage are similar for second stage cesarean and vacuum delivery, and failure rates are low – under 3% for low or outlet procedures.

• That said, operative delivery requires special skill and training, which is becoming less frequent. Cesarean is still the “safety backstop” when these cannot be performed or if a patient declines operative delivery.

• Be prepared for higher rates of endometritis and for more significant bleeding and hysterotomy extensions. 

• Listen to our recent podcast on difficult fetal extractions, too, as you’ll encounter this more frequently with second stage cesarean. 

Obstetric Lacerations: Repair and Prevention

Here’s the RoshReview Question of the Week!

After a forceps delivery of a 9 lb neonate, a perineal laceration is noted with both the external anal sphincter and internal sphincter torn. During the repair, a glistening white fibrous structure is sutured together in a continuous, nonlocking fashion. What tissue is this?

• Anal mucosa

• External anal sphincter

• Internal anal sphincter

• Transverse perineal muscle

Check out if your answer is correct and enter the Qualifying Exam QBank Giveaway at the links above!

---

Anatomic Review

• Perineal body anatomy – most common site of injury

  • This is the fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle  

    • Bulbospongiosus 

    • Superficial transverse perineal muscle 

    • Deep transverse perineal muscle 

  • Below this = anal sphincter complex 

    • External anal sphincter – voluntary control; provide squeeze pressure of the anal canal 

    • Internal anal sphincter – involuntary (autonomic) control and provides up to 80% of resting pressure of the anal canal. Very important for continence 

So how often do obstetric lacerations occur? 

• Varying numbers, but about 53-79% of women will sustain some type of lac during delivery 

• Types 

  • First Degree – injury to perineal skin only 

  • Second Degree – involves perineal muscles but not involving anal sphincter 

  • Third Degree – injury involves the anal sphincter complex 

    • 3a: <50% of external anal sphincter thickness torn 

    • 3b: >50% of external anal sphincter thickness torn 

    • 3c: Both external and internal anal sphincter torn 

  • Fourth Degree – injury involves anal sphincter complex and anal epithelium 

    • Studies show (obviously) that women with 4th degree lacs are at highest risk of reporting bowel symptoms at 6 months postpartum 

    • Report bowel control 10x worse than women with third degrees 

• What about episiotomies? 

  • Surgical enlargement of the posterior aspect of the vagina by incision to the perineum to facilitate the second stage of labor 

  • Rates have decreased since 2006 

    • However, 12% of vaginal births include episiotomies based on 2012 data 

  • Difficult to separate contribution of vaginal birth, operative delivery, episiotomy, and OASIS to pelvic floor function and anatomy 

  • Systematic review showed that routine episiotomy offered no immediate or long-term maternal benefit in perineal laceration severity, pelvic floor dysfunction, or pelvic organ prolapse 

    • In other reviews though, episiotomy has been associated with increased risk of postpartum anal incontinence; seen in one meta-analysis: increased risk of anal incontinence even if no extension into anal sphincter complex 

  • Routine episiotomy did not improve self-reported sexual function outcomes; more likely to have pain with intercourse in months after pregnancy and slower to resume intercourse than women whom episiotomy use was restricted 

  • So… there is a time and place for episiotomies, but don’t routinely cut them 

What are the risks for higher order lacerations, ie. OASIS? 

• Operative deliveries 

  • Forceps (OR 5.50), VAVD (OR 3.98) 

• Midline episiotomy (OR 3.82)  

• Increased fetal birth way (mean difference 192.88g) 

• Midline episiotomy + forceps substantially increases the risk of 3rd and 4th degree laceration 

• Other ones that are less modifiable: 

  • Primiparity 

  • Asian ethnicity (problematic)

  • Labor induction 

  • Labor augmentation 

  • Epidural use 

  • Persistent OP 

Ok, so now that we’ve talked about all the scariness, how do we prevent them? 

• Antepartum or intrapartum perineal massage 

  • Thought is to decrease perineal muscle resistance and reduce likelihood of lacs 

    • In studies that compared antenatal perineal massage to no-massage, digital massage from 34 weeks gestation on was associated with modest reduction in perineal trauma that required suture repair (RR 0.91), and decreased episiotomy 

    • Perineal massage during second stage of labor may reduce 3rd and 4th degree lacs when compared with “hands off” methods but was not associated with significant changes in rate of birth with intact perineum 

  • Perineal support: data is so-so 

    • Meta-analysis with >6600 women – did not demonstrate protective effect for OASIS 

    • However, three nonrandomized studies showed significant reduction 

    • But techniques of support not well described 

• Warm compress 

  • Meta-analysis with 1525 women 🡪 randomized to warm compress or no in second stage of labor 🡪 did reduce 3rd and 4th degree lacs 

  • Did not increase rate of women having intact perineums 

• Birthing position 

  • Upright or lateral birth position compared with supine or lithotomy associated with fewer episiotomies and operative deliveries, but higher rates of second-degree lacs (overall low quality data) 

  • Meta-analysis of five randomized trials showed no clear benefit 

  • Recent randomized trial: lateral birth position with delayed was compared with lithotomy positions 🡪 lateral positive with delayed pushing more likely to deliver with intact perineum 

• Delayed pushing – no difference in lacerations

How do we manage obstetric lacerations?

• Periclitoral, periurethral, labial lacerations 

  • Small tears of the anterior vaginal wall and labia are relatively common 

  • If superficial and no bleeding – can be left unrepaired 

  • However, if bleeding or distort anatomy, should repair and also consult experts if you do not feel comfortable with it 

• First and second degree 

  • Insufficient evidence exists to recommend surgical or nonsurgical repair of first or second degree lacs 

  • A lot of data does not include long-term outcomes 

  • Use clinical judgement about repair 

    • Continuous suturing is preferred over interrupted suture 

    • Associated with less pain up to 10 days postpartum, less analgesia used, and lower risk of having suture material removed postpartum 

    • Use absorbable synthetic suture like polyglactin (ie. Vicryl) 

• OASIS injuries 

  • Overt OASIS reported in 4% of women in the US

    • Occult OASIS may be later identified by endoanal ultrasonography, but have no clinical findings – occur in 27% of women after first vaginal delivery 

  • The first thing to do: really look! If you suspect, do a digital rectal exam. Examine the perineal body and also the vaginal mucosa. See if you can start to see fibers of the internal and external anal sphincter 

    • SIM has been shown to be helpful in helping providers identify and repair these 

  • How to repair for OASIS 

    • Anal mucosa – expert opinion varies on technique and suture material 

      • Subcuticular running repair that uses a transvaginal approach and interrupted sutures with knots tied in the anal lumen have been described 

      • Suggest using 4-0 or 3-0 polyglactin or chromic 

      • No comparative trials have been done 

    • Internal/external anal sphincter 

      • Identify the area of the internal and external anal sphincter 

      • Because of retraction, we will usually place an Allis on either side of the external anal sphincter muscle to bring them together. Can cross the Allis’s and do a rectal to see if you are bringing the right muscles together 

      • Suture fascial sheath as well as muscle! 

      • Methods: End-to-end and overlap repair 

        • Remember: overlap requires full thickness disruption and 1-1.5 cm torn muscle on either end, so don’t use it for 3a or partial thickness 3b sphincter injuries 

        • Expert opinion: use 3-0 or 2-0 polyglactin suture

        • Meta-analysis of six randomized controlled studies showed no difference between two techniques at 12 months of perineal pain, dyspareunia, or flatal incontinence, but there were lower incidence of fecal urgency and lower anal incontinence scores in women with overlap repair 

        • No significant difference in quality of life or anal incontinence symptoms 36 months after repair  

      • We tend to do end-to-end because of visualization; PISA technique

• Antibiotics for OASIS 

  • Wound complications (ie. Infection, breakdown) are decreased when intrapartum antibiotics are administered 

  • So single dose of antibiotics (studies looked at single dose of second gen cephalosporin) is reasonable. Further research is needed to determine whether severe perineal lacerations warrant routine postpartum partum antibiotics to prevent complications 

Complications from severe perineal trauma 

• First six weeks 

  • After OASIS, 25% of women experience wound breakdown, 20% experience wound infection 

  • Those with complications will have more pain than women with normal healing 

  • Possible to have fistulas (9% of rectovaginal fistulas in the US are associated with OB trauma) 

• How to care for them? 

  • Pain control, avoid constipation, and evaluate for urinary retention 

  • In one study, use of oral laxative was associated with significantly less pain and earlier bowel movement 

  • Monitored frequently for wound healing 

  • Pelvic floor exercise + biofeedback physiotherapy has been suggested 

What about next pregnancies? 

• Increased risk of OASIS in the next pregnancy, but absolute risk is low (3%) 

• Can have elective cesarean 

  • But there is no difference when there is vaginal delivery or elective cesarean in fecal urgency, anal incontinence, or bowel-related quality of life 

Operative Vaginal Birth

So today’s episode won’t be a “how to” on operative birth; that requires some years of residency and even fellowship, but we want to help you recognize what operative births are and when to use them. For more reading, check out the new ACOG PB 219.

Operative vaginal birth is when an obstetrician or other trained birthing provider uses a device such as vacuum extractor or forceps during the second stage of labor to achieve or expedite a vaginal birth for maternal or fetal indications. The two tools generally available are forceps or vacuum extractors.

Forceps 

• Generally, metal devices with two blades that are placed around the head of the fetus to assist in birth.

• Consist of the components of blade, shank, lock or articulating portion, and handle 

• The blades have a toe (front) and a heel (back toward the provider), as well as a pelvic curve and cephalic curve:

View fullsize

OBGynKey

• Some history on forceps:

  1. First developed by the Chamberlen family of surgeons in France as early as possibly 1634, though they kept them secret for about 150 years.

  2. They largely haven’t changed. Simpson forceps (split shanks), for example, were created in 1848, and Elliot forceps (overlapping shanks) in 1860.

  3. There are multiple types, but the majority of forceps in use today are in the Simpson or Elliot class. Some you may encounter:

     1. Simpson - Luikhart: split shank (Simpson type), pseudofenestrated blade.

     2. Luikhart - McLain: Elliot type with pseudofenestrated blade.

     3. Tucker McLain: Elliot type, no fenestration to blade.

Vacuum Extractor 

• A suction cup that is placed on the head of the baby approximately 2-3 cm anterior from the posterior fontanelle over the flexion point to guide the head through the birth canal.

• Some history 

  1. The first vacuum extractor was developed by James Young Simpson in 1849.

  2. Didn’t really catch on until a Swedish doc named Tage Malmstromo developed the “ventouse” or Malmstrom extractor in the 1950s.

View fullsize

A Kiwi vacuum extractor

Indications and Prerequisites for Operative Vaginal Birth

1. Indications 

   1. Prolonged second stage of labor.

   2. Suspicion of immediate or potential fetal compromise.

   3. Shortening of second stage of labor for maternal benefit (ie. maternal exhaustion or maternal cardiac issues that may make it difficult for them to Valsalva for an extended amount of time).

2. Prerequisites (“checks” before attempt).

   1. Cervix is fully dilated and membranes are ruptured.

   2. Engagement of the fetal head.

   3. Position of fetal head is known (either by exam or by ultrasound).

   4. EFW has been performed and assessment that the pelvis is adequate for vaginal birth (don’t want to pull into a shoulder!).

   5. Adequate anesthesia.

   6. Maternal bladder has been emptied.

   7. Patient has agreed after being informed of risks and benefits of procedure.

   8. Willingness to abandon the attempt, with back-up place (ie. cesarean) in case of failure to deliver.

   9. We do not recommend doing a prophylactic episiotomy anymore, but if you have to, reasonable to give prophylactic antibiotics, per the ANODE trial, and also give if there is a 3rd or 4th degree laceration.

3. When should you NOT perform an operative vaginal birth: 

   1. If fetal head is unengaged or fetal head position is unknown.

   2. If fetus is suspected to have osteogensis imperfecta or other both demineralization condition.

   3. If fetus is thought to have bleeding disorder (ie. thrombophilia or von Willebrand disease).

4. Categorization of forceps deliveries (we don’t do high forceps anymore… YIKES!) 

   1. Midforceps 

      1. Station is above +2 cm, but head is engaged.

   2. Low forceps 

      1. Leading point of the fetal skull is at station +2 cm or more and not on the pelvic floor.

      2. Without rotation: rotation is 45 degrees or less (ROA, ROP, LOA, LOP).

      3. With rotation: Rotation is > 45 degrees, requires rotation with rotational forceps or Scanzoni maneuver.

   3. Outlet forceps

      1. Fetal scalp is visible at the introitus without separating the labia.

      2. Fetal skull has reached the pelvic floor.

      3. Fetal head is at or on perineum.

      4. Sagittal suture is in an AP diameter or ROA, ROP, LOA, LOP.

      5. Rotation does not exceed 45 degrees.

Counseling a Patient on Operative Vaginal Birth

• Benefits 

  1. Avoidance of cesarean delivery for the indications above.

  2. Operative vaginal delivery is undeniably faster to achieve delivery, and when indicated, helps to avoid major surgery and its recovery and potential complications.

• Maternal Complications 

  1. Higher risk of anal sphincter injury (10-20%), though it may be difficult to separate this out from other risks that are associated with operative vaginal birth like prolonged second stage, fetal size, episiotomy, etc. 

     1. One study that controlled for all these other clinical factors: forceps still associated with 6x increase in 3rd and 4th degree tears, and vacuum associated 2x increase.

     2. However, other studies do not clearly show that there is a significant difference in fecal or flatal incontinence through 1 year postpartum.

• Fetal/Newborn Complications 

  1. Very low in general! Intracranial hemorrhage occurs 1/650-850 operative vaginal births and neurologic complication 1/220-385.

  2. Vacuum: usually due to traction on fetal scalp, ie. laceration, cephalohematoma, subgaleal or ICH.

  3. Forceps: facial lacerations, facial nerve palsy, corneal abrasion, and external ocular trauma, skull fracture, ICH.

     1. Rates of ICH are similar for forceps, vacuum, and cesarean deliveries performed during labor.

  4. Compared to those delivered by cesarean, those delivered by:

     1. Forceps: higher rates of fracture, facial nerve palsy, and brachial plexus injury, but lower rates of neurologic complications (ie. seizures, IVH, subdural hemorrhage),

     2. Vacuum: higher rates of cephalohematoma, fracture, and brachial plexus injury, but not central neurologic complications.

  5. Few data assess long-term consequences of operative vaginal birth on the infant, but of the studies we have, there does not appear to be significant differences in cognitive development from those born from forceps or vacuum compared to spontaneous vaginal birth.

When should you abandon operative vaginal birth? 

1. Traditionally, it’s 3 pop-offs for the vacuum extractor, but this may depend on the type of vacuum and institutional policy.

2. With deterioration of the fetal heart tracing without progress, or just no progress in general.

3. Maternal request.

A Pros and Cons Comparison of Methods of Operative Vaginal Birth

View fullsize