The Twin Birth Study

Here’s the RoshReview Question of the Week:

Which of the following needs to be met to undergo vaginal delivery with a monochorionic-diamniotic twin pregnancy with vertex twin A?

• Estimated fetal weight of twin B < 1,500 g

• Growth discordance < 20%

• Minimum 24 weeks gestation

• Vertex-vertex presentation

Check your answer and get a special RoshReview deal for listeners at the links above!

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Actual title: A Randomized Trial of Planned Cesarean or Vaginal Delivery for Twin Pregnancy

https://www.nejm.org/doi/full/10.1056/nejmoa1214939 

Background:

• Where was the study published?

  • NEJM, October 3, 2013

• Why was the study done?

  • Tthrough the 1990s and 2000s there was a significant rise in twin births in the USA, likely attributed to advancing maternal age (when twinning is more common spontaneously) and the use of reproductive technology – ovulation induction and IVF.

  • In the wake of the Term Breech trial, as well as some observational studies looking at twins specifically, there was concern that breech birth risks could be extended to twins – and practice was changing!

    • In 1995, 53.9% of twin births were by CS. By 2008, this number was 75%. 

  • Not all observational studies were in agreement about the risk of “breech extraction” of a second twin, specifically – so a new study was planned and performed.

• Who performed the study?

  • The “Twin Birth Study Collaborative Group” – a large multinational collaborative, but with the main site at the University of Toronto and funded by the Canadian Institutes of Health Research – the same funders that brought you the Term Breech Trial!

    • You’ll note a lot of similarities (but also some important differences!) between this study and the Term Breech Trial. We definitely recommend a compare-contrast session!

• What was the research objective?

  • To compare the risk of fetal/neonatal death or serious morbidity between planned cesarean or planned vaginal delivery for twin pregnancies between 32w0d and 38w6d, if the presenting twin was in cephalic presentation. 

Methods:

• Who participated and when?

  • Recruitment between December 13, 2003 and April 4, 2011 at 106 centers in 25 countries.

  • Enrolled 1392 patients in the planned cesarean group and 1392 patients in the planned vaginal delivery group.

• Eligibility:

  • Needed to have:

    • Twin pregnancy between 32w and 38w6d

    • First twin in cephalic presentation

    • Both fetuses alive with EFW between 1500g and 4000g, confirmed by ultrasound within 7 days before randomization

  • Exclusions:

    • Monoamniotic twins

    • Lethal fetal anomalies

    • Other contraindication to labor or vaginal delivery (including 2nd twin being “substantially larger” than the first)

    • Prior cesarean with vertical incision or more than one LTCS

• Management:

  • Delivery by cesarean or by labor induction was planned between 37w5d and 38w6d

  • If in the CD group, if the first twin delivered vaginally, then a c-section was attempted for the second twin if logistically possible.

  • In the VD group:

    • Continuous EFM was “recommended” during active labor

    • Use of oxytocin and epidural analgesia were left to OB provider discretion

    • After delivery of first twin, use of US was “encouraged” to check second twin presentation

      • If cephalic, amniotomy was delayed until head was engaged and SVD anticipated, unless for other OB indication

      • If non-cephalic, OB decided on best delivery option – spontaneous or assisted breech delivery, total breech extraction +/- internal podalic version, ECV and vaginal cephalic delivery, or intrapartum CD

    • Deliveries were attended by qualified OB experienced in twin delivery, defined as a OB who judged themselves to be experienced at twin delivery and whose department head agreed with this judgment (similarly to Term Breech Trial).

• Outcomes:

  • Primary: fetal/neonatal mortality or serious neonatal morbidity, assessed up to 28 days after birth.

    • Morbidities included many of the same things in the Term Breech Trial, and were serious neonatal morbidities (for the sake of brevity, we won’t list them out).

  • Secondary: maternal death or serious maternal morbidity, assessed up to 28 days after delivery.

    • Again, this was very similar to the Term Breech Trial. 

  • A number of subgroup analyses were planned for the primary outcome, including by nulliparity; gestational age at randomization; maternal age; presentation of the second twin; chorionicity; and the perinatal mortality rate in the mother’s country of residence. 

Results

• Who was recruited?

  • Outcome data was available for 1392 women (2783 fetuses/infants) in the cesarean group and 1392 women (2782 fetuses/infants) in the vaginal delivery group. 

  • Baseline characteristics were overall similar, and most patients (82.4%) underwent randomization between 32w0d and 36w6d. 

    • More than half of the infants in each group were born at 37w0d or later. 

      • Around 5-6% in each group were between 32w and 33w6d, and another 42% between 34w0d to 36w6d. 

    • The time from randomization to delivery was similar but slightly different between groups (12.4 vs 13.3 days).

• In the planned CD group: 

  • 90% had CD

  • 1% had a combined vaginal-cesarean delivery, and 

  • 9% had both twins vaginally.

    • Almost 60% of the CDs were performed before the onset of labor.

• In the planned VD group:

  • 56% delivered both twins vaginally, 

  • 4% had a combined vaginal-cesarean delivery, and 

  • 40% had a cesarean for both twins.

    • Of those in the VD group who had a CD, 67.5% of them were performed during labor (or another way to look at it, 32.5% had a CD prior to labor in the planned VD group).

  • 95% had an experienced OB present, according to the study definition

• Primary Outcome:

  • The frequency of composite primary outcome did not differ between planned CD (60, or 2.2%) and planned VD (52, or 1.9%) groups.

    • The only variable that appeared to modify the risk of the primary outcome was earlier gestational age at randomization. 

    • The number of deaths in each group was 24 (0.9%) in CD group and 17 (0.6%) in VD group. 

      • 11 of these deaths in the CD group and 8 in the VD group were before labor onset.

  • In subgroup analyses, there was no significant interaction with the primary outcome with respect to parity, gestational age at randomization, presentation of the second twin, chorionicity, or national perinatal mortality rate. 

  • The second twin was more likely than the first to have the primary outcome, but this was not different between the groups. 

• Secondary outcome:

  • There were no differences in primary maternal composite outcome rates (7.3% CD, 8.5% VD). 

Impact

• What is the impact of all of this, and what are we doing now?

  • This paper certainly helped to encourage the training and planning of vaginal delivery of the second twin, including by breech delivery by stating that no increased risk was seen with a policy of planned vaginal delivery. 

    • In ACOG PB 231 on multifetal gestation, it notes that vaginal delivery of a non-cephalic second twin is reasonable, provided an OB with experience is present.

    • That’s key – it’s apparent in this paper that, compared with the Term Breech Trial, there was more emphasis on patient counseling / selection (i.e., 13 day median from randomization to delivery, protocolized assessment of EFW by US within 7 days, 95% presence of “experienced OB”). 

      • And this is heavily noted in the conclusions of the paper – stating “only centers that can provide OB management as specified by the protocol, including ability to perform a CD within 30 minutes if necessary” should undertake this.

• Methodologically, this group responded to many criticisms of the Term Breech Trial:

  • An improved randomization scheme that was block-based, stratified by gestational age and parity.

  • Improved use of ultrasound and CTG in labor, as well as higher standard of care at all sites to prevent misappropriation of primary outcome.

  • More explicit counseling – happening weeks before delivery on average, rather than in labor!

• And finally - and most importantly - this represents a well-selected, high-resource, best-case scenario work.

  • For our US listeners who mostly practice in centers where there is ability to perform cesarean within 30 minutes, the Twin Birth Study included:

    • Twins delivering between 32w0d and 38w6d

    • With EFW estimated by US within 7 days of delivery, ranging from 1500g - 4000g

      • Second twin not significantly larger (with expert opinion putting this around a max of 15% discordance)

    • Ability to perform CD within 30 minutes, and use CTG and intrapartum US

    • With someone with experience and ability to perform breech extraction and internal podalic version available 

The Term Breech Trial

Actual title: Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomized multicenter trial

Background:

• Who did the study, and who published it?

  • Another large collaborative group study – the Term Breech Trial Collaborative Group

    • Primary authors of the group based in Canada

    • Participating sites spanned Europe, Canada, Australia, Central/South America, Africa, Middle-East, India & Pakistan

    • Funded by Canadian Institutes of Health Research (like Canada’s NIH)

• Why was the study done?

  • As we covered in our ECV and breech birth podcasts, breech presentation affects about 3-4% of term pregnancies.

  • At the time this was conducted (published in 2000), it was a controversial question for delivery approach:

    • Cohort studies prior to this trial suggested that cesarean section was potentially better.

      • However, these cohort studies were potentially confounded by inclusion of pregnancies that would not be considered for breech birth (i.e., footling presentation) or by lack of experience with breech deliveries by the participating physicians. 

    • Two smaller RCTs prior to this trial and a meta-analysis did not find any substantial benefit to planned cesarean.

  • Thus this ambitious trial was carried out to determine which was truly better.

• What was the research question?

  • “To determine whether planned cesarean section was better than planned vaginal birth for selected fetuses in the breech presentation at term.” 

Methods:

• Who participated and when?

  • Enrollment between Jan 1997 and April 2000 at 121 centers in 26 countries.

  • Eligibility:

    • Breech presentation at or after 37 weeks → assigned to planned cesarean or planned vaginal delivery after consent by telephone system.

    • If assigned to CD group: planned CD was scheduled for 38+ weeks.

      • If patient presented in labor, CD was performed as soon as possible.

      • Presentation was confirmed again prior to cesarean and if cephalic, vaginal birth was then planned.

    • If assigned to VD group: management was expectant until spontaneous labor began, unless an indication to induce labor or a different reason for cesarean developed.

      • Labor management protocol was standardized (a LOT of standards):

        • Induction and amniotomy were allowed for standard OB indications

        • FHR monitoring by intermittent auscultation or cEFM

        • Augmentation with oxytocin was permitted, “so long as the clinician was confident that there was no evidence of cephalopelvic disproportion.”

        • Adequate labor progress in 1st stage was 0.5cm/h after onset of active labor, and in 2nd stage was descent of breech to pelvic floor within 2hr of full dilation, and delivery being imminent within 1hr of active pushing.

          • If fetal heart rate abnormalities were encountered or lack of progress in labor occurred, CD was performed.

        • Anesthesia choice was left to patient and providers.

        • Delivery means was recommended to have no intervention until spontaneous exit of the infant to the umbilicus, and minimum intervention thereafter with no traction on the body; and controlled delivery of the head using forceps or Mariceau-Smellie-Veit maneuver. 

          • Total breech extraction was not permitted.

      • Deliveries were to be attended by an “experienced clinician” – defined as someone who considered themselves to be skilled and experienced at vaginal breech delivery and confirmed by their department head at their institution. 

        • Each clinician was assigned a code number prior to study enrollment and there was info recorded on their qualifications and years of experience with breech delivery. 

• What were they looking for?

  • Primary outcome: perinatal or neonatal mortality at less than 28 days of age, or one or more serious neonatal morbidities such as:

    • Birth trauma, such as subdural hematoma, IVH, spinal cord injury, basal skull fracture, peripheral nerve injury, or clinically significant genital injury; 

    • Seizures at less than 24h of age or requiring 2+ drugs to control; 

    • Apgar of less than 4 at 5 mins

    • Cord base deficit of 15 or greater

    • Hypotonia for at least 2 hours

    • Stupor, decreased response to pain, or coma

    • Intubation and ventilation for at least 24h

    • Tube feeding for four days or more

    • NICU admission longer than 4 days

  • Secondary outcome: maternal mortality or serious maternal morbidity for up to six weeks postpartum, such as:

    • PPH > 1500 cc or need for transfusion

    • D&C for bleeding or retained tissue

    • Hysterectomy

    • Cervical laceration involving lower uterine segment (if SVD)

    • Vertical incision or serious hysterotomy extension (if CD)

    • Vulvar or perineal hematoma requiring evacuation

    • DVT / PE

    • Pneumonia, ARDS

    • Wound infection requiring prolonged hospital stay, wound breakdown

    • Bladder / ureter / bowel injury requiring repair, or development of fistula

    • Bowel obstruction

    • Other serious morbidities

  • They also used multiple logistic-regression analyses to test for interactions between demographic / baseline characteristics and outcomes:

    • I.e., looking at the perinatal outcomes for babies, looked at interaction with maternal age, parity, type of breech presentation, gestational age, labor vs induction, EFW by US vs Leopold’s, etc. 

  • They also looked at center’s standard of care in “usual care” vs “high standard of care” environments (as determined by a pre-study survey) and maternal/perinatal mortality rate in the center’s country

    • High standard of care was defined as:

      • Having ability to perform a cesarean within 10 mins (vs 60 mins)

      • Personnel to bag-mask a baby available immediately (vs 10 mins)

      • Personnel to intubate / provide PPV to baby within 10 mins (vs 30 mins)

      • Ability to ventilate a baby for >24h (vs need for transfer for this)

Results:

• Who was recruited?

  • 2088 pregnant patients were randomized, with 1043 assigned to CD and 1045 assigned to VD

    • Maternal outcomes were available for 1041 (CD) and 1042 (VD) groups

    • Neonatal outcomes were available for 1039 (CD) and 1039 (VD) groups

      • Overall very low loss to follow up!

  • Groups were overall very similar:

    • 52% in each group were nulliparous

    • EFW > 3kg in ~66% in each group (with 60% in each group estimated by ultrasound)

      • 21.9% in each group underwent attempted ECV

    • 35% of deliveries in each arm took place in “high standard of care” centers.

    • ~42% in each group presented in labor, and ~23% in each group had membranes ruptured on presentation.

    • Median GA at delivery was similar in each group (39w3d CD vs 39w6d VD)

  • In the planned CD group:

    • 90% had a CD, and 10% had a VD

  • In the planned VD group:

    • 43.3% had a CD, and 56.7% had a VD

      • CDs most commonly performed for:

        • Fetopelvic disproportion or abnormal progress in labor (50.1%)

        • Fetal heart rate abnormality (28.6%)

        • Footling breech presentation (15.3%)

        • Patient request (13.5%)

        • Medical or OB complication (10%)

        • Cord prolapse (2.7%)

    • ~15% of labor was induced, and ~50% of labor was augmented.

      • Only 9% had a protocol violation of labor management:

        • 3.6% for prolonged labor

        • 1.4% for footling or uncertain presentation of breech at delivery

        • 2.7% had no experienced clinician at delivery 

• Outcomes:

  • Primary

    • There was a significantly lower risk of perinatal/neonatal morbidity in the planned cesarean group:

      • 17/1039 (1.6%) CD vs 52/1039 (5.0%) VD (RR 0.33)

        • This held true in both countries with low perinatal mortality rates and high perinatal mortality rates.

        • This difference lessened (but remained statistically significant) with increasing experience of the attending provider – that is, there was less risk of morbidity when more experienced personnel were present.

        • This difference also lessened (but remained statistically significant) when excluding induced/augmented labor, deliveries without a skilled clinician, and those with footling/uncertain breech presentation 

          • Bottom line: there is higher perinatal morbidity with planned VD, despite increasingly optimal environments in subanalyses

    • There were 3 neonatal deaths in the cesarean group, and 13 in the vaginal delivery group.

      • One of the CD group deaths was actually a vaginal birth with difficult delivery.

      • Two of the vaginal birth deaths were likely prior to enrollment; two were of neonates discharged from the hospital in good condition otherwise; and two were suspected intrapartum demises before a cesarean section could be started.

    • The reduction in perinatal morbidity was much greater in countries with lower perinatal mortality rates, despite a higher likelihood of cesarean birth in the VD groups in those countries

      • I.e., in an area with low perinatal mortality and a higher likelihood to get cut intrapartum, the benefit of planned CD was even greater

    • There was more birth trauma, seizures, hypotonia, low Apgars, cord blood acidemia, need for mechanical ventilation, and longer NICU stays in the planned vaignal delivery group. 

    • Birth weight over 4000g was more likely in the VD group (5.8% vs 3.1%). 

  • Secondary

    • No major group differences in maternal morbidity/mortality. 

Impact

What was the impact of all of this, and what are we doing now?

• Well you kind of know already – how many planned breech births have you done?

  • For most of us, that answer is probably 0 “planned” and maybe 1 or 2 “unplanned.”

• This was absolutely a practice-changing paper – and has guided how we approach the patient with breech presentation at term ever since.

• What criticisms exist of this trial?

  • High number of patients were randomized in labor, and questionable counseling:

    • ~42% in each arm – this begs the question about how “planned” each method actually was, and how much counseling or selectivity may have been realistically applied to each patient.

    • Can also see this in the higher rate of >4kg babies in the VD arm, as well as only 20% in each arm had an attempt at ECV. 

  • Standard of care was not consistent

    • Continuous EFM (for better or worse) was not standard

    • Fetal weight and attitude of the head, while recorded for trial data, did not have to be assessed by US

    • Generalizability is hard to interpret with the pooled results:

      • I.e., would you take your chances on a breech in Australia with a well-counseled patient with CTG in a place where you can do a C-section in under 10 minutes and have highly qualified neonatal staff immediately available? Or in another location where you can’t do a c-section even by 60 minutes? 

        • The subgroup analyses by perinatal mortality rate of countries tried to answer that, but it is curious they didn’t choose to divide it up by their “high standard” versus “usual standard” centers.

      • Subsequent analysis has shown that 30% of the morbidity/mortality in the VD group can be attributed to the 6.7% of vaginal deliveries attended by no experienced provider – also calling into question the impact of experience. 

  • Enrollment scheme:

    • Units would call to centralized location to get allocation and this was not stratified by center – theoretically, a highly experienced obstetrician could call and end up with randomization to cesarean each time, and likewise an inexperienced one could call and randomize to vaginal delivery each time.

  • Numerous protocol violations and enrollment questions

    • Included initially in the trial were: 2 demised infants, 2 sets of twins, an anencephalic baby, a baby with spina bidfida, and another baby with suspected anomalies. 

    • 2 of the vaginal delivery group deaths were suspected to have been prior to randomization, yet counted in the perinatal mortality. 

      • And a number of other deaths in the VD arm may not have been related to the delivery itself – i.e., SIDS, GI issues, anomalies, inadequate respiratory resuscitation or resources.

What about doing breech births? Can we? / should we?

• We don’t recommend breech birth – that would be irresponsible to do outright!

• Well counseled, well-selected patients in centers with experience in breech delivery, ability to perform cesarean, and provide immediate neonatal resuscitation – it may be reasonable, though this trial doesn’t totally answer that question based on problems with generalizability.

  • In the wake of this trial, the PREMODA study was performed in France and Belgium – a prospective observational study allowing providers to select mode of delivery where breech delivery was still an option/standard.

    • ⅔ of women were allocated to cesarean delivery, but 71% of those undergoing planned vaginal breech birth were successful. 

    • There was no difference in perinatal mortality/morbidity was noted between groups in this study – suggesting that rigorous protocols and assessment by those with experience may make breech birth safer.

Interesting critique of trial: https://www.ogmagazine.org.au/14/2-14/term-breech-trial/ 

External Cephalic Version (ECV)

Background / Intro

• Breech presentation occurs in about 3-4% of term pregnancies, with a significant number of these patients delivery ultimately by cesarean. 

• Previously on the podcast, we covered considerations for singleton breech vaginal delivery. While that was a fun one to talk through, as we mentioned then, breech delivery is NOT the standard of care. So how do we avoid cesarean?

• External cephalic version is the answer! Essentially, using pressure on the pregnant person’s abdomen to achieve movement of the fetus to cephalic presentation. 

• In order to offer this service, ACOG recommends an evaluation of presentation beginning at 36’0 weeks. Check out PB 221 for more reading.

Considerations prior to ECV

• Patients who are good candidates for ECV are:

  • At least 37’0 and EFW > 2500g. 

    • Spontaneous version after this GA is less likely.

    • Risk of reversion to breech is significantly lower after this GA or lower than this EFW.

    • If complications arise, the infant is term and can be delivered emergently with less concern regarding sequelae of prematurity. 

  • Of higher parity

    • Multiple studies have reported positive associations between multiparity and success of ECV. 

  • In transverse or oblique presentations

    • While breech is not a contraindication by any means, traveling a little less far makes it easier!

  • With less cervical dilation, and of higher station

    • Babies lower in the pelvis are tough to turn!

• Things you might think make a difference, but actually are less important:

  • Placental location

    • Studies are mixed in this regard; some authors have found improved success with posterior placentation, while others have found no association. 

  • Amniotic fluid volume

    • This was one I always heard about in residency!

    • While it makes intrinsic sense that higher levels of fluid would lower success rates, studies have not actually demonstrated this conclusively. 

  • Maternal obesity

    • Another controversial topic where studies have been mixed in terms of predictors of success. 

  • Obesity

    • Some authors 

  • TOLAC candidates

    • The most recent interaction of the ECV bulletin addressed this question, noting there’s limited evidence for women with a preexisting uterine scar on ECV. However, in four trials, no cases of uterine rupture from ECV were reported, so it’s reasonable to offer. 

  • Ongoing labor

    • There is also limited evidence that ECV can be successful during early labor, lowering cesarean delivery rates and reducing hospital length of stay. 

Counseling for a procedure - risks and benefits

• Benefits

  • Certainly one benefit is the option of avoiding cesarean delivery! There is a significant reduction in cesarean birth rate for women who have successful ECV in randomized studies. 

    • Interestingly, the risk is still higher for cesarean in the ECV population compared to those who present with a fetus in cephalic presentation.

  • This also comes with the benefits of greater likelihood of vaginal delivery - most notably, fewer hospital days and lower odds of endometritis and sepsis. 

  • The success rate of ECV in trials is about 60% -- so a little better than 50/50. 

• Risks

  • Discomfort certainly is the biggest consideration -- we’re going to mash on your abdomen now! Pain medications parenterally or the use of epidurals can help reduce this element. There even is evidence that epidural anesthesia may increase success rates.

    • This should particularly be considered for women who have an unsuccessful ECV at 37 weeks, but wish to retry at 39 weeks. A placement of an epidural, followed by ECV attempt, which if unsuccessful provides anesthesia for cesarean delivery. 

  • Fetal heart rate abnormalities - fortunately, these are often transient decelerations that resolve with a pause or cessation in the procedure. 

  • Additional serious risks - placental abruption, umbilical cord prolapse, membrane rupture, stillbirth, and fetal-maternal hemorrhage have all been reported after ECV; however, all occur at rates of less than 1%. 

  • Need for emergent delivery - because of the rare risks above, women should be counseled that there is the very rare possibility of emergent delivery when ECV is attempted. ECV should only be performed in places where cesarean is readily available. 

After consenting your patient, prepare yourself for a procedure!

• Step 1: get an NST!

  • Certainly a non-reactive or suspicious NST pre-procedure would be a reason to re-consider doing something that might cause the fetus to react poorly. 

• Step 2: consider a cervical exam

  • If your patient has advanced cervical dilation, and you end up in the sticky situation of causing membrane rupture, it’s good to know if that 3cm cervix might drop a cord! 

  • Additionally, if you’re doing an ECV at 39+ weeks, this will let you consider what to use for induction subsequently. 

• Step 3: ultrasound

  • Do a quick survey. Take a look at a number of things, including:

    • True presentation: frank vs complete breech, transverse, oblique. 

      • What are frank and complete breech?

        • Frank we remember this as “Frank smells his feet.” This is the “pike” presentation where the fetus is maximally extended legs and flexed at the hips.

        • Complete this is the classic cross-legged sitting position.

    • Fluid volume

    • Placental location

• Step 4: orders!

  • Medications for ECV:

    • Pain medications -- as we mentioned above, can be considered in the form of parenteral meds or epidural anesthesia. If IV meds are given, be aware of the consequences on fetal heart rate of the med you’re giving. 

    • Tocolytics -- classically terbutaline, the B2-agonist. With relaxing the uterus, a randomized trial found that terbutaline doubled the chances of a successful ECV. 

      • There’s not much data regarding other uterine relaxants, but be aware that the beta-agonist effect of terbutaline often causes tachycardia -- so avoid in patients where that is contraindicated!

    • RhoGam -- we’re essentially inflicting trauma on the uterus. Check a type-and-screen beforehand. If delivery won’t be performed in the next 72 hours, a dose should be given.

      • Re-review our episode on preventing alloimmunization too! 

• Step 5: procedure time!

  • The procedure can be accomplished with one or two people.

  • Use LOTS of gel on the maternal abdomen to prevent trauma to the skin and facilitate easy ultrasound access for fetal heart rate checks. 

  • Classically, the procedure involves lifting the breech out of the pelvis with one hand, and then using pressure on the fetal head to facilitate a forward or backward roll. 

    • The procedure is successful when cephalic presentation is accomplished.

    • The procedure should be abandoned if there is prolonged bradycardia, extreme maternal discomfort, or if a few attempts have been unsuccessful. There’s no “right or wrong” number but having attempted many of these, you get a sense of whether they’ll roll or not. 

    • A great video of technique can be seen at https://www.youtube.com/watch?v=aWTmxPV15DI

  • Usually, institutions will have a monitoring protocol post-ECV attempt -- ACOG recommends at least 30 minutes of continuous monitoring, regardless of success.
    

Malposition and Malpresentation

We start off today with some news — for the foreseeable future, CREOGs Over Coffee will move to every-other-week Sunday episodes. It’s been a wild ride and now that we’ve moved across the country from each other, we want to make sure we deliver the same high-quality content we expect and want you to have! While you may hear less of us for now, we’re also working on some other projects, so stay tuned!

On to the episode! And for further reading, check out this review.

Malposition vs. Malpresentation

Fetal lie: the relationship between the fetal long axis and the mother (i.e., longitudinal, transverse, oblique).

Malpresentation: the fetal vertex is not the presenting part, or the part of the fetus closest to the pelvic inlet.

• Breech: 3-4/100 term pregnancies

• Face: 1/600-800 term deliveries

• Brow: 1/500-4000 term deliveries

• Compound: 1/1500 deliveries

• Shoulder: 1/200 deliveries

Malposition: the fetus is in vertex position, but the position of the fetal head is not optimal for delivery (i.e., rotated away from an occiput anterior, or OA, position in the pelvis).

• Occiput transverse (OT) or occiput posterior (OP).

  • These are given a direction based on rotation of the occiput 45 degrees from the direct position (i.e., right occiput posterior denotes rotation of the occiput to maternal right).

    • If occiput < 45 degrees from vertical, is OA or OP.

    • If occiput is > 45 degrees from vertical, is OT.

• Prior to labor, 15-20% of term fetuses in cephalic presentation are in OP position. At delivery, only 5% will persist this way, as they will often rotate spontaneously.

Action to take with various malpositions and malpresentations:

First, a word on “normal” vaginal deliveries 

• In OA position, the neck flexes to bring the chin to the chest → smaller diameter of the fetal head (about 9.5 cm), which is usually able to traverse the obstetric conjugate (average 10.5cm), which is the shortest anteroposterior pelvic diameter.

  • In other positions (ie. face or brow), the neck is extended and there is larger fetal cephalic head diameter that needs to traverse this area, making it more difficult to pass.

Breech, Transverse Lie, & Shoulder Presenations

• We have previously discussed breech vaginal delivery, but current recommendation for breech and shoulder presentation is cesarean section.

• Shoulder presentations cannot deliver vaginally. The shoulder is wedged into the pelvis, and the head will lie in one of the iliac fossa, and the breech in the other - the baby becomes wedged into the pelvic inlet and cannot get past.

• For shoulder, describe using location of the scapula: 

  • Left scapula anterior (LSA), and RSA. 

  • Left scapula posterior (LSP), and RSP. 

• With transverse lies, just like breech, can offer ECV prior to labor, but once labor occurs, usually versions become very difficult to do.

Face Presentation

• The fetal face from forehead to chin is the leading fetal body part descending into the birth canal. This is usually diagnosed by vaginal exam (can palpate the orbital ridge, nose, mouth, chin), not able to palpate the fontanelles.

• Described using location of the chin, or mentum.

  • At diagnosis, about 60% are mentum anterior and 26% are mentum posterior (ie. chin up or chin down); 15% are mentum transverse.

• Management varies depending on presentation:

  • Mentum anterior The fetal chin needs to pass under the symphysis pubis, and fetal neck may need to extend even more (though it is already extended).

    • After the chin clears the symphysis, it is possible for vaginal delivery, and women should be allowed to push during second stage.

    • Forceps can be used, but engagement doesn’t occur until the face is at +2 station, and the chin, rather than the occiput becomes the focal point for orientation.

    • Vacuums are contraindicated… because where would you put it?!?!

  • Mentum posterior In this case, the fetal neck is maximally extended and cannot extend further to allow the occiput to pass under the symphysis.

    • Will NOT deliver vaginally unless there is spontaneous rotation to mentum anterior. 

    • If discovered early in labor, can have expectant management in the hopes that the mentum will spontaneously rotate to anterior.

    • However, recommendation is for cesarean if persistent mentum posterior with abnormal labor progress.

    • What about attempting rotation? 

      • Not a lot of cases, and there have been case reports of successful internal and external manipulation.

      • Some case reports of uterine rupture, cord prolapse, and cervical spine trauma.

      • Overall: if cesarean is available, would favor cesarean.

Brow presentation

• A variant of face presentation, when presenting part is the anterior fontanelle to the brow (orbital ridge), which does not include the mouth and chin.

• Diagnosis is usually made with vaginal exam (you can feel the forehead, orbits, and nose).

• Management:

  • Can undergo trial of labor, as brow presentation may be transitional 

    • In one study, when brow presentation was diagnosed early, 67-75% of fetuses spontaneously converted to a more favorable presentation and delivered vaginally.

    • If diagnosed later:

      • 50% spontaneously converted and delivered;

      • 30% the neck extended further;

      • 20% the neck flexed and resulted in occiput posterior presentation. 

  • Rotational maneuvers, vacuum, and forceps are not recommended. 

Persistent occiput posterior 

• Most common malposition, encountered very frequently in clinical practice, and will often convert spontaneously.

• Manage expectantly in first stage of labor. In second stage of labor can also be expectant as long as fetal heart rate is reassuring and labor is progressing 

  • 50-80% of OP fetuses at beginning of second stage will rotate spontaneously to OA. 

  • If clinically adequate pelvis with a prolonged second stage - can attempt manual rotation to the OA position.

  • Prospective study - manual rotation vs. Expectant management of OP demonstrated higher likelihood of vaginal delivery and fewer cases of persistent OP presentation.

• Manual rotation techniques 

  • Digital - placing tips of index and middle fingers in the anterior segment of the lamboid suture near the posterior fontanelle, and then used to flex and slightly dislodge the head, and rotation to OA position with the operator’s hand and forearm.

  • Hand - placing operator’s four fingers behind the posterior parietal bone with palm up and thumb over the anterior parietal bone. Right hand for LOP, left hand for ROP.

    • Flex and slightly dislodge the head → rotate.

Considerations for Planned Singleton Breech Vaginal Delivery

Today’s episode dives more into the realm of expert opinion rather than hard science, and we hope some of our listeners will share their own experiences and criteria for offering planned breech labor!

ACOG CO 745, in addition to PB 161 on external cephalic version, deal with this topic, but there is much variation in the literature available. In particular, international guidelines on this topic are rather variable. The ObG Project has a great summary and links to these varying resources that is worth checking out.

There are particular risks to breech labor, and experienced provider hands are necessary, which is why almost 90% of planned term breech birth in the USA is performed by cesarean section. The 2000 Term Breech Trial, a multicenter randomized trial, noted perinatal morbidity and mortality was overall reduced with planned cesarean delivery than with planned vaginal delivery of term breech (1.6% vs 5.0%), with no differences in reported maternal morbidity or mortality. Follow up studies to the Term Breech Trial, however, have noted no differences in maternal or neonatal outcomes at 2 years.

Additional studies performed since this time have been mixed. While some prospective studies demonstrated excellent maternal and neonatal outcomes, both short- and long-term, they utilized very strict criteria and protocols for the selection of candidates offered a trial of breech labor. Cohort studies of breech birth in general populations demonstrates at least short-term risk of neonatal morbidity, including birth injury, nerve injury, and need for assisted ventilation. This risk is present with any trial of breech labor, including if intrapartum cesarean is performed, versus planned cesarean delivery.

Below is a sample protocol based on some of these studies with stricter inclusion criteria. We recognize there is likely some significant debate to be had on these criteria, and in particular clinical scenarios, so be sure to discuss with experienced obstetricians in your area as well as check your hospital’s own breech birth protocol.

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(c) CREOGs over Coffee, 2019. Adapted from Hofmeyr/UpToDate, 2019.

Finally, intrapartum management should proceed according to usual obstetric practice. However with breech presentations, providers should closely consider a number of factors outlined below. Notably, these factors are largely based on expert opinion and guidelines from international societies.

• Avoidance of early amniotomy, and preference for spontaneous rupture of membranes.

• The progress of labor in the active phase, and progress of descent during active pushing. 

  • Cesarean delivery should be recommended with a protracted labor course, particularly in the active phase, as this may be indicative of fetopelvic disproportion. 

  • Use of oxytocin in the active phase of labor is discouraged.

  • With the achievement of full cervical dilation, the breech should reach the pelvic floor.

  • Passive descent should not be permitted for more than 90 minutes after achieving full cervical dilation.

  • With onset of active pushing, delivery by cesarean should be considered if the infant has not delivered within 30-60 minutes.