PBLD9: Anesthetic Management of External Cephalic Version

Breech presentation occurs in 3-4% of term pregnancies. (1) Breech presentation has a higher incidence at lower gestational ages. It occurs in approximately 35% of 28 week gestational pregnancies and declines to 20% at 32-34 weeks, and 2-3% by 36 weeks due to natural progression to vertex. (5) Breech presentation is responsible for 6-8% of all (emergency and elective) cesarean deliveries and 98% of all breeches are delivered by cesarean delivery (CD). (2) Following a cesarean delivery for breech presentation, 91% of women will deliver via cesarean for subsequent pregnancies. Pregnancy after a CD is more likely to result in such complications as placenta previa, placenta accreta and hemorrhage. (2) Having a CD for a current and subsequent delivery increases the incidence of death, hemorrhage, infection, and embolism. (4) External cephalic version (ECV) is a means to decrease breech presentation, and hence cesarean delivery, by manually applying pressure to the woman’s abdomen to turn the fetus in either a forward or backward roll to achieve a vertex position.

The patient is flustered and confused about having an ECV. She has her dates mixed up and asks you when she is going to have it done and possible contraindications.

The timing of ECV is crucial. Spontaneous transition to vertex presentation typically occurs by week 37. While successful version is more likely earlier than 37 weeks, reversion to breech following a successful version is also more likely prior to week 37. Neonatal age is also relevant to fetal outcome should the EVC result in the need for delivery. The aim is to avoid poor outcomes associated with preterm delivery. (1)

ECV has an overall complication risk of 6.1% (5) Factors that preclude attempting ECV include: placental anomalies that are indications for CD {placenta accreta, placenta previa}, fetal or obstetric conditions requiring CD, severe oligohydramnios or ruptured membranes, nonreassuring fetal heart tones, significant fetal or uterine anomaly (including septate uterus), hyperextended fetal head, placental abruption, multiple gestations, and untreated fetal anemia or hydrops. Relative contraindications include maternal hypertension/preeclampsia, decreased amniotic fluid level, and IUGR. (5)

After much discussion with her obstetrician previously and with your current visit she understands much more about the process of ECV. She is wondering what method of anesthesia you will use, but before that she is curious if adding anesthesia is really necessary for a procedure they just “push some on my belly.”

The overall success rate for ECV is approximately 58%. (1) Using any neuraxial technique has shown to increase the success of ECV by 15.3% over no neuraxial technique. (4) Another study showed overall success rates for ECV with neuraxial anesthesia (surgical level) of 68%, with neuraxial analgesia (similar level provided during labor analgesia) of 45%, and for no neuraxial technique to be 37%. (2) Curiously, increasing the dose of spinal anesthetic in one study did not increase the success rate of ECV, but did marginally improve pain scores, increased hypotension, and increased hospital length of stay. (4)

Case Presentation continued:

Your patient presents to her next scheduled obstetric appointment and is currently at 35 4/7 weeks gestation. She relates some increase in fatigue as her pregnancy has progressed. She is still going on a daily walk but shortened her route yesterday and took her rescue inhaler when she arrived home. Her shortness of breath did improve after using the short acting Beta agonist inhaler.

Current vital signs: BP 120/64, P 82, R 16, Temp 36.4, SpO2 = 96% on room air, Weight = 96 kg, Height = 1.67 meters (5’ 6”), BMI = 34.4

Exam reveals: Lungs clear to auscultation. No peripheral edema

She was impressed by the increased success rate of ECV that occurs when any type of neuraxial anesthesia is implemented. After talking to her obstetrician she is wondering if there are other factors that increase the success of ECV—especially in her case—but she forgot to ask. Additionally she is wondering if there is something that has similar success to neuraxial anesthesia that she could have thru her IV or possibly nitrous oxide.

Factors influencing success of ECV have long been sought and assessed. Several scoring systems have been tried and implemented. Multiparity, transverse or oblique fetal presentation, as well as complete breech presentation have been associated with increased success rates of ECV. (1,2,5) Obesity has been associated with increased risk of failure, but in other studies it has also been found to have no effect on ECV success. (1) A small fetus of less than 2,500 grams has been shown to increase risk of ECV failure, although a smaller than average fetus has overall been shown to increase risk of success. Advanced cervical dilation, nulliparity, low station and anterior placenta decrease the success of ECV. (1)

There have been multiple studies looking at less invasive modalities for decreasing pain from ECV and increasing the success rate. Remifentanil infusion at 0.1 ug/kg/min did significantly decrease pain associated with ECV but did not increase the success rate. (6) A 50:50 mix of nitrous oxide:oxygen also resulted in lower pain scores, but did not increase the success rate of ECV. (5)

 

The change to admission irregardless of the outcome of the ECV may have changed your plans. Intrathecal local anesthetic may have been part of your approach prior to the change in plans, and it can certainly still be, but not in and of itself. If epidural placement was not part of your previous plan, then it will be now due to the possibility of successful ECV and laboring the patient. So options moving forward include either combined spinal epidural (CSE) or epidural anesthesia. Which one would YOU do and why?

The patient has a family history of malignant hyperthermia and MH precautions should be taken now in the event of an emergent cesarean section in the OR. This includes preparing the OR anesthesia machine, room and availability of drugs with standard MH precautions. Please take a moment to describe how you would do this at your facility.

There has been no statistically significant difference shown in ECV with using spinal versus epidural anesthesia. (1) Tocolysis is the standard of care and its use combined with neuraxial anesthesia increases success of ECV. Neuraxial anesthesia additionally helps to relax the abdominal wall musculature. Both surgical level anesthesia and analgesia have been shown to increase ECV success, (68% vs. 45% vs. 37% with no anesthesia). (2) Although surgical anesthesia has been shown to increase ECV success more than analgesia, there are significant questions about the optimum intrathecal dose of local anesthetic. One study compared doses of 2.5, 5, 7.5 and 10 mg and found no change in success rate with increasing dose. Increasing dose did marginally improve pain scores, increase hypotension and length of stay. (4)

Case presentation continued:

You are going to place a CSE and decide upon 15 ug of fentanyl intrathecally but are unsure of the dose of 0.75% hyperbaric bupivacaine you want to use.

Thought question:

What dose of intrathecal bupivacaine would you use and why?

Case presentation continued:

You decide on 10mg and proceed after everyone is ready and the fluid bolus is finished. Additionally you bring phenylephrine both as an infusion and as a syringe for bolus injection. You attempt at the L3-4 and get a good loss of resistance at 7 cm of depth and place the spinal needle. There is slow but steady flow of CSF thru the 27 gauge needle and you inject your 10 mg of hyperbaric bupivacaine along with 15 ug of fentanyl. Then you withdraw your spinal needle and pass the epidural catheter and pull it back to a skin depth of 12 cm. You tape it into place and do not administer the test dose.

The obstetrician proceeds with the ECV as the nurse monitors the patient. The patient complains of feeling nauseous. You start phenylephrine at an infusion of 50 ug/min and give her a dose of ondansetron 4 mg IV. Her next set of vitals are: BP 90/56, P 88, so you bolus 100 ug of phenylephrine and increase the phenylephrine infusion to 75 ug/min. The patient’s heart rate is now 64 and the pulse oximeter has a poor wave form and isn’t giving a reading. Fetal tracing show a decrease in heart rate to the 90s.

The obstetrician abandons the procedure for the moment and the patient is repositioned and supplemental oxygen applied. The patient’s next set of vitals are: BP 112/50 P 48. You decide to administer glycopyrrolate 0.2 mg and to keep the phenylephrine infusion at 75 ug/min.

Fetal tracing rebounds to 100-110 with decreased variability. Maternal vital signs are now: BP 130/66, P 68. Maternal vital signs remain stable but fetal heart rate again decreases to 60-70 and does not rebound. The decision is made to proceed with emergent cesarean delivery and the patient is rushed next door into the OR while the NICU is called to assist.

Cesarean is performed and a 2,950 gram male infant is delivered with Apgars of 2 and 8. He is taken to the NICU for further observation overnight. Examination of the placenta is within normal limits, however the umbilical cord shows a true knot in its mid-portion. Closure of the uterus and incision is unremarkable and the patient is taken to the recovery area.

Discussion:

The overall complication rate for ECV is roughly 6.1%, with transient fetal heart rate changes (4.7%) being the most commonly observed complication. (5) Adverse events such as placental abruption, umbilical cord prolapse, rupture of membranes, stillbirth, and fetomaternal hemorrhage all occur at rates less than 1%. (1) The overall risk of progressing from ECV to emergent delivery has been commonly reported at 0.43%, with one study reporting a high rate of 3.3%. (3) If ECV were significantly implemented the breech cesarean delivery rate could be cut in half. (2) There is a significant cost benefit noted with the use of ECV. In one analysis, ECV was cost-effectiven as long as its success rate was greater than 32%.(5) And a separate study noted that from a hospital and health care insurance payor perspective, neuraxial analgesia was cost saving when the ECV success rate exceeded 48% and 44% respectively.(1) Finally, by using neuraxial anesthesia for ECV an average per patient savings of $276 was observed by reducing the number of attempts at ECV and a reduction in the breech cesarean delivery rate. (5)
In this particular patient there were several indications to go with a heavier spinal dose for ECV. First off, the patient has a family history of MH and would need to be treated for MH precautions and thus succinylcholine and inhaled anesthetics would be contraindicated. Secondly, she has several factors that portend to a difficult intubation including: obesity, increased Mallampati score, and decreased thyromental distance. Finally, intubation for an emergent CD would not be as desirable due to the patient’s asthma that appears to be moderate in nature (although this certainly not an absolute contraindication). All of these factors steer toward trying to avoid intubation altogether in the event that an emergent CD—although statically unlikely—is needed. The rate of progressing to emergent CD after attempted ECV is 0.4%. (5)

When deciding an anesthetic approach and dosage to ECV there are a myriad of factors to consider. Patient characteristics including, but not limited to: gestational age, anesthetic history, physical exam, co-morbidities, personal social and family issues, as well as laboratory results are factors to be considered. Whether the patient will stay for vaginal delivery if ECV is successful is an important factor as well. This of course depends on the gestational age and discussions with the obstetrician. Close collaboration with the patient and obstetrician are vital to produce the best plan amenable to all issues and concerns.

References:

1. American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics—External Cephalic Version; Interim Update; Number 135, 2020. Obstet Gynecol May;135(5):e203-212
2. Carolyn F. Weiniger (2013). Analgesia/Anesthesia for External Cephalic Version. Curr Opin Anesthesiol 26: 278-287
3. Brendan Carvalho and Brian T. Bateman (2017) Not Too Little, Not Too Much – Finding the Goldilocks Zone for Spinal Anesthesia to Facilitate External Cephalic Version. Anesthesiology, 127(4) 596-598
4. Laurie A. Chalifoux, et al. (2017) Effect of Intrathecal Bupivacaine Dose on the Success of External Cephalic Version for Breech Presentation. A Prospective, Randomized, Blinded Clinical Trial. Anesthesiology, 127 (4) 625-632
5. Stephanie Lim and Jennifer Lucero (2017) Obstetric and Anesthetic Approaches to External Cephalic Version. Anesthesiology Clin 35, 81-94
6. K. S. Khaw et al. (2015) Randomized trial of anaesthetic interventions in external cephalic version for breech presentation. British Journal of Anaesthesia 114 (6): 944-50