External Version: Can We Spare Patients from a Cesarean Section?
By John C. Hobbins, MD
As pointed out in previous OB/GYN Clinical Alerts, about 1 in 4 patients in the United States are delivered by cesarean section, a procedure still classified as a "major operation." Newer figures from year 2002 are not available, but the cesarean section rate (CSR) is sure to increase based on the apparent backlash against vaginal birth after cesarean section (VBAC). Also, a relatively recent randomized controlled trial (RCT) suggests greater neonatal morbidity when breeches are delivered vaginally, rather than by elective section.
Many women with breeches would prefer to avoid a cesarean section and are requesting an attempt at external version (EV). This Special Feature will deal with the risks and benefits of EV and will touch upon a few of the maneuver’s ramifications.
Success Rates of EV
Success rates vary appreciably in the literature and often reflect single operator experience. These figures vary between 20% to more than 70% and, along with representing operator skill, zeal, and patient tolerance, also depend upon which patients are selected for EV (where in some clinical situations any effort is doomed from the start). Also, in these studies many variables, other than the procedure itself, are put into play such as the use of conduction anesthesia, tocolytics, etc. Last, the timing of the version may have a significant effect on success rates.
Early vs Late EV
Some of the same authors that published the above New England Journal of Medicine RCT that set the stage for a move toward elective cesarean section for all breeches, recently published an RCT comparing early (34-36 wks) vs late (36-38 wks) versions for breeches. They carefully selected nulliparous women with any breech presentation and multiparas with frank breeches (feeling these would represent the fairest test of the maneuver).
Two hundred thirty-three women were randomized in 25 centers around the world. Tocolytics were used in about half of the patients, but conduction anesthesia was used rarely.
The rate of noncephalic presentation at birth was 56.9% in the early group and 66.4% in the delayed group. The CSR in the early group was 64.7% and 71.6% in the late group. The above differences were not statistically significant, but more patients would have had to be recruited to have the power to validate the above 9% difference in presentation at term. The authors concluded that the results were encouraging for early EV, but a larger trial was needed.
There are a number of interesting spin-off findings in this study:
1. Fetal heart rate abnormalities were noted in 7% of the early EVs and 2% of the late EVs, requiring the procedure to be discontinued;
2. Patient discomfort in 8% and 6% of patients, respectively, resulted in discontinuation of the procedure;
3. Spontaneous version occurred in 10% of the early group (while awaiting the procedure) and in 19% of the late group patients; and
4. Spontaneous reversion to breech was rare in both groups after successful version.
Stepwise Description of the Method
In the past, the technique has consisted mostly of attempting to lift the breech out of the pelvis and muscling the fetus around with brute force until the patient or fetus said, in his or her own way, "uncle." Some operators have even advocated using 2 sets of hands to accomplish this feat.
The following represents a kinder, gentler way of accomplishing this goal while lowering complications and diminishing patient discomfort.
Step 1: Careful Ultrasound Evaluation
Fetal Alignment: Not all breeches are alike. A frank breech deep in the pelvis in a nullipara is going to be more difficult to vert than a floating incomplete breech in a multipara. Ultrasound will allow the provider to roughly predict procedure success.
i) Presentation: Oblique lies or transverse lies are easier to vert because the fetus has a shorter arc through which to travel.
ii) Type of Breech: Frank breeches theoretically can be more difficult to turn because a fetus in a tenaciously piked position represents a larger north/south axis to deal with than a fetus in a tucked position.
iii) Station: One less step is necessary if the breech is already at a high station.
iv) Position: Toward term the fetus spends about 75% of the time on his or her side. On ultrasound, if the spine is at 12 o’clock or 6 o’clock, the success rate diminishes appreciably because of the potential pinwheel effect of splayed out limbs.
v) Fetal Extension: Much has been made of extended heads when delivering a breech vaginally, but this plays little role in a version, since, barring the extremely rare case of torticollis, an extended head represents only a temporary whim of a fetus who generally can be encouraged to flex.
Placental Position: Many have backed off during a version in the face of an anterior placenta. Although this might make empiric sense, there is little in the literature, other than the potential of transferring fetal cells into the maternal circulation, to contraindicate version in special cases. Placenta previa obviously is a contraindication to version, where malpresentation is common. Here a successful version would represent a very dubious triumph.
Fetal Anomalies: If a patient has slipped through pregnancy without an anomaly assessment, she should have one prior to a version since fetuses with anomalies often present as breeches.
Fluid Assessment: Many have decided that oligohydramnios is a contraindication to version. This would depend upon the clinical situation and the degree of oligohydramnios. Interestingly, I found one report of amnio-infusion of 500-700 cc of saline being used after unsuccessful version followed by a successful version in all 6 cases in which this was attempted.
Umbilical Cord Assessment: About 12-18% of fetuses at term will have a single loop of cord around the neck and 2.5% will have 2 loops. The multicenter RCT study mentioned above indicated that in about 4% of total cases version had to be abandoned because of fetal heart rate abnormalities, and it is rare for us to have to do an emergency cesarean section for fetal distress during a version. Because of the dangerous potential for cord avulsion, tethering, or occlusion, a double loop of cord or a single tight loop of cord could represent a contraindication to version. On the other hand, a loose single loop or a cord in the neighborhood of the shoulder or neck should not be a contraindication, as long as the fetal heart rate is carefully monitored with ultrasound during the procedure.
Step 2—The Technique Itself
The patient should have an empty bladder. Before the rotation portion of the procedure is undertaken, the breech should be out of the pelvis. This can be accomplished often with superpubic pressure upward. If this fails after a very short time, the breech can be gently pushed out of the pelvis by a vaginal hand. A Trandelenberg position makes sense during this portion of the procedure, but any length of time in this position makes this maneuver doubly uncomfortable for a full-term patient.
Once the breech is out of the pelvis, the operator, who has decided ahead of time whether to use the forward or backward roll technique, guides the breech into either lateral quadrant of the uterus, while encouraging the head to move downward into the opposite side of the uterus. Everyone has his or her own "wrinkles," but I give more emphasis to the downside hand than the one on the head and will often spend many seconds simply encouraging the breech to move upward before even thinking about the head.
The procedure should be done in stages, and each stage should be accompanied by an ultrasound assessment of the long axis of the fetus and the status of the fetal heart rate. I know of operators who will retry a version after a bradycardic fetus’ heart rate returns to normal, but I consider this to be a message to call it a day.
If one can get the long axis of the fetus rotated to more than 90° from the starting point, the success rate (barring a bradycardia) is virtually 100%. For this reason, if this is not accomplished after a reasonable amount of time (a few minutes) and reasonable pressure (no discomfort), an attempt can be made to move the fetus in the opposite direction.
Once the head is in a cephalic presentation, or a reasonable facsimile, gravity can be used to finish the job by having the patient stand and walk (unless she has an epidural).
Variables to Consider When Doing EV
Forward vs Backward Roll: In oblique breeches, the shortest distance to the pelvis should be considered first. When the fetal long axis is straight up and down, "gestalt" gets put into play. The benefit of the forward roll is that the fetus has a tendency to stay tucked during the maneuver, but the backward roll allows the operator better control. My recent informal poll of some experienced operators yielded a 50/50 split regarding this question and I could find nothing in the literature pitting one option against the other.
Placental Position: A very low lying placenta (< 2 cm from the cervical os), or placental previa are contraindications to EV. Rregarding anterior placentas, I found isolated instances where fetal cells were found in the maternal circulation with anterior placentas. However, in a Chinese study looking for evidence of fetal-maternal hemorrhage in 70 patients undergoing EV, the rate of this finding was only 1.8%, irrespective of placental position. Also, a German study showed no relationship between placental position and success of EV, while an Italian study showed better success with a posterior placenta.
Vaginal Birth After Cesarean (VBACs): Many have labeled this as a contraindication to version, but I could find little to back this dictum up. One study showed a remarkable success rate in patients with uterine scars.
Tocolytics: Almost all of the tocolytic studies in the literature have involved the use of beta mimetics in EV (terbutaline, salbutamol, ritodrine) and the majority have shown a beneficial effect of tocolytics. One study from Hong Kong was very interesting. The investigators pitted ritodrine against a placebo in 50 patients. The overall EV success rate in the ritodrine group was 68% vs 32% in the placebo group, but after the first 20 patients were studied, there was no difference between groups. This suggested that the experience gained by the operators during the early stages of the trial was the most important variable regarding success, and not the tocolytic.
I have been enamored with the use of nitroglycerine in breech extractions for a second twin because of its short-term capabilities as a uterine relaxant. Therefore, I was disappointed to find only one British RCT that suggested its efficacy. Unfortunately, a review of the literature by a Toronto group involving 13 RCTs did not yield information to support the use of nitroglycerine in EV.
Some studies in the literature have suggested benefit from epidural anesthesia in EV, but a randomized trial from our group showed no benefit from spinal anesthesia. A group of patients who might particularly benefit from epidural anesthesia would be those who initially failed EV with tocolysis. One study by Neiger et al showed a 71% success rate with epidural in 83 patients with a previously unsuccessful version.
It seems that this expensive and invasive anesthetic method could be used in a pre-cesarean "last ditch" attempt at EV in the operating room in patients highly motivated to avoid a section.
Through the years one hears of various adjunctive EV fetishes used by obstetricians. These will not be discussed with one exception—the use of talcum powder to improve traction (or something). I tried this once and it did not seem to accomplish anything except making me sneeze. Counter intuitively many operators will use a lubricant to do the same thing.
Alternative Measures to Encourage Spontaneous Version
Many have advocated the use of gravity a few times a day to encourage spontaneous version (the "ironing board trick"). Although this has not been rigorously tested scientifically, anecdotal experience suggests its usefulness when used 1-2 times a day for 15-20 minutes at a time.
In JAMA, a randomized trial using moxibustion, an ancient Asian technique appeared to show benefit in stimulating spontaneous version, and acupuncture techniques have also been described to accomplish the same aim.
It is interesting that about 50% of the patients in the multicenter RCT involving early vs late version, had already tried some form of "alternative" version method before enrolling in the study. This speaks to the fact that today many patients remain highly motivated to avoid cesarean section, and we, as providers, should continue to respect our patients’ autonomy, especially when their wishes are not incompatible with sound medical judgment.
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Dr. Hobbins is Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver.
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