Nomenclature:
Three types of breech presentation are described (Figure 14.1) :
(i) frank breech,
(ii) complete breech, and
(iii) incomplete [footling] breech.
Obstetric risks of breech presentation:
Perinatal mortality and neonatal morbidity are 3 to 10 times higher than for cephalic presentation, but current data are imperfect. After excluding fetal congenital anomalies, birthweight and gestational age are the most significant determinants of outcome. Many obstetric complications are also more frequent than in the non-breech delivery (Table 14.2).
Principles of obstetric management:
External cephalic version (ECV) performed close to term lowers the caesarean section (CS) rate (4, 5) and is successful in 40 to 80 percent of non-laboring gravidae (Table 14.3). Some obstetricians favour uterine tocolysis to facilitate ECV but this is controversial. The administration of epidural analgesia for ECV may increase its success rate (59% vs 24%) by lessening pain (6).
The choice of method of delivery (CS vs trial of vaginal delivery) is dependent on fetal gestational age. For a term breech, obstetrical consensus supports vaginal delivery of selected cases provided that management protocols are strictly adhered to (Table 14.4) (7). If the management criteria cannot be satisfied, elective CS is indicated. The obstetric manoeuvres used in breech delivery are outlined in Figure 14.2. For a preterm breech, the choice of CS is not controversial when the fetal weight is < 1500gm. Studies confirm that the peri- and neo-natal mortality/morbidity are reduced if these infants are delivered by CS. Some obstetricians advocate a trial of labour after 32 weeks gestation when estimated fetal weight is > 1,500gm. The survival of a preterm breech is mainly determined by the gestational age and infant birthweight.
Vaginal breech delivery - Obstetric management:
There are three possible methods by which a vaginal delivery can be achieved:
1. spontaneous breech delivery - the infant is born with support of the trunk but without traction or manipulation;
2. assisted breech delivery (preferred technique) - spontaneous delivery of the breech up to the level of the umbilicus followed by obstetrician-assisted delivery of the shoulders and aftercoming head (Figure14.2); and,
3. total breech extraction - the obstetrician extracts the entire body of the infant. This method of delivery is unacceptable for a term singleton breech (2, 8).
Vaginal breech delivery - Anaesthetic management:
Epidural analgesia is the "gold standard" for breech vaginal delivery, but it presents an anaesthetic challenge because:
1. the technique must obtund the involuntary urge to push which often occurs before full dilatation;
2. it must give good analgesia yet allow effective 2nd stage pushing;
3. delivery of the shoulders and aftercoming head (especially forceps-assisted) may require profound perineal anaesthesia and relaxation.
There are four approaches to the anaesthetic management of breech vaginal delivery which are effective:
1. 'Two catheter' epidural.
This technique may be preferable and is described in Table 14.5.
2. Combined spinal-epidural (CSE).
CSE analgesia can also provide excellent conditions and is described in Table 14.6.
3. Single catheter epidural (Chapter 1).
If a single catheter technique is to be used, a dilute local anaesthetic plus opioid solution (eg. bupivacaine 0.0625% with fentanyl 0.0004%) is used for the 1st stage. Additional doses of epidural fentanyl can be used to obtund early pushing.
4. Subarachnoid analgesia (Chapter 63).
Some anaesthetists advise subarachnoid block alone in selected situations. Dilute local anaesthetics (eg. lignocaine 1.5%) preserve the ability to push while providing excellent sensory anaesthesia.
Anaesthetic 'standby' for general anaesthesia for breech delivery should now be obsolete!
Caesarean section - Anaesthetic management:
Epidural or spinal anaesthesia are preferable and GA (which can cause neonatal depression) is very rarely indicated.
Fetal head entrapment remains the obstetrician's greatest fear. It typically occurs with premature vaginal breech delivery when the fetal buttocks and thighs pass through an incompletely dilated cervix and the uterus then clamps tightly around the fetal head. It can also occur during CS particularly if the uterine incision is too small. Successful treatment requires immediate tocolysis (Table 14.7) (Chapter 52) (9). Local anaesthetics are not tocolytic (Chapter 24); no advantage accrues from extending the block.
References:
1. Writer WD. Breech presentation and multiple pregnancy: obstetric aspects and anaesthetic management. Clinics in Anaesthesiology 1986 4:305-20.
2. Seeds JW. Malpresentations. In: Obstetrics: normal and problem pregnancies. (Gabbe SG, Niebyl JR, Simpson JL, eds) Churchill Livingstone p.539-72. 2nd Edition New York. (1991)
3. Mokriski BK. Abnormal presentation and multiple gestation. In: Obstetric anesthesia: principles and practice. Chestnut DH, editor. St. Louis: Mosby-Year Book, 1994:669-85.
4. Hanss, JW Jr. The efficacy of external cephalic vesion and its impact on the breech experience. Am J Obstet Gynecol 1990 162: 1459-1464.
5. Gifford DS, Keeler E, Kahn KL. Reductions in cost and cesarean rate by routine use of external cephalic version: a decision analysis. Obstet Gynecol 1995 85:930-936.
6. Carlan SJ, Dent JM, Huckaby T, et al. The effect of epidural anesthesia on safety and success of extemal cephalic version at term. Anesth Analg 1994 79:525-528.
7. Society of Gynaecologists of Canada. The Canadian Consensus on Breech Management at Term. Journal SOGC 1994 16:1839-1848.
8. Baskett TF. Essential management of obstetric emergencies. Essential management of obstetric emergencies. 2nd Edition Bristol: Clinical Press, 1991 126-135.
9. Mayer DC, Weeks SK. Obstetric forum: antepartum uterine relaxation with nitroglycerin at caesarean delivery. Can J Anaesth 1992 39: 166-169.