NONVERTEX PRESENTATIONS, SHOULDER DYSTOCIA, AND CORD ACCIDENTS pot

403

BREECH PRESENTATION

DEFINITIONS, ASSOCIATIONS,

INCIDENCES, AND IMPORTANCE

Breech is a longitudinal presentation in which the cephalic pole oc￾cupies the fundus and the caudal (podalic) pole lies in the lower

segment of the uterine cavity or within the birth canal. Overall

breech presentation occurs in 3%–4% of singleton pregnancies com￾mencing labor, but has a much higher incidence in multiple gesta￾tions (e.g.,
25% of first twins and
50% of second twins are

breech). The incidence rises further in higher order multiple preg￾nancies. Other associations with breech presentation include: ear￾lier gestations (35% at 28 weeks, 25% at 28–32 weeks, 20% at

32–34 weeks, 8% at 34–35 weeks, 2%–3% at
36 weeks), a prior

breech (over 4-fold increase after one and up to 30-fold after three),

placental placement (i.e., placenta previa), oligohydramnios, fetal

congenital anomalies (e.g., hydrocephalus), pelvic tumors imping￾ing on the uterus or birth canal (e.g., leiomyomata), and uterine

anomalies (e.g., bicornuate, septate uterus).

As presentations are thought to be a matter of fetal–uterine ac￾commodation, breech presentation may be caused by any aberration

of this adaptive process or of the fetal attitude. Thus, breech presen￾tation is not a disease or an abnormality. However, breech presenta￾tion may be an important sign of congenital fetal compromise. For

example, breech presentation is increased with chromosomal anom￾alies (e.g., trisomies 18 and 21), neuromuscular abnormalities (e.g.,

familial dysautonomia), and skeletal malformations(e.g., spina bifida,

meningomyelocele). The incidence of major congenital anomalies

14

NONVERTEX PRESENTATIONS,

SHOULDER DYSTOCIA, AND

CORD ACCIDENTS

CHAPTER

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404 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

(e.g., anaencephaly, hydrocephaly) in breech presentations is more

than double (
6%) that found in vertex. Additionally, delivery of the

breech fetus imposes perinatal risks of birth anoxia and birth trauma

as well as maternal risks of traumatic delivery, or cesarean section.

There are three types of breech presentation (Fig. 14-1): frank

(legs flexed at the hip and extended at the knee), complete (legs

flexed at the hip and flexed at the knee), and footling (legs extended

at the hip and extended at the knee). The amount of both hip and

knee extension in footling breech is variable and may involve one

FIGURE 14-1. The three types of breech presentation.