Breech

Chapter 20 Breech




The presenting part of the fetus is the breech with the sacrum as the denominator. It is more common before 28 weeks (20%) than at term (3%). Associated causes such as disproportion, obstructing pelvic masses (e.g. fibroids, ovarian cysts), uterine abnormalities (e.g. septate uterus), hydramnios, fetal prematurity or abnormalities and multiple gestation will influence the management of labour. Breech presentation is a marker for potential fetal handicap as it is more common in preterm and structurally abnormal fetuses.



DIAGNOSIS













ANTENATAL ASSESSMENT





If gestation is uncomplicated, 37 weeks or more and not in labour, offer external cephalic version (ECV) (see Box 20.1). This involves turning the baby to a cephalic presentation by gentle manual rotation, with or without tocolysis. If the procedure is performed on a Rhesus negative woman, anti-D should be administered. ECV is most likely to be successful in a flexed breech that is not engaged in the pelvis, when liquor is adequate and in multiparous women. Facilities for immediate caesarean section must be available. Epidural anaesthesia can increase success rates of ECV.






Box 20.1 External cephalic version (ECV)









SPONTANEOUS BREECH DELIVERY


The widest part of the pelvic brim is usually the transverse diameter whereas the anteroposterior diameter is the widest part of the pelvic outlet. In spontaneous delivery the three fetal diameters, the bitrochanteric, bisacromial and anteroposterior of the fetal head, enter in sequence through the pelvic brim in the transverse or oblique diameter and are then guided by the levator ani muscles to fit the anteroposterior diameter of the outlet (see Figure 20.3).



The breech enters the pelvis with the trochanters aligned in the transverse or oblique diameter of the brim. Rotation takes place so the bitrochanteric diameter delivers through the anteroposterior diameter of the outlet. Once delivered, the breech rotates to the sacroanterior position so that the shoulders enter in the transverse diameter of the brim. Internal rotation allows the delivery of the shoulders in the anteroposterior position of the outlet and the passage of the head through the brim in the occipitolateral position. Following delivery of the shoulders (anterior shoulder delivers first) aided by lateral flexion of the trunk, the sacrum again rotates anteriorly so the posteroanterior diameter of the head (with the occiput beneath the symphysis pubis) delivers by flexion in the anteroposterior diameter of the pelvis. Figure 20.2 shows the possible positions of breech presentation.


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Mar 16, 2017 | Posted by in NURSING | Comments Off on Breech

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