Certain concepts in the handling of breech and transverse presentations in late pregnancy

Abstract 1. 1. We have presented the underlying causal mechanisms of persistent breech and transverse presentations of the fetus in single pregnancies at or near term. 2. 2. We recommend, in applying this knowledge clinically, that the implantation site of the placenta be determined in all cases of breech and transverse presentations of the fetus persisting after 30 to 32 weeks of pregnancy. 3. 3. The knowledge of where the placenta is implanted is of great aid when one is performing external cephalic version, since this permits the manipulation of the fetal poles without handling that portion of the uterus in which the placenta is implanted, and thus the risk of traumatic placental separation (which is the one dangerous accident that may occur during the performance of external version) may be obviated. 4. 4. In primigravid women in whom any degree of cephalopelvic disproportion is suspected, the conversion of breech presentation to a cephalic one will permit a test of labor and may obviate the necessity of section. 5. 5. A general method of external cephalic version is pictured and described, and the performance of this valuable maneuver is recommended in the routine management of persistent transverse presentation because it permits delivery through the birth canal in two-thirds of these cases. It should also be performed on all patients with breech presentation persisting after 32 to 34 weeks of pregnancy so as to obviate the two to three times increased risk to the fetus which is attendant upon breech delivery throughout the country as a whole. 6. 6. The optimum time for the initial performance of external cephalic version is about 34 weeks of pregnancy, in general, although nulliparous patients had best have their fetuses turned first at about 32 weeks. Engagement of the breech occurs fairly early in primigravid women, and disengagement of the breech becomes increasingly difficult as term approaches. Failure to disengage the breech is the most common cause of failed version. 7. 7. Unfavorable accidents involving the umbilical cord resulting from external version are very rare. The fetal heart should be carefully ausculted before and just after performance of version, and if, after 30 to 60 seconds, it is not normal the fetus should at once be returned, by reverse maneuver, to its original position. 8. 8. Anatomic factors which in general make the performance of external cephalic version difficult or impossible are: primigravidity, frank breech with extended legs, deep engagement of the breech, oligohydramnios, “extended attitude” of the fetus, and elongation of the amniotic sac resulting from relatively low implantation of the placenta in the cornual region it principally occupies. When external version cannot readily be accomplished, even though the breech has been successfully disengaged from the pelvic canal, it is probably because the placenta is offering mechanical blockage to the swinging past it of a pole of the fetus. Since the main precaution is to avoid placental separation, one should be willing not to attempt to force such a situation and should abandon the attempt for the time being. About one-fourth of such patients will undergo spontaneous cephalic version within the next week, but if this has not occurred, version should again be attempted, because it may then, surprisingly enough, be successfully performed with ease. 9. 9. Since external cephalic version is an extremely safe and valuable obstetric maneuver, and one which any physician familiar with obstetric practice can easily teach himself to do, it is hoped that it will enjoy increased and wide-spread usage.