=Vaginal Examination.= The information obtained by vaginal examination, before the cervix is dilated, is rather uncertain since the child’s presenting part must be palpated through the fornix. But after complete, or even partial dilatation, the exploring finger is able to feel the sagittal suture and one fontanelle, in a vertex presentation, and diagnose the position by discovering the direction of the suture and whether it is the anterior or posterior fontanelle that is felt. The anterior fontanelle, it will be remembered, is relatively large and four-sided, while the posterior is small and more nearly triangular in shape. In a face presentation, the features may be felt; in a breech the examining finger can palpate the buttocks and genital crease. Because of the possible danger of introducing infective material into the birth canal, the tendency is to make fewer and fewer vaginal examinations, and then only after the most painstaking preparation which will be described presently. Needless to state, vaginal examinations are not within the province of the nurse. =Rectal Examinations.= More and more frequently rectal examinations are being employed to obtain information about the child’s position, as the examining finger is able to feel the surface of the presenting part through the recto-vaginal septum, after the cervix is dilated, and there is no danger of infecting the birth canal while so doing. For this reason nurses are frequently taught to make rectal examinations, thereby increasing the value of their assistance to the doctor in watching the progress of labor. (Fig. 62.) =Auscultation of the fetal heart= is valuable in confirming the diagnosis of presentation and position which has been made by palpation. In vertex and breech presentations the heartbeat is best heard through the baby’s back and in face presentations it is transmitted through the chest, which presents a convex surface in this case and fits into the curve of the uterine wall. In anterior vertex presentations the heart is heard a little to the side and below the umbilicus; in transverse, further to the side, and in posterior, well toward the back. CHAPTER XI SYMPTOMS, COURSE AND MECHANISM OF NORMAL LABOR Labor may be defined as the process by means of which the product of conception is separated and expelled from the mother’s body. It ordinarily occurs about 280 days from the beginning of the last menstrual period. (See p. 93.) The cause of labor is not known. Many theories have been advanced to explain why the uterine contractions, which have occurred painlessly throughout pregnancy, and without expulsive force, finally become painful at the end of the tenth month and so changed in character as to extrude the uterine contents; but as yet, none is wholly satisfactory nor generally accepted. Nor is it known why some labors are premature and some delayed.