Although in primiparæ engagement usually occurs about four weeks before labor begins, it does not normally take place in multiparæ until immediately before labor. This difference is accounted for in the increased tonicity of the uterine and abdominal muscles of primiparous women. In certain abnormalities, or marked disproportion between the diameters of the child’s head and mother’s pelvis, engagement may not take place until labor is well advanced, or possibly not at all.
The presentation and position of the fetus are ascertained by means of abdominal palpation, vaginal examination, rectal examination and auscultation of the fetal heart.
Palpation of the child’s body through the mother’s abdominal wall is possible under ordinary conditions, because the uterine and abdominal muscles are so stretched and thinned that the various parts may be made out through them. But it is sometimes difficult in hydramnios and is practically impossible in very fat patients or in the case of a ruptured uterus when the fetal outline is obscured by hemorrhage. This procedure has been practiced only during comparatively recent years, and is regarded by many obstetricians as one of the most important factors in reducing the frequency of puerperal infections and thus in decreasing maternal deaths. The explanation is that in general the dangers of puerperal infection are believed to increase in direct proportion to the number of times a patient is examined vaginally; and since it has been known how to diagnose the child’s position by means of abdominal palpation, the necessity for vaginal examinations is not so great and they are accordingly made less frequently.
Fig. 57.—First maneuver in abdominal palpation to discover position of fetus.
Rectal examinations may also be regarded as a factor in preventing infection, for, since much the same information may be obtained by means of them as by vaginal examinations, after the onset of labor, they often replace direct exploration of the easily infected birth canal.
Abdominal palpation, as usually practiced, consists of four maneuvers, with the patient lying flat and squarely on her back with the abdomen exposed. The nurse should bear in mind that successful palpation requires even pressure. Cold hands applied to the abdomen or quick, jabbing motions with the fingers will usually stimulate the muscles lying beneath them to contract, thus somewhat obscuring the outline of the child. Such palpation is also very uncomfortable for the patient; but firm, even pressure, started gently, with warm hands, does not hurt.
Fig. 58.—Second maneuver in abdominal palpation.
First Maneuver. The purpose of the first maneuver is to ascertain what is in the fundus; this is usually either the head or the breech. The nurse should stand facing the patient and gently apply the entire tactile surface of the fingers of both hands to the upper part of the abdomen, on opposite sides and somewhat curved about the fundus. (Fig. [57].) In this way the outline of the pole of the fetus which occupies the fundus may be made out. If the head is uppermost, it will be felt as a hard, round object which is movable or ballottable between the two hands, and if the breech, it will be felt as a softer, less movable, less regularly shaped body.