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Kymograph records of uterine contractions
Correspondence Kymograph
Records of Uterine
Contractions
To the Editor: In the May issue of this JOUKKAL (47: 815, 194%) appears an article by “A Study of Contractions in Labor Based on KymoWilliam Bickers, entitled graphic Records Obtained From an lntrauterine Balloon.” It is based on data from four patients. This article contains a statement of interest to me, since it misinterprets and attempts to disqualify certain views and facts which I have advanced. This would be of no significance were it not that several other investigators and clinicians have likewise misconstrued my views in this respect from time to time. “It has been suggested that the onset of labor may The above article states: result from distention, which puts the muscle fibers under tension; ischemia This is represented as the view of the underresults and contractions follow.” signed, as expressed in Chapter XII in my monograph, PhysioZogy of the Uterus (Hoeber, 1939 j. It is dismissed by the following statement: ‘ i The well-known fact that artificial rupture of the membranes at term will induce labor tends to invalidate the distention theory as a cause of labor. ” The facts of the situation are as follows: In the above-mentioned chapter, an evaluation is made of the physiologic relationships in the uterus at term. In the initial sentence, the following statement appears: “There is no known single cause for the onset of labor as the numerous theories of the past and present imply. Rather, it now seems that parturition begins as a result of the gradual, accelerating convergence of a number of factors, structural, humoral, nervous, nutritional, and circulatory, which, at a time characteristic for each species and adapted to the morphologic conditions present in each, are so associated that they lead to evacuation by the uterus of its contents.” A clearly speculative, tentative and hypothetical set of physiologic relationships is then given diagrammatically. The scheme refers to distention factors (which clearly exist), hormonal factors (which have never been denied), metabolic conditions in the myometrium (that are seldom considered), the rudiments of simple muscle physiology (which are affected by either a balloon in the uterus at term, or by rapid loss of fluid from rupture of the membranes), and other factors. The following statement also appears: “Physiological coordinating factors-unknown.” In the face of these factual considerations, a “ distention theoq” for the onset of labor, based on these views written in 1938 and published early in 1939, is ascribed to me today. There is
no
‘Ldistention
theory.”
To quote my views more correctly, Dr. Bickers should have referred to a paper entitled: “Physical Conditions in the Uterus Governing the Duration of Pregnancy, ’ ’ published late in 1939 (dnatomlcnl Record 75: 175-190). The essence of this work, established by measurements, is that until shortly before the onset of labor, the tensions on the uterine wall are different in different parts; this is apparently provided for by several mecha.nisms, structural, physical, and hormonal. As term approaches, the ‘ ‘slack ” is progressively taken up, and the maximal uterine tension becomes about uniform over the surface of the whole organ. The significance of this condition is given in the following quotation: “This appears to be, accordingly, the physical condition at the end of gestation which signals impending parturition. ” But what happens later, amid a complexity of conditions, to effect coordination of uterine contractions in labor remains as unknown as ever. Conse355
Records of Uterine
Contractions
To the Editor: In the May issue of this JOUKKAL (47: 815, 194%) appears an article by “A Study of Contractions in Labor Based on KymoWilliam Bickers, entitled graphic Records Obtained From an lntrauterine Balloon.” It is based on data from four patients. This article contains a statement of interest to me, since it misinterprets and attempts to disqualify certain views and facts which I have advanced. This would be of no significance were it not that several other investigators and clinicians have likewise misconstrued my views in this respect from time to time. “It has been suggested that the onset of labor may The above article states: result from distention, which puts the muscle fibers under tension; ischemia This is represented as the view of the underresults and contractions follow.” signed, as expressed in Chapter XII in my monograph, PhysioZogy of the Uterus (Hoeber, 1939 j. It is dismissed by the following statement: ‘ i The well-known fact that artificial rupture of the membranes at term will induce labor tends to invalidate the distention theory as a cause of labor. ” The facts of the situation are as follows: In the above-mentioned chapter, an evaluation is made of the physiologic relationships in the uterus at term. In the initial sentence, the following statement appears: “There is no known single cause for the onset of labor as the numerous theories of the past and present imply. Rather, it now seems that parturition begins as a result of the gradual, accelerating convergence of a number of factors, structural, humoral, nervous, nutritional, and circulatory, which, at a time characteristic for each species and adapted to the morphologic conditions present in each, are so associated that they lead to evacuation by the uterus of its contents.” A clearly speculative, tentative and hypothetical set of physiologic relationships is then given diagrammatically. The scheme refers to distention factors (which clearly exist), hormonal factors (which have never been denied), metabolic conditions in the myometrium (that are seldom considered), the rudiments of simple muscle physiology (which are affected by either a balloon in the uterus at term, or by rapid loss of fluid from rupture of the membranes), and other factors. The following statement also appears: “Physiological coordinating factors-unknown.” In the face of these factual considerations, a “ distention theoq” for the onset of labor, based on these views written in 1938 and published early in 1939, is ascribed to me today. There is
no
‘Ldistention
theory.”
To quote my views more correctly, Dr. Bickers should have referred to a paper entitled: “Physical Conditions in the Uterus Governing the Duration of Pregnancy, ’ ’ published late in 1939 (dnatomlcnl Record 75: 175-190). The essence of this work, established by measurements, is that until shortly before the onset of labor, the tensions on the uterine wall are different in different parts; this is apparently provided for by several mecha.nisms, structural, physical, and hormonal. As term approaches, the ‘ ‘slack ” is progressively taken up, and the maximal uterine tension becomes about uniform over the surface of the whole organ. The significance of this condition is given in the following quotation: “This appears to be, accordingly, the physical condition at the end of gestation which signals impending parturition. ” But what happens later, amid a complexity of conditions, to effect coordination of uterine contractions in labor remains as unknown as ever. Conse355