Lacerations of the perineum : their causes, formation, and primary repair : with report of forty-eight illustrated cases / by Ellice McDonald.

  • McDonald, Ellice, 1876-1955.
Date:
1908
Catalogue details

Licence: In copyright

Credit: Lacerations of the perineum : their causes, formation, and primary repair : with report of forty-eight illustrated cases / by Ellice McDonald. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    or biparietal diameters. The various circum- ferences of the fetal head offer too much possi- bility of error in measurement to make them useful as indications. Therefore, in attempting to estimate the size of the presenting part in its relation to the size of the perineal ring, the greatest engaging diameter, the occipito-frontal, is taken as a criterion. However, as the size of the head increases in direct proportion to the weight of the child, the increase of weight in its relation to perineal lacerations is also considered. This increase in the size of the fetal head in proportion to the weight was shown to be con- stant in ioo cases studied in its relation to intra-uterine cephalometry (19). In this series, the 48 perineal lacerations may be divided into two classes: 1. Those not involving the muscle, and 2. Those involving the muscle of the perineum. Of those not involving the muscle, there were 21. The average weight of the 21 babies was 3,310 grammes, and the average occipito-frontal diameter was 11.27 cm- The 27 cases of lacerations involving the muscle had children averaging 3,550 grammes, and with an average occipito-frontal diameter of 11.75 cm- The average weight of 100 babes, of whom these 48 cases here reported are a part, was 3,300 grammes, and the average occipito-frontal diameter was 11.40 cm. Therefore the result may be summarized: O.-F. Diam. Weight. 21 cases of laceration not involving muscle 11.27 3,310 gm. 27 cases of laceration involving muscle n.75 3,550 gm. 100 cases, including 48 cases of laceration 11.40 3,300 gm From this summary it will be seen that the babies causing lacerations not involving the skin were of average weight, but of less than average size of head; while those causing lacerations involving muscle were of more than average weight and size of head. However, the slight increase in weight of two hundred grammes (7 oz.) can hardly explain the causa- tion of the lacerations in view of the fact that the heads were but slightly larger than average. Nor will the fact that, in 21 cases of minor lacerations, the fetus was of average weight and less than average size of head explain the causation of these tears. The causation of perineal lacerations, while undoubtedly influenced by considerable increase in size of the fetal head, does not depend to any extent upon this condition. It must, therefore, depend more upon the size and condition of the perineum itself than upon the size of the fetus and fetal head. The dispro- portion may be due to firmness of fiber and rigidity of perineal structure. Faulty mechanism of labor is undoubtedly the cause of a small percentage of lacerations, but this has an influence in but a small number of cases. Amongst them are those cases where the occiput does not present under the symphy- sis as in delivery by face to pubes. When- ever the flexion of the head is not sufficient, a larger diameter than necessary must pass the perineal ring. If flexion is good, the occiput may pass under the pubic bones before the occipito-frontal diameter engages in the outlet. In breech deliveries the reverse must ensue, i. e. the occiput remain within the ring and pivot under the symphysis, allowing the sinciput to engage first in the ring. The use of forceps as a causative force is one which varies very much with the methods of different operators. The harm they cause depends upon —-1. The kind of forceps em- ployed; and 2. Upon whether the operator delivers the head with the forceps or not. Forceps with long blades of the type of the Simpson forceps may cause laceration of the perineum in two ways. First, directly on a backward pull by the breadth between the shanks where they join the handles, which unduly stretches and wounds the outlet at a level with its greatest frailty, the posterior fourchette. Second, the blades themselves do not closely approximate the fetal head, and the edge of the blade extending beyond the head, impinges upon the vaginal floor and is forced into the tissue. This condition is quite common when attempts are made to deliver the head through the ring without removing the forceps. When he handles of the forceps are turned upward in order to ex- tend the head, the blades, not fitting snugly over the head, but grasping the parietal pro-