Traction and compression forces exerted by obstetric forceps and their effect on fetal heart rate

Ullery, John C.; Teteris, Nicholas J.; Botschner, Andrew W.; McDaniels, Betty A.

doi:10.1016/s0002-9378(16)35641-1

Cited by 13 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[10][11][12][13][14][15] These studies were performed during an era when operative deliveries were more common than today and high and mid forceps deliveries were obstetric state-of-the-art. Principal results from these studies are summarized in Table 1, and include the following:…”

Section: The Fetal Response To Mechanical Stressmentioning

confidence: 99%

On the Mechanical Aspects of Shoulder Dystocia and Birth Injury

Allen

2007

Clinical Obstetrics &Amp; Gynecology

View full text Add to dashboard Cite

This article presents objective evidence about shoulder dystocia and its associated mechanical injuries, namely clavicle fractures, and brachial plexus injuries. Specifically, the review focuses on the mechanical response of the fetus to forces applied to it or its anatomic components, including possible force thresholds for injury. This is followed by presenting the medical and engineering literature on the mechanical aspects of shoulder dystocia with emphasis on kinematics, the forces associated with labor and with traction forces associated with delivery. Finally, the paper discusses the mechanical characteristics of maternal and fetal maneuvers for shoulder dystocia and demonstrates how shoulder dystocia models can be used to train clinicians in the performance of maneuvers that stress the fetus the least. From a mechanical point of view, there are obstetric methods and training that can be employed to reduce the stresses induced by the fetus while alleviating shoulder dystocia, thereby reducing, but not eliminating, the risk of mechanical injury.

show abstract

Section: The Fetal Response To Mechanical Stressmentioning

confidence: 99%

On the Mechanical Aspects of Shoulder Dystocia and Birth Injury

Allen

2007

Clinical Obstetrics &Amp; Gynecology

View full text Add to dashboard Cite

show abstract

“…The influence of cephalic pressure on the fetal heart rate has been known since 1839 when Nagele 2 reported fetal bradycardia in response to manual compression of the fetal head through the maternal abdominal wall. Since that time, fetal bradycardia has been documented with forceps application and traction, 3 digital pressure on the skull, 4 and in association with uterine contractions. 5 Wolkoff and Flowers 6 observed irregularities in fetal aortic pressure in exteriorized fetal lambs when a cuff around the head was inflated to greater than 50 mm Hg.…”

Section: Discussionmentioning

confidence: 99%

Effect of Cephalic Pressure on Fetal Cerebral Blood Flow

O’Brien¹,

Davis²,

Grissom³

et al. 1984

Amer J Perinatol

View full text Add to dashboard Cite

During vaginal delivery, the fetus is exposed to a variety of stresses including pressure applied to the fetal skull. In order to study the effects of this stress on fetal homeostasis, we monitored the response to external cephalic compression applied to the acutely prepared near-term fetal lamb. In response to cephalic pressure, we noted initial bradycardia followed by sustained tachycardia. Mean arterial pressure and pulse pressure rose during cephalic pressure and gradually returned to baseline levels. Cerebral blood flow fell approximately 95% early in the period of compression. This fall in total cerebral blood flow was accompanied by a redistribution of cerebral flow. During this time, a smaller percentage of cerebral blood flow was found in the cortex and a greater percentage was directed to the brainstem.

show abstract

Response of Fetal Acid—Base Balance to duration of Second Stage of Labour

Roemer

Harms

Buess

et al. 1976

Intl J Gynecology & Obste

View full text Add to dashboard Cite

Data from 4081 vaginal deliveries (no caesarean sections) were analyzed retrospectively (IBM 730/158) with regard to duration of second and "final stage" of labour and fetal outcome (acid-base balance and apgar scores). The average duration of the two periods amounted to 22.8+/-29.6 and 9.9+/-7.8 min. Mean pH (UA) was 7.268+/-0.084 and the acidotic risk (pH less than 7.20, pH less than 7.10) 13.4 and 1.6% respectively. The distribution of the Apgar-scores after 1 min was assessed: 0-3: 1.7%, 4-6: 5.4%, 7-10: 92.9%. The dependance of the time variables from parity was studied. Two samples (N1=1755, N2=1098) of uncomplicated term pregnancies were chosen according to 7 clinical selection criteria differing only in the presence of cord entanglements at birth. The association between the two time variables and parameters of the fetal acid-base balance in cord blood was evaluated using rank correlation- and polynomial regression analysis. Highly significant correlations (tau) were found between the variable time and actual pH in blood of the umbilical artery and vein as well as pCO2, BEECF and HbO2 in the umbilical vein. The association however is not very close and thus clinically not of great importance. The deltapH (UA & UV) pro 60 min of second (and "final") stage of labour was computed and amounted to -0.024 (-0.087) in blood of the umbilical artery and -0.036 (-0.115) in blood of the umbilical vein and -0.017 (-0.062) (UA) and -0.032 (-0.120) units (UV) in the sample with and without apparent cord entanglements at birth respectively. The response of fetal acid-base balance to cord compression during second stage of labour was assesses: The acidotic risk (pH less 7.2) was doubled: 14.5% (7.7%) and AV-differences of all variables were "opened" if cordcoilings were observed. Apgar scores were not significantly different. Moreover, the association between AV-differences of each parameter and the variable time was studied: it became evident that with passage of time AV-difference is "closed" (-0.052 AV DpH/60 min "final stage" of labour, N=1098) indicating time related impairment of placental function. From these observations and data of the literature the conclusion is drawn that second stage of labour should not exceed 45 min in any patient. Furthermore it is concluded that in cases without signs of impending fetal distress it seems to be possible to wait more than 20 (Multipara) or 30 min (Primipara) duration of "final stage" without increased risk of fetal peril measured in terms of acidemia and clinical depression. This is valid only in term pregnancies with the possibility of continuous monitoring of FHR, in cases with normal uterine activity, uneventful course of first stage of labour and cooperative, vigorous patients. The indications for termination of delivery by vaginal operations in cases without impending fetal distress are discussed.

show abstract

Traction and compression forces exerted by obstetric forceps and their effect on fetal heart rate

Cited by 13 publications

References 3 publications

On the Mechanical Aspects of Shoulder Dystocia and Birth Injury

On the Mechanical Aspects of Shoulder Dystocia and Birth Injury

Effect of Cephalic Pressure on Fetal Cerebral Blood Flow

Response of Fetal Acid—Base Balance to duration of Second Stage of Labour

Contact Info

Product

Resources

About