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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the period 1988-1993 the route of delivery in 482 infants with birth weight > or = 4000 grams was studied. Normal vaginal delivery occurred in 396 (82.1%) cases, vacuum extractor in 8 (1.6%) cases and caesarean section in 78 (16.1) cases. Elective induction of labor with oxytocin and/or amniotomy was carried out in 25 cases of macrosomia. Perinatal death and shoulder dystocia never occurred in these macrosomic babies, but clavicles abruption (27 cases), cephalohaematoma (2 cases), shoulder-bladehaematoma (1 case) and birth brachial palsy (1 case) were observed. Because, in our experience, elective induction of labor increased the operative delivery rate (caesarean section, vacuum extractor), we conclude that mothers with macrosomic fetuses can safely be managed expectantly unless there is a indication for induction or caesarean section.
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PMID:[Fetal macrosomia and mode of delivery]. 763 May 13

To investigate the effect of initiating labor by oxytocin infusion on the outcome of delivery in cephalic presentation, the dystocia rate and final modes of delivery were analyzed in 3,090 cases of head presentation using oxytocin infusion and 2,982 cases with spontaneous onset of labor as control group. The results showed that 562 of the cases using oxytocin developed cephalic dystocia, a rate of 18.2%, while 371(12.4%) of the control group had dystocia. Besides, cephalic dystocia, rates of episiotomy, vacuum extraction and cesarean section were all significantly higher in the oxytocin group than those in the control (P < 0.005). Data also showed that the higher dosage, the more frequency and the longer time of pitocin infusion the higher the rate of dystocia.
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PMID:[Planned delivery by oxytocin infusion in relation to cephalic dystocia]. 795 48

The effects of cyanide and nitrogen on contractile activity in rat uteri was investigated. Hypoxia significantly reduced contractile activity produced either spontaneously, or by application of carbachol (50 mumol l-1) or oxytocin (20 nmol l-1) in preparations from pregnant and nonpregnant rats. Hypoxia had, however, significantly smaller effects on agonist-evoked than on spontaneous contractions. Application of agonists under hypoxic conditions restored some degree of force to preparations in which spontaneous activity had been abolished. This result suggests that the loss of spontaneous contractions was, in part, due to decreased excitability of the uterus, rather than to an impairment of the contractile machinery. Hypoxia significantly decreased the force produced by depolarization of the uterus. The effects of hypoxia on contraction produced by agonists or depolarization were not significantly different, suggesting that a similar mechanism may maintain force under these conditions, and that this mechanism does not occur during spontaneous activity. Lowering the external Ca2+ concentration to 0.1 mmol l-1 resulted in production of significantly less force in the presence or absence of agonist. The ability of hypoxia to decrease agonist-induced force was found not to be due to the intracellular acidification it produces. It was concluded that uterine hypoxia may decrease uterine contractions in vivo and a possible role in dystocia during labour was discussed.
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PMID:Effects of hypoxia on force produced by agonists and depolarization and arising spontaneously in the rat uterus. 810 37

The intrapartum background of fetal injuries associated with shoulder dystocia was studied retrospectively on the basis of 107 relevant medical records. Intrapartum use of oxytocin and protraction-arrest disorders, the latter particularly during the second stage of labor, were frequent findings. Delivery was effected by forceps or vacuum extraction in almost one-half of the cases. Shoulder dystocia related permanent fetal impairments were closely connected to macrosomia. The fetal weight was > or = 4,000 grams in about 75% and > or = 4,500 grams in approximately 40% of the instances. Permanent hypoxic or traumatic cerebral damage was documented in almost one-third of the cases. The data indicate that in connection with coincidental neonatal afflictions, the birth weights of the fetuses are higher and instrumental extractions are more frequent than in relation to all clinically diagnosed cases of shoulder dystocia.
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PMID:Common intrapartum denominators of shoulder dystocia related birth injuries. 814 78

The diagnosis of dystocia is currently a leading indication for cesarean delivery in the United States. Efforts to identify abnormal labor and correct abnormal contraction patterns, fetal malposition, and inadequate expulsive efforts may help eliminate many cesarean deliveries without compromising the outcome for either mother or fetus. Cesarean deliveries for dystocia should not be performed in the latent phase of labor or in the active phase of labor unless adequate uterine activity has been achieved. Cesarean deliveries in the second stage of labor may be reduced if, after reevaluation of the fetus and pelvis, there is potential for correction of uterine forces with oxytocin, correction of malposition, operative vaginal delivery, or safe continued observation. Use of either a low-dose or high-dose oxytocin regimen is appropriate for augmentation of labor. Regardless of the regimen used, oxytocin should be administered by trained personnel capable of responding to complications. A physician who has privileges to perform cesarean delivery should be readily available.
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PMID:ACOG technical bulletin. Dystocia and the augmentation of labor. Number 218--December 1995 (replaces no. 137, December 1989, and no. 157, July 1991). American College of Obstetricians and Gynecologists. 873 11

The aim of this study was to measure oxytocin receptor concentration in myometrial tissue from term pregnant women with normal and dysfunctional labor and to relate this concentration to the progress of labor and to the levels of estradiol and progesterone in the same myometrium. Myometrial biopsies were obtained from 50 term pregnant women undergoing cesarean section. The patients were categorized as follows: not in labor, normal labor, successful oxytocin-augmented labor, and oxytocin-resistant labor. Specific binding of [3H]oxytocin to high-affinity sites in membrane preparations from myometrial tissues was determined. Estradiol and progesterone were assayed using tritiated steroids with a sensitive radioimmunoassay technique. Oxytocin receptor density was significantly lower in oxytocin-resistant labor compared to successful oxytocin-augmentated labor (P < 0.04) and to spontaneously active normal labor (P < 0.02). Oxytocin receptor concentration was also significantly lower in non-labor patients compared to normal spontaneous labor (P < 0.01), and successful oxytocin-augmented labor (P < 0.02). There was a positive relationship between the progress of cervical dilatation (cm/h) and oxytocin receptor density in the myometrium (r = 0.408, P < 0.025). The concentration of progesterone and estradiol in the pregnant myometrium did not differ in patients with different types of labor or with the state of uterine contractile activity. Our results suggest that individual myometrial sensitivity is an important determinant of the response to administered oxytocin in humans. Furthermore, myometrial oxytocin receptor expression in vivo seems not be related to ovarian steroid concentration in the myometrium. The low oxytocin receptor density in oxytocin-resistant dystocia needs further investigation.
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PMID:Myometrial steroid concentration and oxytocin receptor density in parturient women at term. 877 95

The purpose of this study was to investigate the elemental composition of myometrial cells from term parturient women with normal and dysfunctional labour. Myometrial biopsies were obtained from forty-four term pregnant women undergoing Cesarean section. The patients were categorized according to uterine activity as follows: before labour, normal labour, labour successfully augmented by oxytocin, oxytocin-resistant labour, and labour arrested by terbutaline. X-ray microanalysis of freeze-dried sections (16 mu m thick) of the myometrium was carried out. An increase in intracellular phosphorus level (p < .01) was noted in the normal labour group compared to before labour. In patients with normal labour, higher phosphorus (p < .009) and potassium (p < .005) were found compared to oxytocin resistant labour. Patients with oxytocin resistant labour had lower intracellular potassium (p < .0006) and phosphorus (p < .02), and higher chloride (p < .05) and sodium (p < .03) compared to levels found in patients who responded to oxytocin treatment. In dysfunctional (oxytocin-resistant) labour the ion distribution in the myometrial cells might be disturbed. The reduced level of potassium and phosphorus together with the high sodium and chloride levels found in patients with oxytocin resistant labour may be connected to an impairment in sodium-potassium pump and muscle dysfunction, clinically diagnosed as dystocia.
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PMID:X-ray microanalysis of myometrium in parturient women at term. 892 28

The aim of this study was to quantify gap junction expression in the human myometrium in relation to progesterone and oestradiol concentrations, and to establish whether oxytocin-resistant dystocia is due to an abnormality in gap junction expression. Three groups of patients were investigated: (i) before labour (at term), (ii) normal labour and (iii) oxytocin-resistant dystocia (eight patients per group). For each patient, the concentrations of oestradiol and progesterone in maternal blood and in myometrial tissue were measured, and the number and area of immunostained connexin43 gap junctions per unit volume of tissue determined by quantitative analysis of digital images obtained by confocal microscopy. No significant difference in connexin43 gap junction content was observed between the three patient groups. When all groups were pooled, there was a significant positive correlation (P < 0.05) between the quantity of immunolabelled gap junctions and the oestradiol:progesterone ratio, but there was no significant difference in this correlation between the groups. Gap junction immunolabelling was not correlated with the progesterone or oestradiol concentration in the maternal blood or the myometrium. These data suggest that in human myometrium: (i) dystocia is not due to a reduced level of immunodetectable connexin43 gap junctions, (ii) onset of labour is not associated with a sudden increase in immunodetectable gap junction protein and (iii) gap junctions can be expressed in the presence of high progesterone concentrations.
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PMID:Quantitative immunoconfocal analysis of human myometrial gap junction connexin43 in relation to steroid hormone concentrations at term labour. 904 22

The suggestions offered in this article represent an effort to reduce the incidence of cesarean delivery for dystocia while maintaining a safe course to vaginal birth. Avoiding difficult labor induction in which a compelling indication is lacking, providing prompt and effective oxytocin therapy of arrested first stage labor, and liberalizing the use of oxytocin therapy in selected cases of second-stage arrest are emphasized. With the widening use of conduction analgesia, indicated operative vaginal delivery has an increasingly important role in tempering cesarean birth rates. Operative vaginal delivery can play an effective role only when strict conditions to insure its safety are met.
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PMID:Managing difficult labor: avoiding common pitfalls. 932 32

Induction of labor has increased from 9% to 18% of all U.S. deliveries in recent years. Several useful oxytocin induction protocols are available, both from the ACOG Practice Bulletin #10 and institutional sources. Higher-dose protocols tend to result in fewer cesarean deliveries for dystocia but more "fetal distress." There is no consensus as to which protocol is best, and the clinician is advised to understand the trade-offs involved and how those trade-offs could relate to the clinician's local situation. Given the availability now of prostaglandin agents for induction with an unfavorable cervix, the advantage of less hyperstimulation in low-dose oxytocin protocols may become increasingly important. The most important risks include hyperstimulation (frequent but usually brief and well-tolerated), failed induction (occasional and important), and uterine rupture in some studies (rare but dangerous). Pain was not a sensitive indicator of uterine rupture in a large 1989 study. Fetal heart rate changes were much more likely to herald uterine rupture in that study. Oxytocin's greatest weakness is that some patients will not respond well to it, especially with marked cervical unfavorability. However, given an individual patient whose uterus will respond adequately to this drug, oxytocin has the advantage of short half-life and the option for prompt cessation if desired. Intrauterine pressure catheters with oxytocin usage are usually well-worth their minor risks. Current ACOG literature lists induction of labor in the setting of one or more previous low-transverse cesarean deliveries as necessitating "special attention" and "close patient monitoring." The well-informed clinician will be familiar with the issues involved.
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PMID:Oxytocin for labor induction. 1094 53


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