Third Stage Of Labor Research Paper

Preparation

Commence preparations for the third stage of labor well before delivery of the baby. In the antepartum period, discuss with the patient and her partner their preferences for the delivery process with an open dialogue regarding any risk factors present and what implications they might have for the woman. Thoroughly discuss any concerns or variations from accepted practice. It is important that the patient understand the implications and potential risks involved if management options are limited.

Physiological versus active management

The controversy surrounding third-stage management exists between authorities who advocate the physiological, or expectant, approach and those who advocate the active approach. The basic components of the two management strategies are outlined in Table 1.

Table 1. Physiological Versus Active Management (Open Table in a new window)

. . .Physiological ManagementActive Management
Uterotonic None or after placenta delivered With delivery of anterior shoulder or baby
Uterus Assessment of size and tone Assessment of size and tone
Cord traction None Application of controlled cord traction* when uterus contracted
Cord clamping Variable Early
*Gentle downward cord traction with countertraction on the uterine body

 

Proponents of physiological management argue that the natural processes outlined above promote normal separation and delivery of the placenta and lead to fewer complications. If PPH develops, it may be effectively managed with available techniques and drugs. Proponents express concern that active management increases PPH and uterine inversion rates due to cord traction and increases the risk of retained placenta due to entrapment caused by uterotonic agents. Delivery of the placenta occurs by uterine contractions and maternal expulsive efforts, and cord traction is prohibited. Concern also exists regarding the case of an undiagnosed second twin if uterotonics are routinely used at the time of delivery.

Advocates of active management argue that administering prophylactic uterotonic agents promotes strong uterine contractions and leads to faster retraction and placental delivery. This decreases the amount of maternal blood loss and the rate of PPH. [7] They also argue that the more effective uterine activity leads to a reduction in the incidence of retained placenta.

Gentle cord traction is only applied when the uterus is well contracted, and the uterus is manually controlled above the level of the symphysis with countertraction (Brandt-Andrews maneuver). This maneuver is referred to as controlled cord traction (CCT). [7] Cord traction must never be applied in the absence of countertraction and is applied in the axis of the birth canal. Advocates point out that an undiagnosed second twin is an increasingly rare problem and that clinical assessment in labor and following delivery of the first baby can establish the diagnosis before uterotonic administration. [8]

Several large, randomized, controlled trials have addressed the question of whether physiological management or active management is preferable. These trials have consistently shown that active management leads to several benefits compared to physiological management. These trials use 1 of 3 uterotonic agents: ergonovine, oxytocin, or Syntometrine, (a combination of ergometrine and oxytocin).

Seven trials have been the subject of a meta-analysis in the Cochrane Library, [9] in which active management showed a reduction in the average risk of maternal primary hemorrhage (more than 1000 mL) at birth and of maternal hemoglobin less than 9 g/dL following birth. No difference was found in the incidence of admission to neonatal units or of infant jaundice requiring treatment.

The authors also reported a significant decrease in primary blood loss greater than 500 mL with active management, as well as a decrease in mean maternal blood loss at birth, maternal blood transfusion, and therapeutic uterotonics. Significant increases in maternal diastolic blood pressure, vomiting after birth, after pains, and analgesia use from birth to discharge were reported. Decrease in the infant's birthweight was also found with active management. [9]

Choice of uterotonic agent

Randomized trials have examined the use of oxytocin alone, ergot alone, misoprostol alone, and Syntometrine in active management protocols compared with physiological management. Trials have also compared the various uterotonics to each other in active management protocols and have been the subject of meta-analyses in the Cochrane Library.

Trial findings suggest that while Syntometrine may have a slight advantage in reducing PPH by 500 mL or more (RR, 0.74; 95% CI, 0.65-0.85) and possibly by 1000 mL or more (RR, 0.79; 95% CI, 0.59-1.06), oxytocin alone is very effective and does not have the adverse effect profile associated with preparations containing ergot. [10] Trial results suggest that increasing the intramuscular dose of oxytocin from 5 IU to 10 IU increases the effectiveness of oxytocin. An additional randomized controlled trial found that infusing 80 U or 40 U, as opposed to the usual 10 U, did not decrease postpartum hemorrhage overall; however, it did decrease the need for additional oxytocin infusion and of the risk of a decline in hematocrit of 6% or more. [11] It has also been suggested that initial or continued intravenous administration of oxytocin increases effectiveness. Do not administer more than 5 IU of oxytocin as a bolus intravenous injection.

Trials using oxytocin alone showed reduced rates of manual removal of the placenta, whereas those using ergot preparations demonstrated increased rates. The slight trend of increased manual removal mentioned in the Cochrane meta-analysis above was entirely due to the results of the single trial that used intravenous ergot. [12] The increases in nausea, vomiting, and blood pressure are all exclusively observed in the trials using ergot preparations. [13]

The likely explanation for these differences is that ergot preparations act systemically on smooth muscle, whereas oxytocin is specific for uterine smooth muscle. Oxytocin causes increased contraction strength and frequency, but the uterus does not undergo tetanic contraction, as is the case with an ergot. Studies undertaken by the WHO also favor oxytocin because it is more stable when exposed to heat and light compared to ergot preparations. This makes oxytocin more useful in settings where storage capabilities, especially refrigeration, may be an issue. A potential benefit of ergot preparations is a longer duration of action. Trials have been performed using a synthetic oxytocin analogue, carbetocin, which has a prolonged action. [14, 15] A Cochrane review concluded that carbetocin should not be used as a first-line agent in place of other proven uterotonic agents. [16] Carbetocin is not available in the United States.

Misoprostol has shown early promise in the treatment of PPH. Additionally, its low cost, pill form, and heat stability make it a potentially excellent agent for prophylaxis in the third stage of labor. Unfortunately, randomized trials have shown it to be inferior to injectable uterotonics and to not be significantly more effective than placebo. [17] Adverse effects, such as shivering and fever, are common; in regimens using higher doses, nausea, vomiting, and diarrhea occur more frequently. [18] Clearly, the presence of prostaglandin-induced pyrexia and shivering in the postpartum period may lead to confusion in the diagnosis of sepsis.

Misoprosotol may still be a useful uterotonic in some settings. A recent trial in a low resource setting showed it to be as effective as intramuscular oxytocin following vaginal delivery. [19] Many have also pointed out that in low resource settings, even if misoprostol is somewhat less effective than injectable uterotonics, that it’s low cost and ease of storage and use should mandate it’s widespread availability. Another trial has shown that buccal misoprostol given at the time of cesarean section reduces the need for the use of additional uterotonic agents. [20] Other prostaglandins have not been sufficiently investigated to warrant recommending them over oxytocin, and they all elicit more adverse effects.

Early suckling or nipple stimulation is thought to increase uterine contractility; however, a trial involving 4227 women did not suggest that early suckling reduced the rate of PPH of 500 mL or more (odds ratio [OR], 0.93; 95% CI, 0.75-1.17) or other adverse outcomes. [21] Early suckling should still be encouraged because it promotes bonding and breastfeeding and may help maintain uterine tone.

Mode of uterotonic administration

Active management protocols involve administering a uterotonic agent with the delivery of the anterior shoulder or with the completed delivery of the newborn. In practical terms, these 2 events are separated by only seconds, and the distinction is unlikely to be important. Importantly, the anterior shoulder must be delivered prior to uterotonic administration. In the event of shoulder dystocia, strong uterine contractions serve to further impact the anterior shoulder, make curative maneuvers more difficult, and decrease already compromised fetal oxygenation. Immediately following delivery, the fundal position and size of the uterus is determined. This serves to exclude the presence of a second baby and to establish the baseline size of the uterus.

Avoid uterine massage, or "fundus fiddling," as it has been called, before placental delivery. Draw up the uterotonic before the delivery in order to facilitate rapid administration. Typically, at vaginal delivery, a dose of 10 IU of oxytocin is administered intramuscularly. In patients with intravenous access in place, 10-20 IU is placed in 500-1000 mL of crystalloid and run quickly. With cesarean deliveries, 5 IU is often administered as an intravenous bolus, followed by a similar infusion. Some authorities advocate the same practice for vaginal deliveries.

Higher-dose infusions may somewhat decrease the risk of subsequent atony, but they result in more fluid retention. [22] Keep in mind the adverse effects of oxytocin, although they are rarely problematic in this setting. Administer ergot-containing preparations intramuscularly. The usual dose of ergonovine is 0.2-0.25 mg, although some trials have used 0.5 mg. (Syntometrine contains 0.5 mg of ergonovine with 5 IU of oxytocin.) Avoid ergot preparations in patients with hypertension, history of migraine, and, possibly, Raynaud phenomenon.

Routine administration of a uterotonic following delivery of the placenta using physiological management has not been shown to provide the same benefits observed in active management. [8] A trend in the reduction of PPH is present, but the effect size is less than that observed with active management. The need for therapeutic uterotonics may be reduced compared with no uterotonic following placental delivery. Findings of a much more recent trial suggest that if CCT is used, the timing of oxytocin administration (with presentation of the anterior shoulder or immediately following placental delivery) does not alter the rate of PPH, manual removal, or other outcomes. [23] There was a trend to less PPH and the need for manual removal was not increased in the early oxytocin administration group. Both of these findings support the practice of administering oxytocin with delivery of the anterior shoulder as in true active management.

Cord management

Cord traction is applied during active management only when countertraction is applied. Countertraction is performed by trapping the body of the uterus above the symphysis pubis and directing it cephalad and back. Traction is applied in a continuous, downward manner only when the uterus is well contracted. A delay occurs between the administration of the uterotonic and good contraction of the uterus. Several issues must be considered during this interval.

Most active management protocols include early clamping of the cord. However, of the 3 active management components, this practice seems the least important in conferring the observed benefits. Early cord clamping may be indicated in order to facilitate newborn assessment or resuscitation. Barring these indications, rushing to clamp the cord is unnecessary because traction cannot be applied until the uterus is well contracted. Delaying cord clamping until the cord is pulseless, usually 2-4 minutes, results in higher hemoglobin and hematocrit values in the newborn and, possibly, lower levels of early childhood anemia and greater iron stores. [24, 25] These effects are probably more profound in preterm infants and may result in fewer transfusions in the neonatal period [26] and lower rates of neonatal intraventricular hemorrhage and sepsis. [27]

Balance these potential benefits against the potential for an increase in newborn polycythemia and jaundice; however, these risks may be overstated. Recent reviews have yielded conflicting results with regard to adverse effects but not potential benefits. One meta-analysis suggested that delayed cord clamping did not result in any increase in respiratory distress or statistically significant increases in bilirubin levels or use of phototherapy in newborns. [28] However, a second meta-analysis did show an increased risk of jaundice requiring phototherapy (RR 0.59, 95% CI, 0.38-0.92; 5 trials of 1,762 infants). [29]

Regardless, holding the newborn below the level of the placenta or "milking" the cord toward the baby to exaggerate this transfer is discouraged. Parents may have a preference regarding the timing of cord clamping and the position of the baby immediately following delivery. Barring any contraindication, follow such preferences. The issues around the timing of cord clamping have not been extensively studied, and the practice of early cord clamping is not based in strong evidence. This observation is especially true with respect to newborn implications.

Given the current evidence, the recommendation to give oxytocin with delivery of the anterior shoulder and then to wait 1-2 minutes before clamping and dividing the cord if the baby appears well, does not seem unreasonable. [30]

In the instance of a nuchal cord, attempt to avoid clamping and cutting the cord before delivering the baby. This may be accomplished by passing the loop(s) of cord from back to front over the baby's head or by delivering the baby through the loop of cord. While these maneuvers are preferable and usually successful, clamps must be ready in case the maneuver fails or the cord is inadvertently torn. Clamping and dividing a nuchal cord is most problematic when it is followed by a shoulder dystocia. The divided cord prevents what little placental support that would have been present from reaching the baby. Additionally, no intrauterine resuscitation can occur if the clinician resorts to a Zavanelli (cephalic replacement) maneuver.

At the time of cord clamping, the cord should be singley clamped; a second clamp should then be placed after the blood has been milked from the segment of cord between the 2 clamps. The cord is then divided between the clamps in a relatively bloodless manner. Place the clamps a reasonable distance from the newborn so that the newborn caregivers can place the cord tie or disposable cord clamp at the appropriate place. Attempting to immediately place the cord clamp or tie on the newborn is generally not time well spent. A hastily placed clamp may need to be replaced if the cord stump is too long or, worse, may interfere with access to the cord vessels or lead to later problems with the site if placed too close to the abdominal wall. This practice also minimizes the risk of damaging vital structures in the rare case of abnormalities at the cord insertion site.

Cord blood may be taken following cord clamping and division if no signs of placental separation are observed. Practices vary, but commonly taken specimens include those for a CBC count, group and screen, and, possibly, blood gas analysis. Some physicians choose to draw the samples from an isolated piece of cord or from the delivered placenta and cord following the third stage. The emergence of fetal stem cell harvesting has created new issues in this area. This practice should not compromise the care of the mother or the newborn, and the caregiver must not become distracted by the procedure at this critical time. Ideally, an additional designated member of the team can perform this procedure. Cord blood can be efficiently collected following delivery of the placenta by having an assistant hold the placenta above the level of the cord.

Cord blood harvesting (CBH) should not delay uterotonic administration. In fact, uterotonics may increase the amount of blood harvested due to placental compression. CBH has not been shown to increase the risk of PPH; however, there was a trend to increased PPH in a recent meta-analysis. (RR 1.22, 95% CI, 0.96-1.55, 5 trials including 2,236 women). [29] Further research on the optimal and safest techniques for CBH at both vaginal and cesarean deliveries should be undertaken.

The potential benefit of completely draining the cord of blood is unclear. This measure would be performed after taking cord blood samples or setting aside a clamped cord segment for sampling. Some investigators believe that this practice promotes placental separation. Limited evidence supports this belief. [31, 32, 33, 34] Before the advent of Rh D immune globulin prophylaxis, interest existed regarding whether fetomaternal bleeding was reduced by the maneuver, which might therefore reduce the risk of maternal sensitization. Findings from small, nonrandomized studies from the early 1970s suggested a reduction, but further work has not been performed. [35] Draining the cord reduces the potential for caregivers being splashed with blood in the rare case of cord avulsion; however, the routine exposure to this blood during and after drainage may also carry a slight risk.

Trials that have examined administering uterotonics at the time of delivery but then taking an expectant approach to placental delivery suggest that some reduction in PPH rates may occur, but that the effect is less than with an active management protocol. Additionally, there is a trend toward an increase in retained placenta and no reduction in the number of patients receiving blood transfusions.

A single trial examined the effect of CCT with and without the administration of oxytocin upon delivery of the baby. The results suggest that CCT alone does not reduce the incidence of PPH or severe PPH. Another trial, discussed earlier, found that CCT used in conjunction with oxytocin immediately following placental delivery resulted in outcomes similar to those with true active management. [23] A third trial showed that true active management resulted in lower PPH rates when compared with CCT followed by oxytocin at the time of placental delivery. [36]

Some authors advocate the use of uterine massage and CCT if a uterotonic agent is not available for prophylactic use. No good evidence supports this recommendation and many are strongly against any form of fundus fiddling. The risks of cord traction when the uterus is not well contracted are substantial.

Uterine assessment

The fundus is assessed immediately following delivery of the baby, thus excluding an undiagnosed twin and giving a baseline fundal height. A uterotonic, preferably oxytocin, is then administered. If twin pregnancy has been previously excluded, as is usually the case in the developed world, a uterotonic may be administered prior to fundal assessment. The fundus is periodically assessed to determine when uterine contraction occurs, at which time CCT is applied.

Oxytocin-induced contractions are periodic; when the uterus relaxes, stop CCT until the next contraction. The direction of cord traction mirrors that for an instrumental delivery from the mid cavity because the placenta must follow the same path through the birth canal. Traction should initially be downward, then parallel to the floor, and finally upward as the placenta delivers. Do not perform uterine massage before delivery of the placenta, and never apply downward fundal pressure.

Periodic assessment of the uterus also serves to detect the signs of placenta separation and to assess whether an atonic uterus is becoming distended with blood. If uterine signs of placental separation are present, the cord has lengthened, but no gush of blood has occurred and the placenta remains undelivered, the placenta may be detached but remain at the level of the internal os. Blood trapped behind the placenta in this position can distend the uterus, preventing further retraction and increasing the likelihood of PPH. Gently running a finger up the cord to feel if the insertion site and the placenta are at the cervix may be helpful. If the placenta is at this level, it may be delivered with the aid of maternal expulsive effort or slightly more aggressive CCT.

Placental delivery

The placenta usually presents with the cord insertion and the fetal side of the placenta. Ensure that only the placenta is delivering because a uterine inversion has a similar (although more massive) appearance. Fortunately, most clinicians never experience this rare complication. If inversion is encountered, leave the placenta attached and promptly replace the uterus using the "last out, first in" principle as discussed in Uterine inversion.

The membranes trail the placenta, and measures to prevent them from tearing include slowly rotating the placenta about the insertion site as it descends or grasping the membranes with a clamp. Assessment of the placenta and membranes as they are being delivered provides a good idea of whether they are intact, but delay detailed examination until it is clear that the uterus is well contracted and bleeding is minimal.

Uterine exploration

Routine exploration of the uterus is no longer recommended for normal deliveries or those following previous cesarean delivery. The procedure is uncomfortable and probably increases the risk of complications, especially infectious morbidity. Exploration is justified in patients with bleeding originating high in the genital tract despite the uterus being well contracted. The cervix should be visualized after all forceps deliveries.

Fourth stage

The delivery of the placenta does not mark the end of risk for bleeding; on the contrary, the uterus may have a tendency to relax slightly following placental delivery, and this is the point at which problems most commonly begin. The prophylactic use of a uterotonic helps ensure that the uterus continues to contract and retract, but the caregiver must remain vigilant. Nearly every clinician can recount an episode of being briefly distracted at this point only to have his or her attention abruptly reclaimed by a cascade of blood.

Following delivery of the placenta, palpate the abdomen to assess and monitor uterine tone and size. At this point, uterine massage is reasonable, especially if concern exists regarding uterine tone. Uterine massage can be uncomfortable; therefore, explain the rationale to the patient. If intravenous access is in place, a continuous infusion of oxytocin for a period following delivery is reasonable. If ongoing concerns exist regarding uterine tone, then start an oxytocin infusion or administer a longer-acting agent. Encourage early breastfeeding to promote endogenous oxytocin release.

Once good, sustained uterine tone has been established, the presence of any bleeding from the lower genital tract can be assessed. If bleeding is minimal, assess the placenta for completeness. (First, manage any significant lower genital tract bleeding.) Assessment of the placenta before repair of an episiotomy or any lacerations is advised in order to avoid disrupting these repairs if uterine exploration or instrumentation is necessary.

Examine the fetal side for any evidence of vessels coursing to the edge of the placenta and into the membranes. Such vessels suggest the presence of a succenturiate placental lobe. If the vessels are torn and the lobe is not present, it is quite likely retained and may subsequently lead to bleeding or infection. Turn the placenta over and lay it on a flat surface to examine the maternal side, with special attention to any defect suggestive of a missing, retained cotyledon. Note other abnormalities of the placenta, and consider whether pathological examination is warranted. Cultures of the placenta seem to be of little value in the diagnosis or management of fetal or uterine infection.

The lower genital tract is examined using adequate lighting and appropriate positioning and analgesia. Any episiotomy or lacerations are repaired. During this time, note any ongoing blood loss from the upper vagina, and, if present, reassess uterine tone and size. Closely observe the patient for blood loss over the next hour, with skilled assessment of uterine tone and size at least every 15 minutes. The duration of close observation and the presence and/or length of any uterotonic administration depends on the risk factors present and the clinical course.

Abstract

OBJECTIVE--To compare the effects on fetal and maternal morbidity of routine active management of third stage of labour and expectant (physiological) management, in particular to determine whether active management reduced incidence of postpartum haemorrhage. DESIGN--Randomised trial of active versus physiological management. Women entered trial on admission to labour ward with allocation revealed just before vaginal delivery. Five months into trial high rate of postpartum haemorrhage in physiological group (16.5% v 3.8%) prompted modification of protocol to exclude more women and allow those allocated to physiological group who needed some active management to be switched to fully active management. Sample size of 3900 was planned, but even after protocol modification a planned interim analysis after first 1500 deliveries showed continuing high postpartum haemorrhage rate in physiological group and study was stopped. SETTING--Maternity hospital. PARTICIPANTS--Of 4709 women delivered from 1 January 1986 to 31 January 1987, 1695 were admitted to trial and allocated randomly to physiological (849) or active (846) management. Reasons for exclusion were: refusal, antepartum haemorrhage, cardiac disease, breech presentation, multiple pregnancy, intrauterine death, and, after May 1986, ritodrine given two hours before delivery, anticoagulant treatment, and any condition needing a particular management of third stage. INTERVENTIONS--All but six women allocated to active management actually received it, having prophylactic oxytocic, cord clamping before placental delivery, and cord traction; whereas just under half those allocated to physiological management achieved it. A fifth of physiological group received prophylactic oxytocic, two fifths underwent cord traction and just over half clamping of the cord before placental delivery. ENDPOINT--Reduction in incidence of postpartum haemorrhage from 7.5% under physiological management to 5.0% under active management. MEASUREMENTS AND MAIN RESULTS--Incidence of postpartum haemorrhage was 5.9% in active management group and 17.9% in physiological group (odds ratio 3.13; 95% confidence interval 2.3 to 4.2), a contrast reflected in other indices of blood loss. In physiological group third stage was longer (median 15 min v 5 min) and more women needed therapeutic oxytocics (29.7% v 6.4%). Apgar scores at one and five minutes and incidence of neonatal respiratory problems were not significantly different between groups. Babies in physiological group weighed mean of 85 g more than those in active group. When women allocated to and receiving active management (840) were compared with those who actually received physiological management (403) active management still produced lower rate of postpartum haemorrhage (odds ratio 2.4;95% CI1.6 to 3.7). CONCLUSIONS--Policy of active management practised in this trial reduces incidence of postpartum haemorrhage, shortens third stage, and results in reduced neonatal packed cell volume.

0 Thoughts to “Third Stage Of Labor Research Paper

Leave a comment

L'indirizzo email non verrà pubblicato. I campi obbligatori sono contrassegnati *