Which physiological occurrence after birth indicates to the nurse that the placenta is beginning to separate from the uterus and is ready to be expelled?

Summary

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Problems in the third stage of labour include: overlong labour, haemorrhage, consequences of perineal tearing, retention of the placenta and membranes, exhaustion and deficiency of Blood and Qi, and problems of the newborn baby including low heart rate, asphyxia and vitamin K deficiency.

Acupuncture points used during the third stage of labour include:

general tonic: BL-17 and 18 or 20

shock: HT-7

retained placenta: CV-4 or CV-3 and BL-60, with LI-4 and LR-3 or SP-6.

Structural physiology and aetiology

The third stage of labour is the most hazardous for the mother and a mismanaged third stage can be fatal due to torrential haemorrhage. Therapists who are not midwives must discuss with the midwife to determine if it is safe or appropriate to use RZT to expedite the placental delivery. They must also understand fully the relevant physiopathology of the individual mother. The length of the third stage of labour will depend on whether it is managed physiologically or actively by the midwife. A natural third stage may last between 20 and 60 minutes, whereas a third stage for which the mother has received oxytocic medication is usually completed within 5 to 20 minutes, although there are fairly wide variations. If the third stage becomes prolonged (after about an hour) the most common reason is that the placenta has not yet separated; alternatively it may have separated and have not been expelled, perhaps being trapped behind the cervix or lying in the vagina.

Midwifery management of a retained placenta is dictated by whether the mother is bleeding and whether the uterus is well contracted. If the uterus is not well contracted there will be heavier vaginal bleeding than expected and this can rapidly lead to maternal collapse, if not attended to; the urgency of the situation is in direct correlation to the amount of blood loss and the reason for the haemorrhage. Other causes of bleeding include lacerations in the vagina or cervix, a full bladder preventing adequate uterine contraction or haematological conditions, such as severe anaemia or clotting disorders. If the mother is bleeding profusely it is entirely inappropriate for her to be treated with RZT.

Delivery of the Placenta and Fetal Membranes

The third stage of labor can be managed either passively or actively. Passive management is characterized by clamping of the cord once spontaneous pulsations have ceased and delivery of the placenta by gravity or spontaneously, without manipulation of the uterus or traction on the cord. Placental separation is heralded by lengthening of the umbilical cord and a gush of blood from the vagina, signifying separation of the placenta from the uterine wall. With passive management, uterotonic medications are not given until after delivery of the placenta. With active management of the third stage, uterotonic medication is administered shortly after delivery of the baby but prior to delivery of the placenta. Controlled umbilical cord traction and countertraction are used to support the uterus until the placenta separates and is delivered, followed by uterine massage after delivery of the placenta. Two techniques of controlled cord traction are commonly used to facilitate separation and delivery of the placenta: in the Brandt-Andrews maneuver, a hand pressed against the abdomen secures the uterine fundus to prevent uterine inversion, while the other hand exerts sustained downward traction on the umbilical cord; with the Créde maneuver, the cord is fixed with the lower hand, and while the uterine fundus is secured and sustained, upward traction is applied by a hand pressed against the abdomen. Care should be taken to avoid evulsion of the cord.

Implementation of active management strategies in the third stage of labor can significantly decrease the risk of postpartum hemorrhage. In a meta-analysis of three RCTs to compare active to expectant management, subjects randomized to active management were 66% less likely to have postpartum hemorrhage (estimated blood loss [EBL] ≥1000 mL; RR, 0.34; 95% CI, 0.14 to 0.87).122,123 Active management of the third stage of labor is recommended by ACOG District II and the California Maternal Quality Care Collaborative (CMQCC) as an integral component of multifaceted perinatal quality initiatives to reduce the severe maternal morbidity and mortality that results from obstetric hemorrhage. Active management of the third stage of labor specifically includes administration of dilute IV oxytocin or 10 units of intramuscular oxytocin after delivery of the fetus and prior to delivery of the placenta (ACOG District II). In the CMQCC obstetric hemorrhage protocol, additional components of the active management strategy include umbilical cord clamping at or prior to 2 minutes after delivery, controlled cord traction to facilitate delivery of the placenta, followed by fundal massage to facilitate uterine involution (CMQCC).

After delivery, the placenta, umbilical cord, and fetal membranes should be examined. Placental weight (excluding membranes and cord) varies with fetal weight, with a ratio of approximately 1 : 6. Abnormally large placentae are associated with such conditions as hydrops fetalis and congenital syphilis. Inspection and palpation of the placenta should include the fetal and maternal surfaces and may reveal areas of fibrosis, infarction, or calcification. Although each of these conditions may be seen in the normal term placenta, extensive lesions should prompt histologic examination. Adherent clots on the maternal placental surface may indicate recent placental abruption; however, their absence does not exclude the diagnosis. A missing placental cotyledon or a membrane defect suggestive of a missing succenturiate lobe also suggests retention of a portion of placenta and should prompt further clinical evaluation. Routine manual exploration of the uterus after delivery is unnecessary unless retained products of conception or a postpartum hemorrhage is suspected.

The site of insertion of the umbilical cord into the placenta should be noted. Abnormal insertions include marginal insertion, in which the cord inserts into the edge of the placenta, and membranous insertion, in which the vessels of the umbilical cord course through the membranes before attachment to the placental disc. The cord should be inspected for length; the correct number of umbilical vessels, normally two arteries and one vein; true knots; hematomas; and strictures. The average cord length is about 50 to 60 cm. A single umbilical artery discovered on pathologic examination is associated with an increased risk of fetal growth restriction and up to a 6.77-fold higher risk of one or more major congenital anomalies (OR, 6.77; 95% CI, 5.7 to 8.06).124-127 Therefore this finding should be relayed to the attending neonatologist or pediatrician, and any abnormalities of the placenta or cord should be noted in the mother's chart.

Third stage

The third stage of labor starts with fetal expulsion and ends with delivery of the placenta. Delivery of the placenta usually takes less than 30 minutes. The placenta is normally delivered on its own by uterine contractions. If the delivery is prolonged more than 30 minutes, the obstetrician is forbidden to manually pull the umbilical cord because it may cause uterine inversion and massive hemorrhaging (over 500 mL). A physiological hemorrhage up to 500 mL is expected during the delivery of the placenta. Uterine massage or oxytocin augmentation is recommended when placental delivery is delayed. Placenta accrete/increta/percreta (terms for when the placenta grows into myometrium or through the entire thickness of uterus) is often the preexisting condition for placental delivery difficulties. After delivery, the placenta will be visually inspected for its integrity. A placenta that has ruptured into pieces and retained in the uterus often causes massive uterine bleeding and subsequent intrauterine infections. Manual extraction from the uterus is often needed together with oxytocin for complete placental removal. Hysterectomy is recommended when all above attempts have failed. Some experts also include an additional stage of parturient recovery after delivery of the placenta. The parturient recovery refers to the uterus returning to the status prior to the pregnancy which is usually 6 months.

Disorders of the Third Stage

The third stage of labor is the period from delivery of the infant to the expulsion of the placenta. Separation of the placenta is the consequence of continued uterine contractions. Signs of placental separation include a gush of blood, lengthening of the umbilical cord, and change in shape of the uterine fundus from discoid to globular with elevation of the fundal height. The interval between delivery of the infant and delivery of the placenta and fetal membranes is usually less than 10 minutes and is complete within 15 minutes in 95% of deliveries.18 The most important risk associated with a prolonged third stage is hemorrhage; this risk increases proportionally with increased duration.19 Because of the associated increased incidence of hemorrhage after 30 minutes, most practitioners diagnose retained placenta after this time interval has elapsed. Interventions to expedite placental delivery are usually undertaken at this point.

Management of the third stage of labor may be expectant or active. Expectant management refers to the delivery of the placenta without cord clamping, cord traction, or the administration of uterotonic agents such as oxytocin. Active management consists of some combination of early cord clamping, controlled cord traction, and administration of a uterotonic agent. Oxytocin is the usual uterotonic agent given, but others have been used, such as misoprostol or other prostaglandin compounds. Compared with expectant management of the third stage, active management has been associated with a reduced risk of postpartum hemorrhage.20 Cochrane reviewers evaluated five trials that comprised 6486 women and compared active and expectant management. They confirmed that active management reduced the risk of maternal hemorrhage (relative risk [RR], 0.34; 95% CI, 0.14 to 0.87) but that significant increases in maternal diastolic blood pressure, afterpains, and analgesia use occurred as well. These adverse events may reflect the side effects of the various uterotonic medications used in different countries.

Some debate exists regarding the timing of oxytocin administration when active management of the third stage is practiced—that is, whether it should be after the placenta has delivered or after the anterior shoulder of the fetus has delivered. A randomized controlled trial (RCT) that included 1486 women compared the effects of oxytocin administration upon delivery of the anterior shoulder to administration after delivery of the placenta and showed no significant differences in blood loss or retained placenta between the groups.21

Retained placenta can usually be treated with measures such as manual removal or sharp curettage. Attempting manual removal can be performed under regional anesthesia or conscious sedation. If this is not successful, a sharp curettage can be performed under sonographic guidance. Prophylactic broad-spectrum antimicrobial agents are often administered when manual removal of the placenta is performed, although little evidence supports or refutes their use.22

VII. SOR A RECOMMENDATIONS

E. Active Third-Stage Management of the Placenta

In a Cochrane review, the active management of the third stage of labor when compared with expectant management was associated with reduced maternal blood loss, reduced postpartum hemorrhage of more than 500 ml, and reduced length of the third stage.5 Active management was associated with an increased risk for maternal nausea, vomiting, and hypertension (when ergotamine was used). No advantages or disadvantages were noted for the neonate. The reviewers conclude, “Routine active management is superior to expectant management in terms of blood loss, postpartum hemorrhage, and other serious complications of the third stage of labor. Active management should be the routine management of choice for women expecting to deliver a baby by vaginal delivery in a maternity hospital.”5

Abruption and retroplacental haemorrhage

The placenta is normally firmly adherent to the uterus at the basal plate until the third stage of labour. If abnormally premature separation occurs, either centrally or at the margin, the consequence is retroplacental haemorrhage, which most often tracks along the uteroplacental junction, resulting in vaginal bleeding, but is occasionally ‘concealed’, being retained retroplacentally. In addition, because separation has occurred, no functional uteroplacental circulation remains in these areas, with associated complete loss of functional capacity of the supplied villous areas, which may result in ischaemic necrosis (infarction) of the overlying placenta. It should be noted that although in some cases, unequivocal abnormal retroplacental haemorrhage with secondary overlying changes may be identified in the delivered placenta, in other cases, especially with marginal separation and vaginal bleeding, the delivered placenta may not demonstrate characteristic changes of abruption even in the presence of a typical clinical history. Ultrasound may occasionally diagnose chronic abruption,22 although often abruption is such an acute event in labour and delivery that clinical management and delivery override the utility of ultrasound imaging (Fig. 9.10).

Placebo-controlled studies

Oral misoprostol 400 micrograms has been compared with placebo in the routine management of the third-stage of labor. In this study shivering was a specific adverse effect of oral misoprostol in the puerperium (19% versus 5%; RR = 3.69; 95% CI = 2.05, 6.64) [15].

Adverse reactions to misoprostol have been evaluated in a large double-blind, randomized, placebo-controlled trial sponsored by the WHO in 15 clinics in 11 countries in 2219 healthy pregnant women requesting medical abortion after up to 63 days of amenorrhea [16]. They were given oral mifepristone 200 mg on day 1, followed by 800 micrograms either orally or vaginally on day 3. The oral group and one of the vaginal groups continued taking oral misoprostol 400 micrograms bd for 7 days and the vaginal-only group took oral placebo. Pregnancy-related symptoms abated in all the groups after misoprostol and breast tenderness was reduced by mifepristone. Oral misoprostol was associated with a higher frequency of nausea and vomiting than vaginal administration at 1 hour after administration. With oral misoprostol, diarrhea was more frequent at 1, 2, and 3 hours after administration. Misoprostol caused fever during at least 3 hours after administration in up to 6% of the women, the peak being slightly higher and later with vaginal administration. Lower abdominal pain peaked at 1 and 2 hours after oral misoprostol and at 2 and 3 hours after vaginal misoprostol. In the two groups of women who continued to take misoprostol, 27% had diarrhea between the misoprostol visit and the 2-week follow up visit, compared with 9% in the placebo group.

Delivery Care

As with antenatal care, delivery care is provided at two levels. At the community level, routine delivery care is given to all women having uncomplicated pregnancies and deliveries; referral to a higher-care center is sought at the first sign of any complication. The challenges of delivery care in developing countries center around the safety of childbirth, whereas in countries where safety is accepted as the norm, the issues are more around choice and giving every woman the right to choose how and where they give birth.

Basic delivery care consists of the following:

Clean birthing technique;

Active management of the third stage of labor;

Early cord clamping;

Controlled cord traction;

Oxytocics on the birth of the anterior shoulder;

Essential newborn care.

In addition to this, the United Nations Population Fund (UNFPA) also recommend that the following elements be available at the primary level of care:

Parenteral antibiotics;

Parenteral oxytocic drugs;

Parenteral sedatives/anti-convulsants (e.g., magnesium sulfate) for pre-eclampsia/eclampsia;

Facilities for vacuum or forceps delivery;

Facilities for manual removal of placenta;

Facilities for removal of retained products of conception.

These elements form what is termed ‘basic essential obstetric care.’ Over and above these, the services constitute ‘comprehensive essential obstetric care,’ usually delivered at a district hospital level, if facilities are available for:

Cesarean section;

Blood transfusion.

At the tertiary level, consultant-led maternity units providing a full range of services to women with high-risk pregnancies should have available:

Obstetric/midwifery specialist services;

Anesthetic services and access to adult intensive care;

Neonatal resuscitation facilities and access to neonatal intensive care;

Round-the-clock radiology and imaging;

Round-the-clock laboratory facilities;

Blood transfusion.

It is also recommended that maternity services have a holistic approach providing a fully integrated childbirth service tailored to the individual needs of women, preferably with continuity of care.