Fourth Stage of Labour

Fourth stage of Labour

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 obstetrician 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. If this is the case, 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.

Complications 

Postpartum hemorrhage 

The most common complication of the third stage of labor is PPH. Active management of the third stage has clearly been shown to reduce the frequency of this complication and therefore most likely has a positive impact on maternal mortality and longer-term morbidities such as anemia. 

Retained placenta 

Retained placenta is defined in various ways. The most common definition is retention of the placenta in utero for more than 30 minutes. This is an arbitrary definition, and management is greatly influenced by the clinical assessment of whether significant bleeding is occurring. This bleeding may be visible or may manifest only by the increasing size of the uterus. In the absence of any evidence of placental detachment, consider the diagnosis of complete placenta accreta or a variant. This condition may be present with bleeding if only a portion of the placenta is abnormally implanted.

Ensuring that the bladder is empty may speed the delivery of the placenta and at least aid in the assessment and control of the uterus. Ideally, women should have an empty bladder at the time of delivery. This usually occurs naturally because of pressure from the presenting part and maternal expulsive effort. Encouraging the woman to attempt to void late in the second stage or following delivery is not unreasonable, although this may be difficult. Emptying the bladder is mandatory before any attempt at assisted vaginal delivery.

Manual removal of the placenta is warranted if  significant bleeding occurs. The retained or partially detached placenta interferes with uterine contraction and retraction and leads to bleeding. Perform manual removal with a level of analgesia that matches the clinical urgency of the situation. The cessation of an oxytocin infusion or the administration of uterine relaxants to promote uterine exploration and manual removal is of questionable value and may lead to increased bleeding. Ultrasound may be useful in select cases.

When possible, an elbow-length glove is worn and attention is paid to asepsis. The perineum and vagina must be prepared. The vaginal hand may be immersed in povidone-iodine solution (Proviodine) to facilitate easier entry. The hand is passed into the vagina through the cervix and into the lower segment following the umbilical cord. Care is taken to minimize the profile of the hand as it enters, keeping the thumb and fingers together in the shape of a cone to avoid damage.

Control of the uterine fundus with the nonvaginal hand is essential. If the placenta is encountered in the lower segment, it is removed. If the placenta is not encountered, the placental edge is sought. Once found, the fingers gently develop the space between the placenta and uterus and shear off the placenta. The placenta is pushed to the palmar aspect of the hand and wrist; when it is entirely separated, the hand is withdrawn. Ensure that an oxytocin infusion is running rapidly as the hand is withdrawn in order to encourage strong uterine contraction, and then perform uterine massage. Care must be taken to tease out the membranes. Once uterine contraction is established, examine the placenta and membranes to determine whether further exploration or curettage is necessary. The administration of antibiotics following manual removal is sometimes advocated.

How to gain experience with potentially lifesaving procedures such as manual removal poses a dilemma. The days of regional anesthesia being an indication for manual removal are hopefully past, and this opportunity no longer exists. Manual removal at cesarean delivery allows the clinician to gain the most critical skills needed for this procedure. 

Uterine inversion 

This condition is very rare. The risk of uterine inversion is increased in abnormalities of placentation, such as accreta, and is more likely with fundal cord insertions and any condition that predisposes patients to uterine atony and prolapse. Cord traction should never occur without countertraction or in the absence of uterine contraction. Leave the placenta attached, and focus management on maternal resuscitation and rapid return of the uterus to the abdominal cavity.

The fingers are formed into a single cone-shaped unit and placed at the most dependent portion of the protruding mass, which represents the inverted uterine fundus. Gentle upward pressure is exerted in the axis of the birth canal with the fingers and thumb together to minimize the risk of uterine perforation. The action has been likened to that of placing the fingers at the toe of an inside-out sock and pushing to make the sock right-side out. Following uterine replacement, vigorous massage and uterotonic administration should undertaken.

Manual removal of the placenta may be performed when the mother's vital signs are stable unless concern exists regarding abnormal placentation. Uterine relaxants, such as nitroglycerin, may be helpful. 

Placenta accreta 

Placenta accreta and its variants are not complications of third-stage management but are most commonly recognized during the third stage. These life-threatening abnormalities of placentation may occur spontaneously; however, they are much more common in situations in which the placenta has implanted over a previously scarred uterus. The routine use and improving capabilities of ultrasound may suggest this diagnosis in the antepartum period, and the diagnosis should be considered in high-risk situations. The possibility of placenta accreta mandates that preparations for the management of severe PPH are in place and, if suggested based on ultrasound findings, that expertise is available to deal with the complications of placenta percreta.