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Management of Normal Delivery
Many obstetric units now use a combined labor, delivery, recovery, and postpartum (LDRP) room, so that the woman, support person, and neonate remain in the same room throughout their stay. Some units use a traditional labor room and separate delivery suite, to which the woman is transferred when delivery is imminent. The father or other support person should be offered the opportunity to accompany her. In the delivery room, the perineum is washed and draped, and the neonate is delivered. After delivery, the woman may remain there or be transferred to a postpartum unit. Management of complications during delivery requires additional measures (see Abnormalities and Complications of Labor and Delivery).
Options include regional, local, and general anesthesia. Local anesthetics and opioids are commonly used. These drugs pass through the placenta; thus, during the hour before delivery, such drugs should be given in small doses to avoid toxicity (eg, CNS depression, bradycardia) in the neonate. Opioids used alone do not provide adequate analgesia and so are most often used with anesthetics.
Several methods are available.
Lumbar epidural injection of a local anesthetic (see Normal Labor and Delivery:Analgesia) is the most commonly used method. Epidural injection is being increasingly used for delivery, including cesarean delivery, and has essentially replaced pudendal and paracervical blocks. The local anesthetics often used for epidural injection (eg, bupivacaine) have a longer duration of action and slower onset than those used for pudendal block (eg, lidocaine).
Spinal injection (into the paraspinal subarachnoid space) may be used for cesarean delivery, but it is used less often for vaginal deliveries because it is short-lasting (preventing its use during labor) and has a small risk of spinal headache afterward. When spinal injection is used, patients must be constantly attended, and vital signs must be checked every 5 min to detect and treat possible hypotension.
Methods include pudendal block, perineal infiltration, and paracervical block.
Pudendal block, rarely used because epidural injections are used instead, involves injecting a local anesthetic through the vaginal wall so that the anesthetic bathes the pudendal nerve as it crosses the ischial spine. This block anesthetizes the lower vagina, perineum, and posterior vulva; the anterior vulva, innervated by lumbar dermatomes, is not anesthetized. Pudendal block is a safe, simple method for uncomplicated spontaneous vaginal deliveries if women wish to bear down and push or if labor is advanced and there is no time for epidural injection.
Infiltration of the perineum with an anesthetic is commonly used, although this method is not as effective as a well-administered pudendal block.
Paracervical block is rarely appropriate for delivery because incidence of fetal bradycardia is > 15%. It is used mainly for 1st- or early 2nd-trimester abortion. The technique involves injecting 5 to 10 mL of 1% lidocaine at the 3 and 9 o’clock positions; the analgesic response is short-lasting.
Because potent and volatile inhalation drugs (eg, isoflurane) can cause marked depression in mother and fetus, general anesthesia is not recommended for routine delivery. Rarely, nitrous oxide 40% with O 2 may be used for analgesia during vaginal delivery as long as verbal contact with the woman is maintained. Thiopental, a sedative-hypnotic, is commonly given IV with other drugs (eg, succinylcholine, nitrous oxide plus O 2 ) for induction of general anesthesia during cesarean delivery; used alone, thiopental provides inadequate analgesia. With thiopental, induction is rapid and recovery is prompt. It becomes concentrated in the fetal liver, preventing levels from becoming high in the CNS; high levels in the CNS may cause neonatal depression. Increased interest in preparation for childbirth has reduced the need for general anesthesia except for cesarean delivery.
A vaginal examination is done to determine position and station of the fetal head; the head is usually the presenting part (see Figure: Sequence of events in delivery for vertex presentations.). When effacement is complete and the cervix is fully dilated, the woman is told to bear down and strain with each contraction to move the head through the pelvis and progressively dilate the vaginal introitus so that more and more of the head appears. When about 3 or 4 cm of the head is visible during a contraction in nulliparas (somewhat less in multiparas), the following maneuvers can facilitate delivery and reduce risk of perineal laceration:
The clinician, if right-handed, places the left palm over the infant’s head during a contraction to control and, if necessary, slightly slow progress.
Simultaneously, the clinician places the curved fingers of the right hand against the dilating perineum, through which the infant’s brow or chin is felt.
To advance the head, the clinician can wrap a hand in a towel and, with curved fingers, apply pressure against the underside of the brow or chin (modified Ritgen maneuver).
Thus, the clinician controls the progress of the head to effect a slow, safe delivery.
Forceps or a vacuum extractor (see Operative vaginal delivery) is often used for vaginal delivery when the 2nd stage of labor is likely to be prolonged (eg, because the mother is too exhausted to bear down adequately or because regional epidural anesthesia precludes vigorous bearing down). If anesthesia is local (pudendal block or infiltration of the perineum), forceps or a vacuum extractor is usually not needed unless complications develop; local anesthesia may not interfere with bearing down. Indications for forceps and vacuum extractor are essentially the same.
An episiotomy is not routinely done for most normal deliveries; it is done only if the perineum does not stretch adequately and is obstructing delivery. A local anesthetic can be infiltrated if epidural analgesia is inadequate. Episiotomy prevents excessive stretching and possible irregular tearing of the perineal tissues, including anterior tears. An episiotomy incision that extends only through skin and perineal body without disruption of the anal sphincter muscles (2nd-degree episiotomy) is usually easier to repair than a perineal tear. The most common episiotomy is a midline incision made from the midpoint of the fourchette directly back toward the rectum. Extension into the rectal sphincter or rectum is a risk with midline episiotomy, but if recognized promptly, the extension can be repaired successfully and heals well. Tears or extensions into the rectum can usually be prevented by keeping the infant’s head well flexed until the occipital prominence passes under the symphysis pubis. Another type of episiotomy is a mediolateral incision made from the midpoint of the fourchette at a 45° angle laterally on either side. This type usually does not extend into the sphincter or rectum, but it causes greater postoperative pain and takes longer to heal than midline episiotomy. Thus, for episiotomy, a midline cut is preferred. However, use of episiotomy is decreasing because extension or tearing into the sphincter or rectum is a concern. Episioproctotomy (intentionally cutting into the rectum) is not recommended because rectovaginal fistula is a risk.
When the head is delivered, the clinician determines whether the umbilical cord is wrapped around the neck. If it is, the clinician should try to unwrap the cord; if the cord cannot be rapidly removed this way, the cord may be clamped and cut. After delivery of the head, the infant’s body rotates so that the shoulders are in an anteroposterior position; gentle downward pressure on the head delivers the anterior shoulder under the symphysis. The head is gently lifted, the posterior shoulder slides over the perineum, and the rest of the body follows without difficulty. The nose, mouth, and pharynx are aspirated with a bulb syringe to remove mucus and fluids and help start respirations. The cord should be double-clamped and cut between the clamps, and a plastic cord clip should be applied about 2 to 3 cm distal from the cord insertion on the infant. If fetal or neonatal compromise is suspected, a segment of umbilical cord is doubly clamped so that arterial blood gas analysis can be done. An arterial pH > 7.l5 to 7.20 is considered normal. The infant is thoroughly dried, then placed on the mother’s abdomen or, if resuscitation is needed, in a warmed resuscitation bassinet.
After delivery of the infant, the clinician places a hand gently on the abdomen over the uterine fundus to detect contractions; placental separation usually occurs during the 1st or 2nd contraction, often with a gush of blood from behind the separating placenta. The mother can usually help deliver the placenta by bearing down. If she cannot and if substantial bleeding occurs, the placenta can usually be evacuated (expressed) by placing a hand on the abdomen and exerting firm downward (caudal) pressure on the uterus; this procedure is done only if the uterus feels firm because pressure on a flaccid uterus can cause it to invert. If this procedure is not effective, the umbilical cord is held taut while a hand placed on the abdomen pushes upward (cephalad) on the firm uterus, away from the placenta; traction on the umbilical cord is avoided because it may invert the uterus. If the placenta has not been delivered within 45 to 60 min of delivery, manual removal may be necessary; appropriate analgesia or anesthesia is required. For manual removal, the clinician inserts an entire hand into the uterine cavity, separating the placenta from its attachment, then extracts the placenta. In such cases, an abnormally adherent placenta (placenta accreta—see Placenta Accreta) should be suspected.
The placenta should be examined for completeness because fragments left in the uterus can cause hemorrhage or infection later. If the placenta is incomplete, the uterine cavity should be explored manually. Some obstetricians routinely explore the uterus after each delivery. However, exploration is uncomfortable and is not routinely recommended.
Immediately after delivery of the placenta, an oxytocic drug (oxytocin 10 units IM or as an infusion of 20 units/1000 mL saline at 125 mL/h) is given to help the uterus contract firmly.
Active management of the 3rd stage of labor involves giving oxytocin after delivery of the infant and before delivery of the placenta. Active management should be considered for women with anemia or at high risk of postpartum hemorrhage because risk of postpartum hemorrhage is lower with active management. Oxytocin should not be given as an IV bolus because cardiac arrhythmia may occur.
The cervix and vagina are inspected for lacerations, which, if present, are repaired, as is episiotomy if done. Then if the mother and infant are recovering normally, they can begin bonding. Many mothers wish to begin breastfeeding soon after delivery, and this activity should be encouraged. Mother, infant, and father or partner should remain together in a warm, private area for an hour or more to enhance parent-infant bonding. Then, the infant may be taken to the nursery or left with the mother depending on her wishes. For the first hour after delivery, the mother should be observed closely to make sure the uterus is contracting (detected by palpation during abdominal examination) and to check for bleeding, BP abnormalities, and general well-being. The time from delivery of the placenta to 4 h postpartum has been called the 4th stage of labor; most complications, especially hemorrhage (see Postpartum Hemorrhage), occur at this time, and frequent observation is mandatory.
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* This is a professional Version *