gynecology and obstetrics
Management of Normal Delivery
Delivery of the Fetus
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. Operative Vaginal Delivery None 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 inhibits vigorous bearing down). The woman has a disorder such as a heart disorder and must avoid pushing during the 2nd stage of labor. 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. Both procedures have risks. Third- and 4th-degree perineal tears ( Delivery of the fetus references ) and anal sphincter injuries ( Fetal risks with vacuum extraction include scalp laceration, cephalohematoma formation, and subgaleal or intracranial hemorrhage; retinal hemorrhages and increased rates of hyperbilirubinemia have been reported. Anepisiotomyis 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. angle laterally on either side. This type usually does not extend into the sphincter or rectum ( Delivery of the fetus references ), but it causes greater postoperative pain, is more difficult to repair, has increased blood loss, and takes longer to heal than midline episiotomy ( 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. About 35% of women have dyspareunia after episiotomy ( Delivery of the fetus references ). 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. If appropriate traction and maternal pushing do not deliver the anterior shoulder, the clinician should explain to the woman what must be done next and begin delivery of a fetus with Shoulder Dystocia . 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>7.15 to 7.20 is considered normal. Delaying clamping of the umbilical cordfor 30 to 60 seconds is recommended to increase iron stores, which provides the following: For all infants: Possible developmental benefits For premature infants: Improved transitional circulation and decreased risk of Necrotizing Enterocolitis and intraventricular hemorrhage (however, slightly increased risk of needing phototherapy) An alternative to delayed clamping in premature infants is umbilical cord milking, which involves pushing blood toward the infant by grasping and squeezing (milking) the cord before it is clamped. However, evidence for or against umbilical cord milking is inadequate. The infant is thoroughly dried, then placed on the mother’s abdomen or, if resuscitation is needed, in a warmed resuscitation bassinet. 1.Cargill YM, MacKinnon CJ, Arsenault MY, et al: Guidelines for operative vaginal birth.J Obstet Gynaecol Can26 (8):747–761, 2004. https://doi.org/10.1016/S1701-2163(16)30647-8 2.Fitzpatrick M, Behan M, O'Connell PR, et al: Randomised clinical trial to assess anal sphincter function following forceps or vacuum assisted vaginal delivery.BJOG110 (4):424–429, 2003. doi: 10.1046/j.1471-0528.2003.02173.x 3.Towner D, Castro MA, Eby-Wilkens E, et al: Effect of mode of delivery in nulliparous women on neonatal intracranial injury.N Engl J Med341 (23):1709–1714, 1999. doi: 10.1056/NEJM199912023412301 4.Walsh CA, Robson M, McAuliffe FM: Mode of delivery at term and adverse neonatal outcomes.Obstet Gynecol121(1):122–128, 2013. doi: 10.1097/AOG.0b013e3182749ac9 5.Shiono P, Klebanoff MA, Carey JC: Midline episiotomies: More harm than good?Obstet Gynecol75 (5):765–770, 1990. 6.Thacker SB, Banta HD: Benefits and risks of episiotomy: An interpretative review of the English language literature, 1860-1980.Obstet Gynecol Surv38 (6):322–338, 1983. 7.Bex PJ, Hofmeyr GJ: Perineal management during childbirth and subsequent dyspareunia.Clin Exp Obstet Gynecol14 (2):97–100, 1987. 