OBSTETRIC COMPLICATIONS DURING LABOR
Prolapsed Umbilical Cord
A 34-year-old multigravida with a known uterine septum comes to the maternity unit at 34 weeks’ gestation complaining of regular uterine contractions. She underwent a previous cesarean at 37 weeks’ gestation for breech presentation.
Pelvic examination determines that the fetus is a footling breech. Her cervix is
6 cm dilated with bulging membranes. During the examination, the patient’s bag of waters suddenly ruptures, and a loop of umbilical cord protrudes through the cervix between the fetal extremities.
Umbilical cord prolapse is an obstetric emergency because if the cord gets compressed, fetal oxygenation will be jeopardized, with potential fetal death.
Prolapse can be occult (the cord has not come through the cervix but is being compressed between the fetal head and the uterine wall), partial (the cord is between the head and the dilated cervical os but has not protruded into the vagina), or complete (the cord has protruded into the vagina).
Risk Factors. Rupture of membranes with the presenting fetal part not applied firmly to thecervix, malpresentation.
Management. Do not hold the cord or try to push it back into the uterus. Place the patient inknee-chest position, elevate the presenting part, avoid palpating the cord, and perform immedi-ate cesarean delivery.
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Shoulder Dystocia
Chapter 14 l Normal and Abnormal Labor
OB Triad
A 20-year-old primigravida at 39 weeks’ gestation was pushing in the second stage of labor for 90 min and has just delivered the fetal head. However, in spite of vigorous pushing efforts by the mother, and moderate traction on the fetal head, you are unable to deliver the anterior shoulder. Since delivery of the fetal head, 30 s has passed. The fetal heart rate is now 70 beats/min.
Diagnosis. This diagnosis is made when delivery of the fetal shoulders is delayed after deliveryof the head. It is usually associated with fetal shoulders in the anterior-posterior plane, with the anterior shoulder impacted behind the pubic symphysis. It occurs in 1% of deliveries and may result in permanent neonatal neurologic damage in 2% of cases.
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Risk Factors. Include maternal diabetes, obesity, and postdates pregnancy, which are associ-ated with fetal macrosomia. Even though incidence increases with birth weight, half of shoulder dystocias occur in fetuses <4,000 grams.
Management. Includes suprapubic pressure, maternal thigh flexion (McRobert’s maneuver),internal rotation of the fetal shoulders to the oblique plane (Wood’s “corkscrew” maneuver), manual delivery of the posterior arm, and Zavanelli maneuver (cephalic replacement).
Shoulder Dystocia
• Second stage of labor
• Head has delivered
• No further delivery of body
Obstetric Lacerations
Perineal lacerations are classified by the extent of tissue disruption between the vaginal introitus and the anus.
• First degree: involve only the vaginal mucosa. Suture repair is often not needed.
• Second degree: involve the vagina and the muscles of the perineal body but do notinvolve the anal sphincter. Suturing is necessary.
• Third degree: involve the vagina, the perineal body, and the anal sphincter but not therectal mucosa. Suturing is necessary to avoid anal incontinence.
• Fourth degree: involve all the way from the vagina through to the rectal mucosa.Complications of faulty repair or healing include rectovaginal fistula.
Episiotomy
This is a surgical incision made in the perineum to enlarge the vaginal opening and assist in childbirth. It is one of the most common female surgical procedures. American trained physi-cians tend to prefer a midline episiotomy whereas British trained physicians tend to perform mediolateral episiotomies. It is not practiced routinely in the United States today because the arguments made in its favor have not been shown to have scientific support.
• False arguments: less perineal pain; more rapid return of sexual activity; less urinaryincontinence; less pelvic prolapse.
• Disadvantages: more perineal pain than with lacerations; longer return to sexualactivity; more extensions into the anal sphincter and rectum.
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• Possible indications: shoulder dystocia, non-reassuring fetal monitor tracing, forcepsor vacuum extractor vaginal delivery, vaginal breech delivery, narrow birth canal.
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Obstetric Anesthesia 15
PHYSIOLOGY
Pain relief from uterine contractions and cervical dilation in stage 1 of labor involves thoracic nerve roots, T10 to T12. Pain relief from perineal distention in stage 2 of labor involves sacral nerve roots, S2 to S4.
• Pregnancy predisposes to hypoxia because of decreased functional residual capacity.
• Placental transfer of medications exposes the fetus to lipid-soluble anionic substances.
• Antacids should be given prophylactically because of delayed gastric emptying time in pregnancy.
• Uterus should be laterally displaced to avoid inferior vena cava compression in the supine position.
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