APPROACH TO CATEGORY III FETAL MONITORING TRACINGS
A 20-year-old primigravida at 39 weeks’ gestation is in active labor at 7 cm of cervical dilation. The EFM strip shows a baseline heart rate of 175 beats/min, and variability is 7 beats/min, but repetitive late decelerations are seen after each contraction. No accelerations are noted.
Recognize that most abnormal tracings are not caused by fetal hypoxia. Ask whether the tracing has biologic plausibility.
• Examine the EFM strip carefully looking for baseline heart rate, degree of variability,and presence of periodic changes (accelerations, decelerations).
• Confirm abnormal findings using criteria discussed above (category II or III).
• Identify nonhypoxic causes present that could explain the abnormal findings.
• Initiate the intrauterine resuscitation measures described previously (IntrauterineResuscitation) to enhance placental perfusion and fetal oxygenation.
• Observe for normalization of the EFM tracing.
• Prepare for delivery promptly if resuscitation measures do not normalize EFM tracing.
Specific Interventions If Immediate Delivery Is Indicated
• In stage 1 of labor, the only option is emergency cesarean section.
• In stage 2 of labor, an operative vaginal delivery (e.g., vacuum extractor assisted or obstetrical forceps) may be appropriate, or an emergency cesarean section must be performed.
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Operative Obstetrics 17
Operative obstetrics refers to any method used to deliver the fetus other than uterine contrac-tions and maternal pushing efforts. It may include vaginal or cesarean routes.
OBSTETRIC FORCEPS
Definition. These are metal instruments used to provide traction, rotation, or both to thefetal head.
• Simpson: used for traction only.
• Kielland: used for head rotation and traction.
• Piper: used for the after-coming head of a vaginal breech baby.
• Barton: used to deliver the head in occiput transverse position with a platypelloid pelvis.
Simpson Kielland Kielland-Luikart
Figure I-17-1. Obstetric Forceps
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USMLE Step 2 l Obstetrics
Classification
• Outlet: fetal head is on the pelvic floor. Most forceps use is in this category.
• Low: fetal head is below +2 station, but has not reached the pelvic floor.
• Mid: fetal head is below 0 station, but has not reached +2 station. This is seldom usedtoday.
• High: fetal head is unengaged, above 0 station. This is never appropriate in modernobstetrics because of the risk to both mother and fetus.
Indications
• Prolonged second stage. This may be because of dysfunctional labor or suboptimalfetal head orientation. This is the most common indication for forceps.
• Category III EFM strip. The fetal heart rate monitor pattern suggests the fetus is nottolerating labor.
• Avoid maternal pushing. These include a variety of conditions in which pushing effortsmay be hazardous to the parturient, e.g., cardiac, pulmonary, or neurologic disorders.
• Breech presentation. Shorten the time to deliver the head of a vaginal breech fetus.
Prerequisites
• Clinically adequate pelvic dimensions
• Experienced operator
• Full cervical dilation
• Engaged fetal head
• Orientation of fetal head is certain.
Complications
• Maternal: lacerations to the vagina, cervix, perineum, and uterus.
• Fetal-neonatal: soft-tissue compression or cranial injury caused by incorrectly placedforceps blades.
VACUUM EXTRACTOR
Definition. These are cuplike instruments that are held against the fetal head with suction.Traction is thus applied to the fetal scalp, which along with maternal pushing efforts, results in descent of the head leading to vaginal delivery. The cups may be metal or plastic, rigid or soft.
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Advantages Over Forceps
• Fetal head orientation. Precise knowledge of fetal head position and attitude is notessential.
• Space required. The vacuum extractor does not occupy space adjacent to the fetal head.
• Perineal trauma. Third- and fourth-degree lacerations are fewer.
• Head rotation. Fetal head rotation occurs spontaneously at the station best suited tofetal head configuration and maternal pelvis.
Disadvantages Over Forceps
• Cup pop-offs. Excessive traction can lead to sudden decompression as the cup suctionis released.
• Scalp trauma. Scalp skin injury and lacerations are common.
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• Subgaleal hemorrhage and intracranial bleeding are rare.
• Neonatal jaundice arises from scalp bleeding.
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