Indications Are Similar to Those of Forceps
• Prolonged second stage. This may be because of dysfunctional labor or suboptimalfetal head orientation.
• Nonreassuring EFM strip. The FHR monitor pattern suggests the fetus is not toleratinglabor.
• 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.
Prerequisites
• Clinically adequate pelvic dimension
• Experienced operator
• Full cervical dilation
• Engaged fetal head
• Gestational age is >34 weeks
Complications
• Maternal: vaginal lacerations from entrapment of vaginal mucosa between the suctioncup and fetal head.
• Neonatal: neonatal cephalohematoma and scalp lacerations are common; life-threat-
ening complications of subgaleal hematoma or intracranial hemorrhage, although uncommon, are associated with vacuum duration >10 min.
CESAREAN SECTION
Definition. This describes a procedure in which the fetus is delivered through incisions in thematernal anterior abdominal and uterine walls. The overall U.S. cesarean section rate in 2011 was approximately 33%, which includes both primary and repeat procedures.
Risks. Maternal mortality and morbidity is higher than with vaginal delivery, especially withemergency cesareans performed in labor. Maternal mortality is largely anesthetic related with overall mortality ratio of 25 per 100,000.
• Hemorrhage: Blood loss is twice that of a vaginal delivery with mean of 1,000 mL.
• Infection: Sites of infection include endometrium, abdominal wall wound, pelvis, uri-nary tract, or lungs. Prophylactic antibiotics can decrease infectious morbidity.
• Visceral injury: Surrounding structures can be injured (e.g., bowel, bladder, and ureters).
• Thrombosis: Deep venous thrombosis is increased in the pelvic and lower extremity veins.
Uterine Incisions
• Low segment transverse. This incision is made in the noncontractile portion of theuterus and is the one most commonly used. The bladder must be dissected off the lower uterine segment. It has a low chance of uterine rupture in subsequent labor (0.5%).
– Advantages are trial of labor in a subsequent pregnancy is safe; the risk of bleeding and adhesions is less.
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– Disadvantages are the fetus(es) must be in longitudinal lie; the lower segment must be developed.
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USMLE Step 2 l Obstetrics
OB Triad
Low Transverse Uterine
Incision
• Low risk of rupture (0.5% in labor)
• Less blood loss and adhesions
• Safe for subsequent labor trial
Figure I-17-2. Low Segment Transverse Incision
• Classical. This incision is made in the contractile fundus of the uterus and is lesscommonly performed. Technically it is easy to perform, and no bladder dissection is needed. Risk of uterine rupture both before labor as well as in subsequent labor is significant (5%). Repeat cesarean should be scheduled before labor onset.
– Advantages are any fetus(es) regardless of intrauterine orientation can be delivered; lower segment varicosities or myomas can be bypassed.
– Disadvantages are trial of labor in a subsequent pregnancy is unsafe; the risk of bleeding and adhesions is higher.
OB Triad
Classical Uterine Incision
• High risk of rupture
(5% in labor)
• More blood loss and adhesions
• Risky for subsequent labor trial
Figure I-17-3. Classical Uterine Incision
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