Vacuum extraction is an important maternity care skill for family physicians. Nationally, 82 percent of family physicians delivering infants have hospital privileges to perform vacuum extraction, which is nearly double the 44 percent who have privileges to assist delivery with forceps.1 The ability to perform operative vaginal delivery using forceps or vacuum is important to those who provide maternity care because as many as 25 percent of nulliparous women have operative vaginal delivery.2 Increasing use of operative vaginal delivery is one means suggested by the U.S. Department of Health and Human Services (HHS) to help reduce cesarean delivery rates.3
Vacuum extraction may appeal to many family physicians perceiving modern, semirigid or soft cups as less invasive, less dangerous to mother and infant, and simpler to use than forceps. The family practice community has embraced vacuum extraction with informative articles such as the one by Putta and Spencer4 in this issue of American Family Physician, by including the technique as one of the major skill components in the Advanced Life Support in Obstetrics (ALSO) course5 offered by the American Academy of Family Physicians (AAFP) and by including workshops in the annual Family Centered-Maternity Care course, also offered by the AAFP.6 Recent survey data suggest that vacuum extraction is also gaining favor among obstetrician-gynecologists who have traditionally favored forceps, particularly among those more recently trained, and for midpelvic application.7 More than 10 years ago, a widely quoted article in the obstetrics-gynecology literature declared, “The obstetric vacuum extractor is the instrument of first choice for operative vaginal delivery.”8
Despite the enthusiasm for operative vaginal delivery in general as an alternative to cesarean delivery and for vacuum extraction in particular, many maternity care clinicians and members of the public have been alarmed by a “dark side” of vacuum extraction. This dark side is fetal injury—subgaleal hemorrhage and intracranial hemorrhage—which can be fatal. The HHS published a Public Health Advisory9 from the U.S. Food and Drug Administration about this problem in 1998 that was directed to a broad list of recipients including “obstetricians, pediatricians, family practitioners, hospital risk managers and hospital OB-GYN departments.” In 1999, the American Broadcasting Company produced and aired a segment on its “20/20” television news program10 that graphically detailed the tragic results of subgaleal hemorrhage in two infants and pointed out to professionals some of the pitfalls and technique errors associated with vacuum extraction.
Many texts and articles associate physician technique errors with increased incidence of fetal injury. These errors include cup misapplication, excessive duration of vacuum application, sudden disengagement (“pop-offs”), pulling in the wrong axis and rocking the head. Avoiding these errors is certainly important, but a recent report documents that abnormal labor is an important underlying risk factor for intracranial hemorrhage, whether the baby is delivered by vacuum extraction, forceps or by the cesarean route.11
Against this cautionary backdrop, it is prudent to look for evidence-based answers to a variety of questions that arise during the use of vacuum extraction and that go beyond or supplement those addressed in the article by Putta and Spencer.4 A mnemonic developed for the ALSO course provides a useful summary of proper techniques (see the accompanying table).5
Where should the cup be applied on the fetal head? Whether the infant presents with the occiput anterior, posterior or some degree of transverse, major causes of difficulty with the second stage of labor and failure of assisted vaginal birth are deflexion of the fetal head and acyclitism. Goals of cup positioning are, therefore, maintenance or improvement of flexion and cyclitism. To optimize these factors, the cup should be placed on the “flexion point,” the center of which is located directly over the sagittal suture and about 6 cm behind the anterior fontanelle (Figure 1). In occiput transverse positions, autorotation of the fetal head occurs during assisted delivery without any intentional twisting motion by the operator.
How should suction be applied for best effectiveness and safety? Many references state unequivocally that vacuum should be applied intermittently—on during contractions, off between contractions—and for a specified number of pulls, minutes or pop-offs. One randomized, controlled trial12 using the M-type cup helps answer this question, showing no difference in outcome or complications whether suction is applied continuously or intermittently, and whether or not some traction is held between contractions to prevent loss of station.
The length of vacuum application and number of pulls before abandonment have also been suggested as 20 to 30 minutes and three pulls, respectively. Evidence for these guidelines have previously been anecdotal, but one randomized study13 and one observational study14 show that longer times from initial application to delivery and off-midline cup application are the most important factors correlating positively with an increase in cephalohematomas, although these lesions were mostly of cosmetic significance. The break points for increased scalp injury in these studies were five and 10 minutes of application-to-delivery time, respectively, and the number of pulls required was three or fewer in about 90 percent of cases. This suggests that the “20 to 30 minute” and “three pulls” guidelines seem prudent, even generous, although if steady progress is being made and delivery is imminent, there is no reason to arbitrarily proceed to cesarean delivery. Similarly, if no progress is felt, it probably does not matter how many pulls or minutes have elapsed, the procedure should be terminated.
No study researched for this editorial had sufficient data on pop-offs from which to draw conclusions, although common sense would suggest that if the cup keeps popping off, the operator should be alerted to error in technique, equipment failure or significant cephalopelvic disproportion.
In what direction should traction be applied to aid delivery and prevent pop-offs? Traction should be applied along the axis of the pelvic curve and to maintain flexion of the fetal head. This means that the higher the station, the more “downward” toward the patient's rectum the axis of traction. As the head descends and crowns, the axis should be extended upward toward the patient's abdomen (Figure 2). If the cup has a central stem, the stem should be kept perpendicular to the plane of the cup opening to keep an edge from disengaging. Placing a finger against the cup can give early warning of impending pop-off so traction can be decreased.
How should patients be counseled? Except in emergency cases of severe maternal or fetal distress, there is usually time to counsel the parents about the purpose, procedure, hazards and alternatives. It is also important to discuss what will be done if the vacuum procedure is not successful, including proceeding to cesarean delivery. One concern is whether or not a failed trial of vacuum assist will worsen the infant's outcome when cesarean delivery is performed. The data are conflicting. One retrospective study15 showed no worse outcome for infants delivered by cesarean after failed vaginal assist than for other infants delivered by cesarean during the second stage of labor. However, a much larger study11 of hospital discharge records showed otherwise. The odds ratio for subdural or cerebral hemorrhage was 2.5 for cesarean delivery performed during labor without preceding attempts at operative vaginal delivery but increased to 8.8 when failed operative vaginal delivery preceded cesarean delivery.11 Presentation of this information might cause some patients to forgo vacuum or forceps attempts and proceed directly to cesarean delivery. A useful discussion of risks and a sample consent form can be found at the following Web sites: http://www.obgmanagement.com/cutrisk.vacuum.html and http://www.obgmanagement.com/forms.html.
Where can I get more information? A thorough and well-illustrated handbook and CD-ROM about vacuum extraction are available from Vacca Research Pty Ltd. at their Web site: http://vaccaresearch.com. The cost of the handbook is $35 plus postage and the cost of the CD-ROM is $210 plus postage for personal use and $310 plus postage for institutional use. Instruction and hands-on practice in vacuum extractor technique on mannequins is part of the ALSO course of the AAFP.5