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February
2000
Placenta previa: a 22-year analysis.
Frederiksen MC, Glassenberg R, Stika CS
Am J Obstet Gynecol 1999;180:1432-7.
Commentary by Peter
Dwane, M.D.
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Review Front Page
[ see abstract below ]
Frederiksen's
article in the American Journal of Obstetrics & Gynecology concluded
that in women with placenta previa, general anesthesia increased intraoperative
blood loss and the need for blood transfusion. This conclusion cannot be reasonably
supported because the study design is retrospective and therefore cannot correct
for the selection bias that may have occurred in these patients. As such,
this article should not have appeared, as written, in this major obstetrical
journal.
The authors did not, or could not, classify the patients
into total, partial, or marginal placental previa groups. This information
could have been used clinically by the attending anesthesiologists to
quantify the predicted risk of blood loss. Then, knowing this detail,
they may have used general anesthesia for patients with total placenta
previa, because of a possibility of increased risk of blood loss, and
used regional anesthesia in patients who had marginal placental previa.
A more correct conclusion would be that there is an association between
general anesthesia and increased blood loss during cesarean section for
placenta previa, because cause and effect cannot be demonstrated using
a retrospective study.
As another note, the authors also referenced two older
abstracts as evidence that regional anesthesia decreases intraoperative
blood loss. Abstacts are not critically reviewed articles. And if they
had merit, should or would have been rewritten and published as a bona
fide journal article to be included as a reference in this paper.
When planning anesthesia for a patient with placenta
previa who requires a cesarean section, the patient�s current volume status
and airway accessibility will help determine the type of anesthetic. This
article should have no bearing on which anesthetic you choose.
ABSTRACT
Placenta previa:
a 22-year analysis.
AUTHORS: Frederiksen MC; Glassenberg R; Stika CS.
SOURCE: Am J Obstet Gynecol. 1999 Jun;180(6 Pt 1):1432-7.
ABSTRACT:
OBJECTIVE: Our purpose was to identify what anesthetic method issafer
for women with a placenta previa.
STUDY DESIGN: Weretrospectively reviewed all women with placenta
previa who underwentcesarean delivery during the period January 1, 1976-December
31, 1997at Northwestern Memorial Hospital.
RESULTS: Of 93,384 deliveries, placenta previa was found in 514 women.
Identifiable trends with time included an increasing incidence of placenta
previa (r = 0.54, P <.01); cesarean hysterectomy (r = 0.54, P <.01);
placenta accreta (r = 0.45, P<.03); and regional anesthesia (r = 0.84,
P <.0001). The mean gestational age at delivery was 35.3 +/- 3.4 weeks
and did not change with time. General anesthesia was used for delivery in
380 women and regional anesthesia was used for 134 women. Prior cesarean
delivery and general anesthesia were independent predictors of the need
for blood transfusion, but only prior cesarean delivery was a predictor
of the need for hysterectomy. General anesthesia increased the estimated
blood loss, was associated with a lower postoperative hemoglobin concentration,
and increased the need for blood transfusion. Elective and emergent deliveries
did not differ in estimated blood loss, in postoperative hemoglobin concentrations,
or in the incidence of intraoperative and anesthesia complications. Regional
and general anesthesia did not differ in the incidence of intraoperative
and anesthesia complications.
CONCLUSIONS: In women with placenta previa, general anesthesia increased
intraoperative blood loss and the need for blood transfusion. Regional anesthesia
appears to be a safe alternative.
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