2cms shhould be just fine. Home 2 -3 cms. 10cm is dialation for pushing, not having anything to do with placenta previa. Good luck ladies!!!!! My fingers are crossed for you!!!
> A new classification of placenta previa: Measuring progress in
> Lawrence W. Oppenheimer, MD, FRCOG, FRCSCa, Dan Farine, MD, FRCSCb
> Article Outline
> • References
> • Copyright
> Old obstetric dogmas can take a long time to debunk. Witness castor
> oil, enemas, and lying-in hospitals, to name but a few. So it is with
> the traditional classification of placenta previa. The original
> description of placenta previa is credited to Portal in 1683, although
> Schacher in 1709 was the first to demonstrate postmortem the exact
> relationship of the placenta to the uterus.1 The classification of
> placenta previa into complete, partial, and marginal probably had its
> origins in the 19th century. The description was meant to refer to the
> extent to which the placenta could be palpated through the cervix.1
> Complete previa referred to an implantation over the internal os where
> the margin of the placenta could not be felt; partial previa referred
> to the placenta covering a closed internal os, but not completely
> covering a dilated os; and marginal previa meant an implantation in
> which the margin could be easily felt. Lateral (or low-lying) previa
> is the variety in which the margin of the placenta can only be felt
> with difficulty. In the United Kingdom, the description of placenta
> previa into grades I-IV or major and minor has been used commonly.
> See related article, page 266
> The distinction between placental abruption and previa was based on
> the ability to palpate the placenta through the cervical os; the
> difference was important because the treatment of previa involved
> rupture of the membranes, internal podalic version, and use of the
> fetus as a tamponade! The realization that digital palpation might not
> be such a good idea, and the introduction of conservative management
> with blood transfusion by MacAfee2 in 1945, lead to the need for a
> more accurate diagnosis. Imaging modalities to investigate placental
> location were introduced after the advent of radiology. In the 1930s
> amniography and cystography were explored. Gottesfeld et al3
> introduced the use of ultrasound for placental location in 1966, and
> the first description of vaginal sonography, attributed to Kratochwil,
> followed in 1969.4 Transvaginal sonography (TVS) for the diagnosis of
> placenta previa has become the gold standard.5 Transabdominal
> ultrasound is inaccurate in the diagnosis of previa and should be used
> only as a screening tool.6 TVS is safe, even in the presence of active
> bleeding.7,8 The accurate localization of the placental edge in
> relation to the discrete point of the internal os by TVS makes the use
> of the terms marginal, partial, and low-lying outmoded (Figure). What
> the clinician really wants to know to guide treatment is the
> likelihood of antepartum hemorrhage and need for cesarean section
> delivery, based on the exact distance from the cervix. There is now a
> growing literature on this relationship.9, 10, 11, 12, 13 A placental
> edge lying <2 cm away from the internal os on TVS has become generally
> accepted as the threshold for the performance of cesarean section
> delivery for previa at term. An inherent problem in all the published
> studies to date is the likelihood that knowledge of the distance
> itself may have lead to the decision to perform the cesarean section
> delivery, rather than the clinical features of the case. In this
> respect, the contribution by Vergani et al14 in this edition of the
> Journal is valuable. Although also a retrospective study, the authors
> describe a policy of expectant management in the largest series to
> date of 53 women with a cephalic presentation and a placental edge–to–
> os distance on TVS between 1-20 mm. Cases were divided into 2 groups:
> 1-10 mm from the os (n = 24 cases) and 11-20 mm (n = 29 cases). They
> found a cesarean section delivery rate of 75% and 31%, respectively,
> and an incidence of antepartum hemorrhage of 29% vs 3%, respectively.
> The scans were all performed within 28 days of delivery at a mean
> gestational age of 36.4 weeks, and delivery occurred on average 10
> days later. None of the 11-20 mm group required cesarean section
> delivery for antepartum hemorrhage, and none required cesarean section
> delivery in labor. They conclude that women with a placenta that is
> situated 11-20 mm away can be offered a trial of labor. The data of
> Vergani corroborates well with the 2 other publications that have
> reported the same distance groups.10, 11 Pooling the 3 data sets gives
> a cesarean section delivery rate of 78% (17/50 cases) for a distance
> of 0-10 mm and 34% (39/50 cases) for 11-20 mm.
> FIGURE. Transvaginal sonogram
> The tip of the probe is located at the top of the picture. The
> cervical canal is seen in the upper half of the image, and a posterior
> placenta is seen in the lower half of the image, with the placental
> edge lying 7 mm away from the internal cervical os. Part of the fetal
> head is seen on the left side.
> Oppenheimer. A new classification of placenta previa. Am J Obstet
> Gynecol 2009.
> Vergani et al propose that the time-honored classification of placenta
> previa should be abandoned. We agree with them and others who have
> published the same sentiments.15, 16Admittedly, the data is imperfect.
> The numbers of cases that have been reported is still small and are
> based only on retrospective studies, although it might be difficult to
> mount a trial in which the obstetrician is blinded to the exact
> location of the placenta.
> We need more information on the likelihood of antepartum hemorrhage
> based on placental edge distance and the safety of out-patient
> treatment.17 Treatment decisions should be based on the measured
> distance of the placental edge to the internal cervical os by
> transvaginal ultrasound whenever possible. The routine reporting of
> this distance will enable us to confirm the current assumptions
> rapidly. Recognizing that measurements of <1 cm may be subject to
> error and operator variability, it probably makes sense to group the
> distance to the nearest centimeter.
> A new classification could describe the distance on TVS that is
> performed within 28 days of term in the following way: (1) >20 mm away
> from the internal os; cesarean section delivery for previa not
> indicated; (2) 11-20 mm; lower likelihood of bleeding and need for
> cesarean section delivery; (3) 0-10 mm; higher likelihood of bleeding
> and need for cesarean section delivery; and (4) overlap of the
> internal os by any distance: cesarean section delivery indicated.
> The distance alone should not be a replacement for clinical judgment
> in regard to factors such as unstable lie or significant antepartum
> hemorrhage. As more data accumulates, we can add better estimates of
> the risk of bleeding before and during labor and the likelihood of
> successful vaginal delivery. We still have 4 groups, but the
> description makes a lot more sense. The education exercise really has
> to start not just in the obstetric domain but with the sonographers
> and physicians who perform and report obstetric ultrasound.
> Approximately 3% of the obstetric population in the second trimester
> will have a placental edge low enough to justify follow up with
> transvaginal ultrasound.18 The study by Vergani et al also allows an
> estimate of the incidence of a placenta lying within 2 cm of the os at
> 36 weeks of gestation at approximately 0.6%, one-half of whom will
> have a placental edge overlapping the internal os and a similar number
> will have a placental edge of 1-20 mm away that will warrant a
> decision regarding treatment. The benefits of accurate diagnosis by
> TVS include risk assessment for outpatient treatment, selection for
> trial of labor, and screening for placenta accreta.19 In addition,
> exclusion of vasa previa, which is associated strongly with a placenta
> that is initially located in the lower segment,20 can also be achieved
> with color Doppler sonography. Investigation of antepartum hemorrhage
> by TVS should be routine whenever there is doubt about the exact
> placental location.
> The capability to measure accurately placental location has been
> around for >20 years. All it will take to consign the old
> classification of placenta previa to the history books is a shift in
> our thinking by a couple of centimeters.
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> 268. Abstract | Full Text | Full-Text PDF (197 KB) | Summary PDF (186
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> a Division of Maternal Fetal Medicine, University of Ottawa, Ottawa
> Hospital General Campus, Ottawa, Ontario, Canada
> b Division of Maternal Fetal Medicine, University of Toronto, Mount
> Sinai Hospital, Toronto, Ontario, Canada
> PII: S0002-9378(09)00630-9
> © 2009 Mosby, Inc. All rights reserved.