Volume 187, Number 2 Letters 515Am J Obstet Gynecol

group1 was treated with indomethacin, another potentialconfounding variable.

Last, Zalar suggests that our choice of suture may bethe most significant reason for our inability to demon-strate cerclage benefit. We chose monofilament suturesfor two basic reasons: placement of a braided tape leadsto a significant amount of stromal damage caused by thecoarse texture, and there seems to be significantly moretissue inflammation associated with the use of braidedtape. Cerclage failure in our study was associated with in-creased uterine activity in each case. Our data suggestthat this activity is the result of subclinical contraction,chorioamnionitis, or abruptio placentae. It is our opin-ion, in the face of these obstetric complications, that cer-clage failure can be expected regardless of suturematerial. At this date, we are not aware of any clinical trialthat has demonstrated a difference in perinatal outcomebased on cerclage suture material (perhaps Zalar’s clini-cal opinion should be tested). We are in complete agree-ment with Zalar that we should not be too quick todiscard cervical cerclage as a potential therapy to preventpreterm birth. However, we should be equally hesitant torecommend therapy that does not have a clear demon-strable benefit.

Orion A. Rust, MD, O.A. Atlas, MD, J. Reed, PhD, J. van Gaalen, BA, and J. Balducci, MD

Department of Obstetrics and Gynecology, Lehigh Valley Hospital, CC &I-78, PO Box 689, Allentown, PA 18105-1556

REFERENCES

1. Althuisius SM, Dekker GA, Hummel P, Bekedam DJ, van GeijnHP. Final results of the Cervical Incompetence Prevention Ran-domized Cerclage Trial(CIPRACT): therapeutic cerclage withbed rest versus bed rest alone. Am J Obstet Gynecol 2001;185:1106-12.

2. Guzmen ER, Mellon C, Vintzileos AM, Ananth CV, Walters C,Gipson K. Longitudinal assessment of endocervical canal lengthbetween 15 and 24 weeks’ gestation in women at risk for preg-nancy or preterm birth. Obstet Gynecol 1998;92:31-7.

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ReplyTo the Editors: We appreciate Zalar’s letter speculating onother possible explanations for the differences in out-come between the trials by Rust et al and ours.

We do agree with Zalar that the chances of a type IIerror in the trial by Rust et al and a type I error in our trialare not excluded. Power analysis shows, however, that thechance of a type II error in the trial by Rust et al is muchhigher than that of a type I error in our trial.

We explained the differences in outcome on the basisof a different population, as we discussed in the Com-ment section, and this difference is illustrated by the factthat abruptio placentae was found in 14.8% of the pa-tients in the trial by Rust et al and not at all in our trial.

Other factors might also contribute to the differencesin outcome between both trials. Amniocentesis to rule

out infection in the trial by Rust et al may indeed causeunnecessary trauma without particular benefit. Rust et alcomments in their first paper that there were no compli-cations of amniocentesis.1

The 48- to 72-hour delay from diagnosis to cerclagemay potentially increase the risk of preterm birth. Rust etal comment in their first paper that none of the patientshad prolapsed membranes beyond the external os duringthe 48 to 72 hour waiting period.1 Furthermore, meancervical length at diagnosis was 20 to 21 mm in the trial byRust et al, and although a decrease of a few millimeterspotentially increases the risk of preterm birth, it cannotexplain the difference in mean gestational ages at deliv-ery between the cerclage groups of the trial by Rust et alof 33.8 ± 6.0 weeks and of our trial of 37.9 ± 1.2 weeks.

Rust et al used monofilament and we used braidedpolyester thread (manufactured by B. Braun MelsungenAG, Germany). Material undoubtedly is an important fac-tor to explain the differences in outcome between bothtrials.

Although several additional factors might contributeto the difference in outcome between both trials, we arestill convinced that the majority of differences in out-come is caused by inclusion of different populations,both at high risk of preterm birth. However, in our trialthe aim has been to include only patients with short cer-vical length because of cervical incompetence.

Sietske M. Althuisius, MD, Herman P. van Geijn, PhD,and Gustaaf A. Dekker, PhD

Department of Obstetrics and Gynecology, Vfije UniversiteitMedical Center, PO Box 7057, Amsterdam, 1007MB,

The Netherlands

REFERENCES

1. Rust OA, Atlas OA, Jones KJ, Benhyam BN, Balducci J. A ran-domized trial of cerclage versus no cerclage among patients withultrasonographically detected second-trimester preterm dilata-tion of the internal os. Am J Obstet Gynecol 2000;183:830-5.

6/8/124961doi:10.1067/mob.2002.124960

Usefulness of 3-dimensional color Doppler imaging inthe diagnosis and management of placenta percretaTo the Editors: I have read with interest the article by Chouet al1 describing the 3-dimensional Doppler assessment ofplacenta increta/percreta newly formed vessels. This newmethod, however, may not be particularly helpful, becausediagnosis was reached by standard studies and suggestedby both the history and laboratory tests. Although the au-thors point out that this technique is especially useful to vi-sualize the vascular mesh in all three planes, their excellentimages do not provide additional meaningful data.

The paper states that elective embolization with al-most complete obliteration of placental invasion was per-formed but also asserts that bleeding originated mostly inthe collateral vessels of the involved area. One may ask,then, if arterial embolization in an area with predomi-nantly venous, high flow, newly formed vessels, a fact ap-

516 Letters August 2002Am J Obstet Gynecol

parently not identified by the 3-dimensional approach,makes any sense. According to the results, prophylacticembolization of internal iliac arteries does not seem ap-propriate because pelvic collateral flow is overabundant,2and therefore it may be more sensible to use a reversibleaortic control.3

Although the development of innovative diagnostictools is a promising and captivating field, only those de-velopments that truly improve therapeutic decisionsshould be published. In cases of placenta percreta, such aprocedure should be able to recognize false-negative con-ventional ultrasonographic or Doppler studies andclearly distinguish this condition from placenta accreta.Unnecessary expenses to obtain exceptional images of avery well known entity would thus be avoided.

José Miguel Palacios Jaraquemada, MD, PhDUniversity of Buenos Aires, Avenida Corrientes, 5087 4˚ A, Ciudad deBuenos Air, C141AJD, Argentina; e-mail: Jpalacios@cuidad.com.ar

REFERENCES

1. Chou MM, Tseng JJ, Ho ES, Hwang JI. Three-dimensional colorpower Doppler imaging in the assessment of uteroplacental neo-vascularization in placenta previa increta/percreta. Am J ObstetGynecol 2001;185:1257-60.

2. Burchell CR. Physiology of internal iliac artery ligation. J ObstetGynaecol Br Commonw 1968;75:642-51.

3. Paull JD, Smith J, Williams L, Davison G, Devine T, Holt M. Bal-loon occlusion of the abdominal aorta during caesarean hys-terectomy for placenta percreta. Anaesth Intensive Care1995;23:731-4.

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ReplyTo the Editors: We appreciate Palacios Jaraquemada’s in-terest in and comments on our article. The purpose ofour case report is to describe the 3-dimensional colorpower Doppler appearance of abnormal spatial vascularnetwork architecture in placenta previa percreta. We ac-knowledged that gray-scale ultrasound (US) and conven-tional color Doppler imaging (CDI) are the very usefulprimary screening tools in diagnosing placenta previaincreta/percreta.1 However, neither modality can pre-cisely predict the degree of bladder invasion in placentapercreta.2 The true value of 3-dimensional angiohis-togram technique lies in the ability to allow one to screenthrough the region of the bladder and adjacent placentain a series of slices and simultaneously analyze aberrantplacental-myometrial vessels with different visual perspec-tives from sagittal, coronal, and axial scanning planes.2,3

Hence, 3-dimensional CDI may be a complementary toolto improve our diagnostic confidence for characterizingthe exact site, extent of involvement, and depth of aber-rant vessels invasion throughout the whole uteroplacen-tal region and the surrounding tissues.3

Palacios Jaraquemada stated that prophylactic hy-pogastric artery embolization (HAE) seems to be an in-appropriate procedure for the management of placentapercreta. We disagree with this point. The blood supplymay be interrupted by angiographic means before

surgery to reduce intraoperative blood loss. Recently, atour institution, HAE was chosen rather than balloon oc-clusion catheterization to attempt to decrease intraopera-tive blood loss in patients with invasive placentation inearly gestation. In our preliminary experience, we havebeen impressed by an obvious reduction of operativeblood loss with the use of prophylactic HAE comparedwith those managed without the procedure. We have sub-mitted our data for possible publication.

The third reference mentioned in Palacios Jaraque-mada’s letter appears to be the first occasion on which anaortic balloon procedure has been used during the ce-sarean hysterectomy for placenta percreta. Potential risksof this procedure covered in the text of an article by Paullet al are aortic rupture, dislodgment of a plaque that em-bolizes in a distal vessel, inability to deflate or withdrawthe balloon through the sheath, and death from ischemiccomplications in a patient whose aorta was occluded for90 minutes. The efficacy of hemorrhage control achievedby aortic balloon deserves further trial in high risk obstet-ric patients because this article is the only reference tothis procedure.

Finally, before acceptance of 3-dimensional US as anew imaging tool in diagnosing placental invasion, weagree with the view that 3-dimensional US must demon-strate a significantly increased diagnostic predictive valuein relation to currently accepted diagnostic 2-dimen-sional US and CDI. Therefore, it would be interesting tosee a comparison of the 2-dimensional and 3-dimensionalUS diagnosis of the condition. Further study is needed toaddress the issue concerning the accuracy of 2-dimen-sional and 3-dimensional imaging in diagnosing placen-tal invasion.

M. M. Chou, MD, J. J. Tseng, MD, Esther S. C. Ho, MD Division of Maternal-Fetal Medicine, Department of Obstetrics and Gy-necology, Taichung Veterans General Hospital, Chung Shan MedicalUniversity, Taichung, Taiwan, Republic of China

REFERENCES

1. Chou MM, Ho ESC, Lee YH. Prenatal diagnosis of placenta pre-via accreta by transabdominal color Doppler ultrasound. Ultra-sound Obstet Gynecol 2000;15:28-35.

2. Hull AD, Salerno CC, Saenz CC, Pretorius DH. Three-dimensional ultrasonography and diagnosis of placenta percretawith bladder involvement. J Ultrasound Med 1999;18:853-6.

3. Chou MM, Tseng JJ, Ho ESC. The application of three-dimen-sional color power Doppler ultrasound in the depiction of ab-normal uteroplacental angioarchitecture in placenta previapercreta. Ultrasound Obstet Gynecol 2002. In press.

6/8/124947doi:10.1067/mob.2002.124948

The use of oxytocin administration to manage thethird stage of laborTo the Editors: We read with interest the Jackson et al1study concerning the timing of prophylactic oxytocin inthe postpartum period. Their results show that oxytocinadministration on delivery of the anterior shoulder doesnot significantly reduce the incidence of postpartum he-