AJR 2001; 177:1301-1303
© American Roentgen Ray Society
Nonoperative Treatment of Placenta Percreta
Value of MR Imaging
Andrew Sonin1,2,3
1
Department of Radiology, University of Maryland Medical Center, 22 S. Greene
St., Baltimore, MD 21201.
2
American Radiology Services, 7600 Osler Dr., Ste. 100, Baltimore, MD
21204.
3
Present address: Radiology Imaging Associates, 8200 E. Belleview Ave., Ste.
124, Greenwood Village, CO 80111.
Received March 19, 2001;
accepted after revision May 11, 2001.
Address correspondence to A. Sonin.
Introduction
Penetration of placental tissue beyond the endometrial lining of the uterus
falls into three categories: placenta accreta, in which the placenta invades
the myometrium; placenta increta, which is characterized by deep myometrial
invasion; and placenta percreta, which is placental invasion through the
serosal layer of the uterus and potentially into surrounding organs and
tissues. Any of these conditions can result in severe puerperal bleeding and
inability to deliver the placenta
[1,2,3,4,5,6,7].
Previous reports of MR imaging of placenta percreta have focused on prenatal
diagnosis [1,
4,
7]. I report on a patient whose
case shows the value of MR imaging both in diagnosing placenta percreta after
failure to deliver the placenta at birth and in monitoring nonoperative
chemotherapeutic treatment of the condition.
Case Report
A previously nulliparous 30-year-old woman with no meaningful medical or
surgical history delivered a healthy full-term infant via vaginal delivery
after an uneventful pregnancy. Although the patient experienced no serious
hemorrhage during or after delivery, her placental tissue failed to pass, and
a diagnosis of placenta accreta was considered. After grayscale transabdominal
sonography (performed by the obstetrician, with no color or power Doppler
sonography used) failed to adequately characterize the state of the placenta,
MR imaging was performed; axial and sagittal T2-weighted images and sagittal
T1-weighted images were obtained. The patient was unable to tolerate further
imaging because of claustrophobia. The resulting MR images revealed an
extension of placental tissue through the serosal surface of the uterine
fundus, consistent with the diagnosis of placenta percreta (Figs.
1A,1B,1C).
No signs of placental invasion of adjacent organs were identified.
Nonoperative treatment with two sequential doses of 50 mg of intramuscular
methotrexate was administered, and serial serum ß-human chorionic
gonadotrophin (ß-HCG) levels were monitored to assess progress. Serum
ß-HCG levels were undetectable after 6 weeks of therapy, and a second MR
imaging study was performed using a technique similar to that of the original
examination. This study showed complete obliteration of placental tissue with
no meaningful residual abnormality of the uterus (Figs.
1D and
1E). The patient was
asymptomatic during the course of treatment and has remained well 11 months
after delivery.
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Fig. 1A. —Placenta percreta in 30-year-old woman. Sagittal T2-weighted
MR image of postpartum uterus obtained 2 days after delivery 5 cm to right of
patient's midline shows fairly well-defined mass (black arrows) with
heterogeneous signal characteristics and thin low-signal rim extending from
interior of uterus beyond serosal surface. Note relatively homogeneous
intermediate signal characteristics of adjacent myometrium (white
arrows). Open arrow indicates psoas muscle.
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Fig. 1B. —Placenta percreta in 30-year-old woman. Axial T2-weighted MR
image obtained 2 days after delivery through superior aspect of uterus
(open arrows) shows placental tissue (black arrows)
extending beyond serosal margin of uterus (between white arrows).
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Fig. 1C. —Placenta percreta in 30-year-old woman. Axial T2-weighted MR
image obtained 2 days after delivery 5 cm caudad to B reveals uterus
(black arrows) and blood (white arrow) within endometrial
cavity.
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Fig. 1D. —Placenta percreta in 30-year-old woman. After 6 weeks of
methotrexate therapy, placental tissue has been completely reabsorbed.
Sagittal (D) and axial (E) T2-weighted MR images show no
residual placental tissue. Note well-defined normal junctional zone (black
arrows). White arrows indicate bowel.
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Fig. 1E. —Placenta percreta in 30-year-old woman. After 6 weeks of
methotrexate therapy, placental tissue has been completely reabsorbed.
Sagittal (D) and axial (E) T2-weighted MR images show no
residual placental tissue. Note well-defined normal junctional zone (black
arrows). White arrows indicate bowel.
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Discussion
The incidence of all forms of placental adhesion (placenta accreta,
increta, and percreta) has been rising for the past two decades, likely as the
result of increasing cesarean section rates
[3]. Other preexisting
conditions that may predispose a patient to adherent placenta include a
history of other instrumentation of the endometrium, placenta previa, and
multiparity [1]. Some form of
adherent placenta is present in approximately one in 7,000 to one in 93,000
births [1,
2]; nearly 14% of all cases of
abnormal placental adhesion involve placenta percreta
[1,
2]. Because trophoblastic
tissue is highly vascular, mismanagement of any type of placental adhesion can
be catastrophic. Hemorrhage may occur in the endometrial cavity, or, in the
case of placenta percreta, in the peritoneal cavity. Bleeding during attempted
surgical intervention may occur because of the invasion of placental tissue
into adjacent organs, such as the urinary bladder. Maternal death is not an
infrequent outcome, ranging from 7-10% of reported cases of placental adhesion
[1,2,3,
5,6,7].
Fetal death occurs in approximately 9% of the cases, usually because of
extreme prematurity at delivery
[3,
6]. Infection, usually in the
postoperative period, is often associated with the condition.
Treatment for placenta percreta has primarily been surgical, with
hysterectomy chosen as the treatment in 93% of all cases, according to one
large metaanalysis [3].
Conservative management is especially desirable in the rare setting of the
involvement of an adjacent organ, such as the bowel or bladder, because of the
increased risk of uncontrollable hemorrhage. Chemotherapeutic agents, and
particularly methotrexate, have been used with success in several patients
[1,
3,
5], and transcatheter arterial
embolization has also been described
[6].
Imaging of placental adhesion has received scant attention in the
literature; what little exists is predominantly case reports
[1,
2,
4]. This case report differs
from most previous accounts in that all imaging in the patient was performed
after vaginal delivery, with the resulting loss of distention of the gravid
uterus by high-contrast amniotic fluid. One other case report describes the
use of MR imaging to identify placenta percreta after a therapeutic abortion
performed at 20 weeks' gestation
[2].
Both sonography and MR imaging have been used to diagnose or characterize
abnormal placental adhesion, with MR imaging thought by most authors to
provide superior anatomic information and diagnostic accuracy
[1,
4]. There is some evidence that
color Doppler and power Doppler examinations may increase the diagnostic
sensitivity of sonography in cases of abnormal placental implantation
[8], but MR imaging remains the
modality of choice for posterior uterine lesions
[8]. Previous descriptions of
the MR imaging appearance of placental invasion of the myometrium correspond
to the appearance found in this patient, in whom T2-weighted images provided
the most useful tissue contrast with which to distinguish placental tissue
from normal myometrium.
The hallmark of placental invasion on MR images is a well-defined mass of
fairly homogenous tissue with a signal different from that of normal
myometrium. The distance that the signal extends from the endometrial cavity
into the wall of the uterus varies from patient to patient
[1]. In cases of placenta
accreta, thinning and irregularity of the myometrium are seen focally at the
site of placental invasion into the uterine wall, without noticeable invasion
into the myometrium. If placenta increta is present, placental tissue extends
partway through the uterine wall. In cases of placenta percreta, placental
tissue extends through the serosal surface of the uterus and may adhere to
adjacent organs. The distinction among these conditions is important because
the risk of severe hemorrhage increases with each successive stage of invasion
[3].
To my knowledge, this case report is the first on the use of serial MR
imaging examinations to document the success of conservative chemotherapeutic
management of placenta percreta. In similar patients who are candidates for
nonsurgical therapy, T2-weighted MR imaging may, in conjunction with serial
ß-HCG assays, provide an accurate and noninvasive imaging modality to
confirm ablation of residual trophoblastic tissue.
References
-
Maldjian C, Adam R, Pelosi M, Pelosi M III, Rudelli RD, Maldjian J.
MRI appearance of placenta percreta and placenta accreta. Magn
Reson Imaging 1999;17
: 965-971[Medline]
-
Neish AS, Frates MC, Tempany CMC. Placenta percreta post
evacuation: an unusual uterine mass on MRI. J Comput Assist
Tomogr 1995; 19:824
-827[Medline]
-
O'Brien JM, Barton JR, Donaldson ES. The management of placenta
percreta: conservative and operative strategies. Am J Obstet
Gynecol 1996; 175:1632
-1638[Medline]
-
Thorp JM, Councell RB, Sandridge DA, Wiest HH. Antepartum diagnosis
of placenta previa percreta by magnetic resonance imaging. Obstet
Gynecol 1992;80:506
-508[Medline]
-
Legro RS, Price FV, Hill LM, Caritis SN. Nonsurgical management of
placenta previa percreta: a case report. Obstet
Gynecol 1994;83:847
-849[Medline]
-
Hudon L, Belfor MA, Broome DR. Diagnosis and management of placenta
percreta: a review. Obstet Gynecol Surv
1998;53:509
-517[Medline]
-
Otsubo Y, Shinagawa T, Chihara H, Araki T. Conservative management
of a case of placenta praevia percreta. Aust N Z J Obstet
Gynaecol 1999;39:518
-519[Medline]
-
Levine D, Hulka CA, Ludmir J, Li W, Edelman RR. Placenta accreta:
evaluation with color Doppler US, power Doppler US, and MR imaging.
Radiology
1997;205:773
-776[Abstract/Free Full Text]
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Introduction
Case Report
