Images in Women's Health

Placenta Percreta Diagnosed Antenatally With Magnetic Resonance Imaging

Erin Stoehr, DO; Michael L. Stitely, MD

CASE HISTORY

The patient was a 28-year-old woman, gravida 3, para 2, who presented at 28 weeksÕ estimated gestational age with flank pain. She had no contractions or vaginal bleeding, and was not febrile. Her obstetric history was significant for two prior low-transverse cesarean deliveries. She was initially diagnosed with pyelonephritis based on urinalysis results showing 10 to 20 red blood cells (RBCs) and five to 10 white blood cells per high-powered field. Intravenous (IV) antibiotics were initiated.

Ultrasonographic examination demonstrated a placental abruption measuring 11.4 x 6.8 x 10.3 cm, with an anterior marginal placenta previa. The estimated fetal weight was in the 21st percentile for gestational age. Antenatal steroid therapy with dexamethasone was initiated due to concern over the possibility of preterm delivery.

The patient was noted to have significant anemia, with a hematocrit value of 23.3% and no coagulopathy. Transfusion of 2 U of packed RBCs caused no appreciable rise in the hem-atocrit level.

Due to the potential for abruptio placentae with maternal anemia, the patient was transferred to a tertiary care facility. There was a clinical suspicion of placenta percreta or uterine rupture with ongoing bleeding due to the persistent anemia, microscopic hematuria, marginal placenta previa, and the history of cesarean delivery.

A magnetic resonance imaging (MRI) study of the pelvis was performed without gadolinium contrast (Figures 1 and 2). The diagnosis of placenta percreta was confirmed on MRI, and the patient was taken for operative delivery based on the suspicion of persistent hemorrhage. Classical cesarean delivery resulted in a viable, 1,000-g male neonate in the cephalic presentation. The 1-minute and 5-minute Apgar scores were 8 and 8, respectively. After the umbilical cord was clamped and cut, the placenta was found to be densely adherent to the lower uterine segment, and had eroded entirely through the uterine myometrium and serosa in the left lateral portion (Figures 3 and 4).

Figure not available online

FIGURE 1. Coronal section MRI showing placenta (P) located outside the myometrium. Courtesy of Erin Stoehr, DO, and Michael L. Stitely, MD.

Figure not available online

FIGURE 2. Sagittal-section MRI showing the fetus inside the uterus. The cervix (C) and bladder (B) are clearly discernable. Fluid has collected beneath the serosal layer of the uterus (S). The placenta (P), myometrium (M), and myometrial-placental interface (M/P) are shown, illustrating the placenta percreta. Courtesy of Erin Stoehr, DO, and Michael L. Stitely, MD.

Figure not available online

FIGURE 3. Intraoperative photo showing the sutured hysterotomy incision. The umbilical cord is protruding through the inferior portion of the incision. The uterine deformity due to the placental invasion is clearly visible beneath the serosal layer. Courtesy of Erin Stoehr, DO, and Michael L. Stitely, MD.

Figure not available online

FIGURE 4. The placenta is seen extruding through the lower uterine segment on the left side. Courtesy of Erin Stoehr, DO, and Michael L. Stitely, MD.

A supracervical hysterectomy was performed postpartum. The placenta was densely adherent to the posterior wall of the bladder, but had not invaded the mucosa, and cystotomy occurred while mobilizing the bladder inferiorly. Ureteral patency was ensured by directly visualizing urine efflux from the ureteral orifices after the injection of IV indigo-carmine blue dye. Hemostasis of the cervical stump and posterior bladder surface was accomplished by oversewing with suture, argon-beam coagulation, use of fibrin glue, and left-sided hypogastric artery ligation. The cystotomy was closed in two layers.

The estimated blood loss was 3 L. The patient received a total transfusion of 8 U of packed RBCs and 5 U of fresh frozen plasma in addition to blood salvaged using a cell-saver.

Following a brief admission to the intensive care unit for continued postoperative ventilatory management, the patient recovered uneventfully. The infant did well in the neonatal intensive care unit, and did not require mechanical ventilation. Findings from the pathology specimen confirmed the presence of placenta percreta.

back to top

DISCUSSION

Abnormal placental attachment complicates approximately one per 2,500 deliveries.1 Hemorrhage at the time of delivery is usually profuse, and is often life-threatening. Blood-product replacement and hysterectomy are the recommended course of management for total placenta accreta, increta, and percreta. Partial or focal placenta accreta may respond to placental removal and oversewing of the attachment site. This conservative approach can be used cautiously in the young, hemodynamically stable patient who wishes to retain her fertility.

Risk factors for the development of placenta accreta and percreta include placenta previa, advanced maternal age, elevated maternal serum a-fetoprotein levels, multiparity, and a history of uterine surgery or cesarean delivery.2 Clark et al3 estimated the incidence of placenta accreta at 24% in women with a prior cesarean delivery and concurrent placenta previa; this risk increases to 67% in the presence of two prior cesarean deliveries and concurrent placenta previa.3

Antepartum diagnosis of placenta accreta/percreta with imaging modalities has been described in the medical literature. Ultrasonographic and color Doppler imaging has successfully detected placenta accreta by visualizing turbulent blood extending from the placenta into the surrounding uterine tissue.4

Ultrasonographic findings suggestive of placenta accreta include placental lacunae, interruption of the bladder-uterine interface, and absence of the retroplacental clear zone.5 Color Doppler findings that suggest placenta accreta include diffuse or focal high-velocity intraplacental lacunar flow, abnormal blood vessels linking the placenta to the bladder with high diastolic arterial flow, and dilated peripheral subplacental pulsatile venous flow over the uterine cervix.6 Abnormal findings on MRI for placenta accreta include nonvisualization of the uteroplacental interface and thinning of the uterine wall.6,7

The sensitivity of ultrasonography and color-flow Doppler to detect placenta accreta ranges from 82.4% to 93.3%, while the specificity is 78.9% to 96.8%.8,9 There are few published reports describing MRI techniques used for the diagnosis of placenta accreta, and sensitivity and specificity data are lacking.

back to top

CONCLUSION

In the case presented here, ultrasonographic imaging did not detect the placenta percreta, but MRI was able to delineate the diagnosis. This allowed for appropriate preoperative preparation that may have reduced the blood loss encountered intraoperatively.

back to top

Erin Stoehr, DO, is a practicing obstetrician/gynecologist in private practice in Wheeling, WVa; and Michael L. Stitely, MD, is assistant professor, Department of Obstetrics and Gynecology, West Virginia University School of Medicine, Morgantown.

References

1. Read JA, Cotton DB, Miller FC. Placenta accreta: changing clinical aspects and outcome. Obstet Gynecol. 1980;56(1):31-34.
2. Hung TH, Shau WY, Hsieh CC, Chiu TH, Hsu JJ, Hsieh TT. Risk factors for placenta accreta. Obstet Gynecol. 1999;93(4):545-550.
3. Clark SL, Koonings PP, Phelan JP. Placenta previa/accreta and prior cesarean section. Obstet Gynecol. 1985;66(1):89-92.
4. Lerner JP, Deane S, Timor-Tritsch IE. Characterization of placenta accreta using transvaginal sonography and color Doppler imaging. Ultrasound Obstet Gynecol. 1995;5(3):198-201
5. Comstock CH, Love JJ Jr, Bronsteen RA, et al. Sonographic detection of placenta accreta in the second and third trimesters of pregnancy. Am J Obstet Gynecol. 2004;190(4):1135-1140.
6. Kim JA, Narra VR. Magnetic resonance imaging with true fast imaging with steady-state precession and half-Fourier acquisition single-shot turbo spin-echo sequences in cases of suspected placenta accreta. Acta Radiol. 2004;45(6):692-698.
7. Taipale P, Orden MR, Berg M, Manninen H, Alafuzoff I. Prenatal diagnosis of placenta accreta and percreta with ultrasonography, color Doppler, and magnetic resonance imaging. Obstet Gynecol. 2004;104(3):537-540.
8. Chou MM, Ho ES, Lee YH. Prenatal diagnosis of placenta previa accreta by transabdominal color Doppler ultrasound. Ultrasound Obstet Gynecol. 2000;15(1):28-35.
9. Finberg HJ, Williams JW. Placenta accreta: prospective sonographic diagnosis in patients with placenta previa and prior cesarean section. J Ultrasound Med. 1992;11(7):333-343.

back to top