Placenta Accreta. An Association With Fibroids and Asherman Syndrome. Case Series

Transcription

1 Case Series Placenta Accreta An Association With Fibroids and Asherman Syndrome Amal Al-Serehi, MD, Anna Mhoyan, MD, Michelle Brown, MD, Kurt Benirschke, MD, Andrew Hull, MD, Dolores H. Pretorius, MD Objective. Placenta accreta is a life-threatening problem that is rising in incidence in the developed world. The increased risk of placenta accreta in women with placenta previa and 1 or more prior cesarean deliveries is well established and prompts careful sonographic evaluation. Our objective was to emphasize that accreta is also identified at sites other than cesarean scars. Methods. Two cases of placenta accreta without placenta previa seen in association with uterine scarring from myomectomy and uterine fibroids are described. Results. The sonographic and magnetic resonance imaging findings of accreta are reviewed in the classic setting of prior cesarean deliveries as well as myomectomy and uterine fibroids. Conclusions. We suggest that when the placenta overlies any uterine abnormality, a careful search for invasive placentation is warranted. Key words: accreta; sonography, fibroids; sonography, placenta. Abbreviations MRI, magnetic resonance imaging Received June 5, 2008, from the Department of Maternal-Fetal Medicine, University of Ottawa, Ottawa Hospital, Ottawa, Ontario, Canada (A.A.); Department of Pathology, Kaiser Permanente, San Diego, California USA (A.M.); and Departments of Radiology (M.B., D.P.), Pathology (K.B.), and Reproductive Medicine (A.H.), University of California, San Diego, La Jolla, California USA. Revision requested July 3, Revised manuscript accepted for publication July 22, We thank Vivian Cohen for assistance with manuscript preparation. Address correspondence to Dolores H. Pretorius, MD, Department of Radiology, University of California, 9300 Campus Point Dr, 7756, La Jolla, CA USA. dpretorius@ucsd.edu Placenta accreta occurs when there is a defect in the decidua basalis, allowing the anchoring villi to adhere to the myometrium. The frequency of abnormal placentation has increased 10-fold over the last 20 years and is now observed in 9.3% of women with placenta previa or in 1 per 533 deliveries. 1 Cesarean delivery is probably the most common cause of decidual defects, and the increase in placenta accreta may be attributed primarily to the rising cesarean delivery rate, which has risen to greater than 30% in the United States at the time of writing. Among those with previous cesarean deliveries who have placenta previa or a lowlying anterior placenta, the risk of placenta accreta increases from 24% for a single cesarean delivery to 67% for 4 cesarean deliveries. 2 Other risk factors for accreta include subserosal uterine myomas, previous myomectomy, Asherman syndrome, maternal age older than 35 years, smoking, and elevated α-fetoprotein levels. 3,4 Massive hemorrhage at the time of delivery is the most important clinical issue in cases of placenta accreta by the American Institute of Ultrasound in Medicine J Ultrasound Med 2008; 27: /08/$3.50

2 Placenta Accreta: Association With Fibroids and Asherman Syndrome It has now become the most common indication for obstetric hysterectomy. The maternal mortality risk is substantial and may reach 7%; morbidity is related to massive transfusions, urologic injury, and fistula formation. 3 Diagnosis of placenta accreta prenatally has a considerable impact on morbidity and mortality in women because the surgical team can be prepared for a complicated delivery. It is important to think about the diagnosis in women who are in the high-risk categories mentioned above. We describe 2 cases of placenta accreta in which the patients had a history related to fibroids and Asherman syndrome, yet the diagnosis of placenta accreta was not made prenatally. Case Descriptions Case 1 A 48-year-old woman, gravida 4, para 1, had in vitro fertilization using eggs from a 30-year-old donor, resulting in dichorionic-diamniotic twins. Her surgical history included myomectomy and lysis of intrauterine adhesions secondary to Asherman syndrome as well as 1 prior cesarean delivery. First-trimester sonography confirmed a dichorionic-diamniotic twin gestation at 12 weeks 4 days, consistent with dates. Normal nuchal translucency and nasal bones were seen in both twins. Follow-up sonography at 18 weeks 1 day showed appropriate growth for both twins, no congenital abnormalities, and a posterior low-lying placenta. Three anterior intramural fibroids, each about 2 cm in diameter, were also visualized. Sonography at 27 weeks showed twins with adequate symmetric growth and a normal amniotic fluid volume. Third-trimester follow-up sonography at 32 weeks showed normal growth for both twins. The placenta was posterior, and there was no evidence of previa. At 34 weeks, sonography showed that the fetuses had normal growth and a normal anterior and posterior placenta without evidence of previa. The patient had an emergency cesarean delivery at 34 weeks 6 days for acute antepartum hemorrhage. Both neonates had good Apgar scores at delivery. The mother bled heavily, approximately 5 L, during the procedure. Subtotal hysterectomy was performed, and 12 U of packed red blood cells, 1 U of platelets, and 6 U of fresh frozen plasma were given intraoperatively. The placenta was adherent to the posterior-fundal aspect of the uterus and was diagnosed as placenta accreta on the pathologic specimen (Figure 1). A retrospective review of the sonograms showed only a lobular surface of the placental-myometrial interface posteriorly (Figure 2). There was no evidence of myometrial thinning or serosal interruption. No color Doppler images were available. Case 2 A 39-year-old woman, gravida 8, para 6, had a second-trimester serum screen result positive for trisomy 21 with a risk of 1 in 12. The pregnancy had been complicated by first-trimester bleeding and gestational diabetes. Sonography Figure 1. A, Leiomyomectomy scar (arrow) from case 1. B, A leiomyoma is shown under the placenta. Note the lobular contour of the placenta. A B 1624 J Ultrasound Med 2008; 27:

3 Al-Serehi et al was performed at 18 weeks and revealed a 4-cm intraplacental hypoechoic vascular mass, which appeared to be retroplacental (Figure 3). The mass did not distort the external uterine contours. Both arterial and venous flows were peripheral and appeared to supply the mass. No fetal abnormalities or sonographic markers for trisomy 21 were detected. The sonographic features were most consistent with a leiomyoma. A chorangioma and old hemorrhage were also considered in the differential diagnosis. The mass did not change in size or appearance on subsequent sonographic studies at 27, 32, and 36 weeks. At 39 weeks, the patient had successful induction of labor with vaginal delivery of a live-born 3125-g neonate without complications; specifically, there was no appreciable hemorrhage. The tumor was delivered with an intact placenta. Cross sections of the placenta revealed an intraplacental 4.5-cm spheroid mass on the maternal surface that was histologically diagnostic of a leiomyoma (Figure 4). Overlying the leiomyoma was focal placenta accreta with placental villi directly adherent to muscle fibers of the neoplasm without intervening decidual cells (Figure 5). A normal-thickness decidual cell layer was present at the base of the remaining maternal surface. Discussion Accurate prenatal diagnosis of placenta accreta allows appropriate counseling and management of delivery, which should decrease both morbidity and mortality substantially. Massive hemorrhage continues to be a problem, and hysterectomy is generally accepted as the treatment of choice. In a recent study of 315 patients who required hysterectomy for antepartum or intrapartum bleeding, 38% had placenta previa, and 68% of them also had placenta accreta, increta, or percreta. 4 The prenatal diagnosis of placenta accreta has largely focused on the situation in which the placenta appears to invade a prior uterine scar from a prior cesarean delivery. Only a few cases of accreta related to myomectomy, adhesions, and dilation and curettage have been reported. 4 6 Our 2 cases emphasize the need to critically evaluate the placental/myometrial interface in patients who have a history of uterine scars related to procedures other than cesarean deliveries. In the first case, the lobular placental surface on the posterior wall of the uterus was not recognized as a site of possible placenta accreta related to a prior myomectomy scar. It is unclear whether a lobular placental surface on the maternal side on sonography has the same importance as a lobular surface on magnetic resonance imaging (MRI), where this has been reported to be a sign of accreta. 6 In the second case, the diagnosis of placenta accreta was made only on histopathologic examination, and although there was no excessive bleeding at delivery in this case, medical care providers should be aware that placental invasion into retroplacental/intraplacental fibroids can occur. Figure 2. Sonogram of the placenta showing a lobular contour along the posterior wall in case 1. Figure 3. Sonogram of a retroplacental fibroid from case 2. A hypoechoic mass (arrows) is shown between the placenta and the myometrium. M indicates myometrium; and P, placenta. J Ultrasound Med 2008; 27:

4 Placenta Accreta: Association With Fibroids and Asherman Syndrome Currently, no single diagnostic modality determines the diagnosis of placenta accreta with absolute accuracy; however, sonography remains the primary diagnostic tool in evaluating women for placenta accreta. The probability of prenatally predicting placenta accreta on the basis of the presence of characteristic sonographic findings is highly substantial. In the past, Finberg and Williams 7 made a diagnosis of placenta accreta in 14 of 18 patients who had 1 of the following sonographic markers: loss of the normal hypoechoic retroplacental line, thinning of the uterine serosa-bladder interface, presence of multiple placental lacunae, and presence of focal masses. Their sensitivity and specificity for sonography were 93% and 79%, respectively, based on the above-mentioned features. Warshak et al 6 had slightly lower sensitivity of 82% but higher specificity of 96% in a series of 39 cases with the same sonographic criteria. Additional work will need to be done to determine how often imaging findings can suggest accreta in the setting of a prior myomectomy scar and fibroids. Imagers must look for sonographic findings of accreta in these high-risk patients. The primary difference in these patients is that the area of accreta may be more diffuse into a myomectomy scar or a large fibroid rather than focal into a cesarean scar. Clearly, clinical judgment at delivery is necessary in these cases. The depiction of turbulent blood flow in placental lacunae and the presence of low- resistance arterial blood flow in the serosa-bladder interface on color Doppler imaging are highly predictive of accreta. 8 However, in a small series of 6 cases, Levine et al 5 found that color Doppler imaging added no appreciable information in diagnosing placenta accreta. False-positive diagnoses may occur with these criteria because of technical factors and the presence of bladder varices; therefore, it is important that the examination is made with the proper resolution and focus using both transabdominal and transvaginal transducers. In a review article, Comstock 9 cited several articles regarding color Doppler imaging and found that it added little to the diagnosis of placenta accreta. Magnetic resonance imaging adds additional diagnostic information in equivocal cases or cases of a posterior placenta. Levine et al 5 reported that MRI was helpful in 1 patient with prior myomectomy and a posterior placenta. The presence of a placental mass effect on the uterine wall is highly suggestive of placenta accreta. A depiction of placental adherence to the bladder wall in the lower uterine segment on MRI has also been reported. 10 Other diagnostic features seen on MRI that may be helpful in establishing the diagnosis are uterine bulging and the presence of dark intraplacental bands on T2-weighted images. 11 According to 1 study, the most reliable Figure 4. A, Sections of the placenta showing a 4.5-cm spheroid mass implanted into the placenta from the maternal surface. F indicates the fetal surface of the placenta; and L, leiomyoma, which is present in only some areas of the placenta. B, Sections of the placenta showing a 4.5-cm pale spheroid mass implanted into portions of the placenta from the maternal surface with adjacent areas of placenta accreta. A B 1626 J Ultrasound Med 2008; 27:

5 Al-Serehi et al Figure 5. Placenta accreta over a leiomyoma. Villi are attached to the neoplasm with only a layer of Nitabuch fibrin. No decidual cells are present. The tumor is composed of interlacing bundles of uniform elongated cells with vesicular nuclei. findings on T2-weighted images are an irregular uterine contour, a heterogeneous placental signal, and dark placental bands. 11 Warshak et al 6 showed that the accurate diagnosis of placenta accreta can be facilitated by using MRI for cases in which sonographic findings are indeterminate. These authors found gadolinium-based contrast enhancement helpful in making the diagnosis. Gadolinium-enhanced T1-weighted images help define the maternal-placental interface. 12 However, some authors have not found MRI to be helpful in all cases. 5 Neither of our cases here had MRI examinations. The optimal management of placenta accreta is based on an accurate prenatal diagnosis. For cases in which placenta accreta is suspected, a multidisciplinary team can work together to reduce the substantial risk of hemorrhage. In the past, conservative hysterectomy with the placenta left in situ was a definitive treatment for accreta. Recently, preoperative catheterization of uterine arteries has been reported to play a major role in minimizing the risk of bleeding intraoperatively. 13 Tan et al 13 reported that a notable advantage of vascular catheter placement is that the catheters may be left in situ for several hours postoperatively and then used for selected embolization of small pelvic vessels in the event of postoperative bleeding. The procedure requires the availability of a skilled angiographer. Preoperative endovascular internal iliac artery occlusion balloons reduce the amount of blood loss and blood transfusion requirements in patients with placenta accreta. 13 Only recently have there been reports on the use of methotrexate in treating placenta accreta to preserve the uterus. 14,15 Uterine leiomyomas are associated with multiple complications during pregnancy in addition to placenta accreta, including premature labor, abruptio placentae, malpresentation, dystocia, intrauterine growth restriction, and pelvic pain. 1 It has been shown that the position of the leiomyoma with respect to the placenta might predict the outcome of the pregnancy. 14 Patients with leiomyomas in direct contact with the placenta have had a greater incidence of pregnancy complications. Implantation of the placenta over leiomyomas caused abruptio placentae in 8 of 14 cases (57%) observed by Rice et al. 16 Abruptio placentae in these patients resulted in a 50% fetal death rate. There are only a few case reports of intraplacental smooth muscle neoplasms. In our second case, similar to the cases described in the literature, the leiomyoma was based on the maternal surface and deeply embedded in the placental parenchyma. This tumor most likely represented a uterine submucosal leiomyoma entrapped in the growing placenta. Primary smooth muscle neoplasms of the placenta, derived from blood vessels or from the placental mesoderm, may also occur. However, these tumors are extremely uncommon. With rare exceptions, chorioangiomas are the only benign tumors of the placenta. Cramer 17 reported a case of placenta increta overlying a submucosal leiomyoma, which was eroded by mature, normal-appearing placental tissue. Uterine leiomyomas may also predispose to abnormal placental septum formation by causing pressure atrophy and deficient decidualization of the overlying endometrium. There is considerable underreporting of smooth muscle neoplasms in the literature. Small intraplacental leiomyomas may be mistaken for placental infarcts J Ultrasound Med 2008; 27:

6 Placenta Accreta: Association With Fibroids and Asherman Syndrome on gross examinations. Histologic evaluation of the placental masses is very important to establish their association with placenta accreta/increta. In conclusion, it is important to assess pregnancies for possible placenta accreta when there are risk factors such as previous myomectomy, fibroids, previous uterine scarring, and Asherman syndrome, in addition to patients with placenta previa and prior cesarean deliveries. Thorough pathologic analysis of the placenta is needed to correlate the sonographic findings with the clinical importance to care appropriately for patients with prior myomectomy and intact fibroids. References 1. Wu S, Kocherginsky M, Hibbard JU. Abnormal placentation: twenty-year analysis. Am J Obstet Gynecol 2005; 192: Tanaka YO, Sohda S, Shigemitsu S, Niitsu M, Itai Y. High temporal resolution dynamic contrast MRI in a high risk group for placenta accreta. Magn Reson Imaging 2001; 19: Tan CH, Tay KH, Sheah K, et al. Perioperative endovascular internal iliac artery occlusion balloon placement in management of placenta accreta. AJR Am J Roentgenol 2007; 189: Morken NH, Kahn J. Placenta accreta and methotrexate treatment. Acta Obstet Gynecol Scand 2006; 85: Timmerman S, van Hof AC, Duvekot JJ. Conservative management of abnormally invasive placentation. Obstet Gynecol Surv 2007; 62: Rice JP, Kay HH, Mahony BS. The clinical significance of uterine leiomyomas in pregnancy. Am J Obstet Gynecol 1989; 160: Cramer SF. Invasion and destruction of neoplastic tissue by normal tissue. Pediatr Pathol 1987; 7: Clark SL, Koonings PP, Phelan JP. Placenta previa/accreta and prior cesarean section. Obstet Gynecol 1985; 66: O Brien JM, Barton JR, Donaldson ES. The management of placenta percreta: conservative and operative strategies. Am J Obstet Gynecol 1996; 175: Knight M; UKOSS. Peripartum hysterectomy in the UK: management and outcomes of the associated haemorrhage. BJOG 2007; 114: 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: Warshak CR, Eskander R, Hull AD, et al. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of placenta accreta. Obstet Gynecol 2006; 108: Finberg HJ, Williams JW. Placenta accreta: prospective sonographic diagnosis in patients with placenta previa and prior cesarean section. J Ultrasound Med 1992; 11: Chou MM, Ho ES, Lu F, Lee YH. Prenatal diagnosis of placenta previa/accreta with color Doppler ultrasound. Ultrasound Obstet Gynecol 1992; 2: Comstock CH. Antenatal diagnosis of placenta accreta: a review. Ultrasound Obstet Gynecol 2005; 26: Thorp JM Jr, Councell RB, Sandridge DA, Wiest HH. Antepartum diagnosis of placenta previa percreta by magnetic resonance imaging. Obstet Gynecol 1992; 80: Lax A, Prince MR, Mennittb KW, Schwebachc JR, Budorick NE. The value of specific MRI features in the evaluation of suspected placental invasion. Magn Reson Imaging 2007; 25: J Ultrasound Med 2008; 27: