종설 The Korean Journal of Ultrasound in Obstetrics and Gynecology Vol. 13, No. 3, September 2011 유착태반의산전초음파진단 아주대학교의과대학산부인과학교실 양정인 The Prenatal Sonographic Diagnosis of Placental Adhesion Disorders Jeong In Yang, MD, PhD Department of Obstetrics and Gynecology, Ajou University School of Medicine, Suwon, Korea Adherent placenta, including placenta accreta and its variants placenta increta, and percreta, refers to placental villi penetrating into the myometrium due to a defect in decidua basalis. It is a major cause of obstetric hemorrhage, which increases the rate of maternal morbidity and mortality with increase of cesarean deliveries. Early diagnosis of adherent placenta before birth is very important in preventing serious obstetric complications such as cesarean hysterectomy and massive transfusion. In at-risk patients the sonographic criteria for adherent placenta include a sac implanted low over an anterior sac, cesarean section scar pregnancy, intraplacental lacunae, and disruption of placental-uterine wall interface at first trimester. During second and third trimesters intraplacental lacunae, loss of clear zone with or not disruption of placental-uterine wall interface, and disruption of the hyperechogenic uterine serosa-bladder interface with or not presence of focal exophytic masses are sonographically detected findings. Of these, intraplacental lacunae is the most reliable image for diagnosis of placenta attachment disorders. Antenatal diagnosis of adherent placenta might be done in patients with placenta previa and previous cesarean section to get better perinatal outcomes. The Korean Journal of Ultrasound in Obstetrics and Gynecology 13(3):97-103, 2011 Key Words: Adherent placenta, Prenatal diagnosis, Ultrasonography, Intraplacental lacunae 서 유착태반은드물게발생하지만산과적출혈의주원인이며산전및산후출혈, 자궁천공, 감염등을일으켜모성사망및이환율을높이므로임상적으로매우중요하다. 1 이는자궁하부, 기왕제왕절개반흔, 기왕자궁수술부위등과같이기저탈락막의형성에결함이있는곳에태반이착상될때발생하는데 Read 등 2 은 2,500 건당 1 예, Gielchinsky 등 3 은 0.9% 의빈도를보고하였다. 이와같이유착태반은보고자에따라그빈도가약간씩다르나최근제왕절개술의증가로 론 접수일 : 2011.7.6. 통과일 : 2011.7.19. * 교신저자 : 양정인 443-721, 수원시영통구원천동산 5 아주대학교병원산부인과 Tel: 031-219-5246, Fax: 031-219-5245 E-mail: yangji@ajou.ac.kr 인하여전치태반과동반한유착태반의발생률이높아지고있다. 4 유착태반의산전진단은주산기예후와관련되므로산과영역에서매우중요하나태반이분만될때까지는정확히진단할수없다. 따라서분만전유착태반의위험인자를가진임산부의선별을통해예상가능한합병증대처및분만중실혈에대비한마취과, 산부인과, 비뇨기과, 외과등의협진을통해주산기예후가달라질수있으므로산전진단은임상적으로매우중요하다. 5,6 그러나산전유착태반의진단은쉽지않아진단적정확도는매우낮다. 다행히최근초음파진단기기의해상도발달과더불어색도플러초음파검사, power 색도플러검사방법등이도입되어유착태반의위험인자를가진임산부들중초음파검사를통해산전에진단된증례들이증가하므로분만시상황을미리예측, 준비가가능하여주산기예후가향상되고있다. 7 일반적으로유착태반은유착의정도에따라병리학적으 - 97 -
대한산부인과초음파학회지제 13 권제 3 호, 2011 로태반이자궁근층까지침범한 placenta accreta, 자궁근층을침범하였으나자궁근층내에태반이머물고있는 increta, 태반이자궁장막을뚫고주변장기, 즉방광, 장까지이르게된가장심한형태의 percreta로분류할수있으나임상적으로는구분이어려우므로 placental attachment disorders 또는 adhesion placentas 로총칭하기도하지만일반적으로 incereta, percreta까지포함하여 placenta accreta, 즉유착태반이라부르고있다. 본고에서는유착태반의위험인자를가진고위험산모에서임신시기에따른유착태반의산전초음파소견을알아보아산전진단의정확도, 민감도및특이도를높이고자한다. 위험인자 태아의분만이완성된시점인분만제 2기가끝나면분만제3기에태반박리가일어나자연적으로태반만출이발생하는부분이 Nitabuch s 층으로, decidua 가이층을넘어자궁근층으로침입해들어갔을때유착태반이발생한다고생각되었으나 8 현재는상대적으로적은 decidua가원인으로받아들여지고있으며특히자궁하부는 decidua가적기때문에유착태반의호발부위로이곳에태반이자리를잡게되는경우인전치태반, 또는수술로인해 decidua가적어진경우인기왕제왕절개분만, 기왕자궁수술력등이중요한고위험인자로작용하며그외고령임신도포함된다. 1,9,10 특히제왕절개분만부위를덮고있는전치태반은가장높은연관성을보이므로초음파검사로유착태반동반여부를면밀히살펴야만한다. 이러한고위험인자를가지고있지않은저위험산모에서는현재임상적중요도를보이는초음파소견은보고되지않았다. 임신일삼분기의진단 정상적으로임신일삼분기의임신낭은자궁근층에둘러싸여자궁강내에견고하게위치하고있으며유착태반을시사하는소견들이초음파검사시보이지않는다. 그러나기왕제왕절개분만력이있는고위험산모에서소수의어떤예들은임신일삼분기에비정상적초음파소견을보이기도한다. 1) 임신낭이자궁하부절에위치한경우유착태반의초기징후로 Comstock 등 11 은자궁하부절에위치한임신낭소견을발표하였다. 기왕제왕절개력이있는임산부에서 10주이전에초음파검사를시행하였을때 7예에서자궁체부가아닌하부절에임신낭이위치하고있었으며이중 6예는모두한번이상의제왕절개수술력을가지고있었다. 임신이경과함에따라추적초음파검사에서 7예모두유착태반을시사하는초음파소견을추가로확인할수있었으며이중 6례에서과다출혈로인한전자궁적출술을, 1례에서는양측자궁동맥결찰술을시행하여자궁을보존할수있었으나모성합병증으로 Sheehan 증후군이발생하였다. 2) 제왕절개반흔임신제왕절개반흔임신은기왕제왕절개반흔자리에착상이이루어진것으로자궁강과연결이없이, 임신낭이자궁근층에있는것으로국한하여정의하지만현재는기왕제왕절개반흔자리에착상이이루어지고임신낭이자궁근층에있으며자궁강과연결이있는경우도포함하고있다. 일반적으로제왕절개반흔이있는자궁전벽에임신낭이착상된제왕절개반흔임신은유착태반을동반하며간혹임신기간이경과함에따라완전전치태반을동반한 placenta percreta로발전하기도하므로높은주의가필요하다 (Fig. 1). 12 그러나앞서언급한제왕절개분만을받은임산부에서 deciduas로둘러싸인임신낭이자궁하부에위치하고있으면많은연구에서제왕절개반흔임신의넓은범주안에포함시키고있으므로유착태반에의한소견과제왕절개반흔임신과구분이매우어렵다. 13,14 또한임신초기에불가피하게소파수술을한경우수술후초음파검사상자궁벽과방광사이에고에코의구조물이보이거나수술후과도한양의출혈이나타날경우에는유착태반을동반하거나제왕절개반흔임신인경우가대부분이므로재수술및추가적처치가필요할뿐아니라이미내원당시과다출혈로인해불안한생체징후를보이는경우도있으므로매우주의를요한다 (Fig. 2). 15,16 3) 태반내반월상열공 (Intraplacental lacunae) 반월상열공은다양한크기와모양의저음영병변이태반내에보이는것으로, De Mendoca 17 가 1988년처음으로보 - 98 -
양정인. 유착태반의초음파진단 고하였고 Hoffmann-Tretin 등, 18 Finberg와 Williams 19 에의해유착태반의진단기준으로제시되었다. 일반적으로가장먼저초음파상보이는시기는임신 16주경으로알려져왔으나 Yang 등 20 은기왕제왕절개분만력이있는임신 12주산모의초음파검사에서심한반월상열공소견을보인유착태반을진단한예를보고하기도하였다 (Fig. 3). 16 4) Placental-uterine wall interface 상대적으로 decidua가적은자궁의부분, 즉하부절, 기 왕수술부위등에태반이착상하기때문에자궁근층으로침투가용이하여유착태반이잘발생한다는가설을뒷받침하는초음파소견으로 Wong 등 21 은임신 6주의과거제왕절개분만력이있는산모에서 decidua의일부가제왕절개반흔쪽으로돌출되어불규칙적인 decidual/placental-uterine wall interface 를형성한소견을발견후추적관찰하여임신중, 후반에 placental-uterine wall interface disruption으로변화함을보고하였다. 이증례는임신 36주에 placenta increta 로제왕절개전자궁적출술을시행받았다. Fig. 1. The gestational sac locates in the lower uterine segment of uterine cavity and ended up placenta percreta. The arrow in the echolucent line of anterior uterine wall indicates previous cesarean scar. Fig. 2. Heterogenous oval shaped mass shadow of demarcation with arrows at anterior uterine wall after D&E, suggested placenta accreta. (A) (B) Fig. 3. (A) Transvaginal B mode sonographic scanning revealed multiple large and abnormal shaped hypoechogenic areas and disrupted retroplacental hypoechoic zone (white arrows) at 12 +0 weeks of gestation (white arrowhead indicates internal os). (B) Color flow Doppler imaging showed diffuse dilated intraplacental vasculature and marked periplacental vascularity between bladder and uterine serosa (B). - 99 -
대한산부인과초음파학회지제 13 권제 3 호, 2011 임신이삼분기이후 산모가기왕제왕절개력이있으면서전치태반특히태반이전방에위치한경우에는임신 20주이후부터유착태반의가능성을염두에두고초음파검사를실시하여야한다. 특히이시기에는임신후반부보다방광과자궁의관계및분리선이보다명확히보이므로방광을채운상태에서자궁근층의두께및침범정도, 태반과자긍근층의경계선및방광과자궁장막과의관계, 연속성등을면밀히살피도록한다. 1) 태반내반월상열공 (Intraplacental lacunae) 일반적으로임신중반이후이차원초음파검사상매우분명한, 다수의저에코또는무에코를가진 space, 즉 placental lake가태반내에서관찰되는데이것은정상적인임신과정중태반내에서보이는구조물이며이중유착태반의진단과밀접한연관성이있는반월상열공은가장흔히볼수있는유착태반소견중하나로다양한크기와모양의저 음영병변이불규칙한변연을가지고있으며, 이의발생기전은정확히알려져있지않으나유착태반내의많은혈류량과높은혈류속도, 22 태반의부적절한착상등 23 으로인하여태반이기계적으로파괴되어발생한다고여겨지고있다. Finberg와 Williams 는 19 이와같은열공을갯수, 크기, 모양등에따라 4 단계로분류하였다. 즉 grading 0: none seen, grade 1+: 1-3, small, grade 2+: 4-6, larger or more irregular, grade 3+: many throughout sometimes large and bizarre 로나누었을때열공의단계가높을수록, 더많고크고불규칙한모양의열공이보일수록유착태반의빈도가높다고보고하였다. Yang 등 24 은 Finberg & Williams 의 grading을이용하여산전유착태반의진단적정확도및주산기예후를비교하였을때열공이보이는경우유착태반의진단적정확도는민감도, 특이도, 양성예측도및음성예측도가각각 79.2%, 87.0%, 86.4%, 80.0% 이며또한 2단계이상의열공을보인경우에는모두유착태반소견을보였고열공의단계가높아질수록감입, 침투태반과같은유착태반의심한정도가증가하였으며 2단계이상의열공으로감입태반여부를진단하는민감 (A) (B) (C) (D) Fig. 4. Grading of intraplacental lacunae by transvaginal sonography (A) Grade 0 (B) Grade 1 (C) Grade 2 (D) Grade 3. - 100 -
양정인. 유착태반의초음파진단 도, 특이도, 양성예측도및음성예측도는 93.8%, 100%, 100%, 96.9% 라고하였다 (Fig. 4). Comstock 등 25 은임신이및삼삼분기의초음파검사를통하여태반내열공을보이는경우가유착태반을진단하는데있어민감도 93%, 양성예측도 93% 로가장신뢰성있는지표라고보고하였다. 25 본지표역시전치태반또는기왕제왕절개력등이있는고위험산모에서의의가있으며정상태반에서보이는 placental lakes와반드시비교하여야한다. 일반적으로반월상열공은 moth-eaten 또는 swiss-cheese 모양으로가장자리는불규칙하고보다선형에가까우며크기가다양할뿐아니라혈류의형태는 laminar보다 turbulent 타입을보인다. 2) Clear zone 소실 (disruption of placental-uterine wall interface) 정상적인임신에서는자궁근층과태반사이는매우낮은에코의검은선으로보이는 decidua basalis 층이지만유착태반에서는이층이형성되지않으므로초음파검사상잘보이지않을경우유착태반을의심할수있는소견으로생각되어왔지만정상임신특히자궁전벽에태반이있는경우에는대부분이선이보이지않으므로높은위양성을보이게된다. 26 임신 15주이후에검사하였을때민감도는 7%, 양성예측도는 6% 로실망스러운결과를보고하였다. 25 그러나 Wong 등 27 은통상적인초음파검사상 clear zone이보이 지않으나태반의일부가돌출되어있는소견을보일때에는유착태반진단의민감도 100%, 특이도 96.8%, 색도플러초음파검사를병행하여 disruption된부분의혈관주행을확인한경우에는특이도가 100% 로증가함을보고하기도하였다. 그러나본결과는다른연구자들에의해재현되는성과를보이지는못했다. 3) 방광변연 (Bladder border) 자궁근층과방광의장막사이는통상고에코의매끈한선으로나타나게되는데이러한선형구조물중간에 disruption이있거나 bulging이있는경우에는유착태반의진단에매우특별한소견중하나로여겨진다. 그러나유착태반이없는정상태반에서도다수의제왕절개분만력이있는산모및방광정맥류가있는경우에도같은소견을보일수있다. 또한유착태반의심한형태인 placenta percreta 가능성이다른소견을보이는경우보다높으므로특히주의를요한다. 28 4) 색도플러초음파검사 (Color Doppler sonography) 색도플러초음파검사자체만으로유착태반의진단적정확도를구하기는어려우며이차원초음파검사로앞서언급한태반내반월상열공, clear zone 소실 (disruption of placental-uterine wall interface) 부분을지나는혈관의존재유 (A) PL (B) AF Fig. 5. (A) 2D sonography showed a turbulent and whirlpool patterned blood flow within placenta. (B) The eye of typhoon pattern is revealed by color Doppler ultrasonography. AF, amniotic fluid; PL, placenta. - 101 -
대한산부인과초음파학회지제 13 권제 3 호, 2011 무, 방광내로돌출되는혈관의존재들을확인할때보조적인수단으로도움이된다. 특히태반내반월상열공을정상임신의 placental lakes와비교시 high velocity, turbulent blood flow 소견을보인다면유착태반의진단에보다가까워진다고할수있다. 또한 Shih 등 29 은임신일삼분기시색도플러검사의도움으로유착태반을진단한예를보고하기도하였으며본저자들도색도플러초음파검사로거대한반월상열공의가장자리에있는혈관을확인한바있다 (Fig. 5). 30 결 유착태반의고위험인자인제왕절개분만력, 전치태반및고령임신등을가지고있는산모에서는임신 6주이후 10주이전에제왕절개반흔, 자궁하부절등을초음파검사로주의깊게살펴보아야하며특히제왕절개반흔임신의진단에주의하여야한다. 만약임신일삼분기에특별한의심소견을발견하지못했다하더라도임신 15주이후태반에반원상열공의존재유무, 자궁근층과방광연, 태반과자궁근층간돌출구조물의유무등을반드시검사하여야하며가장신뢰도가높은검사소견으로는반월상열공을들수있다. 또한필요하다면색도플러초음파검사를추가하여유착태반의산전진단적정확도를높이고삼차병원에서의계획된분만이이루어진다면주산기합병증및사망률을감소시켜보다향상된주산기결과를얻을수있다. 론 참고문헌 1. Miller DA, Chollet JA, Goodwin TM. Clinical risk factors for placenta previa - placenta accreta. Am J Obstet Gynecol 1997; 177: 210-4. 2. Read JA, Cotton DB, Miller FC. Placenta accreta: Changing clinical aspects and outcome. Obstet Gynecol 1980; 56: 31-4. 3. Gielchinsky Y, Rojansky N, Fasouliotis SJ, Ezra Y. Placenta accreta-summary of 10 years: A survey of 310 cases. Placenta 2002; 23: 210-4. 4. Silver RM, Landon MB, Rouse DJ, Leveno KJ, Spong CY, Thom EA, et al. National institute of child health and human development maternal-fetal medicine units network. Maternal morbidity associated with multiple repeat cesarean deliveries. Obstet Gynecol 2006; 107: 1226-32. 5. Esakoff TF, Sparks TN, Kaimal AJ, Kim LH, Feldstein VA, Goldstein RB, et al. Diagnosis and morbidity of placenta accreta. Ultrasound Obstet Gynecol 2011; 37: 324-7. 6. Wong HS, Hutton J, Zuccollo J, Pringle KC. Maternal outcome in placenta accreta: the significance of antenatal diagnosis and nonseparation of the placenta at delivery. NZ Med J 2008; 121: 30-8. 7. Warshak CR, Ramos GA, Eskander R, Benirschke K, Saenz CC, Kelly TF, et al. Effect of predelivery diagnosis in 99 consecutive cases of placenta accreta. Obstet Gynecol 2010; 115: 65-9. 8. Pijnenborg R. The human deciduas as a passageway for trophoblast invasion. Trophoblast Res 1998; 11: 229-41. 9. Khong TY. The pathology of placenta accreta, a worldwide epidemic. J Clin Pathol 2008; 61: 1243-6. 10. Tantbirojn P, Crum CP, Parast MM. Pathophysiology of placenta creta:the role of deciduas and extravillous trophoblast. Placenta 2008:29:639-45. 11. Comstock CH, Lee W, Vettraino IM, Bronsteen RA. The early sonographic appearance of placenta accreta. J Ultrasound Med 2003; 22: 19-23. 12. Ben Nagi J, Ofili-Yebovi D, Marsh M, Jurkovic D. First-trimester cesarean scar pregnancy evolving into placenta previa/accreta at term 2003; 22: 19-23. 13. Buetow MP. Sonography of placenta percreta during the first trimester. AJR 2002; 179: 535. 14. Ash A, Smith A, Maxwell D. Caesarean scar pregnancy. BJOG 2007; 114: 253-63. 15. Chen YJ, Wang PH, Liu WM, Lai CR, Shu LP, Hung JH. Placenta previa diagnosed at 9weeks gestation. Ultrasound Obstet Gynecol 2002; 19: 620-2. 16. Gherman RB, McBrayer S, Tichenor J, Wing DA. Placenta increta complicating first trimester D and C. Obstet Gynecol 1999; 93: 845. 17. De Mendoca LK. Sonographic diagnosis of placenta accreta presentation of six cases. J Ultrasound Med 1988; 7: 211-5. 18. Hoffman-Tretin JC, Koenigsberg M, Rabin A, Anyaegbunam A. Placenta accreta. Additional sonographic observations. J Ultrasound Med 1992; 11: 29-34. 19. Finberg HJ, Williams JW. Placenta accreta: Prospective sonographic diagnosis in patients with placenta previa and prior cesarean section. J Ultrasound Med 1992; 11: 333-43. 20. Yang JI, Kim HY, Kim HS, Ryu HS. Diagnosis in the first trimester accreta with previous cesarean section. Ultrasound Obstet Gynecol 2009; 34: 116-8. 21. Wong HS, Zuccollo J, Tait J, Pringle KC. Placenta accreta in the first trimester of pregnancy:sonographic findiongs. J Clin Ultrasonound 2009; 37: 100-3. 22. Chou MM, Ho ES, Lu F, Lee YH. Prenatal diagnosis of placenta previa/accreta with color Doppler ultrasound. Ultrasound Obstet Gynecol 1992; 2: 293-6. 23. Twickler DM, Lucas MJ, Balis AB, Santos-Ramos R, Martin L, Malone S, et al. Color flow mapping for myometrial invasion in women with a prior cesarean delivery. J Matern Fetal Med 2000; 9: 330-5. 24. Yang JI, Lim YK, Kim HS, Chang KH, Lee JP, Ryu HS. Sonographic findings of placental lacunae and the prediction of adherent placenta in women with placenta previa totalis and prior Cesarean section. Ultrasound Obstet Gynecol 2006; 28: - 102 -
양정인. 유착태반의초음파진단 178-82. 25. Comstock CH, Love JJ Jr, Bronsteen RA, Lee W, Vettraino IM, Huang RR, et al. Sonographic detection of placenta accreta in the second and third trimesters of pregnancy. Am J Obstet Gynecol 2004; 190: 1135-40. 26. McGahan JP, Phillips HE, Reid MH. The anechoic retroplacental area:a pitfall in diagnosis of placental-endometrial abnormalities during pregnancy. Radiology 1980; 134: 475-8. 27. Wong HS, cheung YK, Strand L, Carryer P, Parker S, Tait J, et al. Specific sonographic features of placenta accreta: tissue interface disruption on gray-scale imaging and evidence of vessels crossing interface-disruption site on Doppler imaging. Ultrasound Obstet Gynecol 2007; 29: 239-40. 28. Comstock CH. Antenatal diagnosis of placenta accreta:a review. Ultrasound Obstet Gynecol 2005; 26: 89-96. 29. Shih JC, Cheng WF, Shyu MK, Lee CN, Hsieh FJ. Power Doppler evidence of placenta accreta appearing in the first trimester. Ultrasound Obstet Gynecol 2002; 19: 623-31. 30. Yang JI, Kim YM, Kim HS. The eye of a typhoon finding in the case of placenta accreta with previa. J Kor Ultrasound Obstet gynecol 2008; 10: 36. 국문요약유착태반은태반기저층의결함으로태반이자궁근층으로계속침범해들어가생기는질환으로최근제왕절개분만과함께증가추세를보이고있으며산과적출혈을일으키므로주요한모성사망및유병률의원인이다. 유착태반의위험인자인기왕제왕절개력, 전치태반및고령임신을경험하고있는임신부의유착태반진단을위한산전초음파검사소견은임신일삼분기에자궁하부절에위치하고있는임신낭, 제왕절개반흔임신, 태반내반월상열공및태반- 자궁근층의접촉면이잘보이지않는경우등을들수있다. 임신이삼분기및삼삼분기에는태반내반월상열공, 태반-자궁근층의접촉면이잘보이지않으며투명층이보이지않은경우, 고에코의자궁장막및방광의접촉면이잘보이지않는경우및방광쪽으로돌출된종괴양상이보일때의심해볼수있다. 그러나이가운데산전유착태반의가장의미있는초음파진단소견은태반내반월상열공의존재여부이다. 따라서유착태반의산전진단을통해발생가능한합병증에미리대처한다면보다향상된주산기예후를기대할수있다. 중심단어 : 유착태반, 산전진단, 초음파검사, 태반내반월상열공 - 103 -