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Magnetic resonance imaging for diagnosis of placenta accreta spectrum disorders: still useful for real-world practice

      To the Editors:
      Einerson et al,
      • Einerson B.D.
      • Rodriguez C.E.
      • Kennedy A.M.
      • Woodward P.J.
      • Donnelly M.A.
      • Silver R.M.
      Magnetic resonance imaging is often misleading when used as an adjunct to ultrasound in the management of placenta accreta spectrum disorders..
      the leaders of placenta accreta spectrum (PAS) disorders (creta, increta, percreta), showed that magnetic resonance imaging (MRI) after ultrasound frequently leads to an incorrect diagnosis of PAS. MRI revealed clinically meaningful changes in only 19% of cases. They concluded that “MRI should not be used routinely as an adjunct to ultrasound in the diagnosis of PAS … until evidence is clearly demonstrated by more definitive prospective studies.”
      We want to interpret their data differently.
      Of 78 patients, MRI altered the ultrasound diagnosis correctly/incorrectly in 15 (19%) and 13 (17%), respectively, being approximately equal. Thus, Einerson et al
      • Einerson B.D.
      • Rodriguez C.E.
      • Kennedy A.M.
      • Woodward P.J.
      • Donnelly M.A.
      • Silver R.M.
      Magnetic resonance imaging is often misleading when used as an adjunct to ultrasound in the management of placenta accreta spectrum disorders..
      rejected the adjunctive usefulness of MRI. However, we would like to note that in 7 patients (9%), the diagnosis was correctly upgraded to percreta. MRI, but not ultrasound, identified bladder invasion in 1 patient, for whom cystotomy was performed.
      For presurgically diagnosed placenta percreta, we perform cesarean hysterectomy under aortic balloon occlusion and ureteral stent use, whereas for less-degree PAS, we perform it without these presurgery procedures in a case-by-case manner. If bladder invasion is severe, we perform intentional cystotomy using an automatic cutting and stapling device.
      • Matsubara S.
      • Ohkuchi A.
      • Yashi M.
      • et al.
      Opening the bladder for cesarean hysterectomy for placenta previa percreta with bladder invasion.
      • Matsubara S.
      • Kuwata T.
      • Usui R.
      • et al.
      Important surgical measures and techniques at cesarean hysterectomy for placenta previa accreta.
      If the bladder invasion is too severe, we use placenta left in situ instead of hysterectomy to avoid life-threatening bleeding. Thus, the preoperative diagnosis of percreta markedly changes the strategy/preparation.
      The data of Einerson et al should be interpreted that “as many as 9%” of patients were “correctly upgraded to percreta,” greatly benefitting from MRI. Furthermore, because experienced obstetricians can usually discern percreta after laparotomy by directly observing the lesion,
      • Matsubara S.
      Re: Moving from intrapartum to prenatal diagnosis of placenta accreta: a quarter of a century in the making but still a long way to go: obstetricians' intra-surgical 'eyes' keep on shining.
      preparation for the worst before surgery markedly aids obstetricians.
      The worst-case scenario is for obstetricians to encounter percreta unexpectedly after opening the abdomen without an adequate multidisciplinary team or devices. MRI can avoid this scenario in some patients. The same may hold true for any other surgeries, especially difficult surgeries: if the 2 diagnostic modalities provide different disease severity, preparation for the worst may be better.
      If a diagnostic procedure has a risk of being harmful to patients, the present discussion may be different. MRI, although requiring some cost, causes no harm to the patient. Practically, we should prepare based on the severer data irrespective whether it is ultrasound or MRI (Figure).
      Figure thumbnail gr1
      FigureSchema of PAS disorders and proposed diagnostic procedures
      A, In creta, villous tissues attach to the myometrium without interposing decidua (adhesion abnormality), whereas in increta/percreta, villous tissues invade into/beyond the myometrium (invasion abnormality), respectively. B, Upper panel indicates creta and lower panel indicates percreta, with both diagnosed histologically. This figure shows an extreme example of upgrading by MRI scenario. In both creta (upper) and percreta (lower), ultrasound indicates creta, whereas MRI indicates percreta. Eventually ultrasound (upper) and MRI (lower), respectively, correctly diagnose the situation, which becomes evident in retrospect. When planning the surgery, adopt severe diagnosis (bold line) and disregard the less severe diagnosis (fine line) for safety. The final treatment strategy should be decided during surgery (see text).
      MRI, magnetic resonance imaging PAS, placenta accreta spectrum.
      Matsubara. MRI for accreta. Am J Obstet Gynecol 2018.
      Taken together, until evidence is clearly demonstrated, we recommend MRI to avoid/ameliorate the worst-case scenario. Putting this aside, every effort should be made to improve the diagnostic accuracy of MRI.

      References

        • Einerson B.D.
        • Rodriguez C.E.
        • Kennedy A.M.
        • Woodward P.J.
        • Donnelly M.A.
        • Silver R.M.
        Magnetic resonance imaging is often misleading when used as an adjunct to ultrasound in the management of placenta accreta spectrum disorders..
        Am J Obstet Gynecol. 2018; 218: 618.e1-618.e7
        • Matsubara S.
        • Ohkuchi A.
        • Yashi M.
        • et al.
        Opening the bladder for cesarean hysterectomy for placenta previa percreta with bladder invasion.
        J Obstet Gynaecol Res. 2009; 35: 359-363
        • Matsubara S.
        • Kuwata T.
        • Usui R.
        • et al.
        Important surgical measures and techniques at cesarean hysterectomy for placenta previa accreta.
        Acta Obstet Gynecol Scand. 2013; 92: 372-377
        • Matsubara S.
        Re: Moving from intrapartum to prenatal diagnosis of placenta accreta: a quarter of a century in the making but still a long way to go: obstetricians' intra-surgical 'eyes' keep on shining.
        BJOG. 2017; 124: 1287-1288

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