eMedicine Specialties > Emergency Medicine > Obstetrics & Gynecology

Placenta Previa: Differential Diagnoses & Workup

Author: Patrick Ko, MD, Clinical Assistant Professor, Department of Emergency Medicine, New York University Medical School; Assistant Program Director, Department of Emergency Medicine, North Shore University Hospital
Coauthor(s): Young Yoon, MD, Associate Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai Medical Center
Contributor Information and Disclosures

Updated: Aug 10, 2009

Differential Diagnoses

Abruptio Placentae
Disseminated Intravascular Coagulation
Pregnancy, Delivery

Other Problems to Be Considered

Vasa previa
Infection
Vaginal bleeding
Lower genital tract lesions
Bloody show

Workup

Laboratory Studies

The following studies are indicated in placenta previa:

  • Beta-human chorionic gonadotropin (beta-hCG) subunit
  • Rh compatibility
  • Fibrin split products (FSP) and fibrinogen levels
  • Prothrombin time (PT)/activated partial thromboplastin time (aPTT)
  • Type and hold for at least 4 units
  • CBC count
  • Apt test to determine fetal origin of blood (as in the case of vasa previa)
  • Wright stain applied to a slide smear of vaginal blood, looking for nucleated RBCs, not adult blood
  • Lecithin/sphingomyelin (L/S) ratio for fetal maturity, if needed

Imaging Studies

  • Transabdominal ultrasonography
    • A simple, precise, and safe method to visualize the placenta, this ultrasonography has an accuracy of 93-98%.
    • False-positive results can occur secondary to focal uterine contractions or bladder distention.
  • Transvaginal ultrasonography
    • Recent studies have shown that the transvaginal method is safer and more accurate than the transabdominal method. Transvaginal ultrasonography is also considered more accurate than transabdominal ultrasonography. In one study, 26% of placental localization diagnosed by transabdominal ultrasonography was later changed using transvaginal ultrasonography.
    • The angle between the transvaginal probe and the cervical canal is such that the probe does not enter the cervical canal. Some advocate insertion of the probe no more than 3 cm for visualization of the placenta.
  • Transperineal ultrasonography: Transperineal ultrasonography has been suggested as an alternate method, especially when instrumentation of the vaginal canal with a probe is a concern. A recent study suggests that transperineal ultrasonography may compliment transabdominal ultrasonography and help eliminate false-positive results using the transabdominal method alone.
  • MRI: MRI has been suggested as a safe and alternate method and may be useful in determining the presence of placenta accreta. A large trial determining the efficacy and safety of the use of MRI during pregnancy has not been performed, and further investigation is required.

Other Tests

  • Kleihauer-Betke test, if concerned about fetal-maternal transfusion
  • Bedside clot test

Procedures

  • If the location of the placenta is unknown and sonography is not available, a double set-up bimanual examination under anesthesia (EUA) may be performed in the operating room.

More on Placenta Previa

Overview: Placenta Previa
Differential Diagnoses & Workup: Placenta Previa
Treatment & Medication: Placenta Previa
Follow-up: Placenta Previa
Multimedia: Placenta Previa
References
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References

  1. Vergani P, Ornaghi S, Pozzi I, Beretta P, Russo FM, Follesa I, et al. Placenta previa: distance to internal os and mode of delivery. Am J Obstet Gynecol. Jul 23 2009;[Medline].

  2. Milosevic J, Lilic V, Tasic M, Radovic-Janosevic D, Stefanovic M, Antic V. [Placental complications after a previous cesarean section]. Med Pregl. May-Jun 2009;62(5-6):212-6. [Medline].

  3. [Guideline] Royal College of Obstetricians and Gynaecologists (RCOG). Placenta praevia and placenta praevia accreta: diagnosis and management. Oct 2005;[Full Text].

  4. [Guideline] Oppenheimer L. Diagnosis and management of placenta previa. J Obstet Gynaecol Can. Mar 2007;29(3):261-73. [Medline]. [Full Text].

  5. Ananth CV, Smulian JC, Vintzileos AM. The effect of placenta previa on neonatal mortality: a population-based study in the United States, 1989 through 1997. Am J Obstet Gynecol. May 2003;188(5):1299-304. [Medline].

  6. Besinger RE, Moniak CW, Paskiewicz LS, Fisher SG, Tomich PG. The effect of tocolytic use in the management of symptomatic placenta previa. Am J Obstet Gynecol. Jun 1995;172(6):1770-5; discussion 1775-8. [Medline].

  7. Crane S, Chun B, Acker D. Treatment of obstetrical hemorrhagic emergencies. Curr Opin Obstet Gynecol. Oct 1993;5(5):675-82. [Medline].

  8. Dola CP, Garite TJ, Dowling DD, Friend D, Ahdoot D, Asrat T. Placenta previa: does its type affect pregnancy outcome?. Am J Perinatol. Oct 2003;20(7):353-60. [Medline].

  9. Gidiri M, Noble W, Rafique Z, Patil K, Lindow SW. Caesarean section for placenta praevia complicated by postpartum haemorrhage managed successfully with recombinant activated human coagulation Factor VIIa. J Obstet Gynaecol. Nov 2004;24(8):925-6. [Medline].

  10. Glynn JC, Plaat F. Prothrombin complex for massive obstetric haemorrhage. Anaesthesia. Feb 2007;62(2):202-3. [Medline].

  11. Iyasu S, Saftlas AK, Rowley DL, Koonin LM, Lawson HW, Atrash HK. The epidemiology of placenta previa in the United States, 1979 through 1987. Am J Obstet Gynecol. May 1993;168(5):1424-9. [Medline].

  12. Otsubo Y, Shinagawa T, Chihara H, Araki T. Conservative management of a case of placenta praevia percreta. Aust N Z J Obstet Gynaecol. Nov 1999;39(4):518-9. [Medline].

  13. Rani PR, Haritha PH, Gowri R. Comparative study of transperineal and transabdominal sonography in the diagnosis of placenta previa. J Obstet Gynaecol Res. Apr 2007;33(2):134-7. [Medline].

  14. Rathore SS, McMahon MJ. Racial variation in the frequency of intrapartum hemorrhage. Obstet Gynecol. Feb 2001;97(2):178-83. [Medline].

  15. Sharma A, Suri V, Gupta I. Tocolytic therapy in conservative management of symptomatic placenta previa. Int J Gynaecol Obstet. Feb 2004;84(2):109-13. [Medline].

  16. Smith RS, Lauria MR, Comstock CH, Treadwell MC, Kirk JS, Lee W, et al. Transvaginal ultrasonography for all placentas that appear to be low-lying or over the internal cervical os. Ultrasound Obstet Gynecol. Jan 1997;9(1):22-4. [Medline].

  17. Taber. Manual of Gynecologic and Obstetric Emergencies. 2nd ed. Philadelphia, Pa: WB Saunders Co; 1984:313-318.

  18. Taylor VM, Peacock S, Kramer MD, Vaughan TL. Increased risk of placenta previa among women of Asian origin. Obstet Gynecol. Nov 1995;86(5):805-8. [Medline].

  19. Timor-Tritsch IE, Monteagudo A. Diagnosis of placenta previa by transvaginal sonography. Ann Med. Jun 1993;25(3):279-83. [Medline].

  20. Williams, Cunningham, Macdonald. Williams' Obstetrics. 19th ed. Norwalk, Conn: Appleton & Lange; 1993:836-841.

  21. Zhang J, Savitz DA. Maternal age and placenta previa: a population-based, case-control study. Am J Obstet Gynecol. Feb 1993;168(2):641-5. [Medline].

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Further Reading

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Keywords

placenta previa, disseminated intravascular coagulopathy, vaginal bleeding, pregnancy complications, obstetric complications, total placenta previa, partial placenta previa, marginal placenta previa, low-lying placenta previa, internal cervical os, abnormal placental implantation, uterine bleeding, treatment, diagnosis

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Contributor Information and Disclosures

Author

Patrick Ko, MD, Clinical Assistant Professor, Department of Emergency Medicine, New York University Medical School; Assistant Program Director, Department of Emergency Medicine, North Shore University Hospital
Patrick Ko, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Young Yoon, MD, Associate Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai Medical Center
Young Yoon, MD is a member of the following medical societies: Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Joseph J Sachter, MD, FACEP, Consulting Staff, Department of Emergency Medicine, Muhlenberg Regional Medical Center
Joseph J Sachter, MD, FACEP is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Physician Executives, American Medical Association, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Mark Zwanger, MD, MBA, Assistant Professor, Department of Emergency Medicine, Thomas Jefferson University
Mark Zwanger, MD, MBA is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and American Medical Association
Disclosure: Medicines Company Consulting fee Consulting; Pfizer Salary Employment

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Pamela L Dyne, MD, Professor of Clinical Medicine/Emergency Medicine, David Geffen School of Medicine at UCLA; Attending Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center
Pamela L Dyne, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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