eMedicine Specialties > Obstetrics and Gynecology > Obstetrical Complications

Placenta Previa: Treatment & Medication

Author: Saju Joy, MD, MS, Assistant Professor, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Wake Forest University School of Medicine
Coauthor(s): Deborah Lyon, MD, Director, Division of Gynecology, Associate Professor, Department of Obstetrics and Gynecology, University of Florida Health Science Center at Jacksonville
Contributor Information and Disclosures

Updated: Aug 12, 2008

Treatment

Medical Care

For an uncomplicated pregnancy, continue expectant management until an episode of bleeding occurs. Studies have not shown any difference regarding maternal or fetal morbidity with home management versus hospitalization, prior to the first bleed. If, however, bleeding or contractions occur, the patient must rapidly go to the hospital for evaluation and the above mentioned testing. If bleeding persists, and is heavy preparation for immediate surgery is indicated. In cases where placental location remains uncertain, a double setup examination may be considered. However, if bleeding is minimal and fetal reassurance is noted, expectant management may be considered to allow for fetal maturity.

Additionally, tocolytics may also be considered in cases of minimal bleeding and extreme prematurity to administer antenatal corticosteroids. If more than one episode of bleeding occurs during gestation (at viability or >24 wk), the clinician should consider hospitalization until delivery given the increased potential for placental abruption and fetal demise.

Surgical Care

The distance between the placental edge and internal cervical os on transvaginal ultrasonography after 35 weeks’ gestation is valuable in planning route of delivery. When the placental edge is greater than 2 cm from the internal cervical os, women can be offered a trial of labour with a high expectation of success. However, a distance of less than 2 cm from the os is associated with a higher cesarean rate, although vaginal delivery is still possible depending on the clinical circumstances.
 
The timing of delivery is often driven by the patients history and an increased risk for bleeding with advancing gestation. Most authorities recommend delivery at 36-37 weeks' gestation after confirming fetal lung maturity via amniocentesis. However, if the fetal lung maturity testing is immature or is not available, then delivery is often scheduled for 38 weeks' gestation.   

Most often a low transverse uterine incision is used; however, a vertical uterine incision may be considered secondary to an anterior placenta and risk of fetal bleeding. If the patient is at increased risk for invasive placentation (accreta, increta, or percreta), then the patient and surgical team must be prepared prior to delivery. These invasive placentations carry a high mortality rate (7% with placenta accreta) as well as a high morbidity rate (blood transfusion, infection, adjacent organ damage).

These complicated pregnancies must have delivery plans that include patient-matched blood and informed consent for possible cesarean hysterectomy. Predelivery placement of balloon catheters for angiographic embolization of pelvic vessels is a technique described in reducing blood loss associated with cesarean hysterectomy. Other means to control hemorrhage include B-Lynch or parallel vertical compression sutures, uterine artery ligation, hypogastric artery ligation, and, of course, hysterectomy.  In the case of a small and focal placenta accreta, resection of the implantation site and primary repair may allow for uterine preservation.

Consultations

  • Interventional radiology
  • Surgical oncology or general surgery if extensive surgical dissection is anticipated
  • Gynecologic oncology
  • Urology if significant involvement of the bladder is anticipated

Medication

No medication is of specific benefit to a patient with placenta previa. Tocolysis may be cautiously considered in some circumstances. Encourage patients with known placenta previa to maintain intake of iron and folate as a safety margin in the event of bleeding.

Tocolytics

Prevent preterm labor or contractions.


Magnesium sulfate

Nutritional supplement in hyperalimentation; cofactor in enzyme systems involved in neurochemical transmission and muscular excitability. In adults, 60-180 mEq of potassium, 10-30 mEq of magnesium, and 10-40 mEq of phosphate per day may be necessary for optimum metabolic response. Administer IV or IM for seizure prophylaxis in preeclampsia. Use IV route for quicker onset of action in true eclampsia. Discontinue treatment as soon as desired effect is obtained. Repeat doses dependent on continuing presence of patellar reflex and adequate respiratory function.

Adult

Loading dose: 6 g IV over 20 min; then 2-4 g/h continuous infusion; adjust to lessen contractions; not to exceed 4 g/h

Pediatric

Administer as in adults; alternatively, 20-100 mg/kg/dose IV q4-6h prn; in severe cases, may use doses as high as 200 mg/kg/dose; not to exceed 4 g/h

Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade seen with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants and betamethasone; may increase cardiotoxicity of ritodrine

Documented hypersensitivity; heart block; Addison disease; myocardial damage; myasthenia gravis; impaired renal function; severe hepatitis

Pregnancy

A - Fetal risk not revealed in controlled studies in humans

Precautions

Fetal monitoring is essential, may decrease fetal heart rate; maternal magnesium toxicity may occur at low or high rates of infusion; magnesium may alter cardiac conduction, leading to heart block in patients who are digitalized; monitor respiratory rate, deep tendon reflex, and renal function when electrolytes are administered parenterally; caution when administering magnesium because may produce significant hypertension or asystole; in overdose, calcium gluconate (10-20 mL IV of 10% solution) can be administered as an antidote for clinically significant hypermagnesemia

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

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  2. Butler EL, Dashe JS, Ramus RM. Association between maternal serum alpha-fetoprotein and adverse outcomes in pregnancies with placenta previa. Obstet Gynecol. Jan 2001;97(1):35-8. [Medline].

  3. Comstock CH, Love JJ, Bronsteen RA, et al. Sonographic detection of placenta accreta in the second and third trimesters of pregnancy. Am J Obstet Gynecol. Apr 2004;190(4):1135-40. [Medline].

  4. Creasy RK, Resnik R, Clark SL. Placenta previa and abruptio placentae. In: Creasy RK, Resnik R, eds. Maternal-Fetal Medicine. 4th ed. Philadelphia, Pa: WB Saunders; 1999:616-21.

  5. Cunningham FG, MacDonald PC. Obstetrical hemorrhage. In: Cunningham FG, Gilstrap LC, Gant NF, Leveno KJ, Hauth JC, Wenstrom KD, eds. Williams Obstetrics. 20th ed. New York, NY: McGraw-Hill; 1997:755-60.

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Further Reading

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Keywords

placenta previa, complete placenta previa, partial placenta previa, marginal placenta previa, low-lying placenta, placenta accreta, placenta increta, placenta percreta, cesarean delivery, cesarean hysterectomy, transvaginal sonography, transvaginal ultrasonography, tocolysis, continuous fetal monitoring, accreta, increta, percreta, transvaginal ultrasound

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Contributor Information and Disclosures

Author

Saju Joy, MD, MS, Assistant Professor, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Wake Forest University School of Medicine
Saju Joy, MD, MS is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine, American Medical Association, and Society for Maternal-Fetal Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Deborah Lyon, MD, Director, Division of Gynecology, Associate Professor, Department of Obstetrics and Gynecology, University of Florida Health Science Center at Jacksonville
Deborah Lyon, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, Association of American Medical Colleges, Association of Professors of Gynecology and Obstetrics, and Florida Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Ronald Levine, MD, Director, Section of Gynecologic Endoscopy, Professor, Department of Obstetrics and Gynecology, University of Louisville School of Medicine
Ronald Levine, MD is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American College of Obstetricians and Gynecologists, American Medical Association, and Society of Laparoendoscopic Surgeons
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Richard S Legro, MD, Professor, Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology, Pennsylvania State University College of Medicine; Consulting Staff, Milton S Hershey Medical Center
Richard S Legro, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Society for Reproductive Medicine, Endocrine Society, Phi Beta Kappa, and Society of Reproductive Surgeons
Disclosure: Nothing to disclose.

CME Editor

Frederick B Gaupp, MD, Consulting Staff, Department of Family Practice, Hancock Medical Center
Frederick B Gaupp, MD is a member of the following medical societies: American Academy of Family Physicians
Disclosure: Nothing to disclose.

Chief Editor

Carl V Smith, MD, The Distinguished Chris J and Marie A Olson Chair of Obstetrics and Gynecology, Professor, Department of Obstetrics and Gynecology, University of Nebraska Medical Center
Carl V Smith, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine, American Medical Association, Arkansas Medical Society, Association of Professors of Gynecology and Obstetrics, Central Association of Obstetricians and Gynecologists, Council of University Chairs of Obstetrics and Gynecology, Nebraska Medical Association, and Society for Maternal-Fetal Medicine
Disclosure: Nothing to disclose.

 
 
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