In a study comparing misoprostol 200, 400, and 600 ìg given vaginally every 12 hours, the abortion rates were 70.6%, 82%, and 96%,  respectively.  (IA)  Currently,  vaginal misoprostol 200 ìg every 12 hours up to 48 hours appears to be the optimal regimen because as the doses increase or the interval of administration decreases, the number and severity of side effects increase.  The incidence of abortion within 48 hours of this regimen ranges from 70.6% to 87.2%.

Further research is required to determine the optimal dose and frequency for second trimester termination.

Insertion of laminaria tents at the time of the first misoprostol dose did not alter efficacy.  The use of laminaria tents prior to misoprostol, which may improve efficacy, has not been reported. The success interval from initiation to abortion and the failure rate are both increased in viable gestation compared with fetal demise.

Uterine rupture in women with previous Caesarean section has been reported; however, these occurred in gestations greater than 20 weeks and with higher doses or decreased frequency of infusion (200 - 400 ìg every 4 - 6 hours).

D&E Versus Induction
There are no prospective randomized studies comparing current methods for labour induction and D&E.  Older studies that compare these methods and a more recent study indicate that D&E is associated with fewer complications than induction.  The most frequent complication associated with induction was retained placenta. Of the induction methods, misoprostol was the most efficacious but still had more complications than D&E. 

  One consideration in Canada is the lack of physicians who have the experience to perform advanced gestation D&E.

Hysterotomy and Hysterectomy
Hysterotomy is essentially an early classical Caesarean section. With current pharmacologic agents for labour induction in pregnancy termination, the procedure is rarely indicated as a primary method of abortion. The morbidity and mortality associated with hysterotomy are far greater than for any other technique. In most cases, failed abortions are managed   with   parenteral,  oral,  vaginal,  or   rectal prostaglandins even in the presence of a uterine anomaly.

Only after failure of the prostaglandins should hysterotomy be performed.

If pregnancy co-exists with a separate indication for hysterectomy (cervical, uterine, or ovarian cancer) then gravid hysterectomy may be indicated. However, a simpler means of pregnancy evacuation followed by a definitive diagnosis and therapy is preferred and will reduce the associated morbidity and mortality associated with gravid hysterectomy.

 

Summary of Recommendations

REFERENCES

Victoria Jane Davis, MD
These guidelines were reviewed by the Clinical
Practice - Gynaecology Committee and the Social and Sexual
Issues Committee and approved by the Executive and Council of
the Society of Obstetricians and Gynaecologists of Canada.