A large number of treatments described in the literature—and their different combinations—have been reported as relatively small case series. Gynecologic surgeons generally perform D&C, laparoscopy, and hysteroscopy or laparotomy as the first-line approach. Obstetricians, radiologists, and in vitro fertilization specialists usually prefer systemic, parenteral administration of methotrexate or ultrasound-guided local methotrexate (or potassium chloride) as an injection into the gestational sac. On occasion, the help of an interventional radiologist was requested to embolize the area of the CSP through the uterine arteries.
POTENTIAL COMPLICATIONS
In our analysis of 751 cases of CSP, we used a rigorous definition of complication, which included an immediate or delayed need for a secondary treatment for blood loss exceeding 200 mL or requiring blood transfusion. If general anesthesia or major surgery was required, we classified that need as a complication.
Utilizing these criteria, we observed an overall complication rate of 44.1% (331 of 751 cases).1
Complications occurred most often when the following treatment modalities were used alone:
- single systemic dose of methotrexate
- D&C
- uterine artery embolization.
Of the 751 cases reviewed, 21.8% resulted in major surgery or interventional radiology procedures (primary or emergency). The total planned primary (nonemergency) interventions performed were 66 (8.7%), which included 3 hysterectomies, 14 laparotomies, and 49 uterine artery embolizations or ligations. There were 98 (13.0%) emergency interventions, which included 36 hysterectomies, 40 laparotomies, and 22 uterine artery embolizations or ligations.1
Related article: Eight tools for improving obstetric patient safety and unit performance. Henry M. Lerner, MD (Professional Liability; March 2014)
NINE TREATMENTS AND THEIR COMPLICATIONS
1. Systemic, single-dose methotrexate
The usual protocols were 1 mg/kg of body weight or 50 mg/m2 of body surface area. This treatment was associated with a complication rate of 64.6%, mostly because it required a second treatment when the fetal heart beat did not cease after several days.1
We speculate that the high failure rate with this treatment may be caused by its slow action and questionable ability to stop cardiac activity and placental expansion. The expected result can take days, and all the while the gestational sac, the embryo or fetus, and its vascularity are growing. Secondary treatment has to address a larger gestation with more abundant vascularization.
2. Systemic, multidose, sequential methotrexate
In this regimen, the amounts of methotrexate injected are similar to the dose for the single-dose regimen. Two to three intramuscular injections (1 mg/kg of body weight or 50 mg/mm2 of surface area) are given at an interval of 2 or 3 days over the course of a week. Be aware of the cumulative adverse effects of this drug on the liver and bone marrow—and the fact that even multidose treatment can fail.1
We found it impossible to assess the complication rate associated with this approach because it was often used in conjunction with another “first-line” treatment or after it. However, it is clear that methotrexate can be combined with other, mostly nonsurgical treatments.
3. Suction aspiration or D&C, alone or in combination
This option requires general anesthesia. The 305 cases involving this treatment had a mean complication rate of about 62% (range, 29%–86%).1 This approach caused the greatest number of bleeding complications, necessitating a third-line treatment that almost always was surgical.
At delivery or the time of spontaneous abortion, the multilayered myometrial grid in the uterine body is able to contain bleeding vessels after placental separation. However, in CSP, the exposed vessels in the cervical scar tissue bleed because there is no muscle grid to contract and contain the profuse bleeding.
If you choose D&C or aspiration, have blood products available and a Foley balloon catheter handy! In several reports, a Foley balloon catheter was used as backup after significant bleeding occurred following curettage.5,6
In one of the series involving 45 cases treated by methotrexate followed by suction curettage, mean blood loss was significant at 707 mL (standard deviation, 642 mL; range, 100–2,000 mL), and treatment failed in three patients despite insertion of a Foley balloon catheter.
4. Uterine artery embolization, alone or in combination
This treatment requires general anesthesia. The complication rate was 47% among the 64 cases described in the literature.1 Uterine artery embolization appeared to work better when it was combined with other noninvasive treatments. It probably is not the best first-line treatment because the delay between treatment and effect allows the gestation to grow and vascularity to increase. And if uterine artery embolization fails, the clinician must contend with a larger gestation.
5. Excision by laparotomy, alone or in combination with hysteroscopy
General anesthesia is required. Of the 18 cases described in the literature, only five complications were reported—and only when used in an emergency situation.1