Cesarean Scar Ectopic Pregnancy
/Here’s the RoshReview Question of the Week!
A 31-year-old G2P0102 woman at 6 weeks gestation by last menstrual period presents with vaginal spotting. Her history is significant for a previous twin pregnancy where the second twin was emergently delivered by cesarean. Her vital signs are normal, hCG level is 4,440 mIU/mL, and ultrasound findings are shown above. After reviewing the treatment options, the patient indicates she prefers medical management. You further counsel her that compared to medical therapy, most interventional options have a lower risk of which of the following?
Check out the answer at the links above and get 20% off the Rosh Review question bank!
More reading: SMFM Consult Series #49
What is a Cesarean Scar Ectopic?
The implantation of an early gestation in the hysterotomy incision from a previous cesarean birth. Two main types:
Endogenic - implantation in the scar itself
Exogenic - implantation in the defect or “niche” left behind by incomplete healing of the scar
Why do we care?
Overall very rare → 1 in 2000 pregnancies and 6% of ectopic pregnancies in total among patient with history of cesarean delivery.
Doesn’t seem to be related to number of prior cesareans
Risk factors:
Not very well studied, since it is so rare
There may be some increased risk associated with smoking, higher parity
Unrecognized C-section scar ectopics can rupture and cause hemorrhage and death!
How do we diagnose a cesarean scar ectopic?
We may suspect ectopics when there is not an appropriate rise in beta HCG (if following)
Signs and symptoms:
Early on can be asymptomatic
Later on, can result in vaginal bleeding
If ruptured, will lead to hemoperitoneum and hypovolemic shock
Usually patients present early in first trimester
Diagnosis is usually with ultrasound
Can be suspected if hx of C-section
Gestational sac center is low (<5cm from cervical os) and anterior on ultrasound
Appears to be an enlarged hysterotomy scar with embedded mass which may bulge beyond anterior contour of the uterus and toward adjacent pelvic structures
Other findings that support:
Empty uterine cavity and endocervix
Triangular gestational sac and < 8 weeks or rounded or oval sac > 8 weeks that fills the scar area
Thin or absent myometrial layer between GS and bladder (1-3 mm)
Prominent vascular pattern on Doppler suggestive of blood flow at the area
Can also be diagnosed with surgery, where it is directly visualized
Treatment and Management
Termination of pregnancy due to risk of maternal morbidity and mortality
If hemodynamically unstable
To OR
Wedge resection or gravid hysterectomy
If profusely bleeding, usually will require hysterectomy
If hemodynamically stable
Can consider medical or surgical treatment
Medical
Usually methotrexate injection
Options include intrasac injection of MTX or systemic injection of MTX 1mg/kg of maternal weight up to 50 mg
One lit review showed that 74% of the time, no other treatment is needed.
Also, an additional IM or intrasac injection of MTX led to resolution up to 89% of cases
However, numbers vary widely. Another review said the intrasac injection was effective 65% of the time, and UAE made it 69% effective
Other surgical options
Can consider UAE in addition to MTX, which seems to increase efficacy
Expectant management
Not recommended due to likelihood of maternal morbidity/mortality without fetal benefit
May be reasonable if there is already embryonic/fetal demise and lowering bHCGs
Follow up
Should have weekly HCGs drawn (like after MTX injection after other ectopics
Periodic ultrasound evaluation
More likely to have favorable outcome with ectopics that are diagnosed earlier vs later
There have been reports of pregnancy after treatment of C-section scar ectopic, but risks include recurrence (reported at rate of 5-40%), rupture, and PAS