Transrectal ultrasound-guided surgical evacuation of Cesarean scar ectopic pregnancy
Abstract
Objectives
To describe a new technique for the management of Cesarean scar ectopic pregnancy (CSEP): transrectal ultrasound (TRS)-guided surgical evacuation.
Methods
All women who presented at our early pregnancy units (EPU) from November 2006 to July 2008 underwent transvaginal sonography. CSEP was diagnosed if all of the following criteria were met: absence of an intrauterine pregnancy; empty endocervical canal; presence of a gestational sac implanted within the lower anterior segment of the uterine corpus, with or without evidence of myometrial thinning. Women were offered TRS-guided surgical evacuation under general anesthesia. Successful treatment was defined as complete primary evacuation of the CSEP. The need to perform additional interventions (emergency cervical cerclage, insertion of Foley's balloon catheter, blood transfusions) was recorded.
Results
Of 1195 consecutive women who presented at the EPUs, seven (0.59%) were diagnosed with CSEP. Three (43%) of these were viable at the time of diagnosis. Two (29%) of the seven pregnancies followed in-vitro fertilization; six (86%) women had previously had a single Cesarean section and one had had two. One of these women had a previous tubal ectopic pregnancy, and one a previous CSEP. Three (43%) of the women were asymptomatic. Five (71%) women were treated with TRS-guided surgical evacuation as the primary treatment, whilst two (29%) were given systemic methotrexate, one of whom subsequently underwent TRS-guided aspiration because of failure of conservative management. There were no major complications.
Conclusions
The best treatment for CSEP has yet to be established. TRS-guided surgical evacuation is a novel and potentially alternative treatment modality. However, in the absence of further studies we cannot draw any conclusions, and the management of such women should be individualized. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Introduction
A Cesarean scar ectopic pregnancy (CSEP) is a pregnancy embedded in the myometrium of a previous Cesarean scar, outside the uterine cavity. It is considered to be a rare form of ectopic pregnancy, but its incidence is reported to be as high as 1 in 1800 to 1 in 22161, 2.
A delay in diagnosis and/or treatment can lead to uterine rupture, major hemorrhage secondary to placenta accreta or percreta, a need for hysterectomy and serious maternal morbidity3-5. Therefore, the main objectives in the management of CSEPs should be early and accurate ultrasound diagnosis and prevention of severe blood loss while preserving fertility. There is no consensus about the method of choice for managing CSEP. The use of blind or ultrasound-guided surgical evacuation, medical management with methotrexate (MTX), administered either systemically or locally, and expectant management have all been reported in the literature, as have combined treatments1-7.
In this pilot study, we aimed to manage CSEPs surgically using transrectal sonography (TRS)-guided surgical evacuation of the lower anterior myometrial defect.
Methods
This was a prospective study conducted during a 20-month period, from November 2006 to July 2008, in two ultrasound-based units, the Acute Gynaecology Unit (AGU) at Nepean Hospital and OMNI Gynaecological Care, Centre for Women's Ultrasound and Early Pregnancy, both in Sydney, Australia. All pregnant women who presented to these units during the study period underwent transvaginal sonography (TVS) of the pelvis by the same operator (G.C.) using a 7.5-MHz transvaginal probe (LOGIQ-e and Voluson E8 ultrasound machines, GE Medical Systems, Zipf, Austria). Women with a diagnosis of CSEP were identified, the diagnosis being made in the presence of all of the following sonographic criteria: absence of an intrauterine pregnancy; empty endocervical canal; presence of a gestational sac implanted within the lower anterior segment of the uterine corpus, with or without evidence of myometrial dehiscence (Figure 1). Myometrial dehiscence was defined as thinning of the myometrial layer between the bladder and the gestational sac (Figure 2 and Videoclips S1 and S2 online). Age, parity, symptomatology, past obstetric history and number of previous Cesarean sections were recorded.
Transvaginal ultrasound imaging in two different cases of Cesarean scar ectopic pregnancy. The gestational sac with visible fetal pole is within the myometrial defect at the site of a previous Cesarean section.
Transvaginal sonographic evidence of myometrial dehiscence in a Cesarean scar ectopic pregnancy, visualized as thinning of the myometrium between the bladder and the gestational sac (2.5 mm, calipers).
All women in the CSEP cohort were scheduled for surgical management of the pregnancy. Informed consent was given by each woman in accordance with the hospital's protocol. The procedure was explained to each woman, as were the potential surgical complications, i.e. uterine perforation and hemorrhage. As part of the consent process we also explained in detail that in the event of uncontrollable hemorrhage there might be a need for emergency cervical cerclage, emergency insertion of a Foley's balloon catheter as a tamponade, or emergency hysterectomy. Nepean Hospital does not have on-site interventional radiology services and therefore the use of uterine artery embolization as a rescue maneuver was not possible. Each woman also had preoperative hemoglobin and serum beta-human chorionic gonadotropin (β-hCG) levels measured, and two units of blood were cross matched. The anesthetic team was informed pre-emptively about the surgical case and potential complications.
Ultrasound-guided evacuations were all performed by the same operator (G.C.) with the woman under general anesthesia. The cervix was grasped at the 12 o'clock position with a vulsellum and carefully dilated up to 10 mm by the primary operator (G.C.). Intraoperative TRS was performed under sterile conditions by a second operator using a 7.5-MHz transvaginal probe (LOGIQ-e). Under direct TRS guidance, a standard suction cannula (6–8 mm) was inserted through the cervix, beyond the endocervical canal and placed at the level of the gestational sac, i.e. at the level of the Cesarean section scar. The suction mechanism was activated and the contents of the myometrial defect removed under direct ultrasound guidance in order to guarantee complete evacuation of the products of conception (Videoclip S3 online). Successful treatment was defined as complete primary evacuation of the CSEP. The need for emergency cervical cerclage, a Foley's balloon catheter insertion or blood transfusion was recorded.
Results
During the study period 1195 consecutive women presented to the EPUs. Seven (0.59%) of these women were diagnosed with a CSEP. One of these cases was initially classified incorrectly as a cervical pregnancy on ultrasound; she was given 1 mg/kg MTX intramuscularly on days 1, 3 and 5 (baseline serum β-hCG, 48 899 IU/L) with folinic acid rescue on days 2, 4 and 6. On review on day 7 the β-hCG levels had failed to respond to the high multidose MTX and the woman was rescanned. This confirmed a twin CSEP without visible fetal poles rather than the initial ultrasound diagnosis of cervical pregnancy. She was immediately scheduled for TRS-guided surgical curettage.
Table 1 summarizes the clinical data of the seven cases with CSEP. Three of the women presented with vaginal bleeding only, one had both lower abdominal pain (visual analog scale score, 4) and vaginal bleeding, and three (43%) were asymptomatic. Six (86%) of the women had a history of a single lower segment Cesarean section and one had two previous Cesarean sections. One woman had a history of a tubal ectopic pregnancy, and one had a history of a previous CSEP. Two (29%) of the pregnancies followed in-vitro fertilization. Three (43%) of the pregnancies were viable at the time of the initial ultrasound diagnosis.
| MA (years) | Parity | GA at diagnosis (days) | Symptoms | Fetal pole | Embryonic cardiac activity | β-hCG at diagnosis (IU/L) | Treatment | Complications |
|---|---|---|---|---|---|---|---|---|
| 23 | G4, CS2, MISC1 | 42 (US) | Vaginal bleeding without clots, central pelvic pain | Yes | Yes | 1771 | TRS-guided aspiration | None |
| 41 | G2, CS1 | 48 (ET) | None | No | No | 7890 | Systemic MTX | Second dose |
| 30 | G5, CS1, MISC2, TOP1 | 41 (US) | Vaginal bleeding without clots | Yes | Yes | 1563 | TRS-guided aspiration | None |
| 40 | G6, NVD3, CS1, MISC1 | 45 (ET) | None | Yes | Yes | 32 000 | TRS-guided aspiration | None |
| 34 | G9, NVD2, CS1, MISC2, TOP2, EP1 | 44 (US) | None | No | No | 48 899 | Systemic MTX | Third dose failed, TRS-guided aspiration performed |
| 30 | G2, CS1 | 39 (US) | Vaginal bleeding with clots | Yes | No | 8906 | TRS-guided aspiration | None |
| 35 | G3, CS1, CSEP1 | 46 (US) | Vaginal bleeding without clots | No | Yes | 112 863 | TRS-guided aspiration | None |
- β-hCG, beta human chorionic gonadotropin; CS, Cesarean section; EP, ectopic pregnancy; ET, embryo transfer; G, gravida; GA, gestational age; MA, maternal age; MISC, miscarriage; MTX, methotrexate; NVD, normal vaginal delivery; TOP, termination of pregnancy; TRS, transrectal sonography; US, ultrasound.
Five (71%) of the seven women were treated with TRS-guided surgical evacuation as the primary treatment, and two (29%) were administered systemic MTX. All women treated with TRS-guided surgical evacuation had successful resolution of the CSEP without complication. In all cases the presence of chorionic villi in the evacuated specimens was confirmed histologically. No woman required emergency cervical cerclage, insertion of a Foley's balloon catheter or blood transfusion. Although one of the women treated with MTX had been scheduled for TRS-guided surgical curettage, just prior to surgery her serum β-hCG levels were noted to have fallen in 48 h from 7890 to 7771 IU/L and the decision to operate was reversed (G.C.). The woman required a second dose of MTX before successful resolution. This woman required laparoscopic repair of a persistent myometrial defect.
Discussion
Although ultrasound-guided surgical evacuation has been described previously in the management of CSEP2, 8, this is the first series to describe it under TRS guidance. Regardless of the route (TVS, TRS or transabdominal), we advocate the use of ultrasound as part of the surgical management of these women in order to minimize the risk of uterine perforation and retained products of conception (RPOC). TRS enables appropriate visualization of the entire uterine cavity and the CSEP, and simultaneously allows more space for the movements of the suction cannula, compared with ultrasound guidance performed transvaginally. We believe that experience in the use of TVS is essential before undertaking this procedure and all women must be advised of the risks of the surgery, the most serious being hysterectomy.
The CSEP rate in our study was 7/1195 (0.59%), higher than that in other reports1, 2. This may be explained by the fact that our EPUs also work as tertiary referral centers for all women with early pregnancy complications. In our series, 43% of the CSEPs were asymptomatic. This is consistent with the review by Rotas et al.5 including 112 CSEPs, with almost 40% of women being asymptomatic. Usually, women with CSEP are hemodynamically stable at presentation; however, an early uterine rupture due to CSEP with massive hemorrhage in the first trimester has been reported9. In our case series, six of the seven women with CSEP had had only one previous Cesarean section. It seems reasonable to assume that a history of more than one Cesarean section may increase the risk of CSEP compared with a history of only one, but a strong correlation between number of previous Cesarean sections and CSEP has not yet been proven.
TVS is the tool of choice for the diagnosis of CSEP and has an overall sensitivity of 84.6% (95% CI, 76.3–90.5%)5. In our series the myometrial thickness between the gestational sac and surrounding bladder ranged from 2 to 3 mm. The addition of ultrasound is therefore important in reducing the possibility of uterine perforation with damage to surrounding structures. The availability of a rapid serum β-hCG assay is crucial when a diagnosis of CSEP is suspected, to provide a baseline level with which to monitor the regression of the pregnancy with treatment, especially in the case of MTX administration.
In the absence of randomized trials, the modality of treatment in cases of CSEP should be chosen on the basis of gestational age, pregnancy viability, myometrial integrity, severity of symptoms, serum β-hCG levels, the experience of the surgeon and the preference of the woman. Treatments described1-7 include expectant management, operative hysteroscopy, dilatation and curettage (D&C), ultrasound-guided evacuation, transvaginal needle aspiration, uterine artery embolization, systemic or local MTX administration, local embryocide administration and combined approaches. Expectant management is associated with a high risk of uterine rupture, and therefore cannot be recommended if the pregnancy is evolving1, 7, 10; theoretically, only those CSEPs which are failing (i.e. with falling serum β-hCG levels) can be offered expectant management. For evolving CSEPs (i.e. increasing serum β-hCG levels), systemic MTX can be an option to avoid surgery under general anesthesia. However, we believe that despite MTX being effective in normalizing serum β-hCG levels, there is often incomplete reabsorption of the gestational sac, with ongoing irregular vaginal bleeding. Eventually, many of these women need curettage to surgically remove the persistent gestational sac and resolve the bleeding11-13. For these reasons we believe surgical management could be a reasonable alternative to MTX treatment.
Ayoubi et al.8 were first to describe the technique of US-guided evacuation of CSEP. In another series of eight women, the technique was successful in all cases and there were no cases of RPOC following surgery2. In the most recent review on CSEPs, Rotas et al.5 concluded that surgical evacuation is a suboptimal procedure because three of 21 surgical cases had severe hemorrhage that necessitated hysterectomy. However, of these three women, one was initially misdiagnosed as incomplete miscarriage and a blind D&C was performed1, one was managed with blind curettage14, and one had already undergone early (first-trimester) uterine rupture at the time of presentation, due to the CSEP9. Halperin et al.15 described a case of CSEP treated by hysterotomic wedge resection of the entire CSEP, combined with bilateral uterine artery ligation. We believe, however, that this should be reserved for women with intractable bleeding who are hemodynamically unstable, or women who are not responding to more conservative approaches (MTX, ultrasound-guided D&C). Transvaginal needle aspiration has been described in only two cases of CSEP7. In both cases this technique was combined with the use of local MTX administration and in one case a course of systemic MTX had already been administered before needle aspiration. In our cases MTX was not given in combination with surgery. Furthermore, the authors7 commented that the remaining placenta and residual sac structure were still detectable on ultrasound for more than 2 months after the procedure.
Although the numbers in our study are small, other studies suggest that surgical evacuation is safe for women who are not eligible for MTX treatment or expectant management2, 5, 8. The rate of emergency hysterectomy in women undergoing surgical evacuation is 6%5. The use of ultrasound guidance during surgical evacuation may reduce the risk of uterine perforation and the risk of missing the gestational sac.
In conclusion, ultrasound guidance is essential for the safe surgical management of CSEPs. There are no data to support that one form of ultrasound-guided curettage is superior to the other. In our series we successfully used TRS; however, other units use transabdominal sonography. The relative rareness of CSEP means that units will need to collaborate in the context of a multicenter trial in order to reach any firm conclusions on the management of these women.
SUPPORTING INFORMATION ON THE INTERNET
The following supporting information may be found in the online version of this article:
Videoclip S1 Transvaginal imaging of the Cesarean scar ectopic pregnancy in Figure 2. The gestational sac with visible fetal pole and yolk sac is within the myometrial defect at the site of a previous Cesarean section.
Videoclip S2 Transvaginal Doppler imaging of the Cesarean scar ectopic pregnancy in Figure 2. The presence of peritrophoblastic flow suggests that the gestational sac is implanted at the site, rather than passing through the lower uterine cavity.
Videoclip S3 Transrectal ultrasound-guided surgical evacuation of a Cesarean scar ectopic pregnancy.
