Ectopic Pregnancies in Unusual Locations

Thomas A Molinaro, M.D.; Kurt T Barnhart,M.D.,M.S.C.E.

Disclosures

Semin Reprod Med. 2007;25(2):123-130. 

In This Article

Cesarean Scar/Intramural Ectopic Pregnancy

Intramural pregnancy refers to pregnancy implanted within the myometrium of the uterus. This type of pregnancy is extremely rare, with less than 50 reported cases described in the literature.[75] These cases frequently are complicated by uterine rupture and hemorrhage. Predisposing risk factors include prior uterine trauma, cesarean section, and adenomyosis.[76,77] Diagnosis is difficult to make by ultrasound and may require laparoscopy or MRI.[76,78] Imaging should demonstrate myometrium completely surrounding the gestation with no communication to the endometrial cavity. The etiology of intramural pregnancy is unclear and may result from assisted reproductive technology, uterine trauma, and/or defective migration of an implanting pregnancy.[79,80]

Optimal treatment of intramural pregnancy is largely unknown and in the past hysterectomy was routine.[76] Bernstein et al[75] reported a case of a 6 week intramural pregnancy followed expectantly to resolution. Katano et al[76] reported successful treatment with ultrasound-guided laparoscopic methotrexate injection. Laparotomy and/or hysterectomy may be required for more advanced cases.[79,80] There are no data regarding future fertility in these patients.

Intramural pregnancy with implantation in a previous cesarean scar has been reported and is probably the rarest of ectopic pregnancies.[81,82] These patients often present with uterine rupture and hypovolemic shock; however, they may also present with painless vaginal bleeding.[83,84] Ultrasound with Doppler and hysteroscopy have been used to make the diagnosis.[81] These pregnancies can also be confused with cervical ectopic pregnancy.[84] Ultrasound appearance of an anterior bulging mass outside the contour of the uterus may be indicative. Three-dimensional Doppler ultrasound may prove useful.[85] MRI has also been used to confirm the diagnosis.[82,86]

The etiology of cesarean scar pregnancy is unclear. Previous cesarean section, myomectomy adenomyosis, IVF, previous dilation and curettage, and manual removal of the placenta have been linked as risk factors.[81,83,87] Vial et al[84] theorized that these pregnancies may be partially implanted in the uterine cavity where they might proceed to term, or else implant deep in the scar and be predisposed to early rupture in the first trimester. It has also been proposed that these pregnancies enter the cesarean scar via microscopic fistulae.[87] Vial et al[84] proposed sonographic criteria for diagnosis of a cesarean section scar pregnancy that was very likely to rupture including (1) trophoblast between bladder and anterior uterine wall, (2) no fetal parts in the uterine cavity, and (3) discontinuity of the anterior uterine wall in the sagittal plane.[84]

The optimal treatment of cesarean section scar ectopic pregnancies is unknown. Presentation of the patient often dictates the mode of treatment, given that many patients present with hemoperitoneum and require hysterectomy. Some authors propose that dilation and curettage should not be first-line therapy due to the risk of perforation and catastrophic hemorrhage.[81] Local injections with KCl or methotrexate have been reported.[82] Lee et al reported laparoscopic resection of a cesarean section pregnancy.[81] Graesslin et al[83] and Marchiol et al[87] report the use of systemic methotrexate followed by dilation and evacuation with success. Uterine artery embolization to reduce hemorrhage has also been described as adjunctive therapy.[87,88]

In a report of 18 cases of cesarean section scar pregnancy, Jurkovic et al[89] used expectant management, local injection of methotrexate, and suction curettage followed by Foley balloon tamponade. Success with methotrexate was five of seven patients (71%), with the two failures requiring emergent surgery. Expectant management was successful in only one of three cases, and was therefore not recommended. The authors of this series believed that dilation and curettage followed by tamponade with a Foley balloon was the most effective surgical technique. There are also reports of successful term pregnancy after cesarean section scar pregnancy.[84] Nevertheless, these patients should be counseled about the weakened nature of their cesarean section scar and should undergo repeat cesarean section.[89]

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