Adapted from Anderson PM, Opfer EK, Busch JM, et al. An early abdominal wall ectopic pregancy successfully treated with ultrasound guided intralesional methotrexate: a case report. Obstet Gynecol Int 2009; Article ID 247452 theoretically an increased risk of infection and sepsis resulting from the rapid tissue necrosis that occurs following methotrexate administration (265). There are reports of successful treatment of abdominal pregnancies with methotrexate in patients not considered to be optimal surgical candidates (266).
Interstitial Pregnancy Interstitial pregnancies represent about 2.4% of ectopic pregnancies (1). This section of the fallopian tube is relatively thick with an increased capacity to expand prior to rupture. This ability may allow these types of ectopic pregnancies to remain asymptomatic for 7 to 16 weeks of gestation (267). Late presentations are rare and these patients typically present between 6 to 8 weeks of gestation, similar to other types of ectopic pregnancies (268,269). The diagnosis of an interstitial ectopic pregnancy can be difficult, because this area has a relatively high level of vascular supply. Interstitial pregnancies represent a disproportionately large percentage of fatalities from ectopic pregnancy with a 2.5% mortality rate (268,270).
Treatment classically was a cornual resection by laparotomy, but early detection allows for a more conservative management approach in hemodynamically stable patients without evidence of rupture. Medical management with methotrexate is well described, with both the single-and multidose regimens. Approximately 10% to 20% of patients treated medically will ultimately require surgery and close follow-up, as is warranted with all medically managed ectopic pregnancies (271).
Although cornual wedge resection by laparotomy is an acceptable surgical option, minimally invasive techniques were described, including cornual excision, minicornual excision, and cornuostomy. Laparoscopic approaches are more widely used and are dependent on surgical skill. Transcervical suction evacuation under laparoscopic or ultrasound guidance is reported (271). The appropriate surgical technique and approach depends on the individual patient presentation and the surgeon’s expertise.
Interligamentous Pregnancy Interligamentous pregnancy is a rare form of ectopic pregnancy that occurs in about 1 of 300 ectopic pregnancies (272). An interligamentous pregnancy usually results from trophoblastic penetration of a tubal pregnancy through the tubal serosa and into the mesosalpinx, with secondary implantation between the leaves of the broad ligament. It can occur if a uterine fistula develops between the endometrial cavity and the retroperitoneal space. As in abdominal pregnancy, with interligamentous pregnancy the placenta may be adherent to the uterus, bladder, and pelvic side walls. If possible, the placenta should be removed; when this is not possible, it can be left in situ and allowed to resorb. Cases of live birth are reported with this type ectopic gestation (272).
Heterotropic Pregnancy Heterotropic pregnancy occurs when intrauterine and ectopic pregnancies coexist. The reported incidence varies widely from 1 in 100 to 1 in 30,000 pregnancies (273). Patients who underwent assisted reproduction have a much higher incidence of heterotropic pregnancy than those who have a spontaneous conception (274,275). An intrauterine pregnancy is seen during ultrasonography examination, and an extrauterine pregnancy may be overlooked, delaying diagnosis. Serial β-hCG levels are not helpful because the intrauterine pregnancy causes the β-hCG level to rise appropriately.