A 40 year old woman, gravida 3, para 2, was referred at six weeks of gestation for a suspected ectopic pregnancy. She had previously undergone lower segment caesarean section twice. Pelvic examination revealed a normal cervix and a normal-sized uterus with no adnexal mass. Transvaginal ultrasound examination showed that both the uterine cavity and cervical canal were empty, and a gestational sac containing a viable fetus with cardiac activity was implanted in the anterior wall of the uterus at the level of the isthmus. The thickness of the uterine wall between the bladder and gestational sac was diminished in comparison with the adjacent uterine wall. The crown–rump length of the fetus was 3.8 mm. The serum human chorionic gonadotropin (hCG) level was 12,755 miu/mL. Colour Doppler ultrasound showed abundant blood vessels distributed around the gestational sac. These findings were consistent with a diagnosis of caesarean scar pregnancy.
The patient was treated with systemic intramuscular methotrexate (four doses of methotrexate 1 mg/kg on alternating each day with folinic acid).1 A small amount of vaginal bleeding was noted on day 4 after the second dose of methotrexate. The hCG level increased to 23,746 miu/mL and ultrasound examination continued to show a viable fetus with heart motion. The crown–rump length had increased to 6.5 mm. We decided to interrupt the pregnancy rapidly by transvaginal ultrasound-guided aspiration of the fetus. Under general anaesthesia, the vagina was cleaned and a 16-gauge double-lumen ovum aspiration needle (K-OPSD-1635-A-L, Cook, Australia) was connected to an aspiration regulator suction pump (Craft Duo-vac suction unit, Rocket Medical, England). The maximum aspiration pressure was set at −150 mmHg. When the needle tip entered the gestational sac, the pump was activated to aspirate. Methotrexate, 50 mg, was injected into the sac immediately after the embryo was removed by aspiration. Ten days later, ultrasound showed an empty sac about 1.5 cm in diameter. The hCG level decreased to 7981 miu/mL. Mild vaginal bleeding persisted intermittently for about eight weeks. Two months after aspiration, the hCG level was less than 5 miu/mL, and the empty sac had completely disappeared.
A 31 year old woman, gravida 3, para 2, was referred at six weeks for treatment of a suspected caesarean scar pregnancy. She had previously undergone caesarean section twice. On transvaginal ultrasound, a gestational sac containing a viable fetus with a crown–rump length of 7.5 mm was located in the anterior wall of the uterus at the level of the isthmus. Both cervical canal and uterine cavity were empty. The myometrium between the bladder wall and gestational sac was only 3 mm thick (Fig. 1). The serum hCG level was 29,377 miu/mL. We therefore diagnosed caesarean scar pregnancy. The patient chose rapid termination of the pregnancy. We performed transvaginal needle aspiration in the same manner as in case 1. Methotrexate, 50 mg, was injected into the sac immediately after the aspiration. One week later, the hCG level decreased to 12,528 miu/mL. On ultrasound, an empty 2-cm sac containing amorphous fluid was located in the anterior wall of the uterus at the level of the isthmus. This patient also experienced mild, intermittent vaginal bleeding for eight weeks following the aspiration procedure. About 10 weeks after aspiration, the serum hCG level was less than 5 miu/mL and ultrasound showed that the gestational sac had completely disappeared.
Caesarean scar pregnancy is the implantation of a pregnancy within the scar of a previous caesarean section.2 Few cases have been reported and it is the rarest form of ectopic pregnancy.2 The incidence seems to be increasing, possibly because of the increased performance of caesarean section and more widespread use of transvaginal ultrasound.3 Because of the high risk of uterine rupture, massive bleeding and life-threatening complications beyond the first trimester, termination in the first trimester is strongly recommended.4,5
Reported procedures include both surgical and medical treatment. Surgical measures include ultrasound-guided transcervical dilatation and suction curettage (D&C),5,6 laparotomy and excision of the gestational sac7,8 and laparoscopic resection.9 Medical approaches include systemic and ultrasound-guided local methotrexate administration. The most commonly used primary procedures are reported to be D&C and ultrasound-guided local methotrexate administration, although D&C carries the risk of serious intraoperative haemorrhage.2,3,5
In the two cases we have reported, we used local methotrexate administration in conjunction with aspiration of the embryo. The usual technique for injection of methotrexate uses 20- to 22-gauge needles.5,10 However, the lumen of these needles are too narrow to allow aspiration of the entire seven-week embryo body. Therefore, we used 16-gauge oocyte-retrieval needles, which contain two lumens, one that serves for aspiration of the embryo and one for subsequent injection of the methotrexate. This modified technique eliminates the need for KCL to arrest the embryonic cardiac motion. Mansour et al.11 reported the use of oocyte-retrieval needles to aspirate a live six- to eight-week embryo in cases of multifetal pregnancy reduction. At this gestational stage, the embryo body is soft and fragile, thus, it can be easily and completely aspirated through a 16-gauge needle.
After aspiration, the embryo completely disappeared. However, despite the immediate administration of methotrexate, the remaining placenta and residual sac structure were still detectable on ultrasound for more than two months. The resulting intermittent vaginal bleeding while the tissue was being resorbed may cause the patient some anxiety. This aspect of the process should be fully explained to the patient.
Based on our experience with these two cases, we suggest that needle aspiration of the embryo can be used as the primary treatment for caesarean scar pregnancy at six to eight weeks of gestation.