Photographs of sections through the myometrium showing a cluster of trophoblast cells present in-between smooth muscle bundles (case 8) (haematoxylin and eosin, Q 200). 

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... of a pregnancy within a Caesarean ®brous tissue scar is considered to be the rarest form of ectopic pregnancy and a life-threatening condition (Fylstra et al ., 2002). This is because of the very high risk for uterine rupture and all the maternal complications related to it (Herman et al ., 1995; Fylstra, 2002; Jurkovic et al ., 2003). Of the many theories for explaining its occurrence, the most reasonable one seems to be that the blastocyst enters into the myometrium through a microscopic dehiscent tract. This may be created throughout a trauma of a previous Caesarean section, any other uterine surgery (Cheng et al ., 2003), or even following manual removal of the placenta (Fylstra, 2002). Another mechanism for intramural implantation is IVF and embryo transfer, even in the absence of any previous uterine surgery (Hamilton et al ., 1992). The true incidence of pregnancy in scar has not been determined because so few cases have been reported in the literature: there are only 18 published cases in the English medical literature between 1978 and 2001 (Fylstra, 2002). Between 2002 and mid-2003, however, 25 additional cases were reported (Fylstra et al ., 2002; Ghezzi et al ., 2002; 278 Human Reproduction vol. 19 no. 2 ã Haimov-Kochman et al ., 2002; Lam and Lo, 2002; Hartung and Meckies, 2003; Jurkovic et al ., 2003; Salomon et al ., 2003), 18 of which took place in a single centre (Jurkovic et al ., 2003). This may re ̄ect both the increasing number of Caesarean sections being performed and the more widespread use of the transvaginal scan that allows earlier detection of such pregnancies (Jurkovic et al ., 2003). Notwithstanding this recent trend, current knowledge continues to be based mainly upon individual case reports. We present our medical centre's experience of eight ectopic pregnancies implanted in Caesarean scars. The clinical course of our eight patients represents a wide range of symptoms associated with this type of ectopic pregnancy. This is from a silent clinical picture in which the diagnosis was made coincidentally (cases 2±6), through slight vaginal bleeding with no other clinical complaints (cases 1 and 7), or profuse vaginal bleeding with abdominal discomfort (case 8) and ®nally missed abortion (cases 6 and 8). The image modality most frequently used was transvaginal sonography although transabdominal scan was added in two other cases. This combined modality helps to con®rm the implantation site and reduces the risk of false diagnosis. The various treatment modalities which were applied and the outcome of all the eight pregnancies are summarized in Table I. Three cases were treated both by sonographically guided intra-amniotic injection of 25 mg methotrexate (MTX) and i.m. (systemic) administration of (50 mg/m 2 ) on the basis of actual body weight (Stovall et al ., 1991; Stovall and Ling, 1993). Systemic MTX only was administered in case 7. This was because she was an obese woman who had a large ®broid uterus, which obscured the access for the intra-amniotic injection. For each case, where indicated, local MTX was injected only once. All procedures were conducted on an outpatient basis. The injection was performed transvaginally, under continuous ultrasound guidance and by using a 20-G needle. Neither antibiotic prophylaxis nor analgesia were administrated. The gestational sac was targeted and the amniotic ̄uid was aspirated. This was immediately followed by the local MTX injected. Our adopted protocol for the systemic MTX administration and the patient monitoring was reported elsewhere (Stovall et al ., 1991; Stovall and Ling, 1993). Transcervical complete aspiration of the gestational sac under ultrasound guidance was performed without any complementary medical treatment in case 2, although the exact aspiration of a very small gestational sac may also facilitate pregnancy absorption (Ravhon et al ., 1997; Jurkovic et al ., 2003). However, this unusual treatment approach should be addressed with great caution in the future. Since in case 6 the diagnosis was missed abortion, expectant management was chosen in this situation. Open surgery was needed only in two cases and both of them underwent an emergency laparotomy because of profuse haemorrhage. In one case (case 1) (Herman et al ., 1995), uterine rupture occurred at 35 weeks gestation. After delivery of a healthy infant, Caesarean hysterectomy was needed. In the second case (case 8; Figure 2), severe vaginal bleeding started during vacuum aspiration of an 8 weeks gestation missed abortion. Since in the specimens no products of conception were found, another ultrasound was conducted and only then was the correct diagnosis made (Figure 2b). Because of the combin- ation of pregnancy in scar and heavy vaginal bleeding, emergency laparotomy (Figure 2C) and excision of the pregnancy located in the scar was carried out. Following surgery, portions of uterine wall consisting of endometrium and myometrium were retrieved. The ®nal histology examination revealed clusters of trophoblast cells as well as scattered syncytiotrophoblast cells invading the myometrium. Decidual stromal changes were also noted and they were accompanied by foci of haemorrhage and disintegration of tissues (Figure 3). Immunostaining with b -hCG and desmin con®rmed the presence of trophoblast cells within smooth muscle myometrial ®bres. Follow-up ranged between 4 and 16 weeks (with the exception of case 1). This was based on weekly serum b -hCG measurements. The women were tested for serum b -hCG levels within the community medical care system. In addition, sonographic examination was performed weekly in our outpatient clinic until pregnancy remnants could not be further detected. In all cases, following the original treatment, maternal recovery was complete and there was no need for additional interventions. No side-effects related to MTX treatment were recorded. The women who were planning future pregnancies were advised to have an early vaginal scan to con®rm the intrauterine location of the new gestation. Two pregnant women (cases 4 and 6) have spontaneously conceived an in utero pregnancy. In one case (case 6), Caesarean section at term was performed because of fetal distress. No signs of previous pregnancy in scar were seen in the repeated operation. In the other case (case 4), the woman had two miscarriages following this event. Although a recent report was published by Jurkovic et al . (2003) describing the outcome of 18 cases of pregnancies implanted in scarred uterus, we believe that additional case series are needed for further elucidate this issue. Vial et al . (2000) proposed that there were two different types of such ectopic pregnancies, both of which were encountered among our patients. The ®rst is due to the implantation of the gestational sac on the scar with progression towards either the cervico-isthmic space or towards the uterine cavity. Such a ...