Interstitial (cornual) pregnancy accounts for 2-4% of all tubal pregnancies [1] and is regarded as a medical emergency due to the risk of severe maternal haemorrhage if it ruptures [2]. Previous goldstandard of treatment involved a Laparotomy due to the increased vascularity of the area. However, laparoscopic surgery can now be considered an alternative option [2]. Other treatment options are explored in the discussion. The following case report demonstrates a successful laparoscopic technique of treating an interstitial ectopic pregnancy.

A 35 year old G1P0 woman who was 8 weeks pregnant, had an endovaginal ultrasound scan, which showed a 2 cm gestation sac in her left adnexa. It was thought to be a tubal ectopic pregnancy. The patient herself was asymptomatic with no pain or bleeding.

A laparoscopy performed on the same day showed a very vascular interstitial pregnancy, which made up about 1/4 of the whole uterus. The cornual mass was excised with a Ligasure blunt tip laparoscopic sealer/divider forceps. The Ligasure forceps was used to coagulate and separate the lateral aspect of the cornual mass from the fallopian tube, suspensory ligament of the ovary and the adjacent broad ligament. The forceps then grasped and separated the inferior edge of the mass, cutting in from the lateral aspect of the uterus into the uterine cavity. The forceps hugged the mass and excised it from the uterine body, removing about 1/3 of the uterine fundus, finishing on the superior medial edge of the mass. The resulting defect was closed in two continuous layers with an ‘O V-Loc 180’ suture (Barbed, selfanchoring dissolvable suture). There was minimal blood loss of <50 mL. The operation on the actual ectopic pregnancy itself took about 20 minutes. Post-operation, only oral analgesics were required. The patient was discharged on the next day.

Her serum beta HCG level was 48,200 IU/L the day before surgery, 23,500 IU/L 12 hours after the operation, and 344 IU/L 9 days after surgery. This is a drop of more than 51% within a day after the operation. A threshold value of more than 50% drop makes a persistent ectopic pregnancy much less likely [3].

Interstitial pregnancy is a rare form of ectopic pregnancy. Bouyer et al. [3] reported an incidence of 2.4% in 1,800 cases of ectopic pregnancies. Traditionally, the most common treatment of an interstitial pregnancy is through cornual wedge resection by Laparotomy. With the advancement of technology and surgical skills, various alternative treatment modalities have been reported. They are often made possible because of the advancement of ultrasound scanning with the consequent early discovery of unruptured interstitial pregnancy.

Methotrexate in single or multiple doses, administered systemically or directly into the interstitial pregnancy, can be a useful option. The advantage is that surgery may be averted. The uterine integrity may be preserved. Direct injection of methotrexate into the lesion was shown to have a three time shorter average time to resolution of serum bHCG compared with systemic treatment [4]. However, it is not appropriate for ruptured ectopic pregnancy. Direct methotrexate injections can be hard to organise during accidental discoveries of interstitial pregnancies in laparoscopic cases thought to be normal tubal ectopic pregnancies. An overall failure rate of up to 35% has been reported [5-8]. There may be an increased risk of recurrent ectopic pregnancy especially on the ipsilateral side. Failure rate for large interstitial pregnancies is likely to be higher. Methotrexate, being an antimetabolite and anti-folate chemotherapeutic agent, has the potential to cause collateral tissue or organ damage and may not be acceptable or appropriate to some patients. Other concerns are multiple doses may be required, treatment prolonged and there is a risk of uterine rupture with catastrophic haemorrhage (Figure 1).

Figure 1: Ectopic pregnancy.

Direct injection of potassium chloride may be a preferable option for the treatment of heterotopic interstitial pregnancies [9]. Patients particularly at risk of heterotopic pregnancies are IVF patients whereby 2 or more embryos are transferred.

Hysteroscopic or combined hysteroscopic and laparoscopic treatment of interstitial pregnancies have also been described [10-14]. The laparoscopy offers some safety against cornual rupture during hysteroscopic resection or suction curettage. This is not a commonly used treatment as there is paucity of data about its safety.

Laparoscopic surgical treatment can be either by cornuostomy or wedge resection. The latter offers more certainty in the complete elimination of trophoblastic tissue, and less risk of subsequent ectopic pregnancy on the same side. However, it is more challenging in the reconstruction of the uterus. Cornuostomy preserve more anatomical integrity but is more likely to have persistent retained trophoblastic tissue.

Methotrexate can be given post-operatively if there is inadequate reduction in HCG levels where retained trophoblastic tissue is suspected. It has been recommended that post-operative methotrexate should be reserved for the few patients in whom the HCG concentration does not decrease by 15% within 48 hours [15].

The main concern about laparoscopic surgery for interstitial pregnancy is the risk of rupture in future pregnancy. As it is a novel method of treatment, there is insufficient data to demonstrate its safety for future pregnancy. Cases of cornual ruptures have been reported [16]. Good surgical technique and keeping diathermy use to a minimum to reduce adjacent tissue damage will likely reduce this risk. A retrospective review of 52 cases of laparoscopic surgical treatment of interstitial pregnancy has provided some promising results [17]. The 52 cases were followed up for at least 18 months. Eighteen women managed to become pregnant and 10 had pregnancies beyond 24 weeks gestation. There was no report of any uterine rupture or dehiscence. For women who wish to have another pregnancy, sonohysterography has been recommended to look for myometrial thinning [18]. Careful monitoring of all subsequent pregnancies is essential and caesarean delivery is highly recommended.

The second main concern of the laparoscopic surgical treatment of interstitial pregnancy is the risk of major haemorrhage. In this case study, the wedge resection was performed using the ligasure laparoscopic sealer/divider forceps. This forceps offers average seal cycles of 2-4 seconds with effective haemostasis and minimal adjacent tissue damage of <5 mm. It significantly reduces blood loss and operation time [19-21].

The third main concern of the laparoscopic method of treating interstitial pregnancies involves the length of time of operation. Currently, most laparoscopic repairs of interstitial pregnancy were by interrupted figure of 8 stitches, involving multiple knot tying. This is time consuming and laparoscopic knot tying is a relatively difficult technique to master. In this case study, by using the O V-Loc suture, the barbed suture ensures tension is maintained in between each stitch, much like an open procedure. A continuous stitch therefore can be performed, maintaining tension throughout the whole wound closure. Knot tying is not required at all as the stitch is self-holding. This ensures more secure tissue approximation, haemostasis and reduces operation time considerably [22].

In conclusion, with the appropriate patients, setting and in the presence of experienced laparoscopic surgeons, laparoscopic management for interstitial pregnancies may be considered a preferable option.