Heterotopic interstitial pregnancy in natural conception is very rare. Definitive diagnosis is
made by systematic pelvic ultrasound. Simultaneous viable conception observed in both intraand extra-uterine is pathognomonic of heterotopic interstitial pregnancy. We report a 34-yearold woman primigravida at 10 weeks’ amenorrhoea who underwent evacuation of retained
product of conception for missed miscarriage. Intraoperatively, minimal product of conception
was retrieved. Bedside pelvic ultrasound showed cystic mass at right superolateral part of
uterine fundus suspicious of interstitial pregnancy. Cornual resection was performed via
laparotomy. Histopathological examination showed presence of product of conception and
interstitial pregnancy. Serum β-human chorionic gonadotropin dropped from 10,027 IU/l on day
one post-ERPC to 210 IU/l at day three post-cornual resection. This case report highlighted
the challenge in diagnosing heterotopic interstitial pregnancy conceived naturally. Timely
diagnosis may avert dire consequences of massive haemorrhage from ruptured uterine cornua
Ectopic pregnancy in the interstitial part of the fallopian tube (cornual pregnancy) is a rare condition but can be fatal. Traditionally, the treatment had been cornual resection or hysterectomy. More conservative approaches had been advocated recently. There is no consensus on the dose or number of methotrexate injections that should be used in the treatment of interstitial pregnancies. Single dose intramuscular methotrexate is one of the treatment options. However, the failure rate is higher if the serum beta-hCG (beta-human chorionic gonadotrophin) level is more than 5000 IU/L. We report a case of cornual ectopic pregnancy with high initial serum beta-hCG level being successfully treated with multiple doses of systemic methotrexate. MRI was used to assess clinical resolution of cornual ectopic pregnancy.