Cornual pregnancy is a rare type of ectopic pregnancy wherein the gestational sac develops within the cornua of a bicornuate or septate uterus or in the interstitial part of the fallopian tube. Despite the availability of modern modalities like ultrasonography and pregnancy tests, it is difficult to diagnose early and as a result, it can present with life-threatening internal abdominal hemorrhage.
A cornual pregnancy is a type of ectopic pregnancy in which the gestational sac develops within the cornua of a bicornuate or septate uterus or in the interstitial part of the fallopian tube. It accounts for less than 1% of all ectopic pregnancies and as the interstitial portion of the myometrium is more distensible, 20% of cornual pregnancies advancing up to 12 weeks of gestation tend to rupture . Despite the availability of modern diagnostic tests, the early detection of a cornual pregnancy remains challenging .
Patients with cornual pregnancy can present with acute abdominal pain following intrabdominal rupture of the gestational sac and an adnexal mass accompanied by features of hemodynamic compromise (hypotension, tachycardia, and shock). Other features of early pregnancy such as amenorrhea, breast tenderness, fatigue, cramps, dyspareunia, and shoulder pain (in the case of peritoneal irritation) may also be present. Occasionally, a cornual gestational sac may be noticed in a patient with amenorrhea during a pelvic ultrasound.
The risk factors for a cornual pregnancy are endometriosis with peri and intra-tubular adhesions, pelvic inflammatory disease, transfer of too many embryos, transferring embryos close to the uterine horn, exerting pressure during embryo injection, problems during embryo transfer , congenital rudimentary uterine horn , or bilateral salpingectomy .
Clinical acumen and suspicion of ectopic pregnancy in a woman presenting with acute abdominal pain, amenorrhea, adnexal tenderness or mass and hemodynamic collapse form the crux of early diagnosis. Missed diagnosis can result in life-threatening hemorrhage and mortality. A detailed menstrual history is crucial as is a history of embryo transfer. Guidelines  based on evidence have been established for the workup and management of ectopic pregnancies and have to be followed rigorously. Serum and urine beta-human chorionic gonadotropin (beta-hCG) levels, blood group and rhesus factor (Rh) antibody screening along with complete blood count, liver function tests should be obtained in all patients.
Using ultrasonographic criteria, a cornual pregnancy can be diagnosed in a patient with positive pregnancy test . The ultrasonography criteria are - an absence of a gestational sac within the uterine cavity; location of an asymmetrical gestational sac in the proximity of the uterus and the presence of a myometrial wall around the gestational sac. A skilled ultrasonographer with a transvaginal ultrasound can identify a cornual pregnancy as a gestational sac located laterally in the uterine fundus with the classic endometrial stripe around 9 to 12 weeks . In addition, advanced radiological techniques like three-dimensional transvaginal ultrasound scanning can detect the exact location of the gestational sac in relation to the uterine cornu by reproducing the coronal plane of the uterus .