Teaching Case

A 29-year-old nulliparous woman presented with 7 weeks amenorrhoea with right sided pelvic pain.

A 29-year-old nulliparous woman presented with 7 weeks amenorrhoea with right sided pelvic pain. Urine pregnancy test was positive. An ultrasound was scheduled to rule out an ectopic pregnancy. A transvaginal ultrasound was performed which revealed an intrauterine gestation of about 7 weeks. The left adnexa was unremarkable. However another gestation sac was noted in the right adnexa measuring 30 mm in size. No free fluid was seen. A diagnosis of a heterotopic pregnancy was made on the basis of the imaging findings. The patient refused surgical intervention. Three weeks later, she presented for a second time with increasing pain and was rescanned. A single live normal intrauterine pregnancy was again identified having a CRL of 312 mm, consistent with a gestational age of 10 weeks. Doppler study of the right adnexal gestation sac showed low resistance flow in the trophoblastic tissue. The patient underwent laparoscopic removal of the heterotopic pregnancy and the intrauterine live gestation was allowed to continue.

Heterotopic pregnancy is defined as the simultaneous presence of an intrauterine and extrauterine gestation. The incidence of heterotopic pregnancy is conventionally considered to be very low estimated to be 1 in 30,000 pregnancies. Review of more recent statistics suggests a higher rate owing to the rampant use of assisted reproduction techniques. Incidence may be as high as 1 in 7000 in pregnancies following assisted reproduction techniques; and 1 in 900 in patients with ovulation stimulation. Other risk factors predisposing to this condition include use of intrauterine contraceptive device, prior tubal surgery, history of pelvic inflammatory disease or history of ectopic pregnancy in the past.

The commonest location of the extrauterine gestation in a heterotopic pregnancy is the fallopian tube. Few cases of cervical and ovarian heterotopic pregnancies have also been reported.

Diagnosis of heterotopic pregnancy is difficult and is not as straightforward as the diagnosis of an ectopic pregnancy. Heterotopic pregnancy often goes unnoticed due to the presence of an intrauterine gestation sac. These patients usually present with lower abdominal pain in the first trimester. A relatively higher beta hCG levels for the period of gestation is a helpful diagnostic clue. Ultrasound examination, especially transvaginal sonography, has proven to be an invaluable tool in the diagnosis of this condition. The extrauterine pregnancy in cases of heterotopic pregnancy has a similar sonographic appearance as that of an isolated ectopic pregnancy. This includes an adnexal mass, live extrauterine embryo, free fluid in the pelvis or peritoneum, and/ or an adnexal "ring-of-fire" sign on colour Doppler study. Intrauterine gestation with haemorrhagic corpus luteum can simulate heterotopic gestation both clinically and on ultrasound.

The management of heterotopic pregnancy remains controversial. The medical management although used successfully for an ectopic gestation, has a limited role in the management of heterotopic pregnancy as one must try to preserve and protect the intrauterine pregnancy. The treatment of a heterotopic pregnancy is selective surgical removal of the ectopic pregnancy through laparoscopy or laparotomy.