Ovarian Ectopic Pregnancy

Ovarian ectopic pregnancy is implantation of the pregnancy within or on the ovary. It accounts for about 1 to 3 percent of ectopic pregnancies and is often mistaken for a ruptured corpus luteum cyst. It matters because it can rupture with life-threatening bleeding.

• Risk factors: intrauterine contraceptive device, assisted reproduction, pelvic inflammatory disease.
• Typically presents at 6 to 8 weeks.
• Diagnosis is often made at surgery.

Patients have lower abdominal pain, amenorrhoea and light bleeding; rupture causes collapse and peritonism.

• Unilateral pelvic tenderness.
• Pain may suggest appendicitis or ovarian torsion.
• Differential diagnosis: ruptured corpus luteum cyst, tubal ectopic pregnancy, ovarian torsion, appendicitis, haemorrhagic ovarian cyst.
• Complications: haemorrhage, shock, loss of ovarian tissue, recurrence.

The approach is transvaginal ultrasound and hCG.

• Ultrasound: wide echogenic ring on or within the ovary with an empty uterus; free fluid.
• hCG elevated, with a rise below that of a normal intrauterine pregnancy.
• Haemoglobin, cross-match 4 units, blood group and Rhesus status.
• Laparoscopy confirms the diagnosis and permits treatment.

The principle is ovary sparing surgery or methotrexate for stable women.

• Supportive: two large-bore cannulae; Ringer's lactate 1 litre if unstable; blood available.
• Pharmacological: methotrexate 50 mg/m2 IM single dose for stable women with hCG below 5000 IU/L and no fetal heart; hCG days 4 and 7 then weekly to negative; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours).
• Procedures: laparoscopic wedge resection or cystectomy with preservation of the ovary; oophorectomy only if bleeding cannot be controlled; laparotomy for instability.
• Special groups: Rhesus negative women give anti-D immunoglobulin 250 IU IM within 72 hours.
• Red flags: severe pain, dizziness, pulse above 100 per minute, falling haemoglobin.
• Follow-up: hCG weekly until negative; ultrasound at 4 to 6 weeks; early scan in future pregnancies.