Pregnancy of Unknown Location

Pregnancy of unknown location is a positive pregnancy test with no intrauterine or ectopic pregnancy seen on transvaginal ultrasound. The outcomes are a failing pregnancy, early intrauterine pregnancy or ectopic pregnancy; some are ectopic. It matters because ectopic pregnancy must not be missed, and safe follow-up depends on serial hCG.

• Common in women with early bleeding or pain.
• Risk factors: previous ectopic, pelvic inflammatory disease, tubal surgery, intrauterine contraceptive device in situ, assisted reproduction.
• Not a final diagnosis; it must be resolved.

Patients have lower abdominal pain, vaginal bleeding or both, with a positive test. The uterus may be normal sized, and adnexal tenderness may be present.

• Pain and bleeding may be absent.
• Haemodynamically stable at first.
• Differential diagnosis: early intrauterine pregnancy, failing pregnancy, ectopic pregnancy, biochemical pregnancy, molar pregnancy.
• Complications: ruptured ectopic pregnancy, haemorrhage, shock, delayed diagnosis.

The approach is serial hCG with repeat ultrasound.

• Transvaginal ultrasound by an experienced operator; check for free fluid.
• Serum hCG at presentation and at 48 hours.
• A rise in 48 hours of at least 49 percent when initial hCG is below 1500 IU/L, 40 percent when 1500 to 3000 IU/L, and 33 percent when above 3000 IU/L suggests a viable intrauterine pregnancy; repeat scan when hCG exceeds 1500 IU/L.
• A steady fall suggests a failing pregnancy; a plateau or a rise of less than expected suggests ectopic pregnancy.
• Haemoglobin, blood group and Rhesus status.
• If hCG is unavailable, repeat ultrasound in 7 days and use urine test results.

The principle is expectant management with safety netting and early recognition of ectopic pregnancy.

• Supportive: explain uncertainty; give written warning signs; ensure the patient can return at any hour; admit if unstable or unreliable for follow-up.
• Pharmacological: paracetamol 1 g oral 6-hourly as needed (maximum 4 g in 24 hours); do not give methotrexate unless ectopic is proven or hCG plateaus above 1500 IU/L with high clinical suspicion and the patient is stable; if methotrexate is chosen, give 50 mg/m2 IM as a single dose.
• Procedures: laparoscopy if ectopic pregnancy is strongly suspected, unstable, or hCG rises above 5000 IU/L with an empty uterus.
• Special groups: Rhesus negative women with bleeding after 12 weeks give anti-D immunoglobulin 250 IU IM within 72 hours.
• Red flags: severe pain, collapse, shoulder tip pain, heavy bleeding, pulse above 100 per minute, peritonism.
• Follow-up: hCG at 48 hours and then every 2 to 7 days until resolved; scan when hCG rises above 1500 IU/L; stop follow-up when a diagnosis is made or hCG is negative.