Biochemical Pregnancy

Biochemical pregnancy is a very early pregnancy loss in which hCG is positive but no gestational sac is ever seen on ultrasound, and hCG falls to negative, usually within a few days of the expected period. Most result from chromosomal abnormality or failed implantation. It is common and is usually found by early home testing or during fertility treatment.

• Often follows assisted reproduction cycles.
• Risk factors: age above 35 years, uterine factors, smoking.
• It is not a risk for later pregnancy in most women.

There is a short delay in the period, a faint positive test, then bleeding that may be heavier than normal, with mild cramps. Examination is usually normal.

• Positive test followed by negative test within 1 to 2 weeks.
• Bleeding at or within a week of the expected period.
• No pregnancy symptoms beyond the first days.
• Differential diagnosis: ectopic pregnancy, pregnancy of unknown location, early miscarriage, false positive test, hCG secreting tumour.
• Complications: missed diagnosis of ectopic pregnancy, anxiety, grief.

The approach is to confirm falling hCG and exclude ectopic pregnancy.

• Repeat serum or urine hCG after 48 hours and then at 7 days; a steady fall to a negative test confirms the loss.
• Transvaginal ultrasound if pain, bleeding or hCG above 1500 IU/L: empty uterus, no adnexal mass.
• Ectopic pregnancy must be excluded if hCG plateaus or rises slowly.
• Urine pregnancy test at 2 weeks confirms resolution where hCG is unavailable.

The principle is observation, because the pregnancy resolves without treatment once ectopic is excluded.

• Supportive: reassurance that loss is common and not caused by activity; advise no restriction on trying again.
• Pharmacological: folic acid 400 micrograms oral daily if planning pregnancy; paracetamol 1 g oral 6-hourly as needed (maximum 4 g in 24 hours); contraception at the patient's choice if conception is not wanted.
• Procedures: none.
• Red flags: severe or one sided pain, heavy bleeding, shoulder tip pain, dizziness, persistently positive test beyond 3 weeks.
• Follow-up: repeat pregnancy test at 2 weeks; return urgently if symptoms worsen; investigate after 3 consecutive losses.