Diagnosis of Pregnancy
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Direct answer
Pregnancy is diagnosed by combining symptoms, signs and tests, classically grouped as presumptive, probable and positive. Presumptive evidence (amenorrhoea, morning sickness, breast tingling, urinary frequency) comes from the woman; probable evidence (uterine enlargement, Hegar sign, positive urine test) comes from examination and basic tests; positive signs (fetal heart sounds, fetal movements felt by the examiner, ultrasound demonstration of a fetus) are conclusive. Modern urine and serum beta-hCG assays detect pregnancy within days of implantation, but a positive test proves trophoblast activity, not viability or site.
What you must remember
- Presumptive symptoms: amenorrhoea is the earliest and most important, followed by morning sickness from about 6 weeks, breast heaviness and tingling, frequency of micturition, fatigue and increased pigmentation.
- Quickening (feeling fetal movements) is appreciated at about 18-20 weeks in a primigravida and 16-18 weeks in a multigravida.
- Probable genital signs: Hegar sign — softening of the lower uterine isthmus on bimanual examination, best elicited at 8-12 weeks; Goodell sign — softening of the cervix; Chadwick (Jacquemier) sign — violet discoloration of vagina and cervix; Osiander sign — increased pulsation in the lateral vaginal fornices.
- Probable abdominal signs: uterus enlarges to a pelvic-abdominal organ palpable just above the symphysis by 12 weeks; intermittent Braxton Hicks contractions appear in the second trimester.
- Positive signs: fetal heart sounds — Doppler from about 10-12 weeks and a stethoscope (fetascope) from about 18-20 weeks at 110-160 beats per minute; fetal parts and active movements palpated by the examiner; ultrasound showing an embryo or fetus, the definitive proof.
- Laboratory tests: serum beta-hCG becomes positive about 8-10 days after conception; urine ELISA tests sensitive to roughly 25 mIU/mL turn positive around the time of the missed period.
- False-positive tests occur with molar pregnancy, recent miscarriage with retained trophoblast, choriocarcinoma, certain drugs containing hCG and laboratory interference; urine dilution or very early testing causes false negatives.
Common confusion
The distinction between probable and positive evidence is the trap. A positive urine pregnancy test, Hegar sign and even uterine enlargement are probable — they can all occur with a blighted pregnancy, a mole or, rarely, a fibroid uterus with an unrelated positive test from trophoblastic disease. Only fetal heart sounds, examiner-felt fetal movements and ultrasonic demonstration of a fetus are positive. A related pitfall is pseudocyesis (false pregnancy), where amenorrhoea, abdominal bloating and perceived quickening occur with a negative hCG; the test settles the issue.
Exam-focused takeaway
Expect classification MCQs (which sign belongs to which group), timing questions (weeks for quickening, Hegar sign, audible fetal heart by Doppler versus fetascope) and vignettes where the answer is the earliest reliable test — serum beta-hCG — or the definitive one, ultrasound. The exam also contrasts primigravida and multigravida quickening weeks and asks for the earliest symptom, amenorrhoea, in short one-liners.
Frequently asked questions
What are the positive signs of pregnancy?
Fetal heart sounds, fetal movements palpated by the examiner and ultrasonic demonstration of a fetus — these alone confirm pregnancy conclusively.
When does quickening occur?
At about 18-20 weeks in a primigravida and 16-18 weeks in a multigravida, as perceived fetal movements.
What is Hegar sign?
Softening of the lower uterine segment (isthmus) elicited on bimanual examination between about 8 and 12 weeks; it is a probable sign.
How early can pregnancy be detected by tests?
Serum beta-hCG turns positive about 8-10 days after conception, while sensitive urine tests detect pregnancy around the time of the missed period.
Can a pregnancy test be positive without a viable intrauterine pregnancy?
Yes — ectopic pregnancy, molar disease, retained trophoblast after miscarriage and choriocarcinoma all produce positive hCG tests, so site and viability are judged by ultrasound and serial values.