B1. Diagnosing pregnancy

Page created on December 16, 2021. Last updated on January 17, 2022 at 19:48

Signs suspicious for pregnancy (presumptive signs)

These signs are not proof of pregnancy but may make a woman suspicious that she is pregnant.

  • Nausea, morning vomiting
  • Affection to unusual things (like food, ice, etc, or reverse feeling for things she liked earlier)
  • Breast enlargement and tenderness

Probable (“warning”) signs of pregnancy

These signs are also not proof of pregnancy but are more specific to it than the presumptive signs.

  • Changes in the reproductive tract
  • Pregnancy tests
  • Missing menstrual bleeding (amenorrhea)
  • Hyperpigmentation of the areola
  • Increased basal body temperature
  • The following signs on physical examination:
Sign Finding on physical examination
Hegar sign Softening of the lower segment of the uterus
Gauss sign Marked mobility of the uterus
Piskacek sign Palpable bulge on the location in one of the two locations where the uterine tube meets the uterus
Noble sign The vaginal cul-de-sac flattens and takes on a globular form

Positive modern pregnancy test is considered a proving sign of pregnancy in most places.

Proving or positive signs of pregnancy

These signs are those which definitely confirms a pregnancy.

  • Ultrasound ->
    • Detectable heart movements at week 6
    • Foetal movements at week 8

Which signs belong under which category varies from source to source.

Pregnancy tests

Over-the-counter pregnancy tests are based on measuring the hormone hCG in the urine. hCG is produced by trophoblast cells, and the amount produced increases exponentially after implantation. These tests can detect hCG in the urine 8 – 9 days after ovulation.

hCG can be measured directly in the blood as well. This is more invasive and less frequently used of course but may be useful in the follow-up of abortion or molar pregnancy. The plasma level of hCG doubles every 1,5 – 2 days.


An hCG test may be false positive due to certain factors, like molar pregnancy, choriocarcinoma, or recent mononucleosis infection. Only ultrasound can confirm whether the cause of hCG increase is actually due to normal pregnancy or not. In the first trimester, the foetus is too small to be visualised on transabdominal ultrasound, and so transvaginal ultrasound must be used.

The earliest sign of normal pregnancy on ultrasound is the detection of foetal heart movements, around week 6. The movements of the foetus itself can be visualised at week 8. In some countries, an ultrasound is scheduled during week 6 – 8 to confirm the pregnancy. (The lecture is kind of ambigous about whether this is performed in Hungary or not, but it’s not performed in Norway at least)

In most countries, a routine ultrasound sometime in weeks 18 – 22 is performed. This is further described in topic B8.

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