6. Diagnosis of early and advanced pregnancy

Covers how pregnancy is diagnosed, moving from the presumptive, probable and positive clinical signs, presented in a table, to laboratory testing of hCG and its expected rise in early pregnancy. It then sets out transvaginal ultrasound landmarks by gestational age in a second table, with the discriminatory zone and its link to ectopic pregnancy. The note ends with signs used in advanced pregnancy and how fetal death is recognised, including late signs and the risk of coagulopathy.

Inside: 5 sections · 2 tables · 16 flashcards · 2 min

Topic 6 of 61 in the MU Sofia syllabus for Obstetrics and Gynecology (Medicine, Year 5). The free AceMed note covers it in 5 sections, about 201 words (2 min of reading), with 16 flashcards.

Introduction

Signs of pregnancy are traditionally grouped as presumptive, probable and positive. Today pregnancy is confirmed by hCG and ultrasound.

Laboratory diagnosis: hCG

β-hCG is detectable in serum about 8–10 days after ovulation; urine tests turn positive around the day of the missed period.
In a normal early pregnancy serum hCG roughly doubles every 48 hours (a rise of at least about 50% in 48 h); a slower rise suggests ectopic pregnancy or a failing pregnancy.
It peaks at about 100,000 IU/L at 8–10 weeks. Very high values suggest twins or a molar pregnancy.

Ultrasound landmarks (transvaginal)

The discriminatory zone is the hCG level above which an intrauterine sac should be visible on transvaginal ultrasound, usually taken as 1,500–3,500 IU/L. An empty uterus above it raises suspicion of an ectopic pregnancy.

Advanced pregnancy

Fetal parts palpable, fetal movements felt by the examiner, fetal heart heard.
Fundal height and ultrasound biometry show the stage and growth.

Diagnosis of fetal death

No fetal movements, no fetal heart; on ultrasound, absent cardiac activity confirms it. Late signs are overlapping skull bones (Spalding's sign) and gas in the fetus. Retained dead fetus for weeks carries a risk of coagulopathy (DIC).

A positive test with no intrauterine sac is an ectopic pregnancy until proven otherwise.