Diagnosis of pregnancy

Diagnosis of pregnancy:

The placenta produces a hormone, called human chorionic gonadotrophin, which is excreted in the urine. This hormone is usually detected in the urine within a week of the first missed period. Biological and immunological tests depend on the detection of human chorionic gonadotrophin in the urine.

Immunological test:

Immunological pregnancy test depends on the fact that human chorionic gonadotrophin has antigenic properties. The test consists of two steps.

1.     HCG antiserum is added to urine of the woman.

2.     Sensitized red cells or latex particles are then added.

The first step neutralizes HCG antibodies; hence no agglutination occurs after the second step, confirming pregnancy.

Signs and symptoms of pregnancy.

There are many signs of pregnancy.

1.     Presumptive signs are suggestive of pregnancy and these signs could be caused by other conditions. So they do not establish a diagnosis of pregnancy.

2.     Probable signs of pregnancy can be documented by physical examinations. These findings could also be caused by other conditions.

Positive signs are physical findings that establish a diagnosis of pregnancy.

Presumptive or possible signs of pregnancy:

1.     Amenorrhoea - Absence of menstruation: It is the first sign and is noticed by the woman herself. Following implantation, of the fertilised ovum, the endometrium undergoes decidual change and menstruation does not occur throughout pregnancy.

2.     Morning sickness: Nausea and vomiting along with or without indigestion occur due to increased human chorionic gonadotrophic hormone level.

3.     Skin changes: Pigmentation of the areola, linea nigra and bluish pink striae on the abdomen are present.

4.     Breast changes: Discomfort, tingling and a feeling of fullness of the breasts may be noticed as early as third or fourth week of pregnancy due to increased vascularisation.

5.     Bladder irritability: Frequency of urination increases due to pressure from the gravid uterus and increased vascularity of the bladder.

6.     Quickening: A woman' s first awareness of fetal movement is called quickening. It is initially felt between 18 to 20 weeks of gestation. In multigravida it may be felt from 16 weeks onwards.

Probable signs:

1.     Presence of HCG in blood and urine between 4 and 12 weeks

2.     Hegar' s sign: Softening of isthmus. Isthmus is the part of uterus between body of uterus and cervix.

3.     Goodell' s sign: Softening of cervix.

4.     Chadwick' s sign: The colour changes from pink to bluish purplish in the mucous membranes of the cervix and vagina due to increased vascularization.

5.     Osiander' s sign: Pulsation in fornices felt at 8 weeks. The above signs may develop due to pelvic congestion also.

Braxton-Hick' s contractions: Painless, mild uterine contractions occur from 16^th week onwards, called as Braxton-Hicks contractions.

1.     Changes in the size and shape of uterus: From 8^th week onwards the size of the uterus enlarges. Its consistency is soft and become globular rather than pear shaped.

2.     Enlargement of the abdomen: The abdomen enlarges in size as the uterus grows.

Positive signs of pregnancy:

1.     Visualization of fetus by x-ray evidence and ultra sound evidence.

2.     Fetal heart sounds may be heard as early as 20^th week.

3.     Fetal movements can be felt per abdomen by the examiner about 22 weeks onwards.

4.     Fetal parts can be felt in about 24 weeks onwards.