Women's health

How pregnancy can be detected

A number of symptoms and signs are detectable by both the woman and her obstetrician doctor when pregnancy occurs. The signs and symptoms persevere through out pregnancy and are very important markers for the continuous diagnosis of a viable pregnancy until the woman puts to birth.

It will not be possible to make a certain diagnosis of pregnancy from just one sign or symptom, but a combination of these signs and symptoms can be highly suggestive of pregnancy especially in the first trimester. The use of pregnancy test and imaging are the absolute confirmatory diagnostic technique for detecting pregnancy in a woman.

It is also vary important to rule out other differential diagnoses that can present with similar clinical features like pregnancy such as uterine fibroids, ovarian cysts, distended bladder and pseudocyesis (or false pregnancy, where the woman only believes she is pregnant) among others.

 

COMMON DETECTABLE SYMPTOMS 

Amenorrhea : Amenorrhea or absent menses is the earliest symptom of pregnancy. If a healthy woman whose menstrual periods were previously regular has a sudden cessation of menstruation, the presumption must always  be that she is pregnant unless some other cause of Amenorrhea can be found.

Breast symptoms : In the early weeks of pregnancy, some tenderness and fullness of the breast may be noticed. The breast increases in size due to the proliferation of the glands and ducts of the breast under the influence of estrogen and progesterone.

Frequency of micturition : During the first 12 weeks, when the uterus is still a pelvic organ, there is often some frequency of micturition because the enlarging uterus presses on the bladder lightly, particularly when the woman is standing during the day time.

Abdominal enlargement : Many women notice some abdominal fullness in early pregnancy at a time when the uterus is not much enlarged. This can only be the result of slight intestinal distention or progesterone effect on the muscles of the anterior abdominal wall.  Later on, the uterine enlargement becomes evident and sometimes it becomes the first thing that brings the woman to the hospital especially in cases where the menstrual periods were previously irregular. Sometimes a woman’s abdomen may swell because of other reasons like fat or ovarian cyst and not pregnancy.

Fetal movements : A primigravida (woman pregnant for the first time) usually feel for the first time fetal movements called quickening between 16th to 20th week of pregnancy but a multiparous woman who has delivered before May recognise the movements 2 or 3 weeks earlier. At first the movements are slight and may be confused with wind. This very subjective symptom is not of much value in the diagnosis of pregnancy.

 

COMMON DETECTABLE SIGNS

Enlargement of the body of the uterus 

A slight enlargement of the body of the uterus is the earliest alteration from pregnancy which can be detected clinically but it is difficult to be certain of this if the woman has had a previous pregnancy. On bimanual examination, the body of the uterus is felt to be globular and as progressive enlargement occurs, the diagnosis becomes more evident. At 12 weeks of pregnancy, the fundus of the uterus is usually palpable in the abdomen just above the pubis symphysis. The fundus reaches the level of the umbilicus at about 22 weeks gestation and just below the xyphisternum at the 36th week of pregnancy.

Softening of the uterus and cervix 

Softening of the uterus due to increased vascularity is a useful sign to the experienced obstetrician to detect pregnancy. Softening and blue colouration of the cervix soon follows the softening of the uterus and are usually complete by the 16th week.  When they are markedly noticed, they are a reliable signs of pregnancy.

Painless contractions 

The pregnant uterus varies in consistency on palpation because it has intermittent painless contractions. If the woman is easy to examine these contractions can be felt even when the uterus is still in the pelvis. When the uterus rises up into the abdomen, the contractions are more easily felt and are reliable evidence that the enlargement is in fact a pregnant uterus.

Fetal heart sounds

On auscultation of the abdomen with a sonicaid, the fetal heart sounds may be heard after the 12th week of pregnancy. The fetal heart rate varies between 120 – 160 beats per minute which is roughly double of the maternal pulse rate.

Palpation of fetal parts

Palpation of fetal parts is usually possible from the 24th week onward and at a later stage, the definite recognition of the head, back and limbs of the fetus are absolute and confirm pregnancy without any doubt.

Funic souffle

The funic souffle is a soft blowing murmur synchronous with the fetal heart sounds and is occasionally heard if the sonicaid happens to be placed to lie directly over the umbilical cord.

 

PREGNANCY TEST AND IMAGING

Human chorionic gonadotropin levels

Pregnancy test depends on the detection of large quantities of the human chorionic gonadotropin (hCG) which is produced by the trophoblast. hCG is a glycoprotrein that is found in maternal circulation after fertilisation and is excreted in maternal urine after implantation. This is the basis for doing pregnancy test on the urine and blood. Usually, pregnancy test on the blood can pick up hCG levels as early as 2 weeks after conception whiles in urine, hCG can be noticed after 2 – 4 weeks.

Ultrasound scan

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With a real time ultrasound scan, the gestational sac can often be diagnosed as early as 5 weeks from the first day of the last menstrual period. A week later, echoes from the embryo within the sac can be obtained and cardiac pulsation may be recognised particularly if a transvaginal transducer is used.

 

 

Source

G. Chamberlain: Obstetrics by Ten Teachers, “Normal Pregnancy” (16th edition).

 

 

 

 

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