Pregnancy Diagnosis - Different Methods

Introduction:

Diagnostic procedures are the backbone of the medical field. Diagnostic tests are used to confirm pathological conditions and disorders present in the body. Also, physiological changes in the body can be identified by diagnostic procedures. These diagnostic methods are used to identify pregnancy. Diagnostic procedures can also be used to diagnose any complications associated with pregnancy.

What Are the Traditional Ways of Pregnancy Diagnosis?

Before the advent of medical diagnostic procedures, different physical signs and symptoms were evaluated for diagnosing pregnancy. These physical signs and symptoms are:

1. Missing the menstrual cycle is one of the key features of diagnosing pregnancy. Though this symptom can be misleading as missing periods can be caused by several factors.

2. Swelling of the breasts, tenderness of breasts, and tenderness around the nipples can be caused by hormonal changes caused by pregnancy.

3. Increased nausea, vomiting, fatigue, rilling of the head, and morning sickness are associated with pregnancy symptoms.

4. Increased urination and constipation are also associated with pregnancy.

5. Frequent mood swings, changes in food habits, and bloating are also considered as pregnancy symptoms.

Assessment of physical symptoms is also part of the diagnostic procedure of pregnancy. Assessment of fetal movement and measurement of fetal heart rate is done to assess the fetus's condition. Enlargement of the cervix and bluish discoloration of the cervix is the physical changes caused by pregnancy.

What are the Diagnostic Procedures?

All the traditional ways need to be more accurate, and the chances of negative results are very high. As a result, several laboratory tests are used to determine the authenticity of the pregnancy. These diagnostic tests include hormonal evaluation methods and image-based diagnostic methods.

What Is Hormonal Evaluation?

Three different hormones, beta-human chorionic gonadotropin, progesterone, and pregnancy factor (EPF), are evaluated during pregnancy. Several other hormones like corticotropin-releasing hormone, gonadotropin-releasing hormone, thyrotropin-releasing hormone, somatostatin, adrenocorticotropic hormone, and human chorionic thyrotropin are also present during pregnancy. But these hormones are not evaluated as evaluating these hormones is not commercially viable.

A. Human Chorionic Gonadotropin (hCG): This hormone is secreted by the trophoblast (a thin layer of a developing embryo); this is a glycoprotein hormone that helps in the secretion of progesterone. This hormone has two subunits alpha and beta. In circulation, the hormone is present either in dimer form, alpha and beta subunit, degraded form, or beta fragment. This hormone is metabolized in the liver, but a certain portion of the beta subunit of this hormone is excreted by the urine. Detection of this hormone is only possible after implantation of the embryo. So around eight to ten days after fertilization, this hormone can be detected. Thus evaluation of the HCG in the urine is essential to determine pregnancy.

The analysis of the presence of this hormone is possible in four methods. These are:

1. Radioimmunoassay: It took around four hours to complete this test. The required sensitivity of HCG hormone for this test should be five milli-international units per milliliter. This test is positive after the third or fourth week of gestation or 10 to 14 days after conception.

2. Immunoradiometric Assay: The sensitivity level of hCG for this test is 150 milli-international units per milliliter. These tests can be done within thirty minutes, and these tests are positive 18 to 22 days after conception. In case of a high level of hCG (1500 milli-international units per milliliter), positive results can be obtained within two minutes.

3. Enzyme-Linked Immunosorbent Assay (ELISA): These tests are sensitive when the level of the hCG is 25 milli-international units per milliliter. These types of tests took around 80 minutes to perform. 14 to 17 days after conception, these tests show a positive result.

4. Fluoroimmunoassay: These types of tests can be positive at a low level of hCG (1 milli-international unit per milliliter). Positive results can be obtained within two to three hours. The first positive result can be obtained 14 to 17 days after conception. This method is used to manufacture different test kits. These test kits can be used to determine the level of hCG in a home or in a laboratory setup.

B. Progesterone: Measurement of serum progesterone level is useful to detect pregnancy. Not only that, other criteria like a viable pregnancy and ectopic pregnancy can be through this method. Radioimmunoassays and fluoroimmunoassays can be used to determine the level of progesterone within three to four hours. A dipstick test using Enzyme-linked immunosorbent assay (ELISA) can also be used. A progesterone level of more than 25 nanograms per milliliter is indicative of viable pregnancy. In nonviable pregnancy, the level of this hormone is less than five nanograms per milliliter.

C. Early Pregnancy Factor: This is a poorly differentiated immunosuppressive protein present in the maternal blood. This is the earliest biomarker that can be found in pregnant women. This can be detected after 36 to 48 hours of conception. This is a useful tool to detect successful embryo transfer in in-vitro fertilization. But detecting this molecule is a complex procedure; as a result, clinical and commercial applications are limited.

What Is the Method of the Home Test?

The home test is a urine-based test. This is an immunometric assay that uses monoclonal or polyclonal antibodies that bind to the hCG molecules and produce a color change. For a successful test maximum concentration of hCG (greater than 20 milli-international units per milliliter) is required. That is why the first few drops of urine samples are collected. Water should not be consumed before the test as it can dilute the concentrate.

What Is the Method of Laboratory Test?

For this purpose, a blood sample is collected. The reagent has two antibodies that bind to the hCG sample. Positive results can be obtained 8 to 11 days after conception.

What Are the Cause of Faulty Results?

False negative and false positive results can be obtained in many cases:

1. Ectopic production of hCG due to hydatidiform mole, choriocarcinoma (a type of cancer in the uterus), and germ cell tumors may cause a false positive result in serum analysis. Even diseases like multiple myeloma (a type of blood cancer) and endometrial cancer show false positive results.

2. Chronic renal failure and plasma transfusion also show false positive results in serum analysis.

3. Too early a test after conception or an excessively high amount of hCG due to abnormal pregnancies are associated with false negative results.

What Is the Image-Based Procedure?

Ultrasonography is an image-based procedure to detect pregnancy. The transvaginal route of ultrasonography is used to detect pregnancy. The accuracy is 100 percent. Not only that, various pregnancy anomalies like ectopic pregnancy and fetal anomalies can be diagnosed using this method.

Conclusion:

Diagnosing pregnancy accurately is important. Hormone-level assessments are routinely used for this purpose. Measurement of human chorionic gonadotropin is economical and can be done at home. But, several pathological conditions may cause false positives and false negative results. Ultrasonography is the most accurate method to diagnose pregnancy. Any anomalies related to pregnancy can also be measured by using ultrasonography.