Obstetric USG Scan & Its Prices

The 1^st sign of early pregnancy seen on ultrasound scan is the presence of gestational sac. It is a spherical, fluid containing sac around the developing embryo. On ultrasound scan, an intrauterine gestational sac appears as two concentric echogenic rings that are separated by a hyperechoic space. This finding is known as Double decidual sac sign and indicates a normal intrauterine pregnancy.

Gestational sac can be seen as early as:

• 5 weeks of gestation by TVS (Transvaginal sonography) scan.  

6 weeks of gestation by Transabdominal ultrasound/obstetric ultrasound scan.

There is no difference between sonography and an ultrasound scan and both the terms can be used interchangeably. However, the term sonogram refers to image produced by an ultrasound scan or sonography test.

Normally 2-3 ultrasound scans are performed during pregnancy. However, if required multiple scans can be done. According to ACOG (American college of obstetricians and gynaecologist), ultrasounds are safe during pregnancy and there is no evidence demonstrating that ultrasonography pose any kind of risk to the growing foetus.

In the first trimester of pregnancy, following ultrasound scans can be done:

1. Obstetric ultrasound: Also known as Dating scan, is performed during 6-8 weeks of pregnancy. It is a mandatory scan recommended for every pregnant woman. Obstetric ultrasound is used to confirm pregnancy, rule out abnormal implantation such as an ectopic pregnancy and evaluate the gestational age of baby.
2. NT NB scan: It is an optional scan recommended for high-risk pregnancy. It is performed during 11-13 weeks of gestation. It is used for screening chromosomal abnormalities such as Down syndrome or identify any structural abnormality in the growing fetus.

Level 2 ultrasound is performed in the second trimester during 18-22 weeks of pregnancy. It is also known as Anomaly scan or TIFFA scan. It is a mandatory scan recommended for every pregnant woman.

Level 2 ultrasound or TIFFA scan is used to detect congenital malformations, growth abnormalities in the fetus as well as identify placental pathologies.

In the third trimester of pregnancy, following ultrasound scans can be done:

1. Fetal well-being ultrasound: It is also known as growth scan and performed during 24-32 weeks of pregnancy to evaluate the progress in growth and development of the baby and to evaluate amniotic fluid volume.
2. Obstetric color doppler ultrasound: It is performed during 28-32 weeks of pregnancy to check the patency, direction and speed of blood flow in maternal as well as fetal vessels or to rule out fetal anemia and placental insufficiency. It is an optional scan recommended for high-risk pregnancy.
3. Ultrasound Biophysical profile: It is usually performed after 32 weeks of gestation to monitor the fetal well-being. It is an optional scan recommended for high-risk pregnancy.

Obstetric Color doppler also known as color doppler ultrasound in pregnancy is a diagnostic tool that is used in pregnancy to check the patency, direction and speed of blood flow in maternal as well as fetal blood vessels. It is commonly done in third trimester of pregnancy. However, in high-risk pregnancies it may be done at an earlier stage. It also provides guidance in deciding time of delivery in such cases. 

Color Doppler ultrasound is a non-invasive, painless and fast modality of imaging which is safe in pregnancy as it doesn’t utilize ionizing radiations or contrast agents rather it utilizes sound waves for depicting any underlying pathology of maternal or fetal blood flow.

Some of the indications/uses of color doppler ultrasound in pregnancy includes:

1. Evaluation of utero-placental circulation
2. Evaluation of fetal circulation
3. Pre-eclampsia
4. Fetal anemia
5. Gestational hypertension 
6. Oligohydramnios
7. Evaluation of fetal heart for congenital anomalies such as Tricuspid regurgitation.
8. Intra Uterine Growth Restriction (IUGR)
9. Twin pregnancy 
10. Twin-twin transfusion syndrome (TTTS)
11. HELLP Syndrome (Hemolysis, Elevated liver enzymes, Low platelet count)
12. Maternal isoimmunization etc. 

It’s not very difficult to read or understand ultrasound reports of pregnancy. However, the only pre-requisite is your basic understanding of some medical terms/terminology.

You will receive the reports with description of your ultrasound findings along with attached picture/sonogram. You may read and understand the printed description of your ultrasound findings but you may not completely understand the sonogram attached with it. 

Usually, the sonogram is provided for your obstetrician reference purpose. So that she may look and analyse the co-relation between the description provided and the sonogram attached with it. This helps your obstetrician in understanding and developing proper management plan according to your current scenario. 

Sometimes urine pregnancy tests are positive but when you go for an obstetric ultrasound scan it turns out to be negative for pregnancy. This is a common finding encountered by many women. Various reasons or causes of this finding includes the following- 

1. False positive UPT (Urine pregnancy test).
2. Very early ultrasounds: Tvs scan before 4.5 weeks of gestation or Transabdominal ultrasound scan (TAS) before 5.5 weeks of gestation can’t detect gestational sac which is the 1^st reliable marker of pregnancy on an ultrasound scan. 
3. Ectopic pregnancy: Implantation at an abnormal site such as fallopian tube, ovaries, c-sec scar results in ectopic pregnancy. Empty uterine cavity is often found on ultrasound scan in case of ectopic pregnancy.
4. Miscarriage or pregnancy loss: After miscarriage or pregnancy loss, beta hCG hormone level remains high for up to 6 weeks and then start returning to its non-pregnant state. 
5. Misinterpretation: In Urine pregnancy test kits, there is one control line and one test line. Sometimes a faint pink line appears on test line which may represent an early pregnancy or it may be a user error leading to a positive urine pregnancy test but an empty uterine cavity on ultrasonography.
6. Abnormal conditions: Some conditions may lead to false positive urine or blood pregnancy test due to an elevated hCG hormone levels in body without an intrauterine pregnancy such as:
   • After medical termination of pregnancy
   • Abortion
   • Pregnancy failure
   • Anembryonic pregnancy
   • Complete molar pregnancy
   • Pituitary abnormality
   • Invasive mole
   • Choriocarcinoma
   • Placental site trophoblastic tumour (PSTT)
   • Epithelioid trophoblastic tumour
   • Germ cell tumours of ovary
   • Infertility treatment such as synthetic hCG injection etc.

Ultrasound is a painless, non-invasive and rapid technique to confirm pregnancy, evaluate gestational age and EDD (expected date of delivery). The presence of gestational sac on USG scans is considered as the 1^st definitive sign of pregnancy and the presence of yolk sac within the gestational sac is considered as the 1^st reliable sign of intrauterine pregnancy.

The best time to calculate gestational age of baby is the 1^st trimester of pregnancy (9-12 weeks) by an ultrasound scan (using the parameter CRL). Gestational age is calculated using CRL (Crown-rump length) in the 1^st trimester of pregnancy as following-

1. To calculate days of pregnancy, formula used is CRL (in mm) + 42.
2. To calculate gestational age in weeks, formula used is CRL (in cm) + 6.5.

However, if pregnant women present for the first time in 2^nd trimester of pregnancy, then the parameters used in ultrasonography to calculate gestational age of foetus is femur length (FL), Head circumference (HC), Biparietal diameter (BPD) or Abdominal circumference (AC).

And if pregnant women present for the 1^st time in 3^rd trimester of pregnancy, then parameters used for the estimation of gestational age includes femoral epiphyseal ossification centers, proximal tibial ossification centers or proximal humeral ossification centers.