US PREGNANCY DATING SCAN

Pregnancy Dating Scan Overview

A pregnancy dating scan is an important ultrasound examination done during pregnancy, usually in the first trimester. Its main aim is to establish the fetal age, set the expected due date and check on the progress and state of development of the pregnancy. Ultrasounds create images of a developing fetus and the maternal reproduction system with the help of high frequency sound waves. This procedure is beneficial to expectant mothers as it is non-invasive and provides vital guidelines that should be followed throughout the prenatal period. 

What is a Pregnancy Dating Scan? 

A pregnancy dating scan is an ultrasound examination which assists in determining the age of the fetus gestationally. This is useful data as it helps healthcare professionals to be able to keep track of the pregnancy stages, perform necessary examinations at appropriate times and prepare for safe delivery. The scan works by placing a small probe on the mother’s stomach and sending sound waves. Internally stored structures reflect these sound waves, and it is these reflected sounds that the ultrasound machine converts into images that the sonographer, as well as other healthcare providers, can use for monitoring the progress of the fetus. 

Types of Ultrasounds for Pregnancy Dating 

• Transabdominal Ultrasound: The most common method where the ultrasound probe is moved on the belly. 
• Transvaginal Ultrasound: Used in case of the need for more elaborated images or early pregnancy dating. With the help of this type the image is a lot clearer in the early stages of pregnancy as it involves insertion of a probe into the vagina. 

List of Parameters which are Considered in the Pregnancy Dating Scan

• Crown-Rump Length (CRL): Finding the distance from the head of the embryo down to the protuberance of the buttocks. 
• Gestational Age: It is computed based on the CRL and compared to the standard growth charts. 
• Fetal Heartbeat: This is assessed in order to establish the pregnancy. 
• Yolk Sac: Information on placental health can be gained from the presence and size of the yolk sac. 
• Uterine and Cervical Structures: To diagnose pathology.

Reasons for Taking a Pregnancy Dating Scan

• To have an exact date of delivery confirmed. 
• For establishing gestational age in non-cycling patients. 
• Determing fetal development intervals at the various periods to establish the growth targets and rates for the fetus. 
• Evaluating the presence of multiple pregnancy and progress. 

When and Who Needs to Take a Pregnancy Dating Scan? 

Who Needs It: 

• The majority of pregnant women are advised to have a dating scan between the 8 to 14 weeks estimate. That is because it is a routine measure. 
• Those experiencing irregular menstrual cycles can also benefit from a dating scan as this will help determine the gestational age more logically. 
• There are women who will not have any idea regarding last menstrual period and such instances may require a dating scan. 

When It's Necessary: 

• For the statement that is given on a clinical management issue such as attendance to antenatal clinics, for example but all other tests would need to confirm the pregnancy. 
• Also to determine more accurately the weeks of pregnancy in cases where this information can be given during the social history, that is, how many weeks missed the last menstrual period. 
• To find out how many babies are present in a womb e.g. twins or triplets. 
• Autopsy of the baby and measurement of the placenta to see which there are some invasive tests to check for any form of disease in the pregnancy can take place. 

Benefits of Taking the Test

• Useful for providing important details necessary in the management of infants in prenatal period. 
• Helps identify risks at the early stage of pregnancy. 
• Facilitates reassurance of the expectant parents by indicating fetal heartbeat and viability. 
• Assists in scheduling of the recommended prenatal examinations at the appropriate times. 

Illnesses Diagnosed with Pregnancy Dating Scan

Diseases are not the main purpose of the scan, but some of them include: 

• Ganerralocal of an embryo (blighted ovum). 
• Type of ectopic pregnancy when the scan is performed transvaginally. 
• Intensive initial signs of an moderate severely constitutive structural abnormality. 

Preparing for a Pregnancy Dating Scan

• Use loose and comfortable clothes that will allow easy exposure of the abdomen. 
• Request the patient to drink water prior to appointment to make bladder capacity moderate enhancing improvement of image. 

Pre-requisites 

• Rather routinely a patient might have to do bladder distension prior to scopia in the case of a pregnancy self-scan. 
• During sessions, patients shall not follow a fasting regimen or taking any medically prescribed tablets. 

Best Time to Take the Pregnancy Dating Scan 

• The best range of pregnancy dating scan is betwee the 14th and 5 weeks of pregnancy but may be done earlier if there are doubts about fetal relations. 

Eligibility 

• Amniocentesis is recommended as part of routine practice in all pregnant females. 
• More so in women with irregularities in getting regular cycles or have no records of last periods. 

Procedure for Taking a Pregnancy Dating Scan 

• Arrival: Confirmations regarding the appointment backgrounds; other relevant clients life info is required. 
• Preparation: After informing full-dressed bladders, complementary cues can be devastating to liquids. 
• Execution: 
• During a transabdominal examination, the gel is applied and the transducer is placed on the external surface. 
• During the transvaginal imaging, the probe is inserted, gently to give a better picture. 
• Duration: In most cases takes approximately 20 - 30 minutes. 
• Completion: The outcome of the examination is discussed and recommendations on the management of pregnancy are given. 

Caution Before Taking the Test 

• Any pain or adverse effects should be reported to the technician. 
• All medical history or other conditions likely to affect the pregnancy should be stated.