LMP 10 and 28 day rules
LMP 10 and 28 day rules – definition and use
LMP stands for the last menstrual period, and in radiography it is a very critical to female patients. It is critical in terms of radiation dose affecting foetus especially in the first stages of pregnancy.
A female patient of childbearing age can only be examined within the first 10 days from the START of her last period. After that date the patient can only be x-rayed if a pregnancy test is negative or if a medical doctor over-rules the 10 day rule on medical grounds. 10 day rule is for high dose examinations such as CT pelvis and Barium Enemas. The 28 day rule states that a female patient of childbearing age can only be examined in the first 28 days from the start of her last period. 28 day rule is for low dose examinations
IN DETAILS
10-days rule
If MORE than 10 days passed from the FIRST day of last menstrual period, the radiographer should NOT expose the patient for high dose examinations (like fluoroscopy and CT) or the examinations which include pelvic cavity. For example, if the LMP was on the 4th of April and she came on the 15th of April, this means that she passed the 10 days rule and she are in a high chance of pregnancy.
28 days rule
28days rule allows x-raying the patient for low dose examinations for body parts which are located away from pelvic cavity like extremities within 28 days from first day of last menstrual period.
For example, if a female patient came on the 17th of February for hand x-ray and her LMP was on the 1st of February. In this case if the radiographer can expose the patient according to 28 days rule because the patient didn’t passed 28 days from the first day of LMP.
NOTE: within 28 days from LMP the risk of developing bioeffects for foetus is low, if the exposure is low and primary beam is away from pelvic cavity. Also, radiation protection methods should be used to minimize the dose to the patient.
Dose reduction methods
• Collimating field size to region of interest
• Applying lead shielding
• Good positioning to avoid repeating
• Using high kV technique
• Viewing images in good viewing conditions
• Using compression devises to minimize thickness and immobilizing the patients
Written by Scorpion Lady (B.M) / 27/06/2008
All rights reserved. BM
Please DO NOT copy this report or use it without the writer's permission
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B.M
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مواقع النشر (المفضلة)