Obdisk 2L: LARGE 2-disc Obdisk Pregnancy Calculator/Wheel (Clinic-Sized)

Product Information

Please note: Different Obdisk versions are now available, so you can choose the Obdisk model that best suits your requirements...

This LARGE clinic-sized 2-disc Obdisk 2L is manufactured in the UK from firm but flexible plastic. It's ideal for professionals, and it makes a unique, practical gift for expectant parents, too.

Approximate diameter: 190 mm [7.5"]. Approximate weight: 49 g.

Supplied with an instruction leaflet - please read the instructions before use.

Obdisk 2LTM 

Designed to be used by doctors, midwives, ultrasonographers and antenatal educators.  

• The Obdisk 2L is intended for professional use, as an aid to calculating the fetal gestational age and the Expected Date of Delivery [EDD]. It provides a means of quickly counting the weeks and days, during pregnancy.
• The timing of antenatal screening tests and assistance with determining fetal viability are two of the areas where the use of a large Obdisk is invaluable - helping professionals to reduce the risks to pregnant women and their unborn babies. 
• The large 2-disc Obdisk Pregnancy Wheel is ideal for the desk-top in maternity units, antenatal clinics and doctors’ surgeries, and it is easily portable in a file or A4 diary. 
• The Obdisk 2L complies with the UNICEF UK Baby Friendly Initiative [BFI], so it may be used in NHS hospitals and clinics – those where BFI status has already been achieved, and those that are working towards it.

Clinical Information and Obdisk 2L Instructions For Use:

A. Using the ‘period dates’:

1. Take the FIRST DAY of the Last Menstrual Period [LMP]. 

2. Moving the top disc, line up the LMP arrow with the date of the patient's LMP.

3. You can read off the fetal gestational age in weeks, throughout pregnancy, by following the calendar around carefully. For a reading that is as accurate as possible, adjust the discs slightly if necessary to match up the days exactly.

4. You can read off the Expected Date of Delivery [EDD] at the triangle marked “EDD DUE DATE”. The date of this simple calculation is therefore based only on the date of the Last Menstrual Period.

B. Using the dating scan result, when available: 

If a 'dating scan' is performed [using ultrasound], simply turn the top disc so that the number of weeks and days agree with the date of the scan. Then read off the fetal gestational age, and the Expected Date of Delivery, by following the calendar around carefully. [Adjust the discs slightly if necessary to match up the days exactly.]

Notes:

1. The Obdisk 2L calculator is based on a pregnancy of 280 days from the LMP if there have been regular 4-week cycles, but the EDD would need a suitable adjustment for irregular cycles and a leap year. 

2. The 'period dates' and scan dates may, or may not, agree. Different hospitals may have different policies about how to deal with a discrepancy between these dates, but a doctor or midwife will be able to explain this to the patient if necessary. 

3. You can use the 2-disc Obdisk 2L Pregnancy Wheel to calculate 'period dates' and scan dates - but not both at the same time.

[The pocket-sized 3-disc Obdisk 3 model is specifically designed for this purpose, and shows any discrepancy between the two calculations.] 

4. Because of the traditional method of estimating human pregnancy in the UK, a woman is considered to be 6 weeks pregnant [from the date of her Last Menstrual Period] when she has only been pregnant for 4 weeks [from conception]. The due date is generally estimated at 40 weeks [280 days] after the LMP, and 38 weeks [266 days] after conception. 

Practical note: No special clinic times or dates for blood tests or scans are marked on the Obdisk 2L. Depending on local practice, dates / weeks could be marked semi-permanently with a CD marker pen. [This may be removed subsequently with a couple of drops of brush-cleaning fluid, then water.] 

This is the Price for one LARGE Obdisk 2L Pregnancy Wheel [Obstetric Calculator], including Delivery within the UK...

Price: £20.00