Fetal health assessment - decision support

Rules according to the Confidetial enquiry into Stillbirths and Deaths in infancy (UK) Programme written by DJR Hutchon copyright Requires Internet Explorer 4.0 or above (or eqivalent) for calculator to work. Year 2000 compliant. If Serum screen or nuchal thickness not available, (or less than 1 mm) leave blank. Only valid for calculating Down risk for CRL 38 - 84mm These calculations assume that the NT measurements are made using the same protocol as the Fetal Medicine Foundation. Instruction for using OFFLINE

CRL using Smith et al formula REFERENCES  US date system  ie month/date/year (4 digits for year)

Patient's ID Date of Birth
Last period date Are you sure? Yes - - - Normal cycle length Default is 28 days
Date of dating scan Nuchal thickness mm. MoM= Down serum screen risk 1:
Enter CRL measurement mm mm or BPD mm (ENTER ONLY ONE) Equiv to wks + days
Fetal Heart rate at time of scan /min
Age alone Down syndrome (DS) risk at birth 1: Integrated Down syndrome (DS) risk at birth 1:
Age alone DS risk at date of scan 1: Integrated DS risk at date of scan 1: (includes FH if entered)
EDD by LMP by SCAN 42 wks on
Best EDD is
Elective delivery inadvisable before 14% risk of labour before this date.
Trisomy 18 risk at 9-14wks= 1 in at 15-20 wks= 1 in at birth= 1 in
Trisomy 13 risk at 9-14wks= 1 in at 15-20 wks= 1 in at birth= 1 in
Gestation by scan on date is wks +days.

Fetal health assessment - expert system

Enter date of scan, measurements, AFI and umbilical artery RI if available

	First		\|\|		Second		\|\|		Third		Normal
	growth scan	Z	\|\|		growth scan	Z	\|\|		growth scan	Z	+1.645 to
Date		score	\|\|	Date		score	\|\|	Date		score	-1.645
BPD			\|\|	BPD			\|\|	BPD
HC			\|\|	HC			\|\|	HC
AC			\|\|	AC			\|\|	AC
FL			\|\|	FL			\|\|	FL
Gestation	wks		\|\|		wks		\|\|		wks
Est fetal wt	Kg		\|\|		Kg		\|\|		Kg
Umb Art RI
AFI

EXPERT OPINION
..................

Normal range for Z score is -1.645 to +1.645. If only two growth measurements are available, please put the scan details in the second and third scan boxes. This calculator is for educational use. It is believed accurate but no responsibility for accuracy of the results is accepted by the author. David J R Hutchon BSc, MB, ChB, FRCOG Consultant Obstetrician, Memorial Hospital, Darlington, England.

Go to OBGYN.net paper on proposal for valid customised charts generation ("Back to the future for Hermanni Boerhaave" published by OBGYN.NET)

Comments and suggestions are welcome and will be included in the comments section.

To E-MAIL me CLICK HERE TO SEND COMMENTS AND PLEASE SEND ME YOUR NAME AND E-MAIL IF YOU INTEND TO KEEP AN OFF-LINE COPY at DJRHutchon@Postmaster.co.uk

This Web page is at www.hutchon.freeserve.co.uk/Growthdown.htm

REFERENCES
Smith GCS, Smith MFS, McNay MB and Flemming JEE First-trimester growth and the risk of low birth weight New England Journal of Medicine 1998;339:1817-22

Kurmanavicius J, Wright EM, Royston P, Zimmermann R, Huch R, Huch A, Wisser J. Fetal ultrasound Biometry: 1. Head reference values. British Journal of Obstetrics and Gynaecology. 1999 106:126-135
Kurmanavicius J, Wright EM, Royston P, Zimmermann R, Huch R, Huch A, Wisser J. Fetal ultrasound Biometry: 2. Abdomen and femur length reference values. British Journal of Obstetrics and Gynaecology. 1999 106:136-143
Altman D G and Chitty L S. New cahrts for ultrasound dating of pregnancy Ultrasound Obstet Gynecol 10 (1997) 174 - 191
Moore T R and Cayle J E. The amniotic fluid index in normal human pregnancy. American Journal of Obstetrics and Gynecology 1990;162:1168-73
Cuckle H S, & Schmi I Calculating correct Down's syndrome risks. British Journal of Obstetrics and Gynaecology 1999;106:371-372
Wald N J, Watt H C, & Hackshaw A K. Integrated screening for Down's Syndrome based on tests performed during the first and second trimester The New England Journal of Medicine 1999;341(7):461-467
Pandya P P, Johnson S, Malligianis P, and Nicolaides K H. First Trimester fetal nuchal translucency and screening for chromosomal abnormalities. Ultrasound and early pregnancy Chapter 7
Cuckle H S, Wald N J, Thompson S G. Estimating a woman's risk of having a pregnancy associated with Down's syndrome using her age and serum alpha-fetoprotein level. Br J Obstet Gynaecol (1987) 94:387-402
Snijders R J M, Holzgreve W, Cuckle H and Nicolaides K H. Maternal age-specific risks for trisomies at 9-14 weeks gestation. Prenatal Diagnosis (1994) 13:543-552 For the purposes of the calculator I have assumed a uniform loss of pregnancy as a result to miscarriage between 9 and 14 weeks and 15 and 20 weeks.
Zosmer N, Souter V L, Chan C S Y, Huggon I C and Nicolaides K H. Early diagnosis of major cardiac defects in chromosomally normal fetuses with increased nuchal translucency. Brtish Journal of Obstetrics and Gynaecology 1999;106:829-833
Morrison J J, Rennie J M, & Milton P J. Neonatal respiratory morbitiy and mode of delivery at term: influence of timing of elective caesarean section. British Jouranl of Obstetrics and Gynaecology 1995 102 101-106
Madar J, Richmond S & Hey E. surfactant deficient respiratory distress after elective delivery at 'term'. Northern Region Maternity Survey Meeting 1999. Accepted for publication in Acta Paediatrica
Hyett J A, Noble P L, Snijders R J M, Montenegro N, & Nicolaides K H. Fetal heart rate in trisomy 21 and other chromosomal abnormalities at 10 - 14 weeks of gestation. Ultrasound Obstet Gynecol 7 (1996) 239-244
I am grateful to Professor Howard Cuckle for information on the Gaussian LR equation for a single variable.
DOWN SYNDROME AGE RISK CALCULATION
This risk assumes no previous affected pregnancy. A previous affected pregnancy increases the risk further, to about 1 in 200 at age 30 and 1 in 25 at age 45. The maternal age specific incidence of trisomy 21 at birth is 54% lower than at 9-14 weeks of gestation.

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