5 Prenatal Screening
At the beginning of 1995 the first version of the SSD
software for Down’s syndrome screening was released. It was
very well received and continues to be used by gynecologists
and prenatal diagnosis units. At the end of 1996 the second
version was introduced, for use by clinical analysis
laboratories. Both versions were developed in the DOS
environment, specifically with the OPEN ACCESS IV integrated
Later on, Ssdw 1 and 2 and SsdwLab 3 and 4 versions were
released for use with Windows operating systems, 3.11 for the
first and 95/98/NT4/2000 for the others.
The current version, SsdwLab 5, has been completely
redesigned and developed with the most up-to-date visual
programming tools (Visual Basic 6, Access 2000, DocToHelp 6,
etc.) for its implementation in Windows 2000, XP and Vista
As in previous versions, the method described by GE Palomaki
and JE Haddow in 1987 is used to calculate the likelihood ratio
(Palomaki GE, Haddow JE. Maternal serum alpha-fetoprotein, age,
and Down syndrome risk. Am J Obstet Gynecol 1987; 156:460-3),
by means of the mathematical calculations for Gaussian
multivariate distribution published by TM Reynolds and MD
Penney in 1990 (Reynolds TM, Penney MD. The mathematical basis
of multivariate risk screening: with special reference to
screening for Down's syndrome associated pregnancy. Ann Clin
Biochem 1990; 27:452-8).
This new version facilitates the simultaneous use of up to
10 biochemical and/or ultrasound markers with known Gaussian
distribution and correlation coefficients, as well as up to 15
markers with known trisomy 21 positive and negative likelihood
ratio, and another 15 markers for trisomy 18. The software
estimates the trisomy 21 and 18 (18-13) individual risks for
each single marker (combined with the maternal age) and for the
different combinations of markers of any type, defined in the
Screening Profiles which can be completely customized by the
A wider range of equations has been added to the traditional
and valued characteristics of previous versions (configuration
and personalization facilities, automatic calculation of
medians and correction factors, multi-language printing, data
server connection, e-mail reports, control of perinatal results
and screening quality, etc.). Specifically, equations for
medians and maternal weight correction, new correction factors
which can be fully defined and calculated by the user, greater
precision in risk estimation for single pregnancies and mono
and dichorial twins, as well as highly effective procedures for
controlling screening quality, such as the percentage of
positive cases, the median MoM of the different markers and
screening test effectiveness.
The program fulfills the criteria specified by the NHS for
Down’s syndrome screening software. National Down's Syndrome
Screening Program for England. National Specification for Risk
Calculation Software and Guidance on Implementation, October
2004. http://www.nelh.nhs/screening /
The total user-configurability of this software, as is usual
in our computer applications, allows innovations in the area of
prenatal aneuploidy screening to be applied by means of our
programs and their updates, to biochemical or
biochemical-ultrasound screening tests.
The authors are confident that this new version, which
incorporates the latest innovations published in the broad area
of prenatal detection of congenital anomalies, will contribute
to the improvement of the clinical performance of prenatal
SsdwLab version 5
Developed using visual programming
tools: Visual Basic 6, Access 2000, DocToHelp 6,
VsView 7, etc.
Usable under Windows 2000 / XP
operating systems, in a single workstation or a
The reliability and precision of
the algorithms and the internal mathematical
calculations of SsdwLab5 have been proved with the
prenatal screening software: “Prenatal Screening
Decision Support QA Tools” version 2.0 from “Media
Innovation Ltd”, partnership of University of Leeds
and UK National Screening Committee
constitutes a prenatal screening reference software
for validation of trisomy 21 software programs
in the United Kingdom.
Database Microsoft Jet 4.0 engine
from Microsoft Access 2000 that guarantees the
compatibility with other systems and the analysis
and treatment of the data (not protected) by means
of other commercial software for database
administration. See the section of limitations in
the same chapter.
Automatic adaptation, according to
Windows Regional Configuration, of the numeric
format (comma or point) and different international
On screen display in multiple
The combo boxes that contain field
names are visualized, when they are from Patient's
table, translated to the predetermined screen
language by means of a tool tip text that appears
when locating the mouse pointer under each field
name. For grids, the translation of the fields name
is direct on each column heading text.
Hardware protection against copy,
not authorized access, etc. using an USB Hasp HL key
and software protection (three levels of security by
user's code and password) of record's access,
modifications, configuration, reports, etc.
Each license of the Program,
necessary for each workstation in which SsdwLab5
executes, is bound to a HASP HL key that possesses
an unique identifier number. The HASP HL key allows
Program license Internet upgrade in cases of new
versions, updates, etc.
Historical file containing new
patient records, modifications to patients
records, identification of the user that has carried
out them as well as the date and time. To accomplish
the legislation on security measures of automated
files that contain data of personal character (Royal
Ordinances 994/1999 of June 11 and 195/2000 of
February 11) and the patient's rights (as the Law
21/2000 of December 29 from the Generalitat of
Catalunya concerning the rights to the health and
the patient's autonomy and the clinical
documentation). This is a protected file that can be
visualized and print but not modified by any user,
independently of their access level, neither by
means of any database administration software.
Control and automatic recording of
Program accesses and exits from different users in
single workstations and networks.
Recording of accreditation of
sonographers that assess ultrasound Gaussian markers
(those biometry related) and configurable lock
of who are not accreditated.
Definition of an unlimited number
of Screening Profiles with simultaneous use up to 10
biochemical and/or ultrasound markers with known
Gaussian distribution and correlation coefficients,
as well as up to 15 markers with known trisomy 21
positive and negative likelihood ratio, and other 15
markers for trisomy 18.
Lock of the configuration for the
most important parameters in the Screening Profiles
when these have already been used to calculate the
Risk of, at least, a patient (number and type of the
markers and number and type of the correcting
factors). It can be defined a new Screening Profile
taking as base anyone of the existent ones, although
their configuration is locked.
Biochemical and ultrasound
markers, correcting factors, measure units, cut-off
levels, truncation limits, population parameters,
etc. totally configurable and user definable.
Calculation of gestational age
from anyone of the following parameters: date of
last menstrual period, ultrasound or biometry (CRL,
BPD, FL, etc.) estimation of the weeks and days at a
certain date, and concepción date.
Definable and customizable
configuration for each computer in a network
environment (a Screening and Printing Profile can be
configured on each computer).
Selection of the moment in what
Down's syndrome risk is estimated (at term or at the
time of the test); and in the last case, correction
possibility for the intra-uterine lethality by means
of discreet method (in a concrete week) or
continuous (variable according to gestational age,
expressed in days, from a user revisable polynomial
Possibility to select the method
of “prior” maternal age risk estimation.
Estimation of combined risks
"age-marker" for 21 and 18 (18-13) trisomies, for
each individual marker and for the combination of
all of those used in each Screening Profile in the
first and in the second trimester of the gestation.
Very complete information, in the same screen of the
result of the risk calculation, presented from
floating tool tip text to avoid an excess of active
visual information, about the median values of each
marker, likelihood ratios (LR) specific for trisomy
21 and 18 for each marker, as well as the combined
LR for all the markers used for both trisomies,
moment in which is considered the risk (at the time
of the test or at term), combined risk only for
Gaussian markers (when positive and negative LR
markers are used simultaneously), maternal age in
the probable date of delivery, total days (and
weeks and days) of gestational age for each used
marker (very useful in sequential screening),
gestational age that corresponds to a biometry used
with an ultrasound marker, method of evaluation for
the markers with positive and negative LR, etc.
Neural tube defects (NTD) risk
estimation by means of a MoM cut-off with the
second-trimester matern serum alpha-fetoprotein.
Possibility to use only some
markers of those included in a Screening Profile and
of storing, without the intervention in the
calculations of Risk neither appear in the printed
Report, some or all the values for investigation,
median calculation, modeling, etc. (very useful in
first-trimester twin screening if we want to
calculate Risk only by means of NT, but we want to
have the values of the biochemistry for later
Possibility of the use of constant
or variable populational parameters according to
gestational age (mean log 10 MoM for T21 and
Optional calculation of the
aneuploidy risk in twins with own populational
parameters, and chorionicity differentiation.
Automatic median calculation from
data obtained of the own screening laboratory, as
well as of the polynomial function (up to quartic,
pondered by the number of determinations in every
week of gestation or interval of a biometry) among
the gestational age (in days), or a biometry in
millimetres, and the value of each marker.
Possibility of application of a reciprocal,
exponential, 10 ^, log e or log 10 transformation to
the polynomial function or the variable x.
Possibility of direct introduction of the medians to
carry out the same calculations in the biochemical
Possibility of manual introduction
of the multiples of the median (MoM) in the
estimations of Risk for verification of the
correction of the calculations and quality control
(UK NEQAS, etc.).
Correction by a previous affected
pregnancy of trisomy 21, 18 or NTD.
Selection of the correction method
for the patient's weight (exponential (10 ^) or
reciprocal) and automatic calculation of the
correcting factors coefficients and the median of
the patients' weight (from the own database) in both
Automatic calculation of the
Median of the multiples of the median (MoM) for each
Marker as a quality screening test.
Automatic calculation (from the
own database) of the correcting factors
(covariables) for the 15 user definable.
Automatic calculation (from the
own database) of the Gaussian distribution
population parameters for each one of the markers
(median and standard deviation), when an enough
number of tests have used the marker.
Automatic calculation (from the
own database) of the correlation coefficients among
markers, when an enough number of tests have used
Automatic calculation of the
Percentage of Positive Cases, median of the MoM of
each marker and of the effectiveness of the
screening test (sensibility, specificity, etc.); in
this last case if the perinatal result is
Recovery (without necessity of
typing them again ) of the administrative and
pregnancy data (in the case of being the same one)
in patients with a previous test.
Possibility to access a
Server that contains the patients filiation data and
automatic introduction in the database and screens
of the Ssdwlab5 program. This access is open to the
most popular databases via ODBC.
Import of patient record groups,
whose tests have been carried out by means of other
software programs, for automatic report edition,
analysis of screening effectivenes, amplification of
the possibilities of risk estimation, etc. This
access is open to the most popular databases via
The compatibility of SsdwLab5 ODBC
connection has been proved with the following
databases: Microsoft SQL Server 2005, Intersystems
CACHE 5.0 and ORACLE Database 10g.
Completely customizable report,
with possibility of a header logo inclusion, and
printable in any language of the western
Printing of multiple reports,
selected by date or registration number, with
election of the number of copies, print of a
postnatal control sheet, electronic signature, etc.
Differentiation among the language in which one
writes the original and the copies for each one of
the different reports.
Possibility to create automatic
compressed and encrypted files, from reports
selected for electronic mail distribution, intranet
Availability of an independent
computer software, of limitless distribution, that
allows decryption, visualization and print of report
files sent using the technique mentioned in the
Automatic system of selected
record export and creation of new Microsoft Access
databases and tables with this records, for shipment
to centralized systems via e-mail, diskette, etc.
(multicentre studies, quality control, etc.)
Integrated backup system (Backup
Zip) with warning of the convenience of carrying it
when it has not been carried out in the 3 previous
Data entry indistinctly by the
mouse or the keyboard.
Visual calendar for the
introduction of dates, without typing the digits,
with the purpose of avoiding the frequent errors in
this type of fields.
Automatic correction of certain
type errors in data input.
Optional recording of requesting
doctors and hospitals, indications and results of
invasive techniques, ultrasound findings, perinatal
result for quality control, etc. totally
configurable and user definable
Centralization of all patient data
and episode (for a certain test) in an unique form
and in the same record of the data Table.
Possibility to install Databases
in an independent remote computer which includes the
Program executable in single a workstation as in a
network, and with independent configuration of the
predetermined Screening Profile, as well as the
printing for each client computer.
Patient's and episode quick search
by surname, clinical record number, NIC or PIC,
indistinctly, or by any field by means of a visual
SQL interrogation with two levels of accessibility
(basic and advanced).
Automatic estimation of the
typical parameters for screening effectiveness
(sensibility, specificity, etc.) from the patients
already tested database, as well as possibility of
hypothesis formulation with different risk cut-off
User definable limitation of the
number of records that are presented simultaneously
in the screen to increase patient search speed.
Very complete Help, contextual in
the status bar and when allocating the mouse pointer
under the data fields, as well as Windows type with
Content, Index and word Search.
Hardware and software diagnostic
program installed on the computer.
This version of the Program is presented in CD ROM support
and includes 4 programs, each one installed in a different
directory: SSDWLAB5 that constitutes the program of aneuploidy
risk estimation for a single workstation or for a network
server; SSDWLAB5_CLIENTE, to install the computer clients on a
network; PRTSSDW5, program of report printing for remote
computers and HASPINSTALL, to install the software protection
key USB HASP HL Pro.
PC compatible computer with Pentium processor or equivalent
at 1 GHz, with a minimum of 256 Mb of RAM memory. It should
have a CD ROM reader, 200 Mb of free space in the hard disk, 1
USB free port and a screen resolution of 800 x 600 pixels.
It is very advisable to dispose of a UPSS (Uninterrupted
Power Supply System) to avoid the corruption of the databases
in the event of failure in the electric supply.
Operating system: Windows 2000 / XP. Regional configuration
of a western country with international alphabet. It is very
advisable to use a date's configuration with four digits in the
year. It is advisable to have installed Internet Explorer (with
Outlook Express) version 5 or later, to make backup copies and
to send reports via e-mail; and Microsoft Access 2000 for
database queries and to facilitate the ODBC configuration.
The use of a continuous up-to-date Antivirus program, and
the realization of periodic backup copies, is of great
importance to avoid the possible lost of data secondary to the
inadvertent access of these intruders.
END-USER LICENSE AGREEMENT FOR SsdwLab5 PROGRAM. IMPORTANT.
This End-User License Agreement ("EULA") constitutes a legal
agreement between you (either an individual or a single entity)
and the authors and companies who own the Program, in respect
of above-identified software which includes software components
and associated media, printed materials and "on screen" or
electronic documentation ("SOFTWARE").
By installing, copying, or otherwise using the SOFTWARE
PRODUCT, you agree to be bound by the terms of this EULA. If
you do not agree to the terms of this EULA, you are not
authorized to use the SOFTWARE PRODUCT.
The SOFTWARE PRODUCT is protected by copyright laws and
international copyright treaties, as well as other intellectual
property laws and treaties. The SOFTWARE PRODUCT is licensed,
USE: The possession of a License (which means you have a
SsdwLab5 program CD ROM and a HASP HL key, programmed for its
execution, with the same and unique identification number in
both, all distributed by SBP-SOFTWARE CB or their legally
authorized representatives) grants you the following rights and
Use of all the functions of the program on a single
computer, or on a computer network, under the conditions that
are detailed in this "EULA".
Technical support via e-mail during the first five years
after its acquisition, free during the first year from the
moment you receive the program's CD ROM and the HASP HL key, of
the latest or only acquired License.
You may not sell, rent or lease the SOFTWARE PRODUCT.
Reverse Engineering, Decompilation, and Disassembly of the
SOFTWARE it is not allowed.
The End-User will be responsible for the custody of the CD
ROM and the Hasp HL keys which grant the possession of the
respective Licenses and SBP Software CB will only replace them
in the event that these are faulty.
The possession of a License for the use of the SsdwLab5
program allows its use, unlimited in time, for a single
computer that will have a HASP specific HL key for its
execution. The number of Licenses which each End-User has
corresponds exactly with the number of HASP HL keys that have
been acquired. The use of the Program on a Network needs as
many Licenses (and HASP keys) as the number of workstations on
which you want to use it, excepting the Server if this is not
used as a workstation. The program proprietors or their legally
authorized representatives will grant the Licenses. The holders
of one, or more, Licenses will be able to download without
additional cost, but with previous identification of the
license number/s, the successive Program upgrades on the web:
www.sbpsoftware.com , while no modification will be done to the
second number corresponding to the version (secondary version
number indexed in "Properties of the SsdwLab5 Project " of the
Visual Basic 6 compiler and in the “About SsdwLab5” form of the
software) acquired, and you will have a 50% discount for the
acquisition of the remaining upgrades or new versions.
The End-User will be responsible for the knowledge and
fulfillment of the laws, effective in his Country, relating to
security measures for automated files that contain data of a
personal nature, and of rights concerning the patient's health,
autonomy and clinical documentation.
and distribution rights
They are reserved, to the authors of the Program, all the
intellectual property rights. SBP Software CB has the
distribution rights of the SsdwLab5 program. The distribution
of copies of the Program and its documentation, for any
technical system whenever it doesn't has as objective the
realization of security copies or the information of the
personnel's attributed to a screening service that has License
for their use (granted by the Program proprietors or their
legally authorized representatives) is completely
The royalties of the Program's background image belongs to
Roger Lleixá and that of the general artistic design to
information and maintenance
SBP SOFT 2007 S.L.
C. Joan Maragall 31,
1º C, 17002, Girona, Spain
Telephone & Fax: +34 972 212099
URL: www.sbpsoftware.com ; www.sbpsoftware.es