Frequently Asked Questions

The FAQ section on this website is for educational purposes only. Not for use in diagnostic procedures. Always follow local guidelines.


Technical Questions

Question: What is the below pattern called and what is the reason for it?











Answer: The pattern is called “fencing” and is simply a part of an active cardiovascular response to alterations in cord blood flow. The “fencing” fetal heart rate pattern can only be associated with an increase in parasympathetic (vagal) activity from an instantaneous and intermittent activation of cardiac volume receptors due to partial compression of the cord vein.  Nothing in the morphology of the ECG to indicate abnormality but rather an example of the ability of the fetus to fine-tune its cardiac response.

Question: Why are there ’spikes’ in some fetal heart rate traces recorded with scalp electrode / FECG? (See example.)









‘Spikes’ pointing upwards are normally extrasystoles. Often but not always, extrasystoles are followed by a delayed beat (spike also pointing downwards). The extra beat results in a momentary increase in fetal heart rate, while a delayed beat results in a momentary decrease. While other CTG brands often filter out these artifacts, Neoventa has chosen to show them in the CTG trace.

As far as Neoventa knows, extrasystoles and delayed beats represent no danger to the fetus, but it is up to the clinician to judge and possibly follow-up after the child is born.

Note that this kind of artifacts are not shown when you monitor with Ultrasound, as the calculation technique for Ultrasound filters them away. However you should be able to hear them if you listen to the ultrasound audio feedback. It should also be noted that some central monitoring systems apply their own artifact filtering, preventing the ‘spikes’ from being seen at the central monitoring stations.


Question: How does the STAN S41 store and transmit patient information?

Answer: The device provides means to enter the patients name and ID number, which will be stored in a recording file. The use of the function to enter the patients name and ID number is voluntary, and nothing that is required for the device to fulfil its intended use. The recording file can be viewed retrospectively on the device itself, and it can also be stored to a USB disk or network archive for retrospective viewing using a software application called STAN Viewer. This STAN Viewer software also has a functions to remove patient name and ID number for the recording file, in case there is a need to send the recording file  to external parties.

The device provides means to delete the recordings stored on the device.

If patient name and ID number is entered, this information is also send to 3’rd party central monitoring systems using RS232 connection, and to STAN Viewer Live which is a software application for remotely reviewing the recording on the device.

Question: How does the STAN S41 interact with wired and wireless network systems?

Answer: The device interfaces with 3’rd party central monitoring systems using wired RS232 serial interface. The use of this function is voluntary for the hospital, and is not required for the device to fulfil its intended use.

The device also interfaces over wired network connection using TCP/IP protocols. The connectivity over this protocol involves:

  1. Network archiving of recording files. The use of this function is voluntary for the hospital, and is not required for the device to fulfil its intended use.
  2. Transmitting recording data to the software application STAN Viewer Live. The use of this function is voluntary for the hospital, and is not required for the device to fulfil its intended use.
  3. Synchronization of the devices internal clock against network time server.
  4. Means to connect to the device using telnet and/or FTP for troubleshooting purposes. The use of this function is voluntary for the hospital, and is not required for the device to fulfil its intended use.

Does the CMOS battery in the Stan S31 Main Unit need to be replaced?

The expected life of the CMOS battery in the Stan S31 Main Unit is 10 years, assuming a usage/power-on rate of 50%. For systems with a usage rate of less than 50%, the expected life is less than 10 years, with a worst case of 5 years for systems that has not been powered on at all since production date.

To replace the battery, follow the instructions in the Stan S31 Service Manual. Make sure you use Panasonic or Sony CR2032 batteries. Do not touch the battery surface with bare fingers during the replacement procedure. Since the replacement procedure requires removal of the main unit back cover, it is recommended to do the replacement during yearly maintenance.

If the CMOS battery becomes depleted, the system clock will be reset to 2003-01-01. Some systems with BIOS version 1.1 that has not been upgraded to 1.2, may stop with black screen after power-on.

Is there a need to connect the separate equipotential
connector (grounding pin) that is available on Stan S31, and on the TR31

The equipotential connectors on the Stan S31 Main Unit
and Trolley may be used if there is poor earth continuity in the hospital mains
supply. This is however not expected in modern hospitals.  

Is Stan Viewer compatible with Windows 10?

Yes, all versions of Stan Viewer (R2 series) are compatible with Windows 10 (both 32- and 64-bit versions). Click here for a complete listing of compatible windows versions.

Why does my Stan monitor not display an FECG average when I connect it to an ECG simulator ?

Given that your Stan monitor produces a fetal heart rate, the most likely reason is that your ECG simulator produces an ECG waveform with characteristics of an adult ECG, and the FECG averaging in Stan is not suited to work with adult ECG.

Since the time-span of a QRS complex correlates with the amount of blood pumped through the heart, the QRS complex of an adult will appear wider than that of a fetus. Depending of the QRS configuration, this wider complex may not fit in the FECG calculation model of Stan.

In some cases, Stan S31 will generate an ECG waveform even if the QRS complex has adult characteristics, but the T/QRS ratio will likely be unreliable.

Which communication protocol version should I choose when I configure my Stan S31 for CMS communication?

If both your Stan S31 and your CMS supports ST analysis, you should choose the latest version of the Stan protocol, setting Stan Protocol (without revision code). The R1A version of the Stan protocol is only necessary for legacy versions of CMS that cannot handle patient name and ID, and the only system that Neoventa is aware about is versions of Milou.standard from Medexa. (Milou.NET works well with the R1B version.)

If your CMS does not support the display of ST information, choose CTG Protocol. Some (legacy) versions of CMS systems may not support this version of the protocol, so if you cannot get the communication to work, you can try CTG Extended Protocol instead.

If your Stan S31 does not support ST analysis you can still choose the Stan protocol if your CMS supports it, although the options are named Stan Protocol for CTG and Stan Protocol R1A for CTG instead.

What is the difference between Stan protocol versions R1A and R1B?

The only difference between the R1A and R1B versions of the Stan protocol is that R1B support intercommunication of patient name and patient ID between Stan and the Central Monitoring Server. Most CMS that support the Stan protocol can handle this kind of information, even if they do not actively do anything with it.

Our IT department requires us to install anti-virus software on Stan S31. Is this really necessary?

Stan S31 uses an embedded operating system (Phar Lap ETS) for which no known vulnerabilities or viruses exist. See for example Further, because Stan isn’t a general purpose computing device, it doesn’t give the user the possibility of downloading and executing arbitrary code, or browsing malicious web sites, which are the major sources of viruses. Therefore, it is neither necessary nor possible to install 3’rd party anti-virus software on Stan.

Is Stan S31 and S41 compatible with IPv6 (Internet Protocol version 6)?

Stan S31 and S41 are compatible with IPv4, but not IPv6. To use Stan in an IPv6-based intranet, we suggest that the customer implements a network with dual network stacks (i.e. both IPv4 and IPv6) for local network communication. This is currently supported by windows server versions today, and it will most definitely be supported in years to come. Note that a Stan system has no need to access the internet. All contact points are normally within the local intranet, e.g. laser printers, storage servers and time servers, so this should pose a problem.

Is there a version of Stan Viewer that works with MacOS?

There is no version of Stan Viewer that works directly on a Macintosh operating system. However, it is possible if you run Microsoft Windows in a virtual machine. There are several options available, please see the following guide from Apple Store:

What is the GMDN code for Stan S31?

The GMDN code for Stan S31 is 37796 (Patient monitor, cardiotocograph).

What is the GMDN code for Stan Viewer Live?

The GMDN code for Stan Viewer Live is 36230 (Information system, obstetrical)

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