Posts Tagged ‘cervical dilation’

The Red/Purple Line: An Alternate Method For Assessing Cervical Dilation Using Visual Cues

October 9th, 2012 by avatar

By Mindy Cockeram, LCCE

Today’s blog post is written by Mindy Cockeram, LCCE.  Mindy explores the “mystical” red/purple line that has been observed to provide information about cervical dilation without the need for a vaginal exam. – SM

When couples in my classes are learning techniques for coping in labor, such as the Sacral Rub (sacrum counterpressure), Double Hip Squeeze and Bladder32 accupressure points,  I always talk about the great position the partner is in for spotting the red, purple or dark line (depending on skin color) that creeps up between the laboring woman’s buttocks and how – by ‘reading’ that line – he or she may be able to assess more accurately the woman’s cervical progress than the health care providers!  This empowering thought is often met with smiles and laughter especially when I translate ‘natal cleft’ into more recognizable words like ‘butt cleavage’.  Strangely, I’ve never had anyone in class mention having heard of this ‘thermometer’ for accessing cervical dilation by sight and I find this interesting considering the number of medical professionals that come through my classes.

Photo CC http://www.flickr.com/photos/alexyra/214829536/

I first came across this body of research as an Antenatal Student Teacher with the National Childbirth Trust in London.  The article I was reading was in Practising Midwife and was a ‘look back’ at the original article (Hobbs, 1998) published in the same magazine.  The original Practising Midwife article was based on a letter referencing a small study by Byrne DL & Edmonds DK published in The Lancet in 1990.

In the 1990 letter to The Lancet, Byrne and Edmonds outlined and graphed 102 observations from eighteen midwifes on 48 laboring women. It states “The red line was seen on 91 (89%) occasions, and was completely absent in five (10.4%) women and initially absent in three (6.25%).”  The report then goes on to talk about the “significant correlation between the station of the fetal head and the red line length.”  Later the authors write: “To our knowledge, this is the first report of this red line.  We believe that it represents a clinical sign which is easy to recognize and which may offer valuable information in obstetric management.”

So how does this line work?  And why does this it appear?  Practising Midwife Magazine presented a graphic which I have attempted to recreate here.  Basically as the baby descends, a red/purplish (or perhaps brown depending on skin color) line creeps up from the anus to the top of the natal cleft in between the bottom cheeks.  When the line reaches the top of the natal cleft, 2nd stage is probably a matter of minutes away.  A line sitting an inch below the natal cleft is probably in transition.  A line just above the anus probably signifies early labor.

Byrne DL & Edmonds DK, the authors of the original study, surmise that the cause of the line is “vasocongestion at the base of the sacrum.” Furthermore, the authors reason that “this congestion possibly occurs because of increasing intrapelvic pressure as the fetal head descends, which would account for the correlation between station of the fetal head and red line length.”  Fascinating and logical!

Interestingly, I came across a 2nd Scottish study from 2010 published by BMC Pregnancy & Childbirth: (Shepherd A, Cheyne H, Kennedy S, McIntosh C, Styles M & Niven C) which aimed to assess the  percentage of women in which a line appeared (76%. ) The study cited only 48-56% accuracy of vaginal examinations to determine cervix diameter and fetal station.  So why aren’t clinicians using this less invasive visual measure – especially considering how much some women may dread vaginal exams in labor??  Wouldn’t the thought of using a methodology to lower infection rate after rupture of membranes has occurred enthuse Health Care Providers instead of using higher risk techniques?  Or how about using the accuracy of the line at the natal cleft to know when a women using epidural should really be coached to push?

My educated guess is that this information has not yet reached Medical Textbooks and non-standard practices can take years to become mainstream (for example. delayed cord clamping) – and then only if or when women request them or media sensation activates them.  In addition, since laboring women are only intermittently attended by Labor & Delivery staff during early and active labor and often encouraged to “stay in bed,” Health Care Providers aren’t necessarily faced with a woman’s buttocks in labor.  Also vaginal examinations are considered “accurate” so staff have no need to peek between a woman’s natal cleft.   However both these studies, paired with the roughly 50% accuracy rate of manual vaginal exams, show that there is potentially a more accurate and less invasive way ahead.

In The Practising Midwife (Jan 2007, Vol 10 no 1, pg 27), Lesley Hobbs writes “Accurate reading would seem to the key to this practice.  I sometimes notice in myself a wish to see the line progressing more quickly than it actually does; when I do this – and check with a vaginal exam – only to find the line is right, I get annoyed with myself and wish I’d trusted my observations.”  Later she goes on to say “I can now envisage a time when I shall feel confident enough to use this as my formal measurement mechanism and abandon intrusive and superfluous vaginal exams.”

Licensed Midwife Karen Baker from Yucaipa, CA commented “The purple line is a curious thing.  It’s definitely not present on everybody but is more prominent on some than others – especially right before pushing.  It tells us when she’s in full swing if we are in a good position to spot it!”

I often urge couples to send me a picture of the so called ‘purple line’ which I promise I will use only for educational purposes but so far a picture is as elusive as the Loch Ness Monster.  So, as I say in class, ‘show me your purple line’!

Are you a midwife, doctor, nurse or doula who has observed this in a client or patient? Partners, have you seen this when your partner was in labor? Has anyone heard of it or witnessed it?  If you are a childbirth educator, do you feel this is something that you might mention in your classes?  Do you think that the families in your classes might be likely to ask for this type of assessment if they knew about it? Please comment and share your experiences.


Byrne DL, Edmonds DK. 1990, Clinical method for evaluating progress in first stage labour.Lancet. 1990 Jan 13;335(8681):122.

Downe S, Gyte GML, Dahlen HG, Singata M. Routine vaginal examinations for assessing progress of labour to improve outcomes for women and babies at term (Protocol). Cochrane Database of Systematic Reviews 2012, Issue 9. Art. No.: CD010088. DOI: 10.1002/14651858.CD010088.

Hobbs 1998. Assessing cervical dilatation without Vaginal Exams. Watching the purple line. The Practising Midwife 1(11):34-5.

About Mindy Cockeram

Mindy Cockeram is a Lamaze Certified Childbirth Educator teaching for a large network of hospitals in Southern California.  She has a BA in Communications from Villanova University and qualified as an Antenatal Teacher through the United Kingdom’s National Childbirth Trust (NCT) in 2006.  A native of the Philadelphia area, she spent 20 years in London before relocating to Redlands, CA in 2010.





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LaborPro: Third Generation of Monitoring Technology Promising to Improve Outcomes, Without Adequate Testing or Proven Benefit

September 23rd, 2011 by avatar

New technology claims to be a ‘breakthrough in non-invasive labor progress monitoring,’ using ultrasound and GPS-like imaging to determine pelvic diameter, cervical dilation, and the position and descent of the baby.  LaborPro claims that their advanced technology can reduce inaccuracies inherent in manual assessment of cervical dilation and fetal head station and position, and that the use of their technology will lead to fewer unnecessary cesarean sections.  Sounds great…doesn’t it?

When I heard about this technology, I got a sinking feeling. Our grandmothers had X-rays to determine pelvic diameter. Oops, that can damage the baby. Our mothers were introduced to continuous electronic fetal monitoring to make sure that babies were coping well. Oops, that has led to an increase in cesareans without improving outcomes for babies.  And now, we could be the generation that uses ultrasound and GPS to create 3D images of what is happening during labour, leading to…oops….?

LaborPro—the name sounds reassuring and promising, as if the machine has been through birth many times, like an experienced midwife. What the technology offers is so tempting…maybe clinicians would make fewer subjective decisions about labour dystocia (failure to progress) if they could SEE the baby’s head descending. Maybe they wouldn’t inaccurately assess ‘your pelvis is too small,’ if they could measure the pelvis.  And yet…

Pelvic Measurements

•    Pelvic measurements taken while lying down are different than if a woman is upright and moving. When a woman is on hands and knees her pelvic outlet is 0.5 cm bigger than when she is lying down, and movement also helps increase pelvic space. This can make a big difference to the ability of the baby to rotate and descend. Also, while measurements can be made to determine the space between the pelvic bones, the pelvis stretches during labour, and no one can predict how much it will stretch. Pelvic movement is one of the reasons labour hurts.

Optimal Positions and Movement During Labour

•    It seems (from the LaborPro video, the way that sensors are placed, and the way ultrasound is used) that women will need to be supine or semi reclining to have LaborPro applied to them.  This is the least effective position to labour in.

•     It seems that during the use of the LaborPro tool, women must be stationary, as they will have sensors attached to their body.  This is the least effective mode to labour in: it is more effective for women to move around freely during labour to encourage descent and optimal positioning of the fetus.

Ultrasound Safety & Accuracy

•    The use of routine ultrasound during pregnancy continues to be a controversial issue, especially in healthy term pregnancies.  The threshold of safe ultrasound exposure has not been established, nor has it been recently studied in an independent or academic manner. The Society of Obstetricians and Gynaecologists of Canada (SOGC), Health Canada, U.S. Federal Drug Administration, and American Institute of Ultrasound in Medicine (AIUM) all advise against the non-medical use of ultrasound, referring to concerns about tissue overheating and cavitation.

•    Particularly, an extended or repeated exposure of ultrasound to the head of an infant, which houses the brain, has not been extensively studied with regards to safety for the unborn baby.  The LaborPro is applied close to the unborn baby’s head during labour.

•    Ultrasonography measurements with regards to fetal size are notoriously inaccurate.  What makes the ultrasound machine suddenly an extremely accurate measurement of size and position?

•    What happens if the sensors slip or move during the use of LaborPro? Will this create inaccurate results, leading to unnecessary interventions?


•    While LaborPro claims its technology is non-invasive, to determine cervical dilation, the technology still requires that clinicians insert a finger into the woman’s vagina. The difference with LaborPro is that a positioning sensor is attached to the clinician’s finger, so the technology can determine how dilated the woman is, rather than the clinician. This means women will continue to have vaginal exams and the use of technology, doubling up on the quantifying, measuring, left brained, logical, medical assessment without evidence of health benefits.

•    Labour is largely a function of the parasympathetic nervous system, particularly the dilatation phase.  Any disturbance, interference in a woman’s privacy, interruptions, or breakdown in her confidence in her ability to give birth will introduce fear into the equation.  Fear counters parasympathetic functions, and slows down labour progression.  LaborPro has the potential to disturb a woman’s concentration and the quiet peacefulness of a birth environment, interfere with her privacy by techs, physicians, or other staff entering and exiting her room more often than before or in a more disturbing manner because of the moving of equipment, and the potential to break down a woman’s confidence because of the implication that technology is a more trustworthy entity than the woman’s body or low tech approach by care providers.  Research shows the benefits of having a low tech approach encourage favourable outcomes.

Loss of Hands-on Skills and Human Touch

•    The LaborPro tool has the potential to undermine care provider hands on skills.  Research (referenced and expanded upon in Atul Gawande’s book “Better”) shows that a low tech approach costs health care systems less and results in better health for patients, regardless of which area of medicine is assessed.

•    In times of emergency (i.e. electrical blackout, fire), natural disaster (earthquake, flood etc.), and widespread lack of access to technology because of a rural environment, hands on skills are imperative. Surges in patient loads can lead to all machines or surgical suites being in use, along with a lack of technicians or physicians trained in using the technology.

•    All medical practitioners recognize the importance of good hands on skills and human touch in medicine.  Despite this, we so often look  to technology to tell us what we can determine clinically.  The use of a pulse oximeter is a great example: a patient’s pulse may be determined by palpating the radial artery and her blood oxygen concentration can be estimated by assessing her skin colour.  The oximeter is sometimes wrong, and a quick assessment is more accurate.  Good manual measurement skills will be lost if technology usurps hands on assessment via LaborPro.

•    Yes, the accuracy of measuring actual centimetres dilated varies between care providers and is subjective.  But knowing the exact number is not as important as assessing progress: is a woman more or less dilated than the last time I measured? And assessing the presence of remaining cervix: is the cervix fully dilated or not?  Exact centimetre accuracy is less important.

Add to all these concerns the fact that NONE of the clinical trials (which were most likely funded by Trig Medical, the company selling LaborPro) showed that the technology was any better than digital examination for determining dilatation, position, and station. The research sample sizes were small, and did not include any outcome data—which means it certainly does not support or even address the claim that LaborPro will reduce caesarean sections, and there is no data on whether the health of mothers and babies are improved with the technology.

One of the selling features of LaborPro is that it automatically stores data on labour—which could then be used to defend medical personnel in malpractice suits. In fact, some have suggested that this may in fact be one of the main reasons hospitals will buy this equipment.

TrigMed is on a circuit in the US, at conventions such as ACOG 2011, Birth 2011, ISUOG 2011, and RSNA 2011. They are presenting their product to obstetricians, promising results that have no academic research behind them.

I have a better idea. Instead of implementing an expensive, untried product, which will most likely lead to more problems and misdiagnoses, let us move towards a proven approach to labour and delivery: supportive one-to-one care, allowing labour to begin on its own, and patience with the birth process.   Let mothers learn to listen to their own bodies and babies, and let mothers be the ones to tell medical personnel what is happening within themselves. Let us allow nature to unfold in the way it is designed, slipping babies into the world with as little interference as possible.


Guest Posted by: By Melissa Vose and Asheya Hennessey, Directors, Mothers of Change for Maternity Care 


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