The Red/Purple Line: An Alternate Method For Assessing Cervical Dilation Using Visual Cues
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.
References
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.
Childbirth Education, Guest Posts, Midwifery, Research, Uncategorized
This is incredibly interesting! I will present it to clients as another possible tool in our arsenal. I’m curious to see it. Thanks so much for sharing this information!
I’ve seen it and it is an observation that contributes to my assessment of labor progress. As one observation, in combination with many others…it’s not always there. I would add knowing the number I centimeters a woman is dilated is less important than her effacement which indicates the degree to which the uterus has migrated muscle cells upward toward the fundus.
Mother’s behavior and coping are much more telling of her progress in labor. Second stage tells US when it has arrived.
I first heard of the “bottom line” or “purple line” from this blog: http://sarahvine.wordpress.com/2010/03/07/how-dilated-am-i-assessing-dilation-without-an-internal-exam/
I tried to assess a mom’s labor at one of my first ever births this way, but I had no idea if there was truly a line or if it was just the way her natal cleft, as you call it, always looked. Also, I wasn’t sure how high it should be or what the length really meant!
Thank you for the informative post, I will try to talk to parents about this and maybe we can try it again in the future
I appreciate the work here, thank you. I would like to offer that when photos showing woman’s body parts without her face, are classical patriarchal objectification–even when the intent is empowerment. We have to carefully choose the images we represent ourselves with, because those looking back are searching for reflections of their whole self, their complete embodiment of childbirth–not merely a part of the body that identifies it. You know?
I was just at a birth last week. I had been with this couple before and knew she was moments away from pushing when she got on her hands and knees on the bed in front of me and I thought “aha! the purple line!” It was so prominent, it was like the color of a rope burn and she began to push in the next contraction.
Hello. I am a nurse-midwife, and just had my first baby 5 weeks ago. I had a lovely home birth, and spent some time on hands and knees in second stage. My midwives, doula and partner all commented on my deep purple line as I was pushing. I have seen this a few times on women in labor (despite having worked in a setting with a very unfortunately high epidural rate of >85%).
I was thrilled to know I had one!
What I did not know prior to this article was that the length of the line was indicative of labor progress. I thought it was simply a phenomenon of active labor. Interesting! When I resume practice after my mat leave (at a new job in birth center and home settings! Yay!), I will take note of this more often.
Thanks!
I have heard of this line and also have seen it in women in labour in my work as a doula. As a result I tell couples about it in my GentleBirth workshops and send them a link to another article about it – I can send them on this article now as well. Thank you!
I am very intrigued by this. I assume is what in Chinese Medicine we call the “conception vessel”. Will have to look it next time I attend a birth. Thank you for sharing.
@Jenn
Congrats on your new baby, and I am so glad you had a Homebirth! It will change your practice I promise! Enjoy your baby moon!
@Jenn
Congrats on your new baby, and I am so glad you had a Homebirth! It will change your practice I promise! Enjoy your baby moon!
I have hemmhorroids, would that obscure the line?
I had the purple line and a photo to prove it
I also refused all VE’s and my midwife was very respectful of my wishes and was happy to observe me to see if I was in established labour before I got in the pool. She was amazing! 
@Walker Karraa
Hi Walker, thanks for your comment. Perhaps we could have a conversation offline (mindy@cockeram.com) b/c I’m not clear on your point and want to understand what you mean. Many Thanks, Mindy
Thank you, Mindy, for this great info! I’m a nurse LCCE, & although I’d never heard of the red-purple line as a way to determine labor progress, I’ve been telling my students to never rely on dilation as a measure of progress in labor. Rather, I tell them to observe the physical & emotional changes the mother presents which are not only more reliable but also keep the mom & her partner from getting so discouraged to be say only 4 cms for several hours, seemingly making no progress if based on dilation alone. They’re less likely to request or give in to the pressure to have an epidural when they know they ARE making progress. I also think that effacement is a better indicator of progress than dilation, but I’m looking forward to teaching about the natal line. Some of my students are more interested in non-invasive apporaches, so this is a potentially great tool for them. I look forward to reading more about this method. What a great study this would make for someone’s PhD!
Is it possible that the red-purple line would show up better using different types of light, such as the UV lights used to visualize trace evidence? Maybe dimming the lights and using a UV or IR flashlight would help it come out of hiding.
I confirtm this fact, ang its use in my practice,,, Since I live in Brasil it is sometimes difficult to see it by darker skins…
It is a well known tool amongst Mayan Midwives of central America.
Thanks for providing the references … and more evidence..
Regine Marton CNM Natal RN Brazil
There is actually a picture of one here: http://wonderfullymadebelliesandbabies.blogspot.com/2011/07/dilation-how-to-check-without-checking.html
@Kirsten
Possibly!
My midwife said two years ago that I am the first woman that she observed ‘the line’ on. New baby due in six weeks. Not sure if I’m brave enough to have someone take a picture though…
i am not sure how to word this correctly, so hopefully i dont cause confusion; is the line just between the butt cheeks covering the coccyx or does it cover part of the cheeks within the crack itself!? like, is the line pencil thin, or does it look like a basting brush width between the cheeks? i recently observed a brownish line in the crack of a mom, it was from the anus to the top of the crack and her baby was out within 5 min of noticing it, i wasnt aware of this sign then, so i just assumed that it was the color of her butt crack as she has darker skin. it was the entire crack, like a basting brush had been run between the cheeks, not just a thin line over the coccyx. sorry for the redundancies, just trying to be as clear as possible.
Your point is well taken.
@Walker Karraa
@sarah I think it is darkest on the line between the cheeks, but it can have some width to it, getting lighter, as it moves away from the “crack” onto the cheeks…at least, the ones I have been able to observe. Hope this helps.
Great post. I sent you a picture!
I have a picture that shows it (baby’s head is born and rotating for the rest of baby to be born), what email address should it be sent to?
@RK Who are you addressing? I can be reached through the blog, if you wish to send me something.
Yes, and with a great photo to boot:)
as a traditional midwife for 30+ yrs I have learned the non intrusive ways to find how a Mom is progressing and one of them is the red/purple or brownish line between the “butt” cheeks. I am sorry that I do not remember how I came to know this but have been using it for many years especially when I am a doula- It is cool to see how accurate it can be when the position of the line matches the VE. I think it would be good to use this method before routine VE’s. We can learn a lot from the Art of midwifery. Just being “with women”.
I have seen this as well and really feel it is accurate. I prefer to assess based on mother’s behavior but it is very interesting to my scientific mind so I watch for it when I can! And as was said, not every woman exhibits it and I rarely mention it except to my partner midwife or assistant. I think it would be a wonderful thing to share with attendants of CBE classes if I was teaching them.
Another fascinating piece of information that I can archive. I’ve passed the link for this onto our Access Group Facebook page for all aspiring midwives. (It also helps that we are being encouraged to reference our findings in journals and on-line so this is very topical right now) thank you.
Absolutely fascinating information! Thank you so much for sharing! I have never come across this until today! I think it will make for a very animated discussion point in my Lamaze courses!
Observe it all the time in our practice.I use it as a clear sign of progress and tell our clients about it.the more you observe the more accurate you get.
@Walker Karraa
I completely agree – though I’d like to know 1) how you can get a good picture of a laboring woman’s crack *and* her face, and 2) what woman would allow such a picture of herself to be used online. In a case such as this, how is it disempowering to show the specific physical phenomenon under discussion? Especially if the woman has consented to having her butt crack picture used to help other women avoid invasive VEs?
Dear Sharon, I am an independent midwife in Hungary (at the moment in house arrest). We with my midwife fellows know and use this red-purple line. But I generally can observe it only from 4-5 centimeters.
Here’s mine. This was the pushing phase with my first baby. My mom mentioned the line to my sisters while I was labouring. She knew about it, as a retired midwife’s assistant. She’s seen it many times.
Hello Sharon,
I am a student midwife and the ‘purple line’ is acknowleged in one of our text books ‘Midwife’s labour and birth handbook’ (2009) Chapman & Charles. Though it is not extensively discussed.
I will be keenly observing this method of estimating dilation!
I see this in women all the time. It is a great Non invasive sign. It is not present all the time but when it is I believe it is quite accurate. If used with what women are also telling us or the noises she makes then it is amazing.
I also look at the ” bulge” in the sacral area to assess head descent
I am a midwife and have seen and used the purple line as an assessment tool. However it is not present in all women, in my experience most women don’t demonstrate it. Further a VE is the only way of being certain of the position and flexion of the head. This detail is as important as dilation in assessing the process of labour and so it is not good practice to replace a necessary VE with observation of the line.
I first learned about the Hobbs line (though it was not called that) from an elderly granny midwife in the late 70s. I think women may have been observing this for a really long time.
Has anyone ever seen the purple line in someone not in active labour? I’m 40 weeks +1 day – had a VE over a week ago and was 3 cm and 75% effaced. Learned abut the purple line today and had a look. It’s very obviously there and right to the top but I’m not in labour. Baby is sunny side up – could that cause it?
thanks
As a homebirth midwife, I feel I am relatively conservative w/ vaginal exams, and will definitely start observing women for this sign of progression. I usually reserve VE’s for times when I want more information that can be put to practical use: as mentioned the position and flexion of the head, and evenness of dilation. I almost always use this information help moms into positions that will encourage even dilation and optimal fetal positioning. The line doesn’t give me this info; that being said, many labors don’t require any VE’s, as the progress is monitored by mom’s sounds and behavior. Its always the whole picture, and I’m glad to have a new tool.
Hello I am a doula and have noticed this many times. I have used it to assess when it might be time for us to leave for the hospital especially if mom wants to stay home as long as possible.
I am a midwife and have seen the purple several occasions with labouring women. Mostly noticed when standing and when almost fully dilated. I find this fascinating and have pointed it out to other midwives who havent heard of it. Always gets a great response
Hi, Im a midwife in NZ I have used this method for assessing cervical dilation for years and it is often accurate BUT I have been tricked several times when the baby is in the OP position ….
@lisap, why do you think that is? Are you tricked into thinking mom is further along then she is? or the reverse? Why do you think the OP baby makes it inaccurate at times? Curious. Thanks, Sharon
So one study only demonstrates about 76% of women have this line, and it only correlates 50% with vaginal exams. Doesn’t sound too reliable. Where are the pictures of this? I have a hard time understanding the 48-56% inaccuracy of vaginal exams. Are they talking about descrepancy between providers? Resident or nurse exams? If you have the same midwife or doctor performing vaginal exams, that person can accurately determine the dilation, effacement, and station and especially progress or a change from exam to exam. Labor is about making cervical change and even if someone disagrees about someone being 5 or 6 cm, if you examine them again hours later, everyone (100%) can tell if the exam is unchanged or progress has been made. If this line is physiologic related to venous congestion then I hypothesize that the longer the labor is or the longer the baby’s head in in the pelvis, then the congestion there will worsen despite change in cervix or station. Just like edema is worse in the legs at the end of the day compared to mornings, pelvic venous congestion may be worse with longer labors. This could very well be a confounding factor in interpretation. A recent article from AJOG showed that the number of vaginal exams while in labor did not increase infection rate. Common sense still dictates to limits exams, but this article was reassuring.
I agree with Molly Fergeson. So many factors are taken into consideration when assessing labor. Over 21 years I have seen women arrive at the birth center or be brought to the hospital by ambulance vocalizing and ready to push, only to find them 1-2 cm. Other stoic women arrive very comfortable and are 8-9 cm along. Maternal signs can be quite variable. If the red line is only present 50-75% of the time, it won’t be reliable for every delivery. If venous congestion is thought to be why the red line occurs, then length of labor, time spent of the fetal head in the pelvis, presence of hemorrhoids, hyper pigmentation of the anus will all be confounding factors. Most labors don’t need many cervical exams. So one can be performed if clinical judgement dictates one. Initial exam can confirm presentation so no surprise breeches are starting in labor. Especially with moms with larger BMI, when Leopold’s exam may be less obvious. All three factors (dilatation, effacement, and station) are important in judging progress. I like to see descent of station. Any baby that remains high worries me about larger babies and SD risk. For those that say effacement is more important than dilatation, do you really feel a fully effaced cervix at 1cm is better than someone complete and 50% effaced? And if the head is high, that is worse. Whether this is the women’s first pregnancy or fifth will determine importance of dilatation and effacement. As first time moms usually efface first than dilate and multips tend to dilate as they efface. Cervical exams can help determine position and asynclitism which helps me put the patient into positions to help move the baby into optimal position for birth. Cervical progress can really only be assessed best by examining the cervix. We don’t assess other body changes (weight, height, BP, heart, kidney infection, pneumonia, stroke, DVT, ) without examining the organ in question. Why not check the cervix?