Dilation - How To Check Without Checking

Recently I have noticed a few blogs writing about dilation and it's benefits, as well as how to do it in other ways besides simple vaginal exams. This is my take on the subject, modified from the hand out that I have available for my clients.

Why Check?

One of the biggest repeat questions a doula/caregiver can hear during labor and birth is ‘how far along am I’. Some women would prefer not to know, some women could care less, and some women desire this knowledge almost habitually.

As with any intervention in labor and birth, cervical checks carry risk. The risks include: increased risk of infection, PROM, false readings (i.e. human error), and regret/disappointment at any 'lack' of dilation.

Regardless of women's reasons for wanting to know their dilation, it is helpful for a doula/care provider to have more than one trick/way of  knowing where mom may be, beyond timing contractions.

Some methods that can help a caregiver or doula know how dilated a woman is during her labor include:

• Teach self exams
• Sounds she makes
• Smell of the room/mom
• Show
• Emotions
• The bottom line
• Physical Make-Up
• Fundal height
• Symphysis Crease
• Mexican Hot Legs
• Pressure

Methods

All of these methods are generalities. It is important to remember that women are not textbooks, they are organic, living, evolving organisms that there are many exceptions to every rule. Each of these cannot be applied to all women.

Self Exams


I have found that the best explanation of self exams can be found from Gloria Lemay. It is a practically applicable explanation that gets good results.

“The best way to do it when hugely pregnant is to sit on the toilet with one foot on the floor and one up on the seat of the toilet. Put two fingers in and go back towards your bum. The cervix in a pregnant woman feels like your lips puckered up into a kiss. On a non-pregnant woman it feels like the end of your nose. When it is dilating, one finger slips into the middle of the cervix easily (just like you could slide a finger into your mouth
while puckering for a kiss). As the dilation progresses, the inside of that hole becomes more like a taut elastic band and by 5 cm dilated (5 finger widths) it is a perfect rubbery circle like one of those Mason jar rings that you use for canning, and about that thick.” - Gloria Lemay

Sounds of Birth
A non-vaginal indicator that can help to detect progress is notable sounds that a woman makes in labor.

Usually, early labor (0-4cm) means little to no 'birth' noise; mom can talk with little to some effort through a contraction.

Around 4-5cm dilation (for a primip) talk with be rather difficult to near impossible, noises may still be quiet, but consistently open voweled or a resonating hum.

5-7cm will typically be presented with louder noises, near to completely impossible to talk through a contraction, and sounds may become repetitive or staccato.

If a woman is a silent laborer, a good way to get a handle on her vocal indicators is to explain what you are about to do... then wait until a contraction starts, and ask a question that necessitates a sentence-long answer. The way in which she is able or unable to answer you during a contraction should be rather reliable. 

Smell

Many birth professionals have spoken about the smell of birth.

Birth smells come about around 6-8cm dilation and are a very good indicator of good active labor. When a mom says that she wants to transfer to her place of birth around 6-8cm, I typically will go by smell and mom's emotions.

The active labor smell is not so much the earthy/wet smell of amniotic fluid, and is not the sweet smell on a woman’s breath during labor (ever notice a laboring mom’s breath always smells sweet?)..

Instead, this smell is deep, dusky (not musky), heavy, familiar... the smell of deep and ancient work. It is something that is hard to explain, but something to definitely be on the look (smell) out for until you have familiarized yourself with it and can use this as a good indicating factor of active labor.

Show
A woman may or may not ‘show’ any bloody or mucousy discharge at the onset of labor,  but blood and mucous often come in copious amounts, usually during contractions, when a woman is around 6-8cm. If a woman’s water broke earlier in the labor, you may see a second gush around 6cm.

Emotions
Early labor (1-4cm, oftentimes) often means mom is in the "this is it" stage - happy, excitable, a good sense of humor, perhaps even denial that she is really in labor.

Moving into active labor (4-6cm, oftentimes) often means that mom is still smiley and may even laugh at little things being said between contractions. Moving in and out of conversation as her contractions go and come.

Active labor (5-7cm, oftentimes) generally means she is more irritated at commonplace conversation or people trying to distract her with quips. It may take her quite awhile after a contraction leaves to become 're-acclimated' to the room, or she may choose to simply remain in her birthing space and not interact with the room. (an aside, the room should be acclimating to her, although it is not always the case, unfortunately).

Around transition (usually, 7cmish) even between contractions, a woman can become doubtful, unable to make concrete decisions ("I don't know" in response to questions), or irrational, a good indicator that mom is on the homestretch.

This method can be tricky, though, as this ‘emotional mapping’ can be skewed from a babies position or a woman’s labor make-up.

If it is from baby settling in a ‘malpresentation’, a mom might experience both an early transition (anywhere from 2cm to 4cm dilation, depending on if she is a primip or multip) and a later transition.

Depending on her labor make-up, some women can have an ‘early transition’ (4-5cm), especially for long-latent early labor patterns with discomfort disproportionate to her cervical dilation, but it will often still mean rapid dilation to complete.

Bottom/Purple Line
A study conducted and published in the Lancet hypothesized that the  purple line that 'grows' up the natal cleft can be a great indicator of cervical dilatation. The line begins at the anal margin at the start of labour and rises like a "mercury thermometer".

When it reaches the top, the woman is fully dilated. The authors propose that an "increase  in intrapelvic pressure causes congestion in the ... veins around the sacrum, which, in conjunction with the lack of subcutaneous tissue over the sacrum, results in this line of red purple discoloration".

• The best way to describe this is, looking at the anus, a purple line will appear and, throughout labor, move up the natal cleft (butt crack for us laypeople)
• The picture shown at right is a fully dilated woman and her purple line.

Physical Make-Up
Many women will find that, as they get very close to the pushing stage, they may exhibit signs similar to the flu. If a mom suddenly feels the urge to vomit or complains of nausea, has a flushed face and feels warm, and/or begins trembling uncontrollably, mom may be at the cusp of second stage. Vomiting alone can be emotions, hormones, or fatigue alone. Flushed face is a good sign of 6-7cm, when noticed alone. And trembling uncontrollably, alone, might mean fatigue or fever. These indicators are most reliable when 2 or all 3 are noticed together.

Other physical indicators of 6cm and beyond:

• involuntary curling of toes during contractions, even when the rest of her body is loose and relaxed (6-8cm)
• if standing, instead of curling her toes, mom may stand on her toes while leaning over something (6-8cm)
• goose bumps on her bottom (buttocks) and upper thighs (9-10cm)

Fundal Height
Anne Frye's Volume II of Holistic Midwifery speaks of the fundal height of being a very reliable indicator of mom's cervical dilation.

When the uterus contracts, it swells upwards and pulls the cervix upward with it, causing more dilation. Around 40 weeks, you can get around 5 finger-breadths of measurement between the fundus and the xyphoid.

As mom dilates, the distance from the xyphoid to the fundus decreases at a rate of about 2cm per fingerbreadths. This way of measuring is not as reliable in primips, but much more reliable in multips. When there is about 1 finger-width or less of space between the fundus and xiphoid, mom is near to at 10 cm dilation. 

To do this, have mom (or partner) ‘mark’ her measurement at the first thought of labor.  Taking into consideration her starting point (from prior VEs (Vaginal Exams)), use this as a start point.

Unfortunately, this assessment during labor must be done at the height of a contraction and mom must be on her back. Using the chart below, determine fingerbreadths (fb) between the fundus and xiphoid:

• 5 fb = no dilation 
• 4 fb = 2 cm
• 3 fb = 4 cm
• 2 fb = 6 cm
• 1 fb = 8 cm
• 0 fm = complete

Symphysis Crease
Late dilation can be measured by watching the symphysis crease. It’s visible mostly in mom’s who have lower BMI prepregnancy. As labor progresses and babies shoulder's descend along with dilation, a line/crease will become visible directly above (parallel to) the symphysis. It will become wider latitudinally as labor progresses.

Around transition, it will be about 3/4 of the way across. If the line is nearly all the way across, mom is most likely pretty close to, or already fully, dilated and will probably start pushing soon.

To do this, check right above mom’s symphysis (pubic bone). If there is a line at all, mom is probably at least 5cm. If you are working with a woman who is intent on laboring at home as long as possible, the crease may be a good indicator for her labor, a drawback is that it can also mean ‘too late’.

Another drawback to this is if baby is riding high throughout the early and active labor stage (aka a 'late descender').

Mexican Hot Legs

As the birthing woman's body works harder, blood is withdrawn from the extremities to be utilized by the womb. Thus, the woman's legs get progressively colder from the ankle to the knee as labor progresses. At the start of birth, the whole leg will be warm. At around 5cm, the leg will be coldre from the ankle to around mid-calf than it is above the calf. Once the whole leg feels coldre up to the knee, then the urge to push should shortly follow.

This technique is less reliable if the woman is having an epidural, as the drugs will also affect the temperature of the hands and legs. If a woman is birthing in water then she'd need to be on dry land for around 20 minutes to allow the temperature in her legs to be measured accurately. - Kath Harbisher

Pressure

As baby descends, pressure will be felt at different levels on her back. This will not necessarily give dilation information, but will help in determining position/station of baby within the pelvic outlet. This pressure will move from the rim of the pelvis all the way down onto the coccyx (tailbone).

As doulas can tell you, as mom continues to dilate, and baby continues to move down the pelvis, the pressure she feels will go lower. This is why back massages turn into butt massages turn into tailbone massages. :)

By the time that mom is 8-10cm and 0 to +1 station, the small rectangular spot of mom’s buttocks (tailbone area) will bow outward as her pelvis makes room for babies decent. This usually means that, if you are at home and mom was planning a hospital or birth center birth, you very well may have waited too long.

Another indicator is that, if mom is feeling pressure between her legs, vomits, and her water breaks simultaneously, she is probably 7-8cm or more. 

A final indicator is, regardless of dilation, if a mom is passing stool involuntarily with her contractions, whether she has the urge to push or not, she is either holding a posterior baby, fully dilated and about to start pushing, or baby is at a low station (more common without full dilation in multips).

In Conclusion
Dilation of the cervix can tell us how far open you are, but not how close you are to the destination of birthing your baby. Listening to your body and the cues it gives can help us know where you are at in your journey though. Some women's journeys take them through jogs and shortcuts, while others are mountainous day-hikes.

More than anything else, these tools can help women to plan their next steps on their birthing journeys; when to move to their expected place of birth, when to enter the birthing pool, what their labor pattern might indicate, what is true labor vs what is practice labor.

Additional Research and Reading

• Byrne DL and Edmonds DK (1990) Clinical method for evaluating progress in first stage of labour in The Lancet Vol 335 No 8681 p122
• Checking Dilation Without A Cervical Exam
• Midwifery, Best Practice, Vol 1 - Hobbs L (2003) Assessing cervical dilatation: Watching the purple line in Wickham S (Ed) Midwifery: Best Practice, Books for Midwives, Edinburgh Ch 4.3 p77-8
• How Dilated Am I
• The purple line as a measure of labour progress: a longitudinal study