Dilation of the cervix is an important test that your physician performs on you to measure your labor progress. However, instead of going that route, people are now moving towards the purple line dilation in labor test.
The test is becoming more popular as a means of monitoring labor progress in place of the painful regular vaginal exams that doctors no longer require.
The purple line on your back is essential as an alternate and less unpleasant or intrusive choice in vaginal exams to find out what is going on with the baby during labor.
When the cervix expands, the baby’s head goes down into the pelvis as the border between the butt cracks widens. A sign of full dilation occurs when the line reaches the top of your butt crack.
Even though scientists have not researched deeply on the purple line, it can be helpful in some labor cases.
This guide will teach you about the purple line dilation in labor, when it appears, its accuracy, and its causes.
What is the purple line dilation in labor?
The purple line, also known as the Hobbs line, has lately received a lot of interest as an alternate, less intrusive method of assessing labor.
Some studies have indicated that cervical dilation’s overall accuracy ranges from 48% to 56% and that the more dilated you are, the less accurate a vaginal examination becomes.
You can see the line between your buttocks as a purple lining. Cervical dilation increases in direct proportion to the length of the line.
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What causes purple line dilation in labor
Red, purple, or brown lines begin to appear in the natal cleft between your baby’s bottom cheeks as they descend deeper into the pelvic cavity. The pressure on the baby’s skull is assumed to be the source of the blood congestion.
Many experts believe that vaso-congestion at the base of the sacrum might increase the development of purple lines. Still, the exact reason for this phenomenon remains a mystery. When pressure is applied, it becomes lighter and gradually recolors.
As the fetal head descended, these congestions emerged as an appositive association between the descent of the fetal head and the increased appearance of purple lines.
These intra-pelvic pressures increased and caused these congestions. It is also possible that the rhombus of Michaelis travels back during advanced delivery, which causes the pelvis to change its form, resulting in the ilea wings expanding and the pelvic diameters increasing.
Purple line dilation accuracy
Although the line is evidence of your cervical dilation, you should know that it doesn’t happen in all women.
According to some research, the overall accuracy of cervical dilation ranges between 48% and 56% with a 1-centimeter error, or 89.5-91.7 percent, and this accuracy decreases as cervical dilatation increases.
Another study shows that only 76% of women experience the purple line dilation in labor.
This statistic concludes that the purple line dilation is inaccurate as few women do not notice this in their lives.
Purple line dilation chart
- 3 -6 cm purple line = 1 -2 cm dilation
- 5 – 8cm purple line = 3 -6 cm dilation
- 7 – 9cm purple line= 7 – 8 cm dilation
- 8 – 11cm purple line= 9 – 10 cm dilation
The purple line’s length and cervical dilatation are not connected directly. As a result, we can’t conclude that a woman’s cervix is 2 cm dilated if her purple line is 2 cm long.
From the table above, when a woman is just 1-2 cm dilated, the purple line can measure between 3 to 6 cm.
Using these figures, you can see how much the purple line differs from the length of cervical dilation.
In summary, it’s impossible to tell how much a woman has dilated using the length of the purple line.
However, at least you can see a trend developing. According to this pattern, the longer the purple line, the more the cervix appears to have dilated.
When you know the length of the purple line, you can at least obtain a rough indication of how much your cervix has dilated and when to expect labor.