Grobman et al developed a nomogram for identifying a woman who is able to have a vaginal birth after a cesarean section (VBAC). The authors are from the Maternal-Fetal Units Network (MFMU) sponsored by the National Institute of Child Health and Human Development (NICHD).
Parameters (can be determined on the first prenatal visit):
(1) age in years
(2) body mass index (BMI)
(3) race
(4) vaginal delivery since last cesarean section
(5) previous vaginal delivery
(6) recurrent primary indication for previous C-section (arrest of cervical dilation or descent)
points for age in years =
= 19.57 - (0.391 * (age))
points for body mass index =
= 45 - (0.6 * (BMI))
Parameter |
Finding |
Points |
African-American |
no |
7 |
|
yes |
0 |
Hispanic |
no |
7 |
|
yes |
0 |
vaginal delivery since cesarean |
no |
0 |
|
yes |
10 |
previous vaginal delivery |
no |
0 |
|
yes |
9 |
recurrent primary indication |
no |
6 |
|
yes |
0 |
where:
• In theory a patient could be both Hispanic and Black, although this usage is not discussed in the paper.
• In theory responses could include No to previous vaginal delivery and Yes to vaginal delivery since C-section.
total score =
= SUM(points for all 6 parameters)
Score |
Probability of Vaginal Delivery After a Trial of Labor |
< 17 |
< 5% |
17 to 38 |
11.87 - (1.109 * (points)) + (0.04144 * ((points)^2)) |
38 to 55 |
-65.98 + (2.619 * (points)) - (0.002847 * ((points)^2)) |
55 to 76 |
-167.2 + (6.536 * (points)) - (0.04062 * ((points)^2)) |
> 76 |
> 95% |
Purpose: To evaluate a pregnant woman with a history of cesarean section for the chance of vaginal delivery using the nomogram of Grobman et al.
Specialty: Obstetrics & Gynecology
Objective: other testing, severity, prognosis, stage
ICD-10: O80-O84,