THE PARTOGRAPH IN THE MANAGEMENT OF LABOR FOLLOWING CESAREAN-SECTION

Objective: To determine whether graphic labor record (partogram) can be used to predict the risk of uterine scar rupture in labor following lower segment cesarean section. Methods: Between 1988 and 1991, 236 women had a trial of labor following cesarean section. After the onset of the active phase (3 cm cervical dilatation), a 1 cm/h line was used to indicate an alert line on the partogram. All the active phase partograms were divided into five time zones: A (area to the left of the alert line), B (0-1 h after the alert line), C (1-2 h after the alert line), D (2-3 h after the alert line), and E and F(>3 h after the alert line). For the action line, different lag times after the alert line were defined according to the time zones. Sensitivity, specificity, cesarean section rates and rupture rates were calculated for the different lag times after the alert line, and a receiver-operating characteristic curve was constructed. Results: Fifty-five (23.3%) trials of labor ended in a repeat emergency cesarean. There were seven (2.9%) cases of scar rupture. Of the 181 vaginal deliveries, 151 (83%) occurred within 2 h after the progress of labor had crossed the alert line (zones A-C). Five out of seven cases of scar rupture occurred more than 2 h after the alert line had been crossed (zones D-F). The 2- and 3-h lag time after the alert line had a sensitivity of 71% and 43%, respectively, and a specificity of 78% and 96%, respectively, in predicting uterine scar rupture. If cesarean sections were performed at 2 or 3 h after crossing the alert line, the projected cesarean rates would have been 36% and 27%, respectively. The scar rupture rates would in turn be 0.8% and 1.6%, respectively. Conclusion: In women undergoing a trial of labor following cesarean section, the partographic zone 2-3 h after the alert line represents a time of high risk of scar rupture. An action line in this time zone would probably help reduce the rupture rate without an unacceptable increase in the rate of cesarean section.