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Trial of labor after a one- or two-layer closure of a low transverse uterine incision
Trial of labor after a one- or two-layer closure of a low transverse uterine incision J. Martin Tucker, MD, John C. Hauth, MD, Pam Hodgkins, RN, John Owen, MD, and Carey L. Winkler, MD Birmingham, Alabama In the subsequent labor and delivery of 292 women who had a prior low transverse cesarean section the incidence of scar separation was low and was not affected by the method of uterine closure. A low transverse incision closed in one continuous layer should not preclude a subsequent trial of labor. (AM J OBSTET GVNECOL 1993;168:545-6.)
Key words: Cesarean section, trial of labor, operative technique
Two standard obstetric texts note that it is reasonable to close a low transverse uterine incision in one layer. I. 2 We undertook this retrospective review to evaluate the safety of a trial oflabor after a one-layer closure of a low transverse uterine incision.
Material and methods We obtained the hospital records of292 of 361 (80%) women who underwent a cesarean section and then had a subsequent labor and delivery at the University of Alabama Hospitals between Jan. 1, 1987, and Nov. 30, 1991. Only women who underwent a low transverse cesarean section without vertical extension were included. Twenty percent of the eligible patients were not included because either the records had been sequestered for microfilming or a trial of labor in the second delivery could not be confirmed from the chart review. We also surveyed The University of Alabama malpractice carrier and the utilization review and quality assurance departments to ensure that no patients with an adverse outcome were omitted. During the study period the type of initial uterine closure (one continuous layer of locking No. I chromic gut suture vs two continuous layers with the first locked) was performed at the discretion of the operating attending or resident physicians. Charts were abstracted for type of uterine closure, demographic data, and perioperative complications associated with the first cesarean delivery in the study period. The charts of the subsequent labor and delivery
From the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, The University of Alabama at Birmingham. Receivedfor publication September 23, 1992; acceptedSeptember25, 1992 Reprint requests:John C. Hauth, MD, The University ofAlabama at Birmingham, Department of Obstetrics and Gynecology, University Station, Birmingham, AL 35233-7333. Copyright © 1993 Mosby-Year Book, Inc. 0002-9378/93 $1.00 + .20 6/1/42968
Table I. Indication for initial cesarean section in study period Initial cesarean closure
Indication Malpresentation Fetal distress Arrest of labor Repeat Other TOTAL
P=
One-layer (n = 149)
Two-layer (n = 143)
(%)
(%)
14.1 44.3 32.9 3.4 5.4
14.7 37.1 34.3 3.5 10.5
100
100
0.49.
were abstracted for route of delivery, asymptomatic scar separation, uterine rupture, and adverse maternal or perinatal outcomes. Statistical analyses were performed with X2 , Fisher's exact test and a two-tailed Student t test where appropriate. A p value ::;0.05 was considered significant.
Results In 149 women the uterine incision was closed in one layer, and in 143 it was closed in two layers. At the initial cesarean section these two groups of women were similar in regard to race, parity, history of previous cesarean section, gestational age, birth weight, wound complications, chorioamnionitis or endometritis, and blood transfusion requirements. The two groups also had similar indications for the initial cesarean section (jJ = 0.49), Table I. Table II lists selected outcomes of the subsequent delivery in the study period. There were three (2.1 %) and five (3.5%) asymptomatic uterine scar separations in the one- and two-layer groups, respectively. By means of a two-tailed, two-sample binomial test, with a = 0.05, a study of this size had a power of 0.81 to
545
546
Tucker et al.
February 1993 Am J Obstet Gyneco1
Table II. Patient outcomes observed during subsequent labor and delivery after prior one- or two-layer clo sure of low transverse incision for cesarean delivery In itial cesarean section closure
I
One-layer
Vaginal (n = 173) Scar separation (detected) (No.) Uterine rupture (No.) Adverse perinatal outcome (No.) Gestational age (wk) Birth weight (gm) Cesarean (n = 119) Scar separation (No.) Uterine rupture (No.) Adverse perinatal outcome (No.) Gestational age (wk) Birth weight (gm)
1 (0.67%)
o o
2
(1.3%)
38.9 3412
detect a maximum difference of scar separation of between 3.5% (observed in the two-layer group) and 12.5%. if such a difference actually existed. There were no symptomatic uterine ruptures or fetal death, and all newborns were vigorous with normal Apgar scores. The two scar separations found after vaginal delivery were not repaired . Comment
We are not aware of data relating the type of closure of a low transverse uterine incision for cesarean delivery to the safety of a subsequent trial of labor. In our series the occurrence of asymptomatic scar separation with a subsequent trial of labor was similar in women who had a one- or two-layer closure . No symptomatic uterine ruptures occurred. This report has shortcomings inherent to many retrospective reviews. Because of lack of documentation in operative and delivery summaries, the incidence of
1 (0.69%)
o o
38.5 3141
38.7 3225
o o
T wo-layer
4 (2.8%)
o o
38.7 3236
Significance
p = 0.94 P = 1.00
P = 1.00
P = 0.60 P = 0.37
P = 0.44
P = 1.00 P = 1.00 P = 0.62
P = 0.13
asymptomatic scar separation may be higher. Furthermore, it was not possible to calculate our power to exclude a type II statistical error for either an adverse perinatal outcome or uterine rupture, because these were not observed in either group . Moreover, there are few reports regarding these occurrences. These data support the premise that a trial of labor should not be altered by whether the patient had a prior one- or two-layer closure of a low transverse cesarean section incision.
REFERENCES 1. Cunningham FG, MacDonald PC, Gant NF. Operative obstetrics. In: Cunningham FG, MacDonald PC, Gant NF, eds, Williams' obstetrics. l Sth ed . Norwalk, Connecticut: Appleton & Lange, 1989:45 I. 2. Depp R. Cesarean delivery and other surgical procedures. In: Gabbe SG, Niebyl JR, Simpson JL. Obstetrics: normal and problem pregnancies. New York: Churchill Livingstone, 1991:650.
Key words: Cesarean section, trial of labor, operative technique
Two standard obstetric texts note that it is reasonable to close a low transverse uterine incision in one layer. I. 2 We undertook this retrospective review to evaluate the safety of a trial oflabor after a one-layer closure of a low transverse uterine incision.
Material and methods We obtained the hospital records of292 of 361 (80%) women who underwent a cesarean section and then had a subsequent labor and delivery at the University of Alabama Hospitals between Jan. 1, 1987, and Nov. 30, 1991. Only women who underwent a low transverse cesarean section without vertical extension were included. Twenty percent of the eligible patients were not included because either the records had been sequestered for microfilming or a trial of labor in the second delivery could not be confirmed from the chart review. We also surveyed The University of Alabama malpractice carrier and the utilization review and quality assurance departments to ensure that no patients with an adverse outcome were omitted. During the study period the type of initial uterine closure (one continuous layer of locking No. I chromic gut suture vs two continuous layers with the first locked) was performed at the discretion of the operating attending or resident physicians. Charts were abstracted for type of uterine closure, demographic data, and perioperative complications associated with the first cesarean delivery in the study period. The charts of the subsequent labor and delivery
From the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, The University of Alabama at Birmingham. Receivedfor publication September 23, 1992; acceptedSeptember25, 1992 Reprint requests:John C. Hauth, MD, The University ofAlabama at Birmingham, Department of Obstetrics and Gynecology, University Station, Birmingham, AL 35233-7333. Copyright © 1993 Mosby-Year Book, Inc. 0002-9378/93 $1.00 + .20 6/1/42968
Table I. Indication for initial cesarean section in study period Initial cesarean closure
Indication Malpresentation Fetal distress Arrest of labor Repeat Other TOTAL
P=
One-layer (n = 149)
Two-layer (n = 143)
(%)
(%)
14.1 44.3 32.9 3.4 5.4
14.7 37.1 34.3 3.5 10.5
100
100
0.49.
were abstracted for route of delivery, asymptomatic scar separation, uterine rupture, and adverse maternal or perinatal outcomes. Statistical analyses were performed with X2 , Fisher's exact test and a two-tailed Student t test where appropriate. A p value ::;0.05 was considered significant.
Results In 149 women the uterine incision was closed in one layer, and in 143 it was closed in two layers. At the initial cesarean section these two groups of women were similar in regard to race, parity, history of previous cesarean section, gestational age, birth weight, wound complications, chorioamnionitis or endometritis, and blood transfusion requirements. The two groups also had similar indications for the initial cesarean section (jJ = 0.49), Table I. Table II lists selected outcomes of the subsequent delivery in the study period. There were three (2.1 %) and five (3.5%) asymptomatic uterine scar separations in the one- and two-layer groups, respectively. By means of a two-tailed, two-sample binomial test, with a = 0.05, a study of this size had a power of 0.81 to
545
546
Tucker et al.
February 1993 Am J Obstet Gyneco1
Table II. Patient outcomes observed during subsequent labor and delivery after prior one- or two-layer clo sure of low transverse incision for cesarean delivery In itial cesarean section closure
I
One-layer
Vaginal (n = 173) Scar separation (detected) (No.) Uterine rupture (No.) Adverse perinatal outcome (No.) Gestational age (wk) Birth weight (gm) Cesarean (n = 119) Scar separation (No.) Uterine rupture (No.) Adverse perinatal outcome (No.) Gestational age (wk) Birth weight (gm)
1 (0.67%)
o o
2
(1.3%)
38.9 3412
detect a maximum difference of scar separation of between 3.5% (observed in the two-layer group) and 12.5%. if such a difference actually existed. There were no symptomatic uterine ruptures or fetal death, and all newborns were vigorous with normal Apgar scores. The two scar separations found after vaginal delivery were not repaired . Comment
We are not aware of data relating the type of closure of a low transverse uterine incision for cesarean delivery to the safety of a subsequent trial of labor. In our series the occurrence of asymptomatic scar separation with a subsequent trial of labor was similar in women who had a one- or two-layer closure . No symptomatic uterine ruptures occurred. This report has shortcomings inherent to many retrospective reviews. Because of lack of documentation in operative and delivery summaries, the incidence of
1 (0.69%)
o o
38.5 3141
38.7 3225
o o
T wo-layer
4 (2.8%)
o o
38.7 3236
Significance
p = 0.94 P = 1.00
P = 1.00
P = 0.60 P = 0.37
P = 0.44
P = 1.00 P = 1.00 P = 0.62
P = 0.13
asymptomatic scar separation may be higher. Furthermore, it was not possible to calculate our power to exclude a type II statistical error for either an adverse perinatal outcome or uterine rupture, because these were not observed in either group . Moreover, there are few reports regarding these occurrences. These data support the premise that a trial of labor should not be altered by whether the patient had a prior one- or two-layer closure of a low transverse cesarean section incision.
REFERENCES 1. Cunningham FG, MacDonald PC, Gant NF. Operative obstetrics. In: Cunningham FG, MacDonald PC, Gant NF, eds, Williams' obstetrics. l Sth ed . Norwalk, Connecticut: Appleton & Lange, 1989:45 I. 2. Depp R. Cesarean delivery and other surgical procedures. In: Gabbe SG, Niebyl JR, Simpson JL. Obstetrics: normal and problem pregnancies. New York: Churchill Livingstone, 1991:650.