Routine revision of uterine scar after cesarean section: Has it ever been necessary?

European Journal of Obstetrics & Gynecology and Reproductive Biology 78 (1998) 29–32

Routine revision of uterine scar after cesarean section: Has it ever been necessary? a a, a b a T. Silberstein , A. Wiznitzer *, M. Katz , M. Friger , M. Mazor a

Division of Obstetrics and Gynecology, Soroka Medical Center and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel b Department of Epidemiology, Soroka Medical Center and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel Received 3 July 1997; received in revised form 3 December 1997; accepted 15 December 1997

Abstract Although a trial of labor after cesarean section (VBAC) is successful and relatively safe, few studies have directly addressed the necessity of routine transcervical revision of uterine scar after prior cesarean section. We performed a longitudinal study of 3469 women who had VBAC. In all patients, uterine scar integrity was examined immediately after placental expulsion. The detection rate of uterine scar dehiscence or rupture was 0.23% (8 / 3469). Only one woman with complete uterine rupture needed immediate laparotomy for severe hemorrhage. Out of seven patients (0.2%), who had evidence of uterine dehiscence, three underwent explorative laparotomy. In conclusion, the potential benefit of routine examination of uterine scar after VBAC is doubtful. Transcervical revision should be performed only in symptomatic patients.  1998 Elsevier Science Ireland Ltd. Keywords: Transcervical revision; VBAC; Uterine scar; Rupture; Dehiscence

Although trial of labor is successful, and relatively safe [1–9], uterine rupture or dehiscence is still a devastating complication that can occur after previous cesarean section [VBAC]. The frequency of uterine rupture after prior cesarean section has been estimated to be 0.3–3.8% and uterine dehiscence 0.6–4% [1–3,10–16]. Few studies with appropriate power have directly addressed the need of routine transcervical revision of uterine scar after prior cesarean section. We performed a longitudinal study of 3469 women in Soroka Medical Center, who previously underwent cesarean section and had delivered a singleton infant in the period from Jan 1990 – Dec 1996. In all patients uterine scar integrity was examined immediately after placental expulsion. In the older literature one may find reference to routine postpartum revision of uterine

*Corresponding author. Tel.: 1972 7 6400559; fax: 1972 7 6400559.

scar following VBAC in order to explore the possibility of uterine dehiscence or rupture [4,17–19]. Although the complications are very rare, and the treatment is controversial [20], there are still some medical centers, that are performing a routine exploration of the scarred uterus after VBAC. The purpose of the present study is to evaluate the justification for a routine revision of uterine scar after a prior C / S in our obstetric population.

1. Materials and methods According to the incidence reported in the literature [1–3,10–16], we determined the sample size needed to evaluate whether a routine revision of uterine scar is still necessary. The following parameters were included: significance level 0.05, incidence 0.3%, and minimal detectable deviance of 80%, by using standard power analysis.

0301-2115 / 98 / $19.00  1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0301-2115( 98 )00005-0

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T. Silberstein et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 78 (1998) 29 – 32

Table 1 Patients Characteristics

Maternal age (Y) Gravidity Parity Gestational age (W) Apgar Score Birth Weight (gr.)

with hemorrhage [18,22,23]. Uterine dehiscence (n57)

Uterine rupture (n51)

24.563.5 3.161.8 2.861.8 39.361.2 9 / 10 30756351

26.0 2.0 2.0 40.5 9 / 10 3195

The calculation was done after testing the validity of standard power analysis following the criteria; p*n.5, where p is a given proportion, p$0.02, and n is the sample size [21]. The obtained sample size was found to be 3300 women. A computer-generated list of all vaginal births after cesarean delivery at the Soroka Medical Center between January 1, 1990 and December 31, 1996 was available for analysis. Our study population consisted of 3469 patients that underwent revision of uterine scar after vaginal delivery following one previous cesarean section (VBAC). According to our management policy, each patient with one previous lower uterine segment scar, and singleton vertex presentation is allowed to have trial of labor. Women with two cesarean sections, or classical uterine incision, were excluded from this study. Artificial rupture of membranes and oxytocin augmentation were used for labor induction. A routine revision of uterine scar was performed immediately after placental expulsion to assess uterine scar integrity. Dehiscence was defined as a silent separation of uterine scar diagnosed on transcervical examination with no maternal compromise. Rupture denotes scar separation

requiring

immediate

intervention

2. Results During the study period, there were 85 710 births. The overall rate of VBAC was 4% (3469 / 85 710). All these patients underwent transcervically examination to detect uterine scar integrity. Uterine dehiscence or rupture was found in 8 patients – 0.23% (95% C.I. 0.08–0.38). Table 1 depicts patients’ characteristics divided into two groups: group 1 (n57), women who have been diagnosed with uterine dehiscence and group 2 (n51) with uterine rupture. Maternal age, gravidity, parity, gestational age at the time of delivery, birth weight and Apgar scores were similar among both groups. There were no cases of perinatal mortality or admission to the neonatal intensive care unit. In group 1, 3 / 7 (42.8%) patients, had a previous history of wound infection (n51) or dehiscence (n51) in the prior cesarean section. The third patient was admitted after delivery and was diagnosed to have uterine dehiscence after a routine examination. Vaginal prostaglandin E2 1.5 mg was used in one patient for cervical ripening. The patient that was diagnosed to have uterine rupture, had a previous cesarean section for non progressive labor, and oxytocin was administered for induction of labor. Four patients underwent explorative laparotomy. One patient with complete rupture of uterine scar needed immediate laparotomy because of hemorrhage. The remaining three patients were asymptomatic and underwent explorative laparototomy for uterine scar dehiscence that was found during the routine procedure. During laparotomy, repair of uterine scar was performed and no additional surgical procedure was needed (Table 2). The remaining four asymptomatic patients with scar

Table 2 Characteristics of patients with uterine rupture or dehiscence after VBAC Patient no.

Previous C / S indication

Induction

Diagnosis

Laparotomy

1 2

N.P.L.* N.P.L.

Oxytocin PG

Rupture Dehiscence

Yes Yes

3 4

Unknown Unknown

No No

Dehiscence Dehiscence

Yes Yes

5 6 7

Breech Fetal distress Fetal distress

No No No

Dehiscence Dehiscence Dehiscence

No No No

8

Breech

No

Dehiscence

No

*, non progressive labor – first stage. **, LOPC-lack of perinatal care. ***, S / P-state post.

Comments

S / P*** wound infection LOPC** LOPC S / P Dehiscence

Admitted after Delivery

T. Silberstein et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 78 (1998) 29 – 32

dehiscence were treated conservatively without any additional complications. There were no cases of late diagnosis of uterine rupture among the study population.

3. Discussion This study is large enough to allow accurate evaluation of the necessity of uterine scar revision after VBAC. Eight cases of uterine dehiscence or rupture (0.23%) were diagnosed during a routine revision of uterine scar integrity after delivery. Predisposing and associated factors in this study were similar to those reported by others. There were no maternal and perinatal mortality in our series. Only in one case was immediate laparotomy needed for severe maternal hemorrhage. This case would have been diagnosed anyhow because of maternal symptoms. In four patients, exploration was warranted because of detection of large dehiscence or hemorrhage. However, no further surgical intervention was needed in addition to uterine scar repair. The management of asymptomatic scar separation is controversial [18,20]. In many patients only conservative management was needed with no apparent adverse consequences [16,18]. Indeed, in our study population, four patients were treated with expectant management with no further complications. There are surprisingly little published data on the need of a routine revision of uterine scar. Herlicoveitz et al. [24] agree that a routine revision of uterine scar is no longer necessary, still the authors remain faithful to uterine revision. Lavin et al. [4] in 1982 reviewed the necessity of postpartum examination of uterine scar. Although most of the authors have advocated postpartum transcervical palpation of the uterine scar, they did not recommended specific treatment for asymptomatic, non hemorrhaging defects. Lavin et al. concluded that there was no apparent increased morbidity associated with this procedure; therefore there is no reason to condemn it. In both the above mentioned studies the reason for routine examination of uterine scar is based on the authors’ feelings and not on their own data. Moreover, recent data in the literature is in agreement with our results. Gemmer et al. [25] in a retrospective study of 475 patients who had VBAC, found 13 cases of scar dehiscence with only one case discovered by transcervical examination. They concluded that the value of routine digital examination of uterine scar is doubtful. In addition, Kaplan et al. [23], reviewed 467 women who had VBAC, and no case of dehiscence of scar was detected. Haddad et al. concluded that revision of uterine scar remains important for the diagnosis of dehiscence or rupture, but this exploration should only be done if symptoms appear [26]. Although those studies do not have the appropriate power to prove their conclusions, these series are consistent with our data. It is doubtful whether postpartum detection of scar separation has a prognostic value in the management

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of future pregnancies. Patients with non bleeding, uncorrected dehiscence discovered after delivery, who had subsequent elective C / S, were reported to have no evidence of scar dehiscence at that time [18]. Indeed, in our study, patient no. 3 had a history of prior dehiscence of uterine scar. This woman underwent laparotomy for asymptomatic scar dehiscence after delivery, however, no further surgical intervention was needed in addition to the scar repair. In addition, the revision of the scar may still miss the detection of dehiscence and also the intervention may possibly make dehiscence more serious. Recently, Rosenberg et al. [27] introduced ultrasonographic measurements of lower uterine segment to assess the potential risk of uterine rupture in patients who have previously had cesarean delivery. The authors showed that the risk of a defective scar is directly related to the degree of thinning of the lower uterine segment (,3.5 mm) at around 37 weeks of gestation. With the above cut-offpoint, the sensitivity of ultrasonographic measurements was 88%, the specificity 73.2%, positive predictive value 11.8%, and negative predictive value 99.3%. In conclusion, there is no benefit of routine examination of uterine scar after VBAC. Transcervical examination should be performed only in symptomatic patients. The roll of ultrasonographic examination of uterine lower segment to predict scar dehiscence or rupture, should be further evaluated in future studies.

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