Unknown uterine scar and trial of labor

Unknown uterine scar and trial of labor Kathleen M. Pruett, MD, Brian Kirshon, MD, and David B. Cotton, MD Houston, Texas A review of 393 patients undergoing trial of labor after one or more previous cesarean sections was performed. Three hundred patients had an unknown uterine scar, 88 patients had a documented low cervical transverse incision, and five patients had a prior low vertical incision. The rate of vaginal delivery and maternal and fetal morbidity was no different in those patients with an unknown prior uterine incision compared with those having a known prior low cervical transverse incision. In 66 of the patients with a documented low cervical transverse incision, the original operative record was reviewed in regard to single-layer closure of the uterine incision versus double-layer closure or imbricating technique. No patient with a double-layer uterine closure had a subsequent dehiscence, whereas three patients with a prior single-layer closure exhibited scar separation. These data suggest that neither an unknown scar nor a single-layer uterine closure places the mother or fetus at greater risk. (AM J OesTET GvNECOL 1988;159:807-1 0.)

Key words: Vaginal birth, unknown scar

Success rates for vaginal birth after cesarean section have ranged from 66%' to 82%.2.3 Beall et al! reported on the results of vaginal birth after previous cesarean section and concluded that a trial of vaginal birth even in the presence of an unknown scar did not pose a significantly increased risk of fetal or maternal morbidity or mortality. It has not previously been discussed whether a single-layer uterine closure technique that does not include imbrication has an effect on the outcome of vaginal birth after cesarean section. It was the objective of this study to demonstrate that prior unknown uterine incision in patients undergoing trial of labor does not place the mother or fetus at a greater risk than that which occurs in patients with a known incision type. Additionally, the safety of a single-layer uterine closure as opposed to double-layer closure was likewise investigated in patients with a prior low cervical transverse cesarean incision. Patients and methods

A review of 393 patients undergoing a trial of labor after previous cesarean section at Jefferson Davis Hospital in Houston, Texas, between July 1984 and December 1985 was performed. All patients who presented in spontaneous labor or had an obstetric indication for induction of labor were offered a trial of From the Department of Obstetrics and Gynecology, Baylor College of Medicine. Received for publication September 24, 1987; revised january 20, 1988; accepted April19, 1988. Reprint requests: Brian Kirshon, MD, Department of Obstetrics and Gynecology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030.

labor. A trial of labor was offered regardless of the number of previous cesarean sections. The sole exception was in a patient with a previous classic cesarean section. Informed consent was obtained after the attendant risks were explained, including the possibility of uterine rupture and maternal and/ or fetal distress or death. A large-bore intravenous catheter was placed and samples for routine laboratory tests and pretransfusion studies were obtained. Type and crossmatching studies were done in patients with a hematocrit level <30%; otherwise, type and screen studies were performed. Amniotomy was performed, and an internal pressure catheter and a fetal scalp electrode were inserted. Continuous fetal monitoring was used throughout labor in all patients. In some instances oxytocin was used to augment labor if inadequate uterine contractions were believed to be present accompanied by poor progress in labor. Epidural anesthesia was offered to all parturient women. The lower uterine segment was routinely palpated transvaginally after successful vaginal delivery to assess the status of the previous uterine scar. Complete uterine rupture was defined as separation of the previous scar with associated maternal and fetal distress. Incomplete uterine rupture or dehiscence was defined as asymptomatic separation of the uterine scar.' Statistical analysis of the data was performed by the X2 test. Statistical significance was defined asp < 0.05. Results

Three hundred ninety-three patients undergoing trial of labor after previous cesarean section were seen

807

October I 'JHH Am.J Obstet (:yne
Table I. Mode of deh>en

!

------.------------

Unknown (n =

No.

Vaginal delivery Repeat cesarean section

186 114

300)

l

Low cervical tramverse cesarean section (n = 88)

%

No.

62 38

46 42

J

% 52.3 47.7

at jefferson Davis County Hospital between july 1984 and December 1985. Successful vaginal delivery occurred in 59%. Three hundred forty-three patients had undergone one cesarean section, whereas 50 patients had a history of two or more prior cesarean sections. In the subset of patients with more than one previous cesarean section, the rate of vaginal delivery was 45%. ·r·he study population consisted primarily of indigent patients with inconsistent prenatal care. However, whenever possible, a copy of the operative record from the previous cesarean section was obtained. The previous uterine incision was unknown in 76.3% of the patients, with 22.4% having a documented low cervical transverse incision. Five patients had a known low vertical incision. The study group comprised 300 patients with an unknown previous scar. One hundred eighty-six patients had a successful vaginal delivery, whereas 114 patients underwent repeat cesarean section for either failure to progress or fetal distress. Similar results were seen in the group of patients with a documented low cervical transverse incision (Table I). The reasons for the prior cesarean sections are presented in Table II. The integrity of the previous scar after trial of labor was also compared between the two groups. During the period of time covered by this study, there was only one true uterine rupture. A 24-year-old woman, gravida 4, para l, abortions 2, presented at 36.5 weeks' gestation and was being monitored to evaluate labor when fetal distress developed. Repeat cesarean section was performed, at which time gross uterine rupture of a previous vertical incision was present with 1500 ml of intraabdominal blood. A female infant with an Apgar score of 9 at 5 minutes was delivered. The cord pH was 7.02. The operative hematocrit level was 25%, and two units of packed red blood cells were transfused. The uterine defect was repaired and the patient had an uncomplicated postoperative course. The incidence of uterine dehiscence was 3.4% and 2.6% for the low cervical transverse and the unknown incision groups, respectively. In the five patients with known low vertical incisions, there were no uterine ruptures. Table

Table II. Indications for previous cesarean section (n = 393) Fetal distress Cephalopelvic disproportion/ failure to progress Breech Twins Pregnancy-induced hypertension Abnormal presentation other than breech Placenta previa Fetal death Herpes Unknown reasons

48 182

68 6 II 4 12

2 3 57

III examines those patients with incomplete uterine rupture. As was mentioned previously, oxytocin was used in selected patients for either augmentation or induction of labor. One patient received two suppositories of prostaglandin Ee 3 mg intravaginally followed by oxytocin for a postdates induction of labor and at delivery was noted to have an intact scar. Oxytocin was used in 35% and 33% of patients with unknown and low cervical transverse scars, respectively. No difference was noted between the two groups in regard to method of delivery. However, when the use of oxytocin was reviewed for both groups combined, the rate of vaginal delivery was decreased when oxytocin was required (Table IV). which agrees with the work of Paul et al.' The most common causes of postpartum febrile morbidity were endometritis, pyelonephritis, and wound infection. The incidence of postpartum endometritis was not significantly different between the two groups when trial of labor failed and repeat cesarean section was performed. The incidence of endometritis was significantly reduced in those patients who had a vaginal delivery, regardless of prior incision type (p < 0.01). One patient presented at 43 weeks' gestation with a history of prior cesarean section because of failure to progress and a documented low cervical transverse incision. She underwent repeat cesarean section because of fetal distress. The postpartum course was remarkable for a protracted course of endometritis, and she underwent exploratory laparotomy for drainage of a periovarian abscess. Two neonates had 5-minute Apgar scores <7. One infant was born precipitately on arrival to the labor and delivery service with a !-minute Apgar score of 3 and a 5-minute Apgar score of 6. The infant died at l day of age as a result of sepsis. The second infant had Apgar scores of 2 and 6 at I and 5 minutes, respectively; however, the umbilical arterial pH at delivery was 7.33. All other neonates had 5-minute Apgar scores >7. In 66 patients with a known low cervical transverse incision, the operative report for the prior cesarean

Vaginal birth after unknown cesarean scar

Volume !59 Number 4

809

Table III. Patients with incomplete uterine rupture*

Patient

Gestational age

Previous scar

No. of prior CIS

Mode of delivery

40 38.5 41.5 42 39 40 40 36 40 42 40

u u u u u u u u

I I I I I I

Repeat CIS Repeat CIS Repeat CIS Repeat CIS Repeat CIS Repeat CIS Repeat CIS Repeat CIS Vaginal Repeat CIS Repeat CIS

I

2 3 4 5 6 7 8t 9 10

II

LCT LCT LCT

2 2 I I

1

Pitocin (mUimin)

Epidural

None 6 None 12 3 None 3 1.5 None 12 1.5

Yes Yes Yes Yes No Yes No Yes Yes Yes Yes

EBL (ml)

Indication for previous cesarean section

700 800 900 700 1800 500 1200 1500 500 800 700

FTP CPD Breech FTP CPD FTP FTP, repeat Breech, repeat CPD Breech CPD

U = Unknown previous inCisiOn; CIS = cesarean section; EBL = estimated blood loss; LCT =low cervical transverse; FTP = failure to progress; CPD = cephalopelvic disproportion.

*All 5-minute Apgar scores >9. tHysterectomy, placenta accreta proved histologically.

Table IV. Oxytocin use and mode of delivery Oxytocin (n = 134) Unknown (n = 105)

Vaginal delivery

42 (40%)

I

LCT (n = 29)

No oxytocin (n = 259)

12 (41.4%)

182 (70.3%)*

LCT = Low cervical transverse cesarean section.

*p < 0.001. section was available to be reviewed. The type of uterine closure was compared with regard to integrity of the scar. In 57 patients the original uterine incision was closed in a single layer, and three patients subsequently had a scar separation during trial of labor. In nine patients a double-layer closure or imbricating technique was used; there were no scar separations in this group. There were no complete uterine ruptures in either group. Of the three patients with uterine dehiscence in the group with single-layer closure, only one received oxytocin augmentation.

Comment The success rate of vaginal birth after cesarean section in our patients was 59%. This was comparable to that found by other investigators.'·' In our patients the type of prior incision, low cervical transverse versus unknown, did not significantly alter the incidence of subsequent vaginal birth. Documentation of the type of prior uterine incision has previously been a prerequisite to allowing a patient to undergo a trial of labor, because low vertical or classic incisions have a larger likelihood of uterine rupture. To test this theory, Tahilramaney et al." compared the type of prior uterine incision, including low cervical transverse, low vertical, low vertical or fundal, and unknown, with the mode of delivery and incidence of uterine dehiscence. They concluded that there was no

significant difference between the different types of uterine scars and the incidence of uterine dehiscence. We and others have demonstrated that the incidence of uterine dehiscence is not statistically increased with an unknown scar over that seen in patients with a prior low cervical transverse incision.'· 4 The use of oxytocin in patients undergoing trial of labor remains a controversial issue. Flamm' presented a review of 600 cases from the literature in which the use of oxytocin was not shown to cause an increase in maternal or fetal morbidity or mortality. Our data are consistent with the finding that oxytocin augmentation is not related to a significantly increased incidence of uterine dehiscence. In the patients with an inadequate labor mechanism necessitating oxytocin augmentation, the rate of vaginal birth was decreased below that of patients in whom oxytocin augmentation was not necessary (p < 0.001 ). This is in accordance with the data of several authors. 3 · 1 · 7 · R The reported incidence of uterine dehiscence ranges from 0.7% 9 to 6%' 0 in patients undergoing a trial of labor. In this study the incidence of uterine dehiscence in those patients having a single-layer uterine closure was 5.2%. The overall incidence of uterine dehiscence in our series was 2.8%. It would appear that the incidence of uterine dehiscence is slightly greater with the single-layer closure; however, the risk of catastrophic

Pruett, Kirshon, and Cotton

rupture does not appear to be increased. Our numbers are small and indicate only a trend. We believe more patients with each type of closure should be examined before a definitive statement can be made. We conclude that allowing a trial of labor in a patient with an unknown uterine scar does not place the mother or fetus at greater risk than the risk for a patient with a known low cervical transverse incision. Oxytocin use does not increase the incidence of uterine dehiscence and may be used judiciously in the laboring patient with a prior uterine incision. Finally, although the risk of uterine dehiscence may be slightly increased with single-layer closure compared with that of double-layer closure, the overall rate of dehiscence is comparable to that of prior reports on trial of labor after previous cesarean section."· 7 This study recommends this tech·· nique as safe for a trial of labor. REFERENCES I. Lavin JP, Stephens RJ, Miodovnik M, et al. Vaginal delivery in patients with a prior cesarean section. Obstet G}necol 1982;59:135.

October 1988 Am J Obstet Gynecol

2. Amir W, Peter J, Etan Z. Trial of labor without oxytocin in patients with a previous cesarean section. Am J Perinato! 1987;4:140. 3. Paul RH, Phelan JP, Yeh SY. Trial of labor in the patient with a prior cesarean birth. AM J OBSTET Gn>ECOL 1985;151:297. 4. Beall M, Eglinton G, ClarkS, et al. Vaginal delivery after cesarean section in women with unknown types of uterine scar. J Reprod Med 1984;29(suppl):3l. 5. Flamm BL. Vaginal birth after cesarean section: controversies old and riew. Clin Obstet Gynecol 1985;28:735. 6. Tahilramaney MP, Bouocher M, Eglinton GS, et al. Previous cesarean section and trial of labor: factors related to uterine dehiscence. J Reprod Med 1984;29(suppl): 17. 7. Horenstein JM, Eglinton GS, Tahilramaney MP, et al. Oxytocin use during a trial of labor in patients with previous cesarean section. J Reprod Med 1984;29(suppl 1): 26. 8. HorensteinJM, PhelanJP. Previous cesarean section: the risks and benefits of oxytocin usage in a trial of labor. AM j 0BSTF.T GYNECOL 1985; 151:564. 9. Whiteside DC, Mahan CS, Cook JC. Factors associated with successful vaginal delivery after cesarean section. J Reprod Med 1983;28:785. 10. Eglinton GS, Phelan JP, Yeh SY, et al. Outcome of a trial of labor after prior cesarean delivery . .J Reprod Med 1984;29:3.

The use of transvaginal sonography for evaluation of postmenopausal ovarian size and morphology M. Hellen Rodriguez, MD, Lawrence D. Platt, MD, Arnold L. Medearis, MD, Maria Lacarra, RN, and Rogerio A. Lobo, MD Los Angeles, California Ultrasonic evaluation has been suggested as a possible screening tool for early changes in ovarian morphology. This study uses transvaginal sonography to evaluate the ovaries in postmenopausal women who were scheduled for gynecologic surgery unrelated to adnexal disease. The findings of ultrasonic ovarian examination are compared with the findings at surgery and the pathologic evaluation of the ovaries. Nine (17.3%) abnormal ovaries were identified by ultrasonography and at surgery and were confirmed at pathologic examination. Among the abnormal ovaries there were one malignancy (10%) and two neoplasmswith known malignant potential (20%). One ovary that was identified to have microscopic areas of Brenner tumor cells at pathologic examination was described as normal by both ultrasound and surgical evaluation. The sensitivity (90%) and specificity (100%) of vaginal sonography were the same as that of gross examination of the ovary at the time of surgery. We conclude that vaginal sonography is a reliable tool in the detection of early abnormalities in the postmenopausal ovary. (AM J OssTET GYNECOL 1988;159:810-4.)

Key words: Transvaginal ultrasound, ovarian cancer screening, postmenopausal ovary ultrasound From the Department of Obstetrics and Gynecology, University of Southern California School of Medicine and Women's Hospital, Los Angeles County/University of Southern California Medical Center. Received for publication December 14, 1987; revised April 7, 1988; accepted May 17, 1988. Reprint requests: M. Hellen Rodriguez, MD, Perinatology Center, Queen of the Valley Hospital, 1135 S. Sunset Ave., Suite 402, West Covina, CA 91793.

810

Ovarian carcinoma is the leading cause of death from gynecologic malignancy in the United States. 1 The high death rate has been attributed to the observation that in as many as 60% of patients, the ovarian carcinoma is diagnosed when the neoplasm has spread beyond the pelvis. This delay in diagnosis is basically the result of the inability to detect early changes in the ovaries by