Rupture of the uterus

International Journal of Gynecology& Obstetrics49 (1995)9-15

Article

Rupture of the uterus M. Saglamtas, K. Vicdan *, H. YalCin, Z. Yllmaz, H. Yegilyurt, 0. Giikmen Dr Zekai Tahir Burak Women> Hospital, Ankara, Turkey

Received16 September1994;revision received15December1994;accepted21 Lkcember 1994

Abstract Objectives: To investigate the frequency of ruptured uterus, possible etioiogic factors and fetomaternal outcomes. Metho&: The birth records of 58 262 deliveries at Dr Zekai Tahir Burak Women’s Hospital from 1 January 1990to 31 December 1992were reviewed and the results compared with those of two previous studies reported from this hospital on the samesubject. Results: Forty uterine ruptures occurred between 1990and 1992,with a frequency of 0.068% (l/1457). All occurred spontaneously but 10 (25%) had no previous surgery, whereas 30 followed previous cesarean section. There was no traumatic uterine rupture during this period. Fetal mortality was 32.5%and no maternal deaths were recorded. Conclusion: The rate of ruptured uterus has declined among our hospital population as etiologic factors responsible for the complication have been reduced. Keywords: Uterine rupture; Uterine dehiscence

1. Introduction Rupture of the pregnant uterus is an emergency condition causing high fetomaternal mortality and morbidity. Various incidences, etiologic factors and fetomatemal mortality and morbidity rates have been reported from different countries and even from different areas within those countries. In the developed countries, where antenatal and obstetric care is adequate, its frequency and that of fetomatemal mortality have gradually declined l Corresponding author, Giivenlik Cad.,AlidedeSok.,23/4 06540,A. Ayrancl, Ankara, Turkey, Tel.: +90 3124262012.

over the years and now the main etiologic factor is dehiscence of previous cesarean section scar [ 1,2]. However in the developing countries, the occurrence of uterine rupture remains high due to the inadequate level of obstetric care as well as the high frequency of home deliveries and grand multiparitY [31. In this retrospective study, we investigated the frequency of ruptured uterus, its possible etiologic factors and fetomatemal outcomes between 1990 and 1992 at Dr Zekai Tahir Burak Women’s Hospital. The results were compared with two previous studies reported from this hospital between 1962 and 1967 and between 1980 and 1985.

0020-7292/95/$09.50 0 1995International Federationof Gynecologyand Obstetrics SSDI 0020-7292(95)02333-8

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2. Materials and methods

vious two studies reported from this hospital on the same subject between 1962 and 1967 and between 1980and 1985and compared their results in order to determine the differences in incidences, etiologic factors and fetomaternal outcomes. The patients with uterine rupture were divided into two groups, those with a scarred uterus due to previous cesarean section and those with an unscarred uterus. The patients with a scarred uterus were then subdivided into those with rupture of a cesarean section scar and those with dehiscenceof a cesareansection scar [4]. Rupture was defined as separation of the old uterine incision throughout its length with rupture of fetal membranes and communication between the uterine and peritoneal cavities. Thus, all or part of the fetus usually extruded into the peritoneal cavity and there was generally bleeding from the edgesof the scar or from extension into previously uninvolved uterus. The term uterine dehiscence was used when the fetal membraneswere not ruptured and therefore the fetus did not extrude into the peritoneal cavity. Typically, with dehiscence the separation does not involve all of the previous uterine scar and therefore bleeding is absent or minimal [4].

The birth records of 58 262 deliveries at Dr Zekai Tahir Burak Women’s Hospital from 1 January 1990to 31 December 1992were reviewed and 40 casesinvolving uterine rupture were identified. The records of these patients were then retrospectively analyzed to determine the possible etiologic factors and fetomaternal outcomes. Improving antenatal and obstetric care at our hospital has in recent years produced a decreasein obstetric complications including spontaneous and traumatic uterine rupture. Until recently there were insufficient staff, both in terms of number and quality, including specialists, residents, nurses, anesthesiologists, neonatologists, sonographers, geneticists and other necessarystaff and equipment to provide adequate care. However, since 1990 there has been rapid progress and a multispeciality approach. Now our hospital is the largest single branch hospital in Turkey, with a 600 bed capacity and it is the main referral hospital in the district. An antenatal clinic and new obstetric and neonatology units are currently in use. We can now provide antenatal care for more patients, continuous electronic fetal monitoring, ultrasound, a 24-h blood bank and other laboratory services,on-site anesthesia, and many physicians capable of performing a cesareansection and other necessaryinterventions in labor, and the ability to move from decision to incision within a few minutes. We have therefore also reviewed the pre-

3. Results In the 3-year period between 1990 and the end of 1992,58 262 women were delivered at this hospital and 40 uterine ruptures occurred, with a fre-

Table 1 Incidence of uterine rupture, rate of cesarean section, fetal and maternal mortality No. of deliveries

1990 1991 1992 Total 1980-1985 1962-1967

Cesarean section

Uterine rupture

Fetal mortality

Maternal mortality

n

%

n

n

%

n

“Al

21813 18 317 18 132

3326 3082 3212

15.2 16.8 17.7

24 8 8

1I909 112289 112266

8 3 2

33.3 37.5 25

-

-

58 262 102097 53 924

9620 7703 NA

16.5 7.5 NA

40 112 119

l/1457 l/l92 11452

13 24 85

32.5 21.4 71.4

2 16

NA, data not available.

Rate

1.78 13.44

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et al. /International

Journal

Table 2 Classification of uterine ruptures Traumatic rupture

Spontaneous rupture

1990 1991 1992 Total

Scarred uterus

Unscarred uterus

”

%

n

18 8 4 30

15 100 50 75

1980-1985 67 1962-1967 28

59.8 24.7

%

n

%

6

25

-

-

4 10

50 25

-

-

38 81

33.2 67

10

1

6.25 8.4

quency of 1 in 1457 (0.068%). Table 1 shows the total number of deliveries and the incidence of ruptured uterus in this period compared with previous years. While 10 ruptures (25O/,)occurred in the unscarred uterus, 30 were in casesof previous cesareansection. All casesoccurred spontaneously and there was no traumatic rupture during this period. Between 1980and 1985and 1962and 1967 the rate of traumatic rupture was 6.25% and 8.4%, respectively (Table 2). In the 3-year period between 1990and 1992, 9620 cesareansections were performed at a rate of 16.5%. This rate gradually increased over the years, from 15.2% in 1990, to 16.8%in 1991and 17.7%in 1992,while it had been only 7.5% between 1980 and 1985. In 2000 cases (20.8%) the indication was previous cesarean section, 1527having one prior operation and 473 havTable 3 Incidence of ruptured uterus in casesof previous cesareansection (C/S) No. of rupture

No. of cases n

%

n

Rate

1 c/s > 1 c/s

1527 413

76.35 23.65

19 11

1180 l/47

Total

2000

20.8

30

l/66

of Gynecology

& Obstetrics

49 (1995)

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ing more than one. The incidence of rupture in patients with previous surgery was 1 in 66, 19 of whom (l/80) had one previous cesarean and 11 (1147)had more than one (Table 3). Table 4 shows the possible etiologic factors identified in thesepatients, nine of whom (22.5%) had visited the antenatal clinic during their pregnancy and all were in the scarred group. The agesof 70% of those in the unscarred group ranged from 30 to 39 years and in 76% of those in the scarred group ranged from 20 to 29 years. Ninety percent of those with an unscarred uterus were multiparous, with a mean parity of 3. In the scarred group 19 had undergone one and 11 more than one cesarean and all had had a low transverse uterine incision. No patients had a classical uterine scar. All patients in both groups were in active labor when they were admitted to hospital, therefore it was not possible to establish the average length of labor. According to our hospital policy, we abide by the ‘once a section, always a section’ rule and all patients with previous sections undergo operation except those admitted to hospital late in labor with a fully dilated cervix. The diagnosis of scar rupture was therefore made in all casesduring cesareansection and none on routine opening of the abdomen for dated elective cesareansection in this series. Half of the casesin the unscarred group were diagnosed during admission for labor and half after delivery. The most common symptoms in these patients were tachycardia, hypotension, uterine bleeding, abdominal pain or tenderness, absence of fetal heart sound and some abnormalities of various severity on electronic fetal monitoring. There were no maternal symptoms but fetal heart rate abnormalities were detectedin nine casesof scar rupture. The rupture site was the lower segment in all cases.Scar dehiscenceoccurred in 76.6%and complete true rupture in 23.3% of patients; live patients had broad ligament hematoma. In the unscarred group, rupture was incomplete in three patients and complete in seven; six patients had broad ligament hematoma (Table 5). While hysterectomy was more commonly carried out in the unscarred group (70%), repair of the uterus was the commonest treatment in those with uterine scarring (83.3%). There were no bowel, bladder or ureteral injuries in either group, but blood transfu-

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Journal of Gynecology & Obstetrics 49 (199s) 9- I5

Table 4 Possible etiologic factors identified in casesof ruptured uterus Etiologic factor

1990-1992

Prior cesarean Forceps or vacuum delivery Internal version Destructive operation Large baby Prolonged labor and oxytocin induction Breech delivery Transverse lie Unknown

1980-1985

n

%

30 -

75 5 12.5

67 3 3 1 10 13

2.5

3 3 9

2 5 1 -

Total

n

2

1962-1967

5

40

n

% 59.8 2.6 2.6 0.9 9 11.6 2.6 2.6 8.03

112

%

28 4 2 4 14 17

23.5 3.4 1.7 3.4 11.8 14.3

3 29 18

2.5 24.4 15.1

119

group, the rate was 26.6% (8/30) in the scarred group. In the scarred group, two fetuseswith macrosomia died after shoulder dystocia, one after a breech delivery due to entrapment of the head and two before admission in patients with uterine rupture of unknown etiology. Thus three fetusesdied during labor and two had already died in the uterus before admission (Table 6). In the scarred group, there were eight fetal deaths, two occurring before admission and six in the early neonatal period. Seven occurred in patients with complete rupture and in one with uterine dehiscence. The most common causes of early neonatal death in these babies were prematurity and respiratory distress syndrome in three and intrauterine asphyxia

sion and duration of operation and hospitalization were higher in patients with unscarred than in those with scarred uterus. There was no maternal mortality during this period whereas between 1962 and 1967 and 1980 and 1985 it was 13.44% and 1.78%, respectively. This decrease in maternal mortality can be attributed to the increasing number of patients seeking antenatal care and to progress in obstetric care as well as to the decreasing rate of home deliveries and grand multiparity in our district. The fetal mortality rate in this serieswas 32.5% (13/40), but all deaths occurred in unregistered patients except for one with a previous cesarean section. While 50% (5110) of the fetuses died in the unscarred Table 5 Type of rupture, management and fetal mortality rates

Rupture in unscarred uterus Rupture in scarred uterus Total

Complete rupture

Incomplete rupture

Total abdominal hysterectomy

Subtotal abdominal hysterectomy

Fetal death

n

%

n

%

n

%

”

%

n

%

7 7

70 23.3

3 23

30 76.6

5 2

50 6.6

2 3

20 10

3 25

30 83.3

14

35

26

65

7

17.5

5

12.5

28

70

Repair

n

%

5 8

50 26.6

13

32.5

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Journal of Gynecology & Obstetrics 49 (1995) 9-15

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Table 6 Fetal mortality rates in casesof ruptured uterus No. of ruptures

1990-1992 1980-1985 1962-1967

40 112 119

Neonatal death

6 NA NA

Death during labor

3 NA NA

Intrauterine death on admission

n

O/u

4 NA NA

13 25 85

32.5 21.4 71.4

Total

NA, data not available.

in three. Although the perinatal mortality rate of 32.5% between 1990 and 1992 was high in comparison with the 1980-1985 period, it should be borne in mind that data regarding the neonatal period were not available between 1980 and 1985. Neverthelessthis rate is still unacceptably high. It may be due to late arrival at the hospital in established labor and the lack of adequate antenatal care due to unawareness or low socioeconomic status of these patients. 4. Discussion Rupture of the pregnant uterus is an unexpected and devastating complication of pregnancy with high fetomatemal mortality and morbidity. Although its general frequency has declined over the years, it is tending to increasein the developing countries. The highest reported incidence was 1 in 93 deliveries in Uganda [5] and 1 in 167 and 1 in 416 deliveries in Nigeria [3,6]. The incidence of ruptured uterus is strictly related to the level of obstetric and antenatal care available in a country and is therefore very rare in the developed countries. The reported incidence is 1 in 1500 in the USA [7], 1 in 2500 in Ireland [8] and Canada has the lowest reported incidence of 1 in 11 365 [9]. In our hospital, the frequency of ruptured uterus was 1 in 452 between 1962 and 1967 [lo], 1 in 912 between 1980and 1985 [1 l] and 1 in 1457in this last series.Fortunately, it showed a decreasefrom 1 in 909 in 1990 to 1 in 2289 in 1991 and to 1 in 2266 in 1992. In addition to the decrease in incidence, etiologic factors have changed considerably. The fre-

quency of rupture in the unscarred uterus as well as traumatic rupture have clearly declined but the number of scar ruptures has been increasing as a consequence of the increasing rate of previous cesareansection [ 1,2]. Factors which play a role in the etiology of spontaneous rupture, including multiparity [12,13], anomalies of presentation, large baby, fetal anomalies such as hydrocephalus, uterine anomalies and placental defects, can now be diagnosed earlier in pregnancy and these complications can be minimized with close follow-up of high-risk patients both antenatally and during labor [ 121.Traumatic ruptures are now rare because the causative factors, including destructive operations, forceps or vacuum deliveries, version, excessivefundal pressure, and manual removal of the placenta, are infrequently required. The earlier diagnosis of fetal anomalies, the more liberal use of cesarean section and close monitoring of patients during labor have also contributed to this reduction [2,12]. As seenin Tables 2 and 4, the improving level of antenatal and obstetric care in our hospital has produced a fall in the incidence of spontaneous and traumatic rupture. However the rate of scar rupture has gradually been increasing as a result of the increasing rate of cesareansection [l-3,5-9,12-15]. In the USA the rate of cesareansection was 4.5% in 1965,reaching 24.1%by 1986 [15, 161.At our hospital the rate of cesareansection was 7.5% between 1980and 1985 and 16.5%between 1990 and 1992 (Table 1). The main factor responsible for the increasing rate of cesareansections is previous cesareansection [ 171. Most clinics practice ‘once a section, always a section’ becauseof fear of uterine rupture, however

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Journal of Gynecology & Obstetrics 49 (1995) 9-15

some clinics advocate that vaginal delivery after cesarean section is safe if the indication for the previous cesarean no longer exists [2]. Although the patients with classic scarring carry a high risk for uterine rupture and it is associated with high fetomaternal mortality and morbidity [4], scar rupture or dehiscence after a low transverse uterine incision is uncommon, ranging from 1 to 2% in most series [18-201. In addition, the vast majority of these cases are asymptomatic silent ruptures, discovered only at the time of cesarean section or after vaginal delivery if the lower uterine segmentis palpated in a previously scarred uterus [2,12,15,17].In contrast to spontaneous rupture of an unscarred uterus, separation of a previous low transverse scar is not associated with significant maternal and perinatal morbidity and mortality [21, 221. Recent evidence suggests that trial of labor is appropriate in patients with one or even more prior cesarean sections [22,23], and the use of oxytocin during labor is also safe [2]. However we have insufficient experience of vaginal delivery following previous cesarean section. Maternal mortality rates of up to 50% and fetal mortality rates of up to 75-100% were quoted at the beginning of this century [12]. Maternal mortality is currently very uncommon but fetal mortality is still high and the reported rates are between 14.2%and 96% [24-261. Although maternal mortality at our hospital was 13.44%between 1962and 1967and 1.78%between 1980and 1985,there was no maternal mortality between 1990 and 1992. Neverthelessfetal mortality is still high (32.5%). It has been reported that if pregnant women were made aware of the benefits of antenatal care and if good obstetric services were available for all pregnant women, a large number of uterine ruptures and their resultant morbidity and mortality could be avoided [26]. A high frequency of maternal morbidity and perinatal mortality in our patients is mostly due to inadequate antenatal clinic visits and late arrival at hospital during labor. In conclusion, this retrospective study shows that the rate of ruptured uterus has clearly declined in our country as a result of improving obstetric and antenatal care. The etiologic factors responsible for this complication have also changed and the most commonly encountered rupture today is in the scarred uterus. If the current rising

trend in cesareansection rates continues, scar rupture is likely to be encountered more frequently. Although the rate of scar rupture has been increasing, most are fortunately asymptomatic and incomplete ruptures which do not causecatastrophic results and which can be easily managed. While maternal mortality is extremely rare, perinatal mortality rates are still unacceptably high. Antenatal care should be provided for each pregnant woman and the labor of high-risk patients carefully managed in order to decreasethe rate of perinatal mortality.

References

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