Evaluation of Risk Factors Associated with Recurrent Cesarean Section Morbidity

Based on individual risk factors, a scoring system was developed to predict the cesarean section morbidity.

Abstract

Objective: To determine the risk factors related to recurrent caesarean section (C.S) morbidity and to suggest a morbidity scoring system based on these risk factors which can help in the prediction of C.S. morbidity.

Patients & Methods: This prospective study included 1000 women undergoing Caesarean Section (C.S) under general anaesthesia, divided into two groups: Group (1): Control Group,500 patients, who underwent C.S for the first time. Group (2): Study Group, 500 patients who had one or more previous C.S. Simple scoring system was developed to record the possible risk factors related to C.S morbidity. 

Results: There were 6 significant pre-operative risk factors. These are: high parity, preterm delivery, placenta praevia, antepartum haemorrhage, medical disorders and bad general condition. There were 5 highly significant risk factors related to intra-operative morbidity which were: high parity, placenta praevia, intra-peritoneal adhesions, low experienced surgeon (P<0.001) and preterm gestational age (P<0.01) and 5 risk factors related to previous C.S operation these were: previous 3 or more C.S (P<0.01), previous C.S at rural hospital or private clinic (P<0.001), previous upper segment C.S (P<0.05), previous complicated C.S (P<0.05) and tender previous scar (P<0.01). Eleven factors related to post-operative morbidity were more significant in the repeated C.S. group. The incidence of overall morbidities were significantly more in the repeated C.S group. Total post-operative morbidity was highly significant starting from previous 4 or more C.S Risk factors related to intra-operative morbidity were used to develop a morbidity scoring system.

Conclusion: Based on a summation of logistic coefficient corresponding to individual risk factor, a scoring system was suggested which can help in the prediction of C.S. morbidity. Further prospective evaluation of this scoring system would be helpful to confirm the usefulness and practicality of this system.

Key words :caesarean section, repeated caesarean, maternal morbidity, risk factors, scoring system.

Tables will open in new windows for easy reference.Introduction & Aim of Work

The Caesarean Section (C.S) rate has increased at an accelerated pace over the past two decades from 5% to 25% in the United States and some other countries ⁽¹⁾, with repeat C.S accounting for as much as 35% to 50% of the increased abdominal deliveries⁽²⁾. A post-partum history of four or more previous caesarean sections is a clear risk factor for intra-operative complications ⁽³⁾.There is objective evidence to support the widely held view that multiple C.S predispose to an increased risk of uterine rupture, severe intraperitoneal adhesions, significant haemorrhage, placenta praevia, placenta acreta, bladder injury and hysterectomy, etc. ^{(3)(4)(5)(6)(7)(8)(9)}.

The rapid increase in C.S rate ⁽²⁾ may lead to a higher number of women facing multiple C.S. Despite their need for information regarding the safety of additional C.S, little data are available ⁽⁵⁾. The rapidly increasing number of diagnostic and therapeutic options, the quality demands of patients and the public, and the emphasis on cost containment all contribute to the need for more explicit clinical reasoning and decision making ⁽¹¹⁾.

This study has been done to determine the risk factors associated with recurrent C.S morbidity (intra- and/or post-operative) and to develop a scoring system, which can help in the prediction of C.S. morbidity and may affect the decision for the current and future pregnancy. 

Subjects & Methods 

This prospective study was performed on 1000 women undergoing C.S delivery, under general anaesthesia, at Al-Azhar University Hospitals, Cairo, Egypt, during a 16 month period from December 1999 to April 2001.

The patients were classified into two groups. The first group included 500 patients who underwent C.S for the first time (control group). The second included 500 patients who had one or more previous C.S. (study group) or (repeated C.S group). All patients in the control group (with no previous uterine scar) or in the study group (with previous uterine scar) were admitted to the hospital for C.S operation.

A detailed history and general, abdominal and pelvic examination were done for each patient. An intra-venous line was connected and a blood sample was taken for haemoglobin (Hb) estimate and cross-matching for a blood transfusion if needed. Ultrasonography was done for patients who had no previous sonographic report or not requiring an urgent C.S. All pre-operative data were recorded in a simplified form designed by the research workers.

All patients underwent C.S. under general anaesthesia in the same operation room for emergency C.S. (connected with the delivery department). All data of intra-operative findings, operative procedures, morbidities and assessment of the newborn data was recorded in a simple data record. 

As the estimate of intra-operative blood loss is subjective and can be inaccurate, comparison of preoperative and postoperative haemoglobin for all patients in both groups provided more objective measures to estimate this finding. Also, patients who needed the transfusion of one or more units of blood during their C.S. operation were recorded so as to determine whether their intra-operative bleeding was moderate or severe.

All patients were observed post-operatively for at least 5-7 days for early detection of any post-operative complication and its management. Follow-up of the newborns and the premature babies who were admitted to the pre-mature baby center and their data were also recorded.
Several risk factors can contribute to C.S. morbidity ^{(3)(4)(5)(6)(7)(8)(9)(10)}.To decide about these risk factors, a scoring system was developed to record the possible risk factors and the different morbidities. Data was recorded for all patients in a manner of a simplified scoring system composed of 0,1,2 for both the pre-operative and intra-operative risk factors on one hand; and the intra-operative and post-operative morbidities on the other hand. The definition of this scoring system was :

For The Risk Factors: 

0: No risk factor 

1: The risk factor may be a cause of morbidity

2: The risk factor is a cause of morbidity

For The Morbidity: 

No = 0 : No abnormality detected

Yes = 1: Mild or moderate degree of morbidity

2 : Severe degree of morbidity

Statistical Evaluation

Statistical analysis by one way analysis of variance (ANOVA) was done between the control and repeated C.S. groups to determine the significant risk factors. 

Each morbidity was statistically analysed and compared to that of the control group. The study group was statistically evaluated to correlate between the number of previous C.S and morbidity. Total scores of risk factors which are included in cases with either intra and/or postoperative morbidity were compared in both groups to evaluate which factor lead to morbidity.

Multivariate logistic regression analysis of pre and intraoperative risk factors was done as separate variables, then the strongest risk factors related to each morbidity were included in logistic regression analysis for the study group to determine the risk factors that dependently and significantly influence or lead to specific morbidity. 

Multi-variate analysis allows each variable to be weighted according to its importance (strength of correlation) and variables with no correlation being omitted. Computer package (Epi-info-ver.5) was used to correlate the regression coefficient for each pair of variables, then the regression coefficient of all possible combinations of variables was calculated. ^(12)(13) 

Each variable was evaluated one at a time (forward selection procedure) until no additional variables made a significant contribution. Backward elimination was also used; the results were identical. 

Odds ratio, Mean, B-coefficient, 95% confidence intervals, Standard error, F-test and P-value were estimated for risk factor which was statistically and strongly related to a specific morbidity in the final analysis.

The risk factors were then evaluated with multiple logistic regression to identify which factors were independently associated with C.S. morbidity. Logistic coefficients were averaged to determine a mean coefficient for all risk factors.

Results

Cesarean deliveries accounted for 14.3% of the 7000 deliveries performed during the study period.

Preoperative risk factors:

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