WRITE UPS - CESAREAN SECTION - Previous Cesarean Section

INTRODUCTION: -

Previous cesarean section makes a pregnancy an instant high risk. Very close monitoring of the entire pregnancy and more so of labor becomes mandatory. Even the academicians of our subject have indulged in lots of debates and controversies as regards the management of pregnancy and labor in a case of previous cesarean section. The scar on a dynamic structure like uterus has created this entire debate. As a student of the subject and as a clinician it becomes necessary for us to learn about all possible aspects related to it.  This subject has been treated with a clinical approach:

HISTORY: -

It becomes imperative to ask some vital points regarding history to this mother. This includes number of previous cesarean sections. It will decide as to whether a trial of vaginal delivery can be given. If she had previous one Cesarean Section (C.S), hospital delivery is a known rule for previous two C.S. most believe that C.S. is absolutely indicated. However a small minority does feel that a vaginal trial can be given if the indications of previous both CS are non-recurrent. These group of workers feel that three and more C.S. only are an absolute indication for C.S.

Type of previous C.S.: Now a days, previous lower segment C.S. is a rule and classical C.S. is an exception. Previous classical C.S. is held against a trial for vaginal delivery.

Timing of previous C.S.: It is believed that uterine wounds heal better if a C.S. is done before the onset of labor. Thus if a mother gives such a history, it becomes a small added point in favor of a vaginal trial.

Extension of the scar: If the operative information of previous surgery is available and indicates an extension of the scar, or an inverted T incision, these go against a vaginal trial, to a significant extent.

Puerperal infection: If the mother in question gives history of puerperal sepsis, it is believed that the strength of the scar is reduced. This has to be borne in mind if a trial for vaginal delivery is to be given in this obstetric performance.

Indication for previous C.S.: This is very vital. A bony contraction of the pelvis is an obvious recurrent indication. Mothers with such recurrent indications are obviously a choice for cesarean section this time.

EXAMINATION :-

A short statured mother (< 145 cms. for Indian mothers) is a high risk for repeat C.S. Cephalopelvic Disproportion (CPD) is to be watched wisely. Failure to progress in labor or dystocia is a leading indication for primary cesarean section and has major impact on escalating CSR in the USA. Recent literature indicates that the diagnosis of CPD has no prognostic value from one pregnancy to the next and generally should not exclude a patient from a trial of labour. Meier & Porreco (1982) studied 230 trials of labor and found that, of 107 patients whose primary section was for CPD, 67.3% were delivered vaginally 31% of which were larger than the one they had by cesarean section. These authors also found that, of 83 women whose first pregnancy ended by cesarean section for CPD, 78% were delivered vaginally following trial of labor.

In patients who had a primary cesarean section for breech presentation, 93.4% were delivered vaginally following trial of labor. However in patients having breech presentation with previous cesarean section scar, the consensus is that they should have a repeat cesarean section. Paul et al examined 72 patients with breech presentation and found that vaginal delivery was achieved in 46% of 18% allowed a trial of labor.

     An anemic mother requires extra efforts to treat her anemia because if she requires a C.S., again, she enters labor, her anemic status be promptly corrected. Presence of any other medical disorder which may have occurred now like jaundice or might have missed last time, like a heart disease, add to surgical risk and be promptly treated.

A systematic obstetric examination of the case helps in identifying malpresentations if any .A previous C.S. with breech, transverse lie or similar unfavorable presentations and lie are not preferred for including a vaginal trial. For breech in present pregnancy, it is stated that rarely but really, breech extraction may be required. This may invite on intra uterine manipulation. This may and increase the stress on the previous scar.

The role of External Cephalic Version was recently addressed in a case with a previous C.S. Version attempts were successful and women went on to have vaginal birth after cesarean section. A total of 19 successful vaginal deliveries occurred (50%) . Success rate of ECV was lowered when breech was the indication of the previous cesarean section. The vaginal delivery rate was increased after successful ECV in patients previously vaginally delivered, but this difference did not reached significance. No maternal or neonatal complications occurred.  It was therefore concluded in this study that ECV is acceptable  and effective in women with a prior low transverse uterine scar, when safety criteria are observed. (Unger JB)

Presence of a fetal macrosomia in a case of previous C.S. requires a close vigilance even if the previous indication was non-recurrent. Presence of multiple pregnancy with favorable presentation remains a controversial issue. Some believe that this has no scope for vaginal delivery whereas others feel it there is no harm if other criteria for a favorable trial are met satisfactorily. In a retrospective study by Gilbert et al, it was shown that a transverse low uterine segment scar does not present a risk because of uterine distension secondary to a twin pregnancy. Strong et al studied the pregnancy outcome 56 women with twin gestation and a previous section birth. In these patients 31 (55%) underwent an elective repeat cesarean delivery and 25 (45%) attempted a vaginal delivery. In the latter, 18 (72%) were vaginally delivered of both infants. The dehiscence rate among women with twin pregnancies who attempted a trial of labor was 4% compared with 2% in women with a singleton pregnancy. The rule is to individualize the case.

Antenatal pelvic assessment is fraught with pit falls except if the deformity or contraction is very distinct. It is therefore not preferred currently by many.

INVESTIGATIONS :-

A routine blood count to rule out anemia, infection and bleeding profile is helpful.

USG is obviously the most important investigative tool. Besides its routine use for any pregnant mother in a case of previous C.S., it is required to localize the placenta. A low-lying placenta on or adjacent to the scar is an important finding of clinical bearing. It will guide one to allow a vaginal delivery or otherwise. It will also make the obstetrician aware of the difficulty he many encounter while doing a C.S. A congenitally malformed fetus is a grave risk. This should be carefully looked for and if found to be present and if the malformation is major, termination is the obvious choice. It is sad to caesar out a baby for failure to progress in a case of previous C.S. and the baby is found to be hydrocephalic, causing this non-progression. The other, aspects revealed by USG are as in any other case as well. These are not repeated for reasons of brevity and relevance.

X-ray pelvimetry has a dying role in modern obstetrics even, in cases of previous C.S. Clinical pelvimetry is any day preferred as dynamic, judges the interplay of maternal passages and the fetus and more accurate. Digital C.T. scan is mentioned to be superior but not popular due to the cost involved.

The above three principles are employed in a case of previous C.S. on booking of a case. The pregnancy is monitored and the events on subsequent visits noted attentively. Gain in weight that has more an adventitious prognostic significance is kept a watch on. Fetal growth noted and the rise or fall in hemoglobin attended to. As the pregnancy advances and if the previous abdominal scar was vertical subumbilical than an inscisional hernia can become obvious. Nothing much really requires to be done for this, at this stage. But, if the skin over the hernia gets ulcerated due to stretching, then admission of the case for dressing is warranted. Also bed rest in such cases will arrest the pressure on the skin

     When the pregnancy zeroes down on term two vital decisions are to be taken:

Vaginal delivery OR

Cesarean section.

 Points in favor of vaginal delivery are:

Previous lower segment C.S.

Previous non recurrent indication

Presently no malpresentation

Adequate pelvis

Presently no placenta previa

No cephalic pelvic disproportion

If these points are fulfilled one can plan a vaginal delivery, if not a repeat cesarean section.

Risks Of Vaginal Trial of Labour:

Risks of a trial are inherent and understandable. Among the 17,613 trial-of –labor cases logged (attempt rate 60.64%), the success rate was 73.73% (65.56% after inducing labor and 75.06% after the previous-cesarean group: maternal febrile episodes (relative risk (RR) 2.77, thromboembolic events (RR 2.81), bleeding due to placental previa during pregnancy.(RR 2.06), uterine rupture ( 92cases: RR 42.18), and perinatal mortality ( 118 cases, including six associated with uterine rupture: RR 1.33). The post cesarean group also showed a 0.28% rate of peripartum hysterectomy (81 cases: RR 6.07). There was one maternal death in the group, compared with 14 maternal deaths in the group without previous cesarean (no statistical significance). The risk of uterine rupture for patients with previous cesareans was elevated in the trial-of-labor group compared with the group without trail of labor (RR 2.07), but all other maternal risks, including peripartum hysterectomy were lower. When comparing the women having a trial of labor, the 70 with uterine rupture more often had induced labor (24.29% compared with 13.92% in the nonrupture group, had epidural anesthesia (24.29% compared with 8.44%:), had an abnormal fetal heart rate tracing (32.86% compared with 8.53%:), and had failure to progress (21.43% compared with 7.98%). Thus, a history of cesarean delivery significantly elevates the risks for mother and child in future deliveries. Nonetheless, a trial of labor after previous cesarean is safe. Induction of labor, epidural anesthesia, failure to progress, and abnormal fetal heart rate pattern are all associated with failure of a trial of labor and uterine rupture. (Rageth JC-1999)

A quality psychological support is also necessary. Results underline that patients are more disposed to accept the operation in repeat cesarean rather than in primary cesarean. Women who have a repeat cesarean section are more likely to accept this kind of delivery since the beginning, with positive effects on their post operative course.  Women who have a repeat cesarean section face more serenely not only prenatal but also post-natal period and show less serious psychophysical sequel with respect to primary cesarean section because of their previous experience. As a result, an appropriate psychological support coupled with adequate information can reduce discomfort in cesarean patients. (Bique C 1999)

It is needless to over assert the need for biophysical fetal monitoring both on USG and cardio tocography. As term approaches in such cases, CTG is regularly repeated and any unfavorable feature, warrants immediate and appropriate intervention.

If the pregnancy has reached term and a trial for vaginal delivery has been carefully decided, it is advisable to induce labour. Now a days it is not considered as harmful and PGE2 gel can be safely used for this purpose. Some workers have expressed fears in the past about giving trials in unknown scars.  This was recently reviewed. Pruett et all reviewed 393 patients undergoing trial of labor after one or more previous section. In this study, 300 patients had an unknown type of uterine scar: 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 transverse incision. Similar findings have been noted in our unit.

At term the labor is induced and closely monitored. Any signs of feto maternal distress in the form of tachycardia or maternal uterine scar tenderness is dangerous and C.S. be resorted to. Fetal Distress In Labor: Although this is an acceptable indication for cesarean section, identification of the fetus at risk from hypoxia in not always easy. The diagnosis of hypoxia based on cardio-tocography alone has led to an increase in CSR.  Some workers found that fetal distress was the cause of one quarter of cesarean sections in their study. Ayromlooi & Garfinkel (1980) found that fetal blood sampling has helped reduce CSR. Mac Donald et al, however, have shown that electronic fetal monitoring did not influence the number of cesarean sections in low-risk pregnancies at the National Maternity Hospital, Dublin.

Development of an unexplained tachycardia &/or vaginal bleeding in a mother with previous C.S. scar can indicate an early dehiscence and immediate intervention is the rule. The role of Intrapartum CTG monitoring in such cases was recently reviewed. Silent tracing appearing during cesarean section usually does not indicate fetal distress. Poor intra-cesarean fetal heart tracings were associated with worse indicators of neonatal well being. Although umbilical pH was lower than scalp values, when the correction described in the literature was applied, the difference was of little clinical relevance. It is concluded that anesthetic, pharmacological and surgical events have slight repercussion in fetal well being. However, in a few cases fetal heart monitoring during cesarean section could detect otherwise undiagnosed cases of transient ischaemia or depression in the fetus.(De Meeus, JB-1998)

If the labor progress is satisfactorily reinforced by a partogram, even augmentation with a syntocinon drip can be done. However care should be taken to prevent an unmonitored administration. Head above the brim is more dangerous than below. This is because the head above can rummage into the previous scar and it is advisable to wait for starting syntocinon upto that time as and when the major portion of the head descends below, the inlet.

     Once the trial progresses satisfactorily, it is advisable to cut short the second stage with ventouse or forceps as per the pre-requisites fulfilled.

Labor does not end till the complete delivery of placenta is ensured. Part of the placental tissue can be adherent to the scar and warrant a manual removal. Routine and universal exploring of the uterus especially the scar line after delivery is now not advocated. Individualization of the case is the order of the day.

MANAGEMENT OF TRIAL OF SCAR (TOS) IN S.S.G HOSPITAL, BARODA: -

The perinatal mortality rate for patients with previous section is higher than the rest of the population, and the need for antenatal surveillance is emphasized. We believe that trial of labor is as safe for the fetus as elective repeat section. In our unit the following rules are applied in the management of TOS.

Oxytocin is administered when required, to a maximum of 12 m U/min, but may be increased to 40 mU/min upon a consultant decision. Induction of labor is associated with high success rates and does not increase the true uterine rupture, provided proper patient selection is made and induction performed and supervised correctly. We believe the use of artificial rupture of the membranes and intravenous oxytocin is safe, when properly managed. Automatic monitoring of maternal blood pressure and pulse recordings should be made at 15-min intervals.

Epidural analgesia for TOS: we demonstrated that epidural analgesia for patients undergoing TOS is safe for mother and fetus in properly conducted trial of labor. Patients are often having their first vaginal delivery and require more pain relief. An increased instrumental delivery rate can be anticipated in patients with trial of labor and a further 15-20% may require termination of trial by cesarean section. Both procedures are often easier and safer under regional analgesia.

Anaesthetic and pediatric staff is informed of the trial.

Compatible cross-matched blood should always be available.

A resident doctor is in attendance at all times.

Cesarean section theatre is available.

Trial of labour following previous section is associated with little risk of true rupture, and with no added risk to the fetus. Our policy and management have helped maintain over the past 5 years an overall CSR of 10-11%. Over the same period, the vaginal delivery rate was 82% no perinatal death was associated with delivery and there was total elimination of true rupture.

In case the mother does not satisfy the criteria for a successful trial, than cesarean section is warranted. A bad disfigured previous scar has to be excised. It is a practice to follow the previous scar and not to create a new scar on the abdomen. Omental adhesions to the previous scar are frequently found and be lysed quickly.  The bladder can be densely adherent warranty a sharp dissection. It is not always possible to go through the previous scar of the uterus as the decision regarding the uterine scar placement is taken in relation to the fetal biparietal diameter. Current practices of not suturing the visceral peritoneum and using synthetic absorbable suture material will reduce the operative difficulties in a case for repeat cesarean section.

EPILOGUE: -

 It is sad but true that defensive obstetrics is practiced more often today. The National Institutes of Health (NIH) consensus committee on cesarean section recommends that hospitals with appropriate facilities, service and staff for prompt emergency cesarean birth in proper selection cases should permit a safe trial of labour and vaginal delivery for women who have had a previous lower segment cesarean section. It also supports the belief that the physician who opts to allow appropriately selected patients to undergo a trial of labour, while following the well-established guidelines for management of such patients, would be subjected to a very low risk of a successful suit for malpractice. Because the medical profession is vulnerable, it must be prepared to fight back against the litigious urge and the small groups of unprincipled lawyers who bring discredit to the legal profession, unnecessary anxiety to the doctor, and inflict hardship, not to mention possible dangers, on the unfortunate and unsuspecting patient. What better way to do this than follow through with what we believe to be the correct management in a given circumstance and so obviate this growing cancer within our specialty known as defensive obstetrics. In management of patients with prior cesarean section, it must be realized that intensive antenatal surveillance is required. In our unit we demonstrated that perinatal mortality associated with delivery following previous cesarean section is increased irrespective of the method of delivery. The risk of true uterine rupture is extremely low with modern obstetric practice. In S.S.G. Hospital, Baroda the incidence of true rupture in the last 5 years was 0.2% and hence it must not be retained as the excuse for choosing elective repeat caesarian delivery. At any instance of time, previous cesarean case is a high-risk pregnancy.  An alert and wise obstetric decision with strong individualization is the rule of the day. 

REFRENCES:

Ayromlooi J, Garfinkel R: Int. Jr. Obst. Gynecol.:1980, 17,391

Bique C: Acta Obstet Gynecol Scand 1999, Mar;78(3):198-201

De Meeus JB: Eur J Obstet Gynecol Reprod. Biol 1998 Oct:81(1):65-8,

Gilbert L, Saunders N, Sharp F: Brit. Jr. Obst. & Gynecol: 1988, 95,1312. 

Mac Donald D, Grant A, Pereira M: Am J Obstet Gynecol.,1985,154,524

Meier & Porreco Am J Obstet Gynecol, 1982,144,671

Paul, Phelan, Yen: Am J Obstet Gynecol,1985,151,297

Pruett K M, Kirshon B, Cotton D B: Am J Obstet Gynecol,1988,159,807

Rageth JC: Obstet Gynecol, 1999,Mar, 93(3): 332-7

Unger JB: Am J Obstet Gynecol 1998 Dec; 176(6Pt1):1473-8-  

 
     

 
         
     

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