Among the 14 cases in this study, the rate of cesarean delivery and preterm delivery was 63% and 64%, which were twice and more than sixfold higher, respectively, compared with the general population in the USA [8, 9]. These results are consistent with previous studies [2, 3]. The cases in our study were older with younger gestational age compared with a previous study [6]. Although the period between renal transplant and cesarean delivery was shorter compared with previous reports [6], it was longer than 2 years, recommended as a safe period by both the USA and European Union guidelines [10, 11].
Most cases received a combination of immunosuppressants and corticosteroids during pregnancy. Although the incidence of epidural abscess caused by regional anesthesia in parturients after renal transplant remains unknown, patients receiving immunosuppressants are vulnerable to infections [12], suggesting that epidural abscess would be more commonly caused by neuraxial anesthesia in those women and strict aseptic techniques are recommended. We removed epidural catheters within 48 h in all patients in order to prevent infections following the suggestion by Gronwald [12].
According to a multicenter cohort study [6], indications for cesarean delivery after renal transplant are previous cesarean delivery (23%), material medical causes (23%), fetal causes (18%), obstetric delivery causes (15%), material preference (21%), and emergency surgery (20%). In the present study, HDP was the most common indication of cesarean delivery. HDP was observed in 57% in the present study, higher than 24% in the previous review [2]. This would result that the mean age of the study subjects was approximately 5 years older than in that review. The proportion of patients who received general anesthesia was 36%, higher than that reported in previous studies [6]. The choice of anesthesia method was at the discretion of the attending anesthesiologists, and there were various reasons for it. Because the incidence of cesarean delivery was high, sharing of information of post-renal transplant parturients would be important to prepare for anesthesia. In this study, post-renal transplant parturients scheduled for cesarean delivery visited the anesthesiology outpatient clinic twice: from 22 to 25 weeks and after 32 weeks. If the physical findings, renal function, and fetal growth information from the outpatient clinic are evaluated, the optimal anesthesia method can be planned and put into practice smoothly even in an emergency.
Specific points to be aware of for effective anesthesia management in cesarean delivery include circulatory management and maintenance of renal function. Prolonged operation time due to previous abdominal surgery should also be considered, although none of the cases required a transition of anesthesia method from regional to general during surgery. The highest systolic and diastolic blood pressure during surgery tended to be higher under general anesthesia than under regional anesthesia, which would be ascribed to a high proportion of patients with HDP. Mean arterial blood pressure < 65 mmHg which lasted for ≥ 13 min during general anesthesia increased the postoperative acute kidney injury in noncardiac surgery [13]. In the present study, this occurred in three patients under general anesthesia and in no patient under regional anesthesia. Our study confirmed that hypotension typically occurred after induction of general anesthesia, after administration of nitroglycerin, and after delivery. Although the kidney is in a different position and we cannot solely focus on achieving a mean arterial pressure ≥ 65 mmHg, prolonged hypotension should be avoided. Hypotension occurred after the administration of nitroglycerin in all patients irrespective of the anesthesia method. Because nitroglycerin is used for rapid tocolysis in preterm delivery, it would be more frequently used in post-renal transplant cesarean delivery. Although there were no cases of postoperative acute kidney injury in our study, prediction and treatment of hypotension to improve circulatory management are crucially important. Despite numerous reports comparing the effect of ephedrine and phenylephrine used for treating hypotension during cesarean delivery [14,15,16,17,18], there is no unified view regarding the agents for the treatment of hypotension, particularly in post-renal transplant patients. Urinary output must be monitored during surgery since transplanted kidneys can be physically compressed by the gravid uterus during pregnancy or during surgery, resulting in hydronephrosis or acute kidney injury [19, 20].
This was a single-institution retrospective study and is limited by an extremely small sample size. Since the details of how the anesthetic method was selected were not always available, in some cases, the reason behind the choice between general anesthesia and regional anesthesia was unknown. Furthermore, the small number of cases precludes any meaningful statistical analysis.