Rotation of the uterus to obtain a lower transverse incision in the posterior wall in a cesarean section: a case report and literature review

Abstract Objective To demonstrate that cesarean section with a transverse incision at the lower posterior wall of the uterus is suitable for some special obstetric cases. Case report A 35-year-old primigravida with a previous surgical history of laparoscopic myomectomy underwent elective cesarean section at 39 weeks and 2 days of gestation. During surgery, there were severe pelvic adhesions and engorged vessels on the anterior wall. Considering safety, we rotated the uterus 180 degrees and made a lower transverse incision on the posterior wall. The infant was healthy and the patient had no complications. Conclusions A low transverse incision in the posterior uterine wall is safe and effective when the incision of the anterior wall encounters a dilemma, especially in patients with severe pelvic adhesions. We recommended this approach should be done in selected cases.


Introduction
Cesarean section is an important skill in obstetric surgery for obstetric emergencies and patients who are not suitable for vaginal delivery. A traditional hysterotomy involves a transverse incision in the lower segment of the anterior wall [1]. However, there are often several complications, such as adhesion and engorged vessels, in our method of obtaining this incision [2]. We present a case of cesarean section by a lower transverse hysterotomy in the posterior wall after rotation of the uterus on purpose.

Case report
A 35-year-old primigravida was admitted to our hospital at 39weeks and 2days of gestation for an elective cesarean section. The prenatal course was uncomplicated. Her history included two laparoscopic surgical treatments for the removal of uterine fibroids 7 and 4 years earlier. The previous myomectomy was resulted in entering into uterine cavity. The physical examination and preoperative investigations were normal.
The cesarean section was performed the next day. Under epidural anesthesia, we entered the abdomen with a Pfannenstiel incision. Upon opening the peritoneum, there were abundant and large vessels on the right uterine horn, and the bladder and sigmoid colon were found to densely adhere to the middle and lower segments of the anterior wall of the gravid uterus (left rotated about 70 degrees), up to the level of the round ligaments ( Figure 1(A)). Given that the incision in the anterior wall could lead to uncontrolled bleeding and injuries of the bladder and sigmoid colon, we rotated the uterus left to 180 degrees to perform a deliberate lower segment hysterotomy in the posterior wall. The hysterotomy placed at the posterior wall was relatively higher than the anterior wall, which was decided at a wider location about 2 cm below the junction of the uterine body and lower uterine segment. Meanwhile, we used bandage scissors for sharp expansion instead of fingers for blunt expansion to obtain a sufficiently large incision, allowing delivery of the fetus. A healthy 3040 g male infant was successfully delivered in a cephalic presentation, and the placenta and membranes were removed completely. Accompanied by uterine contractions, a substantial reduction in venous engorgement vessels was observed ( Figure 1(B)). The contracted uterus was derotated back to its correct anatomical position and pulled out of the peritoneal cavity after volume reduction ( Figure 1(C)). Subsequently, the posterior uterine incision was closed in two layers. After the uterus was gently inserted into the pelvis, the pelvic cavity was carefully examined to ensure complete hemostasis. The intraoperative bleeding was estimated to be 350 ml and a postoperative blood test revealed a drop in hemoglobin level of 6 g/L.
The postoperative care was uncomplicated. She was discharged on the fourth day after the operation, and her 6-week postnatal check was unremarkable.
Written consent for publication was obtained from the patient on August 12, 2022.

Discussion
Postoperative adhesions are one of the most common long-term complications of abdominal surgery and can complicate a second surgery [3]. Although great improvements in surgical procedures have been achieved, especially in minimally invasive techniques, abdominal adhesions after laparoscopic myomectomy remain high (up to 50%) [4]. As in our case, there were severe adhesions between the bladder, sigmoid colon, and anterior wall of the uterus caused by the previous laparoscopic myomectomy, leading to difficulty in dissection of bladder adhesions. Studies have shown that these adhesions are thought to be a causative factor of bladder injury during cesarean section, the majority of which occur in the bladder dome, most commonly during creation of the bladder flap [5,6]. Second, the Pfannenstiel incision prevents us from obtaining an adequate view of the fundus uteri, let al.one retrieving the fetus. Considering the engorged blood vessels in the anterior wall of the uterus, an incision in the anterior wall was considered unadvisable in our case.
At present, there are few relevant studies on transverse incision of the lower segment of the posterior wall by rotation of the uterus on purpose. However, several studies have reported inevitable cesarean section through posterior hysterotomy in cases of uterine torsion [7][8][9]. Among uterine torsion cases, when it comes to the incision in a posterior cesarean section, most authors advocate a longitudinal incision on the fact that the lower segment of uteri was often found to be inaccessible because of dense adhesions or covered with engorged blood vessels [8,10]. However, other case reports demonstrated that the low transverse incision was harmless and did not increase bleeding as long as the anatomical landmarks were defined correctly and the posterior side of the lower segment was clear [9,11]. Other benefits of the lower transverse incision instead of the longitudinal incision include not being concerned with damaging the bladder, reducing the risk of uterine rupture in a second pregnancy, and less bleeding and better healing due to the thin and circular extension of the lower uterine muscle [1,12]. However, uterine torsion is often accompanied with a high head position, and a lower incision might have trouble in the delivery of the fetus. However, blindly pursuing a low transverse incision, which was placed at the junction of the hypertrophic uterine body and the thin lower uterine segment, could lead to inconsistencies in the length of the two surgical edges, resulting in difficult sutures and poor wound healing. In our case, the incision was made in the broadest part of the lower uterine segment of the posterior wall, but was higher than the anterior wall. Thus, even if the uterus was slightly torn, it was impossible to damage the major uterine vessels because the position of the uterine arteries and veins was lower than the incision. In our case, after the uterus was rotated to 180 degrees, we still used the same lower transverse incision as the anterior wall, which did not involve major uterine blood vessels and did not require special hemostasis on the incision. After suturing, we checked the incision to ensure that there was no bleeding. Meanwhile, the incision was located at the level of the fetal ear or neck to avoid the difficulty of fetal extraction and neonatal asphyxia caused by the high position or excessive extension of the fetal head. Therefore, in our case, we rotated the uterus to obtain a proper and low-transverse incision.
It was recognized that immediate surgical intervention was advisable once the diagnosis of uterine torsion was established because delayed surgical intervention could result in increased maternal and fetal morbidity [9]. However, in our case, the duration of uterine torsion was short, and the twisted uterus was deroated to its anatomical position immediately after delivery. Therefore, there was little influence on the blood flow and the fetus.
Transverse incision of the inferior posterior wall of the uterus is an unconventional surgical option for cesarean sections. In our case, to avoid surgical complications, we adopted this strategy after careful consideration and confirmed that it was safe and effective. We recommend this method only in selected cases, when the incision of the anterior wall encounters a dilemma or in an emergency situation, because an inappropriate uterine incision may cause vascular and ureteric injury.