Longitudinal midline uterine incisions have usually been adopted during myomectomy [4, 5]. They were assumed to be more hemostatic, because the anatomical studies of the distribution of myometrial blood vessels showed that arcuate arteries run transversely from lateral to medial, to join at the median plane. They give off radial arteries and spiral arterioles, which course centripetally towards the endometrium in also a transverse plane [19, 20, 21]. This transverse course would thus, at least theoretically, result in transection of more blood vessels by a longitudinal incision. In comparison, a transverse uterine incision will parallel their course, leading to the transection of a fewer number .
Moreover, suturing of a vertical incision places the sutures parallel to the course of the transversely running vessels, which hinders adequate ligation of all transected arteries and veins, together with their branches and tributaries respectively. On the contrary, suturing transverse incisions places the sutures perpendicular to them, and thus, provides an effective hemostatic seal that would surround all transected vessels .
However, all these assumptions were based upon anatomical studies of normal uteri. Few studies addressed the distortion of myometrial vascular anatomy by the growing myomas. Studies of the vascular pattern of myomatous uteri by injection, micro-radiographic and histologic techniques revealed that their vascular supply depends upon localized expansion of the normal myometrial vasculature, where displaced and distorted arcuate and radial arteries give off a number of small arteries that penetrate the myoma anywhere along its circumference . They also revealed that the venous drainage of fibroids is sparse compared to the arterial supply, only few moderate-sized distended arcuate veins are occasionally seen. These distended venous channels contribute substantially to the heavy bleeding during myomectomy . Angiographic study of the course of the arterial blood vessels encircling uterine myomas revealed that the neo-vessels, developing around them, do not follow the normal anatomy of myometrial vasculature. Instead, on the surface of myomas, blood vessels run mostly diagonally with an angle of 0-60⁰ in 70% of cases. In addition, nearly 40% of the vessels crossed the myoma midline .
Based on these findings, it may be concluded that arterial vessels on the surface of myomas can be injured whatever the direction of uterine incision, yet a transverse uterine incision would be less traumatic to the transversely directed myometrial arteries, aretrioles and venous channels, and to the diagonally directed fibroid feeding vessels.
This theory was previously questioned by Morita and his colleagues in the setting of laparoscopic myomectomy. Transverse uterine incisions were associated with significant decline in IBL compared to longitudinal incisions (137.6 ± 88.1 vs. 235.8 ± 169.4 mL respectively). This decline was more evident in large myomas (> 7 cm in diameter); with an estimated blood loss 158.9 ± 87.1 mL in transverse incisions, compared to 362.3 ± 147.3 mL in longitudinal incisions. Whereas no statistically significant differences were found between both incisions in smaller myomas (< 7 cm) . This seems logic, as the traumatic effect becomes more evident with the extension of the longitudinal incision causing more damage to the traversing vessels; in contrast to the extension of the transverse incision that runs almost parallel to the vessels. However, validation by further studies is needed, as the proposed effect of myoma size in the study of Morita is confounded by the large difference in operative time with myomas > 7 cm between longitudinal (165.4 min) and transverse incision (129 min), owing to the easier suturing technique of transverse incisions .
Despite the disparities between the laparoscopic and open approaches for myomectomy, in addition to preoperative treatment with gonadotrophin-releasing hormone analogs and intra-myometrial vasopressin injection in the study of Morita ; yet, the underlying surgical theory of transection of more transversely running vessels by longitudinal incisions might also be held true in case of open myomectomies.
In consistence with the same theory, the results of our study proved that transverse uterine incision resulted in lower volumes of IBL and postoperative drop of hemoglobin and hematocrit compared to longitudinal incision, although this difference did not reach statistical significance. It should be noted that only myomas < 10 cm in diameter were included in our study, with an average myoma size of approximately 8 cm.
We acknowledge the differences between open and laparoscopic approaches for myomectomy [24, 25], yet it is standard practice in our institute to perform myomectomy through the open approach for cases with our inclusion criteria.
The optimum myomectomy technique has always been a matter of debate, especially concerning measures to ensure optimum myometrial healing, considering the difficulty in the assessment of the obstetric quality of the resulting scar. The concept of pseudocapsule preservation in the intracapsular myomectomy technique has been introduced to preserve the neurovascular bundle and promote better healing.
Although based on a sound biological background, much of the assumptions of the impact of pseudocapsule preservation are still theoretical and derived by analogy to the effect of preservation of the neurovascular bundle during prostatectomy . Reports of the reproductive outcomes of intracapsular myomectomy seem favorable . However, up to our knowledge, no trials compared the obstetric quality of the scars of intracapsular myomectomy with those of the conventional surgical approach. Moreover, given the inevitable injury of the pseudocapsule during the incision to reach the myoma, no clear cut limits exist for the maximum accepted damage to the pseudocapsule. It is not known whether the whole pseudocapsule should be preserved or even a smaller part would be sufficient to supply the growth mediators postulated to stimulate myometrial healing.
Elliptical uterine incisions are designed to remove excess serosal and myometrial tissues overlying the maximum fibroid bulge, to avoid leaving behind large dead space after enucleation of the myoma. The idea of removal excess serosal and myometrial tissues is reported in the literature several times . Especially in the setting of minimally invasive myomectomy, many surgeons advocate this incision to ensure obliteration of any dead space .
We adopted an elliptical incision, removing only a small part of devascularized serosa and pseudocapsule overlying the myoma within the boundaries of the ellipse, to minimize dead space and the amount of redundant tissue to be sutured, while sparing the rest of the pseudocapsule.
The mean blood loss in both research groups of our study lies in the average range of blood loss volume observed in previous studies, that indicated that mean blood loss during open abdominal myomectomy would be between 200-800 ml. [13, 30-32]
The mean operative time ranged between 58-88.5 minutes in different studies using the standard longitudinal myomectomy incision,[13, 33, 34] which matches our observed mean operative time in both research groups. The variation between different studies in calculated blood loss and operative time was correlated to the size and number of excised myomas.
In this study, only one case required blood transfusion in the longitudinal incision group representing 4% of cases, while none required in the transverse incision group, making no significant difference between both groups. Studies on average blood loss during myomectomy stated that blood transfusion was widely variable extending from 2 to 28% of cases.
Postoperative pyrexia following myomectomy has been linked to the development of myoma-bed hematoma , that may be followed by weakening of the developing scar . In this study, postoperative pyrexia developed in one patient in the transverse incision group and in two patients in the longitudinal incision group. However, being a secondary outcome, our sample size is underpowered to detect a significant difference in the incidence of such uncommon complication.
By proving that blood loss is comparable in both incisions, it might be convincing to routinely adopt a transverse uterine incision during myomectomy as with cesarean section. Future research is required to investigate long term sequelae of transverse and longitudinal incisions during myomectomy regarding reproductive sequelae, incidence of uterine rupture in subsequent pregnancies and its impact on formation of pelvic adhesions.
Among the strengths of this study: (1) up to our knowledge, this is the first study to explore the effect of uterine incision direction in open myomectomy; (2) homogeneity of patients within the two groups regarding the number, size and site of myomas; (3) estimation of IBL both directly and indirectly. Limitations include: (1) although we tried to restrict the range of myoma sizes, we failed to statistically adjust blood loss to varying myoma size due to limited sample size; (2) different surgeons were involved in the study, although all had similar adequate experience.