Can pelvic diameter measurement have an effect on surgical outcomes in radical cystectomy?

While 70% of patients with newly diagnosed bladder cancer (BC) present with the disease confined to the mucosa (stage Ta, carcinoma in situ) or submucosa (T1), the remaining cases often include BC has invaded the muscle [1]. Today, as in the past, bilateral extended pelvic lymph node dissection and urinary diversion surgery in tandem with radical cystectomy (RC) is the accepted gold standard treatment for muscle-invasive BC [2]. However, perioperative morbidity and mortality increase and continence rates deteriorate after orthotopic urinary diversion in patients who have undergone RC, especially among the elderly [3].

Complications after BC surgery can be classified as early or late and major or minor. A prior study revealed that the most common complications of BC surgery regardless of the patient's age, are ileus and infection-related complications (e.g. fever and pyelonephritis) [4]. Complications can be listed as non-specific (e.g. atelectasis or myocardial infarction), diversion related (e.g. urinary fistula, stoma-related stricture and ureteral stricture), or neurological (e.g. delirium) [5]. Despite surgical and medical advances, RC and urinary diversion are associated with significant postoperative mortality ranging from 4 to 11% within 90 days after surgery [6].

Anatomical variations in pelvic dimensions may play an important role in likelihood of developing operative difficulties and complications during an RC procedure such as radical prostatectomy (RP). These variations may be the cause of a high percentage of negative postoperative outcomes (e.g. major complication or positive surgical margin etc.) and a technically challenging operation. A diagnostic model may be useful in predicting RC needed to predicting RC outcomes.

Thin-section computed tomography (CT) is used to determine a patient’s pelvic dimensions before a RC. The potential advantages of this method of imaging as opposed to others is increased speed, a reduction in distortions due to movement and the need for less contrast material, which reduces the risk of nephrotoxicity fast imaging, image distortions due to movement are reduced, and the amount of contrast material decreases significantly thanks to the speed; reduce the risk of nephrotoxicity.

A number of studies have on the relationship between anatomical pelvic variations and perioperative outcomes and postoperative complications of RP [7‐11]. However, little published information exists on the effects of pelvic dimensions on RC outcomes [12]. To date, no research has shown a link between pelvic dimensions and RC postoperative outcomes. Because the impact of pelvic dimensions on RC postoperative outcomes is not clear, this diagnostic study examined the relationship between pelvic dimensions and the development of operative difficulties and negative postoperative outcomes. This was done through a retrospective examination of the postoperative complications of patients who underwent RC and urinary diversion operations due to high-risk and muscle-invasive BC.

RC, is a morbid procedure with a high postoperative complication rate, frequent hospital readmissions and significant perioperative mortality risk [13]. The rate of complications within 90 days after RC and urinary diversion has been reported by various publications as 19.0–69.6% [14‐17], and mortality rates have been reported in the range of 2.3–9.0% [18‐21]. The overall 90-day postoperative complication and mortality rates in this study were 65.8% and 13.9%, respectively.

Only 27.8% (n = 22) of the patients in this study had pT2 stage BC. Furthermore, the cancer of 30.4% (n = 24) of the patients was upstaging to pT3 and that of 21.5% (n = 17) was upstaging to pT4. Thus,the it mortality rate of the patients in this study was relatively high. In a study by May et al. [22], 35% of patients diagnosed with pT1 cancer were found to have upstaging in their pathology after RC. As a result, the authors suggested that the cancer in patients in the high-risk group may be necessitating prompt operation.

A narrow, deep pelvis or the presence of the prostate at the base of the pelvis are also important considerations in the performance of a RC, such as RP, as both are linked to a higher incidence of postoperative complications and a technically challenging operation [12]. Measurements such as PD, AD, SA may play a role in manipulations during RC, such as deep dorsal vein ligation, apical dissection and the cutting of the lateral pedicles. In addition, pelvic dimensions may impact pelvic lymph node dissection in the obturator fossa [12]. Likewise, a wide and shallow pelvis may be preferable compared to a narrow and deep pelvis by surgeons [12]. All these considerations, it can be called the operative diffuculty.

Various publications have investigated whether pelvic anatomy plays a role in operative difficulty and complications of RP [7, 8, 23]. However, publications concerning the sames for RC are limited. In reference to general surgery, Boyle et al. stated that pelvic size might affect the difficulty of operation in colorectal surgery, finding that patients with smaller pelvic sizes are more likely to have PSM [24]. Likewise, Hong et al. suggested that pelvic dimensions may affect the difficulty of performing open and laparoscopic RP. The use of magnetic resonance imaging (MRI) allowed for a new measurement parameter called the pelvic dimension index (PDI) which can be used to calculate the ISD/AD ratio or ISD index in that low PDI values indicate a narrow and deep pelvis and high PDI values indicate a wide and shallow pelvis [7]. The same study found BMI to be independently associated the OT of open retropubic RP, and while pelvic size does not significantly affect the OT retropubic RP as much as patient-related factors such as BMI or prostate volume, it may have partial effect [7]. Hong et al. noted that the available working area in robot-assisted RP could be estimated using the pelvic cavity index (PCI) and that the dimensions of the pelvis did not affect the difficulty of robot-assisted RP in Korean patients [8]. Another prior study found pelvic dimensions to be correlated with OT and EBL [12]. Using, multivariate analysis, the same study determined that pelvic dimensions do not affect the difficulty of an RC but BMI and pathological stage may affect [12].

Contrary to the findings mentioned above, Mason et al. found that a deep and narrow pelvis might be associated with long OT and increased EBL in robot-assisted RP [23]. Similarly, Yao et al. reported that prostate volume/PCI ratio was a statistically significant predictor of console time and EBL in multiple linear regression analyses concluding that the OT of a procedure on a patients with large prostate volume and a small pelvis is prolonged, adding to the difficulty of the surgery [11]. The current study called these indicators as technical difficulty for RC: OT, perioperative EBL and HS. The multivariate regression analysis performed for OT, obtained results similar to those of the studies discussed above BMI and SA measurement were found to have an impact and that preoperative HCT was found to have an effect on EBL. According to the findings obtained in the present study, a narrow pelvis might cause difficulty in RC, albeit in a limited capacity.

In a study of 88 patients in a general surgery clinic, Boyle et al. found female patients with positive circumferential resection margins after colorectal surgery to have a significantly shorter ISD compared to those with negative circumferential resection margins and that preoperative measurement of ISD taken using MRI could affect the choice of adjuvant treatment [24]. A study by Matikainen et al. also involved the use of preoperative MRI to determine the effect of AD on RP. The authors reported AD to be a significant predictor of apical PSM, independent of the surgical approach and other clinicopathological variables [9]. In the current study, we found pathological T stage, high CCI score and ISD index to be independent risk factors for PSM. This result may be explained by the fact that the risk of PSM is higher in patients with a small ISD index value, narrow pelvis and deep prostate apex.

Surgical site infection (SSI) is a widespread postoperative complication that causes significant pain and suffering. SSI associated with negative economic effects, increased morbidity, extended postoperative HS, readmission, sepsis, and death [25]. Previous research has established that postoperative SSI is diagnosed in (21.8%) cases [25]. Moreover, SSIs following a procedure to treat colorectal cancer has been found to be significantly more common among patients that are older (> 70 years), obese (≥ 30 kg/m2), have ASA scores ≥ 3, have diabetes and with a history of chronic steroid use, undergoing open, dirty or contaminated surgery [25]. In our study, SSI was observed in 12 patients (15.1%).

Thus, evaluating a patient’s pelvic anatomy before a RC may help predict postoperative results, allowing for preparation for the possible difficulties of the procedure and more successful outcomes.

The aim of this research was to examine preoperative predictions of postoperative complications in patients undergoing RC. The primary finding of this study was that SA is an independent predictor of OT, suggesting that surgeons may experience more difficulty performing a RC procedure on the patients with a narrow SA.

The second major finding was that the risk of PSM increased in patients with a narrow and deep pelvis. This suggests that ISD/AD ratio is a significant predictor of PSM and this relationship is independent of patient-related and other clinicopathological variables. Furthermore, the results of this study suggest that other anatomical variations in the pelvis may not be essential factors in terms of operative difficulty or minor or major complications. While patient-related features, such as CCI score and BMI, may increase mortality. This is the first study to present evidence for the pelvic dimensions of PSM in RC.