Hypothesis / aims of study
Ureteral injury is a typical complication in pelvic surgery even though occurring not frequently. However, the trauma of the ureter is not detected throughout the intervention but only a few days later, normally (1).
To speed up diagnosis, some authors recommend the perioperative determination of serum creatine as a reliable parameter of normal bilateral renal function (2). A postoperative increase of serum creatinine of > 0.2 mg/dL has been indicated to seriously alert ureteral injury (3).
The goal of this original study was to classify the importance of perioperative assessment of serum creatinine compared with clinical symptoms as well as imaging and endoscopic explorations in the early detection of postoperative ureteral damage after diverse gynecological and obstetric procedures.
Study design, materials and methods
The postoperative course of seven gynecological and two obstetric patients raising doubt on ureteral integrity was analyzed, retrospectively, using medical records. The collected data involved biometric parameters, clinical symptoms (urinary production, flank pain), and the temporary changes of serum creatinine (µmol/L) measured in the routine laboratory. In addition, interdisciplinary diagnostic and interventional procedures were recorded. Data analysis was done using descriptive statistics, chi-square test, and the Student’s two tailed t test (SPSS).
Results
Mean age and BMI of the nine patients was 53 ±17 years and 25,7 ± 6,3 kg/m2, respectively. In 6/9 cases an anterior colporrhaphy was done because of urogenital prolapse with predominant cystocele. In 5 cases a protective fixation of the apex was carried out, additionally. In 2/9 patient’s obstetric pathology during delivery required a cesarean section. One patient presented with ovarian cancer which was treated by cytoreductive debulking (figure 1).
The suspicion of ureteral lesion in the six urogynecological patients was due to postoperative oliguria and anuria in 4 cases, and flank pain in 2 cases, respectively. In the two patients delivered by cesarean section a one-sided and two-sided lateral tear of the uterotomy raised doubt on the integrity of the ureters. The oncological patient showed backache and flank pain.
Following surgery, the suspected lesion of the ureter was not confirmed in the three non urogynecological patients. Concerning the patients after anterior colporrhaphy, an obstruction of the ureter requiring further intervention was verified in five cases (2x unilateral, 3x bilateral) by means of imaging procedures (renal sonography, CT-assisted intravenous pyelography [IVP]) and cystoscopy. One case revealed a kinking of the left ureter which healed spontaneously (figure 1).
In the entire group of nine patients, the symptom "oliguria and anuria" arose much earlier than the symptom "flank pain", postoperatively (2.8 ± 1.0 vs. 28.8 ± 9.2 hours, p = 0.03).
Obstruction of the ureter was confirmed in all cases presenting with reduced urinary excretion (4/4). In contrast, ureteral obstruction was excluded in 4/5 cases enabling undiminished urinary production (p = 0.04). However, 1/5 patient presented with bilateral obstruction which was detected by CT-IVP via nephrostomy catheters 5 days after surgery.
Flank pain accompanied twice ureteral obstruction and once ureteral kinking (3/4). Conversely, an obstruction of the ureter existed in 3/5 patients despite absence of any pain (p = 0.60).
The mean timeframe of primary diagnostics spanned 32 ± 17 hours after surgery without significant difference between the groups with and without ureteral obstruction (p = 0.19). 5 patients underwent renal sonography. A congestion of the renal pelvis was detected in the case with ureteral kinking and in three cases with obstruction of the ureter. Another sonography after cesarean section was rightly negative and did not differ from the norm (p = 0.20). The findings of CT-IVP (1x) and cystoscopy (2x) proved to be rightly positive.
The group with verified ureteral obstruction revealed a marked raise of serum creatinine (p = 0,03) within a mean interval of 25 ± 17 hours after surgery. The minimal increase was 51 µmol/L = 0.6 mg/dL. In contrast, no significant changes of creatine were observed in the non urogynecological patients and in the case with ureteral kinking. The maximum postoperative increase was 9 µmol/L = 0.1 mg/dL (table 1). The times of measurements did not differ significantly between the groups (p > 0.9).
Intervention in the 5 cases of proven ureteral obstruction was carried out in a range of 18 to 73 hours after primary surgery and involved unilateral or bilateral nephrostomy (3/5) as well as a revision of anterior colporrhaphy (2/5, figure 1). On average, the nephrostomy procedure was performed 42 hours later than the surgical revision (63 ± 14 vs. 21 ± 4, p = 0.03).
Consecutively, a significant decrease in serum creatinine (-55.0 ± 22.7 µmol/L, p = 0.02) occurred within a mean period of 15 ± 9 hours after the intervention. The two intervals (primary surgery to increase and intervention to drop of serum creatinine) did not differ significantly (p = 0.31).
Interpretation of results
Due to the close neighborhood of the ureter to the female pelvic organs, many gynecological and obstetric surgical procedures include the risk of ureteral impairment, especially in operations involving invasive cancer and urogynecological procedures, because of direct or indirect damage of the ureter by ligation and transection or tissue distortion leading to kinking and consecutive functional abolishment of the ureteral patency.
Concerning the early detection of postoperative ureteral obstruction, the present study clearly indicates urinary production after surgery to be a fast and reliable parameter. In case of doubt and/or ureteral kinking, intravenous administration of 20 mg furosemide might be considered to provoke adequate diuresis. If this procedure fails, speedy utilization of a conclusive diagnostic method, preferentially CT-IVP, seems to be appropriate, with the result that an unnecessary delay of treatment will be avoided.
Flank pain does not have proven to be specific or constructive. Renal sonography is a sensitive method but does not definitely discriminate between kinking and obstruction of the ureter.
Perioperative monitoring of serum creatinine is a valuable additional screening method of the diagnostic process. A unilateral or bilateral obstruction of the ureter may be assumed if the postoperative increase of serum creatinine exceeds 18 µmol/L = 0.2 mg/dL (3).