Review Question - QID 107165

This patient has unilateral hydronephrosis following a difficult pelvic surgery, which is most likely due to intraoperative ureter injury.

Hydronephrosis results from increased fluid volume in the kidney secondary to obstruction. As a result of increased hydrostatic pressure, renal damage subsequently occurs. Hydronephrosis can be caused by an obstruction anywhere along the urinary tract. Common causes include kidney stones, prostate hyperplasia, cervical cancer, retroperitoneal fibrosis, and congenital malformation (in children). However, in patients who recently underwent surgery, particularly pelvic surgeries, intraoperative ureter injury is an important consideration.

Morey reviews the obstetric and gynecological (OB/GYN) causes of ureter injury. Ureter injury is unfortunately common in OB/GYN surgical procedures due to the intimate anatomical relationship between the ureters and the uterine vessels. Injuries to the ureter or bladder affect nearly 1% of major gynecologic surgeries, with the majority of these cases being hysterectomy. Predisposing factors include poor visualization because of large pelvic masses, hemorrhage, or pregnant uterus, as well as conditions that distort the native anatomy, such as intrapelvic malignancies or prior pelvic surgeries.

Meirow et al. reported a series of 21 iatrogenic ureteral injuries during OB/GYN operations for non-malignant indications. The authors found that 9 of the ureters were transected intraoperatively, while 12 were injured via post-surgical obstruction. Only two cases of ureteral injury were discovered intraoperatively, with the remainder requiring subsequent corrective procedures.

Figure A shows hydronephrosis. Note the enlarged appearance of the renal pelvis. Illustration A shows the anatomical relationship between the ureter and uterine vessels.

Incorrect Answers:
Answer 1: Urease producing bacteria, such as Proteus, can cause struvite stones, which are large renal stones than can often be seen in the renal pelvis. Struvite stones involving the renal pelvis are staghorn calculi, which can be confused for hydronephrosis on ultrasound. However, these would appear hyperechoic rather than hypoechoic (such as with hydronephrosis).

Answer 2: Posterior urethral valves is a cause of hydronephrosis in male newborns.

Answers 4-5: Bladder malignancy and renal cell carcinoma can cause hydronephrosis, but this patient has no risk factors or signs suggestive of these malignancies.