This postoperative patient's abdominal distension and large amount of intraabdominal fluid is likely due to uroperitoneum (ie, urine within the peritoneal cavity).  In patients who have undergone gynecologic surgery (eg, hysterectomy), particularly those with distorted pelvic anatomy (eg, endometriosis, prior surgery), the most likely cause is from a unilateral ureteral laceration.  The ureter is vulnerable to injury during gynecologic procedures due to its proximity to the ovarian vessels (in the infundibulopelvic/suspensory ligament) and uterine vessels (near the cervix).

• Where the ureter enters the pelvis at the pelvic brim, {{c1::posterior}} to the infundibulopelvic ligament (which contains the ovarian vessels)
• Along the pelvic sidewall as the ureter runs along the {{c3::lateral}} aspect of the uterosacral ligament
• In the cardinal ligament (which contains the uterine vessels) as the ureter dives under the uterine artery ("water under the bridge")
• Along the {{c2::anterolateral}} cervix and vaginal fornix as the ureter enters the bladder

Risk of ureteral injury increases in patients with obesity, distorted pelvic architecture from malignancy (as in this patient), or prior pelvic surgery (eg, cesarean delivery).

Most ureteral injuries are identified during surgery but missed cases can present up to 2 weeks postoperatively as the damaged ureter drains urine directly into the abdomen, resulting in a large volume of intraabdominal fluid and subsequent abdominal distension (eg, diffuse pain, bloating).  As the urine continuously fills the abdomen, it can overflow through the vagina (which is sutured but not fully healed) and cause a watery vaginal discharge.  The caustic effects of the urine may cause signs of peritoneal inflammation (eg, fever, nausea, abdominal pain).  Patients with a unilateral ureteral injury often have regular voiding and normal serum creatinine and urinalysis because the contralateral kidney and ureter continue to function normally.  Diagnosis is typically with CT urography and treatment is surgical repair.

Ureteral injury most commonly occurs due to accidental suturing of the ureter during uterine artery ligation or vaginal cuff closure, which can cause partial or complete ureteral obstruction.  Patients with ureteral obstruction develop hydronephrosis; however, symptoms can be masked initially by postoperative pain medications.  With continued obstruction, patients have nonradiating back pain and costovertebral angle tenderness.  Because only 1 ureter is affected, patients typically have normal renal function (eg, normal creatinine and urinalysis); however, irreversible renal damage can occur if the obstruction is untreated.  Diagnosis can be made by renal ultrasound.  Treatment is surgical correction of the obstruction (eg, suture removal).

• EDUCATIONAL OBJECTIVES
• Ddx