Risk of Ureteral Injury During Cesarean Delivery
Ureteral injury during cesarean delivery is rare, occurring in approximately 0.06% (6 per 10,000) of all cesarean sections, though this risk increases substantially in high-risk scenarios such as placenta accreta spectrum (PAS) where rates can reach 12.8% when combined with bladder injury. 1
Overall Incidence
The baseline risk of ureteral injury during routine cesarean delivery is quite low:
- 0.06% (6 per 10,000) in general cesarean population 1
- 0.107% (approximately 1 per 1,000) when including all urinary tract injuries requiring secondary surgery 2
For context, bladder injuries are more common at 0.08% (8 per 10,000) cesarean deliveries 1.
High-Risk Scenarios: Placenta Accreta Spectrum
The risk profile changes dramatically in PAS cases requiring cesarean hysterectomy:
- Ureteral injury: 12.8% of PAS cases 3
- Notably, all patients with ureteral injuries also had concurrent bladder injuries 3
- Overall urologic injury (bladder or ureter): 26.7% in PAS deliveries 3
- A systematic review of PAS cases found that uterus-preserving techniques and methotrexate use were associated with 16% urinary tract injury rates versus 57% for standard hysterectomy 4
Specific Risk Factors for Ureteral Injury in PAS
Three independent predictors significantly increase risk 3:
- Anterior placentation (OR 2.96)
- Percreta on antenatal ultrasound (OR 2.59)
- >2 pre-delivery vaginal bleeding episodes (OR 4.27)
The cumulative risk is striking: patients with zero risk factors have 11.1% injury rate, while those with all three risk factors have 71.4% injury rate 3.
Central placenta previa is the strongest independent predictor (aOR 4.08) on ultrasound imaging 5.
Risk Factors in Non-PAS Cesarean Deliveries
For routine cesarean sections, ureteral injury risk increases with 1, 6:
- Emergency cesarean during second stage of labor (most common scenario for ureteral injury)
- Extension of uterine incision (frequently accompanies ureteral injury)
- Previous cesarean delivery with abdominal adhesions
- Increasing maternal age
- Active second stage of labor
Importantly, most ureteral injuries (55%) in routine cesarean are diagnosed postoperatively, compared to bladder injuries which are typically identified intraoperatively 1.
Clinical Implications
Diagnosis Timing
- Bladder injuries: 100% diagnosed intraoperatively 1
- Ureteral injuries: 55% diagnosed postoperatively 1
Common Presentations
- Left ureter is most commonly injured (83% of cases) 2
- Postoperative symptoms include continuous urinary leakage, acute abdominal distention, and fluid accumulation 2
Management Outcomes
When recognized and repaired appropriately:
- No long-term adverse effects reported in follow-up studies 1
- Normal kidney function maintained in all cases with proper management 1
- Delayed repair (when renal function not compromised) can be acceptable for ureterouterine fistulae 2
Prevention Strategies in High-Risk Cases
For PAS deliveries, the 2019 BJOG guidelines recommend 4:
- Prophylactic ureteral stent placement reduces urologic injury risk (though no RCTs exist)
- Approximately 26% of US practitioners use prophylactic stents in suspected PAS
- Preoperative cystoscopy when bladder invasion suspected
- Delivery at specialized centers with urologic support immediately available
The key to minimizing morbidity is high index of suspicion, early recognition, and immediate repair when injury occurs 1, 7.