What is the appropriate management of ureteral stones in a patient during the third trimester of pregnancy?

Management of Ureteral Stones in Third Trimester Pregnancy

For pregnant women with ureteral stones in the third trimester, initial management should be observation with trial of passage if symptoms are well-controlled, but ureteroscopy (URS) should be offered as definitive treatment when conservative management fails or symptoms are intractable. 1

Diagnostic Approach

Ultrasound is the mandatory first-line imaging modality 2, though it has limited sensitivity (45%) for ureteral stones 2. When ultrasound results are equivocal and clinical suspicion remains high:

• Low-dose CT should be used as the last-line option 2
• MRI serves as the second-line imaging choice 2
• Avoid routine radiography (KUB) due to radiation exposure

Initial Management Strategy

Conservative Management (First-Line)

Observation with trial of passage should be offered when symptoms are well-controlled 1. However, counsel patients that:

• Stone passage rates are only 40-60% during pregnancy 1
• Mean time to passage is 17-35 days 1
• Delayed intervention may ultimately be required 1

Medical expulsive therapy with tamsulosin has not demonstrated significant benefit in promoting stone passage during pregnancy 1, though it appears safe for mother and fetus.

Pain Management

• NSAIDs are contraindicated in the third trimester due to risk of premature ductus arteriosus closure
• Use opioids (hydromorphine, pentazocine, or tramadol preferred over pethidine) 2
• Acetaminophen as adjunct

Indications for Intervention

Proceed to surgical intervention when:

• Persistent pain unresponsive to conservative management 1, 3
• Intractable symptoms 1
• Signs of infection/sepsis 2
• Progressive hydronephrosis 3
• Uterine contractions 4
• Obstruction of solitary kidney 2

Surgical Management Options

Ureteroscopy (Preferred Definitive Treatment)

URS is safe and effective during pregnancy with no increased endoscopic complications compared to non-pregnant patients 1. The evidence strongly supports this approach:

• Stone-free rates exceed 94% across all series 5
• Success rates of 100% reported in multiple studies 3, 4
• Obstetric complication risk is 4.3% (preterm labor), consistent with non-urologic surgery during pregnancy 1
• Can be performed with rigid 7.0F or 9.5F ureteroscopes without ureteral dilation 6
• Holmium laser or pneumatic lithotripsy are safe energy sources 3, 4

Key technical considerations:

• Coordinate with obstetrics team per ACOG recommendations 1
• Use only ultrasound guidance for double-J stent placement (avoid fluoroscopy) 6
• Neuroleptic analgesia often sufficient; general anesthesia not always required 6
• Most stones in pregnancy are distal ureteral (58.8-79%) 3, 4

Temporary Drainage (Alternative)

Ureteral stent or percutaneous nephrostomy may be offered as temporizing measures 1, particularly when:

• Patient declines definitive treatment
• Stone cannot be reached during URS
• Immediate symptom relief needed before definitive treatment

Important caveats:

• Requires frequent exchanges (typically every 6 weeks) 7
• Most patients ultimately require post-delivery intervention 5
• Stent-related symptoms (bladder irritation) common 3
• Primary URS is more efficient than temporary drainage followed by delayed treatment 5

Emergency Management

For sepsis and/or anuria with obstruction, urgent decompression via nephrostomy or ureteral stent is mandatory 2. In this scenario:

• Obtain urine cultures before and after decompression 2
• Start empiric antibiotics immediately 2
• Delay definitive stone treatment until sepsis resolves 2

Common Pitfalls to Avoid

• Do not delay medically necessary surgery - ACOG states surgery should not be denied regardless of trimester 1
• Do not use NSAIDs in third trimester - risk of premature ductus arteriosus closure
• Do not routinely use fluoroscopy - ultrasound guidance is sufficient for stent placement 6
• Do not assume conservative management will succeed - only 40-60% passage rate 1
• Do not choose temporary drainage as definitive management - most require subsequent intervention 5

The evidence consistently demonstrates that URS is both safe and more efficient than temporizing measures, making it the preferred approach when intervention is indicated 1, 5.