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On-Table (Single-Shot) IVP

The on-table (intraoperative) IVP — also called a single-shot IVP or one-shot IVP — is a rapid, portable intravenous pyelogram performed during emergency laparotomy, primarily to confirm the presence and function of a contralateral kidney before proceeding with nephrectomy in hemodynamically unstable patients who did not undergo preoperative CT imaging.[1][2] While IVP was historically the cornerstone of urologic imaging, its role has been almost entirely supplanted by CT — except in this narrow but critical intraoperative scenario.[3][4]

Part I: Historical context — the rise and fall of IVP​

The IVP era (1930s–1990s)​

Intravenous urography (IVU / IVP) was introduced into clinical practice in the early 1930s and remained the primary imaging technique for investigation of urinary-system disorders for over 60 years.[4][5] It was the reference standard for evaluating urolithiasis (sensitivity 75–87%, specificity 92–94%),[6] hematuria workup, obstructive uropathy, congenital anomalies, renal masses / cysts / tumors, ureteral pathology and fistulas, and pre-endourological planning.[4][7][8]

The CT revolution​

CT urography (CTU) has now replaced IVP for virtually all elective urologic indications.[9][10][11] Key advantages of CT over IVP:

  • Superior sensitivity for renal masses, small tumors, and calculi.
  • Cross-sectional imaging eliminates overlying bowel-gas artifact.
  • Multiphasic imaging (arterial, nephrographic, excretory) provides comprehensive evaluation.
  • IVP-like reconstructions can be generated from CT data.
  • For urolithiasis: noncontrast CT sensitivity / specificity 85–96% / 98–100% vs. IVP 75–87% / 92–94%.[6]

The ACR Appropriateness Criteria now state that IVU is no longer used as a first-line imaging modality for evaluation of hematuria, stone disease, or any elective urologic condition.[6][11]

Remaining niche indications for elective IVP​

Dalla Palma identified a few settings where IVP remains useful:[4]

  • Congenital anomalies of the urinary tract (duplex systems, ectopic ureters).
  • Prior to endourological procedures (providing a "roadmap").
  • Evaluation of possible fistulas.
  • Renal-transplant evaluation.
  • Genitourinary tuberculosis.
  • Ureteral pathology requiring visualization of the entire collecting system and papillae / calyces.

Part II: The on-table / single-shot IVP in trauma​

Definition and purpose​

The on-table IVP is a rapid, portable intraoperative study performed during emergency laparotomy when a renal injury is discovered and preoperative CT imaging was not obtained. Its primary purpose is to confirm the presence and function of the contralateral kidney before proceeding with nephrectomy — not to stage the injured kidney.[1][3][2]

Guideline recommendations​

The ACS Best Practices Guidelines (2025) provide the most current and specific guidance:[1]

  • Prior to exploring an injured kidney (especially without preoperative CT), palpate the contralateral kidney.
  • If the contralateral kidney is present and feels normal to palpation, exploration of the injured side can proceed.
  • If the contralateral kidney is absent or abnormal (polycystic, atrophic), give more consideration to renal salvage.
  • A single-shot, on-table IV pyelogram can be considered in this setting, primarily to confirm a functioning contralateral kidney.
  • Do not use it to exclude injury or to identify urinary extravasation alone, as it lacks sufficient sensitivity for these purposes.

The WSES-AAST Guidelines (2019) similarly state that IVU may be useful in unstable patients during surgery when a kidney injury is found intraoperatively or when CT scanning is not available and a urinary-tract injury is suspected (GoR 2C).[3]

The ACS Best Practices Guidelines on Imaging (2018) further specify:[2]

  • An intraoperative single-shot IVP may be used to confirm a contralateral functioning kidney if the patient is taken directly to the OR without CT and is found to require a nephrectomy.
  • Consider IVP in emergent situations if CT imaging is not available.
  • If GU-tract injury is suspected and CT is not available, consider transfer to a higher level of care.

Part III: Technique — the single-shot IVP protocol​

Standard protocol​

The technique is standardized and straightforward:[1][12]

  1. Contrast dose — 2 mL/kg of IV iodinated contrast material, administered as a rapid bolus through a peripheral or central IV line.
  2. Timing — a single abdominal radiograph (AP KUB) is obtained 10 minutes after contrast injection.
  3. Equipment — a portable X-ray machine is brought into the operating room; the cassette is placed beneath the patient on the OR table.
  4. Interpretation — the study is interpreted immediately by the operating surgeon and / or urologist at the bedside.

Practical considerations​

  • The contrast bolus should be given as a rapid push (not a slow drip) to maximize renal opacification.
  • The 10-minute delay allows contrast to be filtered by the kidneys and opacify the collecting systems.
  • A single film is obtained (hence "single-shot") — this is not a multi-film IVP series.
  • The cassette must be positioned to include both renal fossae to evaluate the contralateral kidney.
  • Adequate patient positioning may be challenging in the setting of an open abdomen with packs and retractors.

Contrast agents​

Any standard iodinated contrast agent can be used. FDA-approved agents for excretory urography:[13][14][15]

  • Iodixanol (Visipaque) — 270 or 320 mg I/mL; standard excretory-urography dose 1 mL/kg (adults), 1–2 mL/kg (pediatric); maximum 2 mL/kg IV.
  • Iopromide (Ultravist) — 300 mg I/mL; 1–2 mL/kg for excretory urography.
  • Diatrizoate meglumine — higher-osmolality ionic agent; historically used but less common now.

For the on-table IVP, the 2 mL/kg dose (as specified by ACS) represents a high-dose bolus designed to maximize opacification in trauma-related hypoperfusion and hemodynamic instability.[12]

Part IV: The landmark study — Morey et al. (1999)​

The definitive study evaluating the quality and utility of the single-shot intraoperative IVP is by Morey, McAninch, et al. from San Francisco General Hospital:[12]

  • 50 patients (1990–1997) underwent single-shot intraoperative IVP for staging renal injuries when clinical instability and / or major associated injuries mandated an intraoperative study.
  • Contrast material (2 mL/kg) was injected IV and images obtained at 10 minutes.
  • Study quality — average score 3.84/5 (generally good).
  • Clinical usefulness — average score 3.96/5 (generally useful for determining urological treatment).
  • In 16 patients (32%), intraoperative IVP findings safely obviated renal exploration.
  • No contrast reactions were noted.
  • No complications attributable to intraoperative IVP.

The authors concluded that intraoperative single-shot, high-dose IVP is safe, efficient, and of high quality in the majority of cases when performed as recommended, and provides important information that facilitates rapid and accurate decision-making.[12]

Part V: Critical limitations — what the on-table IVP cannot do​

1. High false-negative rate for injury staging​

The IVU false-negative rate for renal injury ranges between 37 and 75%.[3] The ACS explicitly states: do not use imaging to exclude injury or to identify urinary extravasation alone, as it lacks sufficient sensitivity in this setting.[1]

2. Cannot reliably detect ureteral injuries​

IVU is an unreliable test for ureteral injury, with false-negative rates up to 60%.[3] The ACS Best Practices Guidelines state that intraoperative single-shot IV pyelography cannot reliably exclude ureteral injuries and should not be used solely for this purpose.[1] For suspected ureteral injury, direct inspection of the ureter during laparotomy remains the gold standard, supplemented by IV injection of renally excreted dye (indigo carmine or methylene blue).[3][1]

3. Cannot adequately stage renal-injury severity​

The on-table IVP cannot reliably differentiate between AAST grades of renal injury, identify vascular injuries, or detect contained vascular injuries (pseudoaneurysms, arteriovenous fistulas) that predict the need for intervention.[1][3]

4. Image-quality limitations​

Several factors degrade image quality in the trauma setting:

  • Hemodynamic instability reduces renal perfusion and contrast excretion.
  • Overlying bowel gas, blood, and surgical instruments obscure anatomy.
  • Patient positioning is suboptimal on the OR table.
  • Single-film technique provides limited anatomic information compared with a multi-film IVP series or CT.

5. Cannot evaluate for bladder injury​

The on-table IVP does not provide adequate bladder distension for evaluation of bladder rupture. Retrograde cystography (conventional or CT) is the diagnostic procedure of choice for bladder injuries.[3]

Part VI: What the on-table IVP can do​

Despite its limitations, the on-table IVP provides critical information in specific scenarios:

Information providedClinical utilityReliability
Contralateral kidney presenceConfirms a functioning opposite kidney exists before nephrectomyHigh — the primary indication
Contralateral kidney functionDemonstrates contrast excretion, confirming functional renal parenchymaModerate — may be impaired by hypotension
Bilateral renal functionIdentifies bilateral injury or solitary kidneyHigh clinical value
Gross collecting-system disruptionMay identify major UPJ avulsion or massive extravasationLow sensitivity — cannot exclude injury
Renal agenesis or ectopiaIdentifies congenital absence or ectopic kidneyHigh — critical before nephrectomy
[1][2][3][4]

Part VII: Decision algorithm — when to use the on-table IVP​

The decision to perform an on-table IVP follows a specific clinical algorithm during trauma laparotomy:[1][2]

Step 1. Zone II retroperitoneal hematoma identified during laparotomy → suspect renal injury.

Step 2. Was preoperative CT imaging obtained?

  • Yes → CT already demonstrates bilateral renal anatomy and function; on-table IVP is not needed.
  • No → proceed to Step 3.

Step 3. Palpate the contralateral kidney.

  • Normal contralateral kidney palpated → exploration of the injured side can proceed; on-table IVP is optional (may still be performed for documentation).
  • Contralateral kidney absent, abnormal, or cannot be assessed → perform on-table IVP to confirm contralateral function before considering nephrectomy.

Step 4. Interpret the IVP.

  • Bilateral functioning kidneys → proceed with exploration / nephrectomy as indicated.
  • Absent or non-functioning contralateral kidney → maximize renal-salvage efforts on the injured side (renorrhaphy, partial nephrectomy, vascular repair).
  • Non-diagnostic study → consider palpation alone; if nephrectomy is life-saving, proceed with clinical judgment.

Part VIII: Alternatives to the on-table IVP​

  1. Contralateral kidney palpation — the simplest and fastest method. The ACS guidelines state that if the contralateral kidney is present and feels normal to palpation, exploration can proceed without imaging.[1] This is the most commonly used method in practice.
  2. Intraoperative ultrasound — can confirm the presence of a contralateral kidney but does not assess function. Not widely used for this purpose in trauma.
  3. IV dye injection (indigo carmine / methylene blue) — for suspected ureteral injury, IV injection of renally excreted dye allows direct visualization of ureteral integrity during laparotomy. The dye is seen exiting the ureteral orifice or leaking from a ureteral laceration. More reliable than IVP for ureteral-injury detection.[3][1]
  4. Intraoperative CT (rare) — some hybrid OR suites have intraoperative CT capability, but this is not widely available and is impractical during damage-control laparotomy.
  5. Postoperative CT — if the patient survives the initial operation and is stabilized, a postoperative CT with delayed phase can be obtained to fully evaluate the urinary tract. This is the preferred approach when the clinical situation allows.[1][3]

Part IX: The on-table IVP in non-trauma surgery​

While the trauma setting is the most common indication, the on-table IVP has historical utility in other surgical contexts:

  • Intraoperative confirmation of ureteral integrity during complex pelvic surgery (though IV indigo carmine with cystoscopic visualization of ureteral jets has largely replaced this).
  • Confirmation of renal function before planned nephrectomy in oncologic surgery when preoperative imaging is incomplete.
  • Low-resource settings where CT is unavailable — IVP remains a viable diagnostic tool for renal colic, hematuria, and obstructive uropathy.[3][4]

Part X: CT vs. IVP — comparative performance​

ParameterCT (with delayed phase)On-table IVP
Renal-injury detectionGold standard (sensitivity ~93–100%)False-negative rate 37–75%
Injury gradingAccurate AAST grading; identifies vascular injury, contrast blush, hematoma sizeCannot reliably grade injuries
Ureteral-injury detectionSensitivity 93%, specificity 100% (with delayed phase)False-negative rate up to 60%
Bladder-injury detectionCT cystography: sensitivity 95–100%Not applicable (inadequate bladder filling)
Contralateral kidney functionExcellentGood — primary strength of on-table IVP
Collecting-system extravasationExcellent (delayed phase)Poor sensitivity
Availability in ORRequires hybrid OR or patient transportPortable X-ray at bedside
Time to result15–30 min (including transport)10 min (contrast injection to film)
Hemodynamic stability requiredYes (for transport)No (performed at bedside)
[1][2][3][4]

Summary — key principles​

  1. CT with delayed phase is the gold standard for all urologic trauma imaging in hemodynamically stable or stabilized patients.[3][1]
  2. The on-table IVP is reserved for hemodynamically unstable patients taken directly to the OR without preoperative CT who are found to have a renal injury requiring potential nephrectomy.[1][2]
  3. The primary purpose is to confirm a functioning contralateral kidney — not to stage the injured kidney or exclude ureteral injury.[1]
  4. Technique — 2 mL/kg IV contrast bolus → single AP KUB at 10 minutes.[1][12]
  5. The IVP has a high false-negative rate (37–75% for renal injury, up to 60% for ureteral injury) and should never be used to exclude injury.[1][3]
  6. Palpation of the contralateral kidney is the simplest alternative and is often sufficient to proceed with exploration.[1]
  7. For suspected ureteral injury during laparotomy, direct inspection with IV dye injection (indigo carmine / methylene blue) is more reliable than IVP.[3][1]
  8. In elective urology, IVP has been almost entirely replaced by CT urography for all indications including hematuria, urolithiasis, and tumor evaluation.[4][9][11]

Cross-references​

References​

1. Johnsen N, Wessells H, Archer-Arroyo K, et al. Best Practices Guidelines: Management of Genitourinary Injuries. American College of Surgeons; 2025.

2. Tominaga GT, Bernstein M, Aquino MR, et al. Best Practices Guidelines in Imaging. American College of Surgeons; 2018.

3. Coccolini F, Moore EE, Kluger Y, et al. "Kidney and uro-trauma: WSES-AAST guidelines." World J Emerg Surg. 2019;14:54. doi:10.1186/s13017-019-0274-x

4. Dalla Palma L. "What is left of i.v. urography?" Eur Radiol. 2001;11(6):931–939. doi:10.1007/s003300000801

5. Elkin M. "Stages in the growth of uroradiology." Radiology. 1990;175(2):297–306. doi:10.1148/radiology.175.2.2183276

6. Gupta RT, Kalisz K, Khatri G, et al. "ACR Appropriateness Criteria® acute onset flank pain — suspicion of stone disease (urolithiasis)." J Am Coll Radiol. 2023;20(11S):S315–S328. doi:10.1016/j.jacr.2023.08.020

7. National Library of Medicine (MedlinePlus). Intravenous pyelogram (IVP).

8. Bell EG, McAfee JG, Makhuli ZN. "Medical imaging of renal diseases — suggested indication for different modalities." Semin Nucl Med. 1981;11(2):105–127. doi:10.1016/s0001-2998(81)80041-4

9. Silverman SG, Leyendecker JR, Amis ES. "What is the current role of CT urography and MR urography in the evaluation of the urinary tract?" Radiology. 2009;250(2):309–323. doi:10.1148/radiol.2502080534

10. Choyke PL. "Radiologic evaluation of hematuria: guidelines from the American College of Radiology's Appropriateness Criteria." Am Fam Physician. 2008;78(3):347–352.

11. Wolfman DJ, Marko J, Nikolaidis P, et al. "ACR Appropriateness Criteria® hematuria." J Am Coll Radiol. 2020;17(5S):S138–S147. doi:10.1016/j.jacr.2020.01.028

12. Morey AF, McAninch JW, Tiller BK, Duckett CP, Carroll PR. "Single shot intraoperative excretory urography for the immediate evaluation of renal trauma." J Urol. 1999;161(4):1088–1092.

13. Food and Drug Administration. Visipaque. Updated 2025-10-17.

14. Food and Drug Administration. Iodixanol. Updated 2023-07-21.

15. Food and Drug Administration. Ultravist. Updated 2026-03-02.