Negative appendectomy rate over 18 years of technological advances

One discussion this week included the rate of negative appendectomy.

Reference: Raja AS, et al. Negative appendectomy rate in the era of CT: an 18-year perspective. Radiology. 2010 Aug;256(2):460-465. doi: 10.1148/radiol.10091570.

Summary: In a retrospective study of records from 1990-2007, researchers from Harvard sought to estimate the correlation between the negative appendectomy rate (NAR) and the rate of preoperative computed tomography (CT) in patients suspected of having acute appendicitis who presented to the emergency department.

The findings showed NAR decreased significantly from 23.0% to 1.7% (P < .0001), the annual number of appendectomies decreased significantly from 217 per year to 119 per year (P = .0003), and the proportion of patients undergoing appendectomy who underwent preoperative CT increased significantly from 1% to 97.5% (P < .0001).

Data from this study also suggest that the use of preoperative CT has been associated with a decrease in the female-to-male NAR ratio from 1.9:1 in 1990 to 0.9:1 in 2007, implying that the use of CT may have been helpful in decreasing the number
of negative appendectomies in women.


(Raja et al, 2010, p.464)

Hyperkalemia: a review of outcomes

One discussion this week included serum potassium levels in the setting of chronic kidney disease (CKD).

Reference: Montford JR, Linas S. How dangerous is hyperkalemia? Journal of the American Society of Nephrology. 2017 Nov; 28(11):3155-3165. doi: 10.1681/ASN.2016121344

Summary: A recent review article by Montford and Linas (2017) summarizes the clinical data linking hyperkalemia with poor outcomes and discusses how the efficacy of certain treatments might depend on the clinical presentation. Below are some points from the section on CKD.

One of the first studies to demonstrate an independent association of hyperkalemia and risk of subsequent death involved a large retrospective study of Japanese patients with advanced CKD presenting for dialysis initiation. An initial serum potassium level >5.5 meq/L at dialysis vintage was the strongest single independent predictor of mortality after an average of 15 years of follow-up. In patients on hemodialysis, potassium levels >5.6 and >5.7 meq/L have been associated with higher mortality. This is also reflected in patients on peritoneal dialysis, with one study suggesting hyperkalemia >5.5 meq/L is associated with a heightened risk of death. Potassium increases during longer intradialytic intervals, and many have attempted to link these fluctuations to the higher incidence of sudden cardiac death in patients with ESRD.

A recently published retrospective observational trial of 52,734 patients on a Monday/Wednesday/Friday hemodialysis schedule revealed that serum potassium levels 5.5–6.0 meq/L were associated with higher risk for subsequent hospitalization, emergency department visits, and mortality within 4 days of measurement.

Management of massive and submassive PE

A discussion this week included the management of massive and submassive pulmonary embolism (PE).

Reference: Aggarwal V, et al. Acute management of pulmonary embolism. American College of Cardiology. 2017 Oct 24.

Summary: The severity of PE is stratified into massive (PE causing hemodynamic compromise), submassive (PE causing right ventricular dysfunction demonstrable by echocardiography, computed tomography or elevated cardiac biomarkers) and non-massive or low-risk (PE without evidence of RV dysfunction or hemodynamic compromise). The International Cooperative Pulmonary Embolism Registry (ICOPER) demonstrated 90-day mortality rates of 58.3% in patients with massive PE versus 15.1% in sub-massive PE.


Anticoagulation therapy is the primary treatment option for most patients with acute PE. The utilization of factor Xa antagonists and direct thrombin inhibitors, collectively termed Novel Oral Anticoagulants (NOACs) are likely to increase as they become incorporated into societal guidelines as first line therapy.

Inferior vena cava filters

The role of inferior vena cava filters (IVCF) in the contemporary management of acute VTE has not been truly defined owing to a paucity of high quality evidence. At present the benefit of IVCF use seems to be in reducing the risk of acute PE in patients who have a clear contraindication to anticoagulation in the form of active bleeding.54,55 In the absence of such a contraindication there appears to be no clear benefit and non-retrieval of IVCF exposes the patient to risk of recurrent VTE, PTS and other mechanical complications such as filter fracture or migration.

Percutaneous Mechanical Thrombectomy (PMT) for Massive and Submassive Acute PE

Several percutaneous approaches have been used alone or in combination in patients with an absolute contraindication to thrombolysis: thrombus fragmentation, aspiration thrombectomy, rheolytic thrombectomy, and suction embolectomy.

Caution must be exercised during the placement of all catheters into the pulmonary arterial circulation. Ensuring proper positioning is vital in order to prevent the risk of catastrophic vessel injury as well as distal embolization of thrombus when using high-pressure injection systems. For this reason, the American College of Cardiology (Aggarwal et al, 2017) advocate the use of available computed tomography to help guide the optimal placement of any drug delivery system. Suction embolectomy devices such as the Greenfield catheter benefit from being large bore catheters capable of achieving thrombus removal without the side effects associated with fragmentation and rheolytic techniques. Despite this, technical difficulties related to catheter size have precluded its widespread adoption.

Ultrasound-Assisted CDT (UA-CDT) for Acute PE

For patients without an absolute contraindication to systemic thrombolysis, UA-CDT can be considered. Low energy ultrasound disaggregates fibrin within acute thrombi, this is exploited by the EKOS device (EkoSonic, Bothell, WA), which combines emission of low energy ultrasound and infusion of a thrombolytic agent via a multi side-hole containing catheter. This strategy has been evaluated in the ULTIMA (Ultrasound-Assisted, Catheter-Directed Thrombolysis for Acute Intermediate-Risk Pulmonary Embolism) trial, which demonstrated superiority to anticoagulation alone in improving hemodynamics without a significant increase in bleeding complications.

IOC vs MRCP for evaluation of the common bile duct during cholecystectomy

One discussion this week included cholangiography (IOC) versus magnetic resonance cholangiopancreatography (MRCP) for the evaluation of the common bile duct during cholecystectomy.

References: Lin C, et al. Initial cholecystectomy with Cholangiography Decreases Length of Stay Compared to Preoperative MRCP or ERCP in the Management of Choledocholithiasis. American Surgery. 2015 July;81(7):726-731.

Sirinek KR, Schwesinger WR. Has intraoperative cholangiography during laparoscopic cholecystectomy become obsolete in the era of preoperative endoscopic retrograde and magnetic resonance cholangiopancreatography? Journal of the American College of Surgeons. 2015 Apr;220(4):522-528.

Summary: There are several treatments available for choledocholithiasis, but the optimal treatment is highly debated.  In a study of 126 patients with suspected choledocholithiasis, Lin et al (2015) found that:

  • 97 patients who underwent initial LC ± IOC had an average LOS of 3.9 days
  • IOC was negative in 47.4% of patients, and they had a shorter LOS compared with positive IOC patients (2.93 vs 4.82, P < 0.001)
  • Laparoscopic common bile duct exploration was successful in 64.7% and had a shorter LOS compared with postoperative ERCP patients (P = 0.01)
  • Preoperative MRCP was performed in 21 patients with an average LOS of 6.48 days
  • Preoperative ERCP was performed in 8 patients with an average LOS of 7 days

In conclusion, initial LC+IOC was associated with a shorter LOS compared to preoperative MRCP or ERCP (Lin et al, 2015).

Additionally, a retrospective analysis of 7,427 patients undergoing laparoscopic cholecystectomy (LC) over 10 years  at a single tertiary care center evaluates the changing practice patterns over time of IOC, MRCP, and ERCP (Sirinek and Schwesinger, 2015).

Despite a shift from IOC and preoperative ERCP to preoperative MRCP alone or with ERCP, a significant percentage (7.6%) of patients still underwent IOC in 2013. Use of IOC during LC has decreased but is not considered obsolete, rather, it remains a valuable tool for the evaluation of bile duct anatomy, bile duct injury, or suspected choledocholithiasis. Intraoperative cholangiography during uncomplicated LC should be emphasized in teaching programs to insure general surgery resident competency with the procedure.

Additional Reading: Badger WR, et al. Utility of MRCP in clinical decision making of suspected choledocholithiasis: An institutional analysis and literature review. American Journal of Surgery. 2017 Aug;214(2):251-255.

Open abdomen: indications and management

One discussion this week included open abdomen (OA) management.

Reference: Coccolini F, et al. The open abdomen in trauma and non-trauma patients: WSES guidelines. World Journal of Emergency Surgery. 2018 Feb 2;13:7. doi:10.1186/s13017-018-0167-4.

Summary: The table below summarizes the guidelines statements, including grades of evidence. Please note, these guidelines are methods for optimal management and are not a standard of practice (p.2).

Indications (p.4):

table2 indications

Closure (p.5):


The Prospective Peri-operative Enoxaparin Cohort Trial (PROSPECT)

Reference: Dunn AS, Spyropoulos AC, Turpie AG. Bridging therapy in patients on long-term oral anticoagulants who require surgery: the Prospective Peri-operative Enoxaparin Cohort Trial (PROSPECT). Journal of Thrombosis and Haemostasis. 2007 Nov;5(11):2211-2218.

Summary: Due to limited data on the incidence of peri-operative thromboemobolic and bleeding during bridge therapy, there is no agreement on optimal peri-operative management of patients on oral anticoagulants (OACs). Dunn et al sought to “examine the incidence of major bleeding of a peri-operative strategy using once-daily therapeutic-dose enoxaparin administered primarily at home, and the effect, if any, of the extensiveness of the procedure on the risk of bleeding during bridge therapy” (p.2211-2212).

The study involved 24 sites in North America between January 2002 and August 2003. The figure below shows the study’s peri-operative management protocol (p.2212): periop mgmt2


Safety outcomes:

  • Incidence of major bleeding while on enoxaparin or in the 24 hours following cessation of enoxaparin treatment
    • Occurred in 3.5% (95% CI: 1.6-6.5)
    • Invasive procedures: 1.4%
    • Minor surgery: 0%
    • Major surgery:  27.5%
  • Rate of minor bleeding while on enoxaparin, or within 24 hours of discontinuation
    • Occurred in 108 patients (41.5%, 95% CI:35.7-47.6)
    • Invasive procedures: 44.6%
    • Minor surgery: 47.2%
    • Major surgery: 20.0%

Efficacy outcomes:

  • Incidence of arterial thromboembolic events for patients with afib
    • 4 events out of 176 patients (2.3%, 95% CI: 0.6-5.7)
    • 2 TIAs, 0 strokes, 2 patients had peripheral arterial thromboembolic events
  • Incidence of venous thromboembolic events for patients with a history of DVT.
    • 1 event out of 96 patients (1.0%, 95% CI: 0.03-5.7)
    • None fatal

Bleeding risk is high when bridging therapy is done peri-operatively in major surgery. In this study, there were 8 instances of major bleeding among 40 total patients in major surgery. Out of 220 invasive procedures or minor surgery, there was only 1 major bleeding event.