Routine Diagnostic Paracentesis for Ascites
Washington University Emergency Medicine Journal Club – October 21st, 2021
You’re working a busy, bustling shift in EM1 on a Monday afternoon when you encounter Mr. S, a 55-year-old male with a history of NASH cirrhosis who has been placed in room 10. Mr. S reports increasing abdominal distension since his last therapeutic paracentesis one month ago as well as new hypokalemia found on labs drawn last Friday. His potassium at that time was 2.6. He denies any associated abdominal pain, fevers, or confusion. He has been compliant with all of his meds, which include spironolactone, furosemide, and lactulose. His vital signs on arrival are:
HR 101 BP 100/64 Temp 36.7 SpO2 96% on room air
His abdomen is moderately distended with a fluid wave and no tenderness, rebound, or guarding. After reviewing the chart, you order a new set of labs, which reveal a K of 2.5, INR of 1.6, platelet count of 98. After discussion with your attending (and given how busy the ED is), you order IV and PO potassium chloride and decide to admit the patient to medicine for a GI consult and a therapeutic paracentesis.
The admitting medicine team calls back and asks if you can perform the therapeutic paracentesis in the ED. After explaining that you simply don’t have the time for a non-emergent procedure, they ask that you at least perform a diagnostic paracentesis to rule-out spontaneous bacterial peritonitis (SBP). You tell them that the patient has no fevers, chills, or abdominal pain, but they assure you that the guidelines still recommend a diagnostic paracentesis for all patients admitted to the hospital with cirrhosis and ascites (AASLD, British Society of Gastroenterology), even in the absence of clear signs of spontaneous bacterial peritonitis (SBP). You perform the paracentesis and admit the patient, but wonder if the evidence really backs up these recommendations…
Population: Adult patients being admitted to the hospital with ascites and cirrhosis
without symptoms of SBP
Intervention: Routine diagnostic paracentesis with cell count and differential
Comparison: No diagnostic paracentesis
Outcome: Diagnosis of SBP, mortality, acute renal failure, sepsis, bacteremia
Article 1: Chinnock B, Afarian H, Minnigan H, Butler J, Hendey GW. Physician clinical
impression does not rule out spontaneous bacterial peritonitis in patients
undergoing emergency department paracentesis. Ann Emerg Med. 2008 Sep;52(3):
268-73. Answer Key
Article 2: Jesudian A, Barraza L, Steel P, et al. Quality improvement initiative
increases total paracentesis and early paracentesis rates in hospitalised cirrhotics
with ascites. Frontline Gastroenterol. 2020 Jan;11(1):22-27. Answer Key
Article 3: Alotaibi A, Almaghrabi M, Ahmed O, et al. Incidence of spontaneous
bacterial peritonitis among asymptomatic cirrhosis patients undergoing outpatient
paracentesis: a systematic review and meta-analysis. Eur J Gastroenterol Hepatol.
2021 Aug 23. Answer Key
Article 4: Orman ES, Hayashi PH, Bataller R, Barritt AS 4th. Paracentesis is
associated with reduced mortality in patients hospitalized with cirrhosis and ascites.
Clin Gastroenterol Hepatol. 2014 Mar;12(3):496-503.e1. Answer Key
Spontaneous bacterial peritonitis (SBP) is a common complication of cirrhosis and ascites, with a prevalence of around 10-30% among hospitalized patients (Oladimeji 2013). In addition to this high prevalence among inpatients, SBP is also associated with a high mortality rate of around 20%, leading several guidelines to recommend that all patients hospitalized with cirrhosis and ascites undergo paracentesis to evaluate for SBP (AASLD, British Society of Gastroenterology). Given the documented association between delayed paracentesis and in-hospital mortality (Kim 2014), it may be prudent for the emergency physician to consider performing a diagnostic paracentesis on these patients, particularly when admission is delayed by boarding.
The benefits of paracentesis have been demonstrated in two large, observational studies (Orman 2014, Gaetano 2016). Both studies utilized the Nationwide (National) Inpatient Sample to identify patients admitted to the hospital with ascites. Mortality rates were compared between those who did and did not undergo a paracentesis. In the earlier study, following multivariate analysis performance of paracentesis was associated with decreased in-hospital mortality, with an odds ratio (OR) of 0.55 (95% CI 0.41 to 0.74). A trend toward increased mortality was seen when paracentesis was delayed by more than 24 hours (OR 1.26, 95% CI 0.78 to 2.02), but this did not achieve statistical significance. The latter study also found a higher mortality among those who did not undergo paracentesis, with an adjusted OR of 1.83 (95% CI 1.66 to 2.02).
A systematic review and meta-analysis found that the prevalence of SBP (based on an ANC > 250 cells/mm3 among patients undergoing outpatient large volume paracentesis was only around 2% (95% CI 1-3%). It should be noted that patients in the admitted studies were entirely asymptomatic, and the prevalence among ED patients is likely much higher. A prior ED study has confirmed that patient characteristics and physician assessment have poor sensitivity, specificity, and likelihood ratios for the diagnosis of SBP. Clinician impression was associated with positive and negative likelihood ratios of 1.16 (95% CI 0.95 to 1.43) and 0.69 (95% CI 0.37 to 1.29). While these numbers were slightly better when considering attending physicians only, the associated negative likelihood ratio of 0.38 suggests that clinician assessment alone is insufficient to exclude the diagnosis of SBP in the vast majority of patients with ascites. While this study was limited by spectrum bias (only patients in whom a paracentesis was planned and fluid was to be sent for analysis), the poor test characteristics would likely change very little if a broader selection of patients was considered.
Initiatives aimed at improving rates of ED rates of diagnostic paracentesis have been undertaken. A before and after study conducted in the ED of New York-Presbyterian Hospital-Weill Cornell Medical Center found that following an extensive quality improvement initiative, the proportion of appropriate patients undergoing paracentesis at any time during admission improved from 71% to 91%, while the proportion of patients undergoing paracentesis within 12 hours improved from 30% to 57%. Unfortunately, given the small sample size this study was underpowered to detect an improvement in mortality, although a strong trend was observed RR 0.6 (95% CI 0.22 to 1.6).
Given the high mortality rate observed with SBP and the poor test characteristics associated with physician assessment, guidelines recommend routine diagnostic paracentesis in all patients admitted to the hospital with cirrhosis and ascites. Considering the strong association between delayed diagnosis and mortality, strong consideration should be given toward early diagnostic paracentesis in the ED for these patients.