Right Lower Quadrant Pain: Platelet Count an Indicator for Laparoscopic Appendectomy?

Christina A Del Pin, MD, FACS, Richard S Feinn, PhD, John Train, MD. Quinnipiac University/Frank H.Netter MD SOM.

Introduction: Right lower quadrant (RLQ) abdominal pain work-up for appendicitis (AP) has evolved from a wholly approach, to a more imaged based one.  Delays in diagnosis due to non-diagnostic imaging, necessitating laparoscopy for critical treatment decisions, urges a revisit to the initial clinical presentation, diagnostic adjuncts and management of RLQ pain.

Methods: A retrospective case control study  was conducted for RLQ pain patients, all of which had underwent appendectomy. Those negative for AP pathologically (NAP)(n=17) were compared to an AP control group (n=34), matched for age, gender, lean body weight,  and were evaluated by logistic regression. NAP group included cases with lymphadenitis, pelvic inflammatory disease, endometriosis, benign appendices(ranging from atrophic, fibrotic , or obliterated,  to dilated or with mucocele) and carcinoid. Variables included laboratories, imaging (ultrasound and computed tomography), OR time (OT) and length of stay (LOS). Laparoscopy was preferred approach (n=47), sensitivity, specificity and predictive values for AP were calculated.

Results: Imaging is most sensitive for appendicitis but the least specific. AP diagnosis in RLQ cases is related to a lower platelet count (plt) (NAP 335K, AP 271k p=0.002), and as well as a lower platelet: white blood cell ratio (plt/wbc) (NAP 31.05, AP 21.18, p=0.002). Using both plt and imaging results in logistic regression, sensitivity and specificity increased (from 79 to 91%, and 69 to 87%, respectively), as well as the predictive values (PV) ( seeTable1). Similarly, imaging and plt/wbc combination showed an increased sensitivity, specificity, PPV, NPV. Plt correlation with LOS was close (r=0.264) (p= 0.061) but not significant for all RLQ pain cases (n=51). Streptococcus+ peritoneal microbiology (n=11) did not affect Plt, OT, LOS. Longer OT was related to longer LOS (r= 0.286, p=0.042).

Table 1.RLQ Pain cases’ Platelet (plt), Platelet:WhiteBlood Cell ratio(plt/wbc) and Imaging(positive for AP) with Sensitivity, Specificity, Predictive Values (PV) for AP
exams Sensitivity(%) Specificity(%) Positive PV(PPV)(%) Negative PV (NPV)(%)

Conclusions:  For RLQ pain cases, clinical laboratories, specifically plt and plt/wbc ratio, coupled with positive imaging, predicts AP more accurately, and warrants appendectomy. Consideration of alternative diagnosis is necessary  with RLQ pain cases having higher plt counts, high plt/WBC ratios and non-diagnostic imaging.  Laparoscopy remains both a diagnostic and treatment adjunct for RLQ pain, and its timely completion predicts shorter hospitalization.


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