Preoperative hemostasis assessment in adenotonsillar surgery: is it really necessary?

INTRODUCTION

Adenoidectomy, tonsillectomy and adenotonsillectomy are among the most frequently performed procedures in otorhinolaryngology. Despite the constant innovation in surgical techniques and the progressive optimization of perioperative care, these procedures are still associated with some complications and considerable morbidity. The most common factors contributing for such morbidity include postoperative pain, nausea and vomiting, difficulties in oral intake, bleeding and dehydration. Postoperative hemorrhage is, by far, the most feared complication, with an estimated incidence between 0.6 and 13% in several reported studies, with those who need major intervention (such as blood transfusion or returning to the operating room) being around 1.2-6%.^1-3 This wide variation described in the literature could be explained by the existence of several definitions and different criteria for identifying and reporting these postoperative complications.¹

The rationale for routine preoperative screening is to identify potential unsuspected hemostatic disorders in otherwise healthy patients, and then, be able to minimize the risk of perioperative complications, by implementing directed medical measures and applying the most appropriate surgical decision.^4,5 The need for this laboratory study has been questioned and debated over the recent years.⁴ The American Academy of Otolaryngology–Head Neck Surgery Current Opinion advises laboratory evaluation only for patients whose family background or medical history suggests a bleeding disorder, or if genetic information about the biologic family is unavailable.⁶ Of course the patient history may be unreliable due to several reasons, or may even be unknown. Because of this, many physicians continue to systematically request preoperative hemostasis assessment, based on the believe that it can detect even a very small percentage of occult bleeding disorders, this way being worth the time and cost to the patients and health care system.⁷

The aim of our study was to clarify the role of preoperative hemostatic assessment in ENT elective surgery, mainly tonsillectomy and adenoidectomy, by reviewing the available literature on the subject.

METHODS

Articles addressing preoperative assessment on adenotonsillar surgery were searched in PubMed® database from its inception through April 2020. The following medical terms were used: “adenoidectomy”, “tonsillectomy”, “adenotonsillectomy”, “preoperative assessment”, “pediatric ENT surgery” or “postoperative bleeding”. A total of 102 articles were selected. Exclusion criteria were the following: clinical case-reports, studies describing exclusively preoperative studies in surgeries other than ear, nose and throat ones, non-human studies, and papers not written in portuguese, english, italian or spanish language.

RESULTS

A total of 25 articles were included after abstract processing: 8 prospective studies (Table 1), 14 retrospective studies (Tables 2 and 3), and 3 systematic reviews and meta-analysis (Table 4).

Prospective studies

From the 8 prospective studies included, 4 of them analyzed only children undergoing adenotonsillar surgery; the other 4 included adult population undergoing tonsillectomy (Table 1). Burk included 1603 children and concluded that coagulation screening tests have high specificity but low sensitivity, thus a low positive predictive value of the bleeding risk.⁸ However, although the low positive predictive value of bleeding risk, they concluded that coagulation tests allow to detect occult hemostatic disturbs, recommending its routine use before this kind of surgical procedure. Kang and Bolger support the same recommendation, arguing that an initially abnormal coagulation profile may identify those more likely to bleed after surgery (22.6% versus 5.5%), as well as the finding about clinical history, which failed to detect any previously unrecognized coagulation disorder, being the preoperative hemostatic screening essential for the detection of occult hemostatic defects, allowing for appropriate alterations in perioperative care.^9,10 On the other hand, some authors recommend selective preoperative hemostatic assessment. Zagolski and Gabriel found that a prolonged aPTT did not statistically correlate with postoperative bleeding rate, in such a way that, in healthy patients, coagulation test results are irrelevant for the course of tonsillectomy and postoperative bleeding.^11,12 Jhonson found no association with post op complications or postoperative admissions, and Close and colleagues found a 2% rate of bleeding in patients with no history and normal screening study.^13,14

Retrospective studies

Reviewing the retrospective reports, it was verified that only 3 reports actually recommended the routine use of preoperative assessment (Tables 2, 3). Two major and recent studies, with an elevated number of patients included, support the selective use of preoperative assessment before adenotonsillar surgery. Yonekura included 13.018 children who underwent adenotonsillar surgery and other pediatric non-cardiac surgeries.¹⁵ It was verified that 1 patient needed postoperative transfusion; 37 patients needed postoperative reoperation for surgical bleeding after tonsillectomy; and finally no statistically significant difference in postoperative reoperation for surgical bleeding was found between patients with or without preoperative coagulation tests. Beloeil studied 312991 children; the incidence of re-operation for bleeding after adenoidectomy and re-admission within 7 days after adenoidectomy and tonsillectomy were very low, and not different between patients with or without preoperative tests.¹⁶ They concluded that standard laboratory coagulation tests and ABO blood typing before surgery and anaesthesia are still performed routinely even in clinical situations in which they are not medically justified.

aPTT – activated partial thromboplastin time; BT – bleeding time; Hb - hemoglobin ; INR – international normalized ratio ; Plt – platelet count; PT - prothrombin time

aPTT – activated partial thromboplastin time;BT – bleeding time; Hb - hemoglobin; INR – international normalized ratio ; Plt – platelet count; PT - prothrombin time..

aPTT - partial thromboplastin time;BT – bleeding time; Hb - ; INR – international normalized ratio ; Plt – platelet count; PT - prothrombin time

aPTT - partial thromboplastin time;BT – bleeding time; Plt – platelet count; PT - prothrombin time

Zwack and colleagues (n= 4374 children) found that laboratory screening has a very low positive predictive value in detecting occult bleeding disorders or perioperative hemorrhage.¹⁷ Perez et al (n=3131) showed that the value of routine preoperative tests to detect clinically unapparent abnormalities in American Society of Anesthesiologists (ASA) I and II patients is very small, providing even further evidence against the practice of preoperative tests in all these patients, and supporting the need rational and selective ordering of preoperative tests, based on clinical assessment.¹⁸

On the other hand, on the study conducted by Myssiorek et al (n=1138), there were 14 patients with abnormally elevated PT/PTT; two of these patients had postoperatively hemorrhage and were, after laboratory studies, diagnosed with von Willebrand’s disease.⁷ Although these results did not achieved statistical significance due to the small number of cases with abnormal coagulation profiles, the authors suggest that PT and aPTT analysis is an excellent screening device for the detection of occult hemostatic defects, and that, when these defects are recognized, a full hematologic workup is warranted to prevent bleeding after surgery. Also Smith (n=91) reported, in their studied population, only four cases with abnormal preoperative coagulation profile; however, out of these patients, one was diagnosed with von Willebrand disease, another one with hyperfibrinogenemia, and two with a transient acquired lupus-like anticoagulant.¹ Although small, this report made the authors to conclude and to show that coagulopathies occur frequently enough to justify preoperative screening, even in the absence of positive clinical and familiar history.

Systematic reviews and meta-analysis

All three systematic reviews and meta-analysis included in this report recommend, based on its results, a selective application of preoperative hemostatic assessment in otherwise healthy patients. However, not all of them stick to the study of adenotonsillar surgery; only Krishna et al performed a meta-analysis to assess the value of preoperative coagulation for patients undergoing tonsillectomy, which involved 3384 prospective studies and 8988 retrospective ones.²⁰ They observed no difference in the rate of post-tonsillectomy bleeding in patients with abnormal or normal coagulation studies, supporting its selective use before surgery.

DISCUSSION

The need for preoperative hemostatic laboratory study before adenotonsillar surgery remains a controversial and very debated subject. Routine preoperative tests for children do warrant a reconsideration of their clinical utility, as they are costly, time consuming and especially stressful and even painful for children.¹⁵ In fact, previous studies have shown that false positive results can lead to delay in surgery, and potentially to costly and harmful incorrect treatments.²¹ Additionally, other studies showed that true abnormalities found in healthy patients did not greatly influence treatment approaches, which supports the lack of requirement for routine testing in healthy patients.⁴ Despite this evidence, some recent studies continue to report over-requesting of preoperative tests, reflecting the lack of clear guidelines or consensus with level 1 evidence concerning preoperative testing, especially in children.¹⁶

The most frequently requested preoperative screening tests include prothrombin time (PT), activated partial thromboplastin time (aPTT), and platelet count (Plt). Here we resume its utility and clinical significance.

Platelet Count (Plt)

Platelet count (Plt) is measured using an automated counter, together with red cell and white cell counts. Thrombocytopenia is defined as a platelet count below 150,000 platelets per mm3, 22 and is a very rare finding, particularly if we consider that we are dealing with apparently healthy children with no bleeding history; several causes may be at the origin of this problem, both congenital or acquired. The most common acquired causes of thrombocytopenia in children are those caused by infection; immune thrombocytopenic purpura can occur in response to a viral infection, and is generally self-limiting, with spontaneous remission, but can have major hemorrhagic repercussions in this context. Iatrogenic causes are usually caused by drugs such as heparin, a cause that is not usually seen in children., and congenital causes are extremely rare. From the congenital causes, von Willebrand disease is the most common disorder, which constitutes a disturbance of platelet function rather than a quantitative problem; it is caused by missing or defective von Willebrand factor (VWF), a clotting protein.²³ It has a variable penetration, so it may not present with a prolonged aPTT, mainly in the mild forms of the disease. Similarly to what happens in patients suffering from thrombotic thrombocytopenic purpura or idiopathic thrombocytopenic purpura, von Willebrand's disease can occur without major clinical manifestations before surgery; these hemostatic disturbances will most likely be detected in a clinical history collection with a hemorrhagic risk questionnaire; a history of bruises in places of difficult trauma, gingival hemorrhage, frequent epistaxis or the presence of petechiae is proven to be more useful in measuring hemorrhagic risk than the laboratory value of platelet count.^11,24

Prothrombin time (PT), activated partial thromboplastin time (aPTT)

Activated partial thromboplastin time (aPTT) is the time needed for prothrombin to be converted to thrombin so a clot can form. The longer this time, the longer the time required for blood clotting. This parameter provides assessment of the intrinsic pathway, as well as the common coagulation pathway (Figure 1).²⁴ APTT is more frequently used to screen for deficits in intrinsic pathway factors, such as factors VIII or IX (found for example in hemophilia patients). It may also be prolonged in deficits of factor XII, pre-kallikrein or high molecular weight kininigen, as well as in the presence of lupus anticoagulant, conditions that do not increase the hemorrhagic risk.²⁵

Prothrombin time (PT) reflects the main coagulation pathway (or ‘extrinsic’ pathway). It is very short (12–13 seconds in normal individuals), and is used to assess the function of factor VII as well as those factors common to the intrinsic pathway (II, V, X, and fibrinogen). An isolated increased PT can only be due to a factor VII deficiency, which is very rare as an inherited deficiency (1 in 500 000 in the general population).^10,25

The International Normalized Ratio (INR) represents the relationship between the patient's prothrombin time and a standard prothrombin time value, reflecting the time required for blood to clot relatively to an average predetermined value. It is useful, for example, to monitor of patients taking vitamin K antagonists (VKA), but has no utility in non-selective preoperative screening.²⁴

It becomes relevant to mention that these described tests are not enough to explore the entire hemostatic system. Some disturbances with potential bleeding risk disrupt neither aPTT nor PT, as in the case of factor XIII or antiplasmin deficiency, for example. Besides, hemostatic function in vivo involves not only the clotting system, but also blood vessels and endothelial cell system, and secondarily the fibrinolytic system.²⁴

The role of hemostasis preoperative assessment in adenotonsillar surgery is still controversial. The present literature on the subject highlights the fact that a normal hemostatic study does not exclude the possibility of hemostatic disease, and that changes in test results are not correlated with the probability of postoperative hemorrhage.²⁶ Besides, international guidelines from American Society of Anesthesiologists, National Institute for Health and Care Excellence (NICE) and French Society of Anesthesiology and Intensive Care, recommend not to obtain baseline laboratory studies in patients without significant systemic disease, as well as to avoid routine preoperative coagulation and ABO blood type screening tests for elective pediatric surgery.^27-29

Unfortunately, despite these recommendations, health care professionals continue to conduct preoperative tests in a systematic and universal manner before adenotonsillar surgery in healthy children. It is observed a regular unnecessary preoperative tests being performed, proving the poor compliance to guidelines by otorhinolaryngologists.²⁸ Several factors justify this behavior, namely the personal experience that does not agree with the data of most studies, the existing reports that represent a divergent position from the guidelines, in addition to the medico-legal pressures that health professionals are subject to in their daily lives, which are increasingly prevalent.³⁰

Concluding, preoperative assessment of bleeding risk in adenotonsillar surgery should be based on patient's clinical history, including personal and family background, and physical examination. By reducing unnecessary testing, several deleterious acts can be avoided, including venopunctures, extra cost, delays in surgery, potential false positive results that may induce anxiety in patients and respective families, and possible harmful effects from incorrect treatment.

CONCLUSION

The role of hemostasis preoperative assessment in adenotonsillar surgery is still controversial. Most studies show that a normal hemostatic study does not exclude the possibility of hemostatic disease, and that changes in test results are not correlated with the probability of postoperative hemorrhage. Besides, international guidelines do not recommend routine preoperative coagulation and blood tests for these elective procedures. Despite the recommendations, most health care professionals continue to conduct preoperative tests in a systematic manner. The authors emphasize the need to discuss the subject and to properly protocol the preoperative approach for these patients, given the fact that existing data are confusing and divergent, in such frequently performed procedures in the otolaryngology field.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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