Author's personal copy
Herniahttps://doi.org/10.1007/s10029-020-02169-8

ORIGINAL ARTICLE

Continuation of antithrombotic therapy increases minor bleeding
but does not increase the risk other morbidities in open inguinal
hernia repair: A propensity score-matched analysis
S. Poudel1,2 · K. Miyazaki3 · S. Hirano1
Received: 23 December 2019 / Accepted: 2 March 2020
© Springer-Verlag France SAS, part of Springer Nature 2020

Abstract
Purpose An aging population has led to an increased number of patients with cardiovascular comorbidities requiring
antithrombotic therapy. Perioperatively, surgeons should consider the increased risk of bleeding and thrombotic events inpatients continuing or discontinuing these medications. We aimed to analyze the safety of continued antithrombotic therapy
during open inguinal hernia repair.
Methods In this single-center, retrospective study, 4870 adult patients who underwent open inguinal hernia repair surgery
by the same surgeon from 2008 January to 2019 March were included. Patients who underwent surgery while continuing
antithrombotic therapy were included in the antithrombin group (n= 523) while those who were not under any antithrombotic
therapy during the surgery were included in the control group (n= 4333). Using propensity score-matching, we then selectedpatients from each group with similar backgrounds. Surgery time, anesthesia time, postoperative bleeding, reoperation, andthrombotic event data were compared between the groups. Subgroup analysis based on the type of medications used was
performed within the antithrombin group.
Results Ten patients in the antithrombin group and seven patients in the control group experienced postoperative bleeding (p < 0.001). The rate of postoperative bleeding was the highest in patients taking multiple medications. However, mostwere managed conservatively. Three patients from the antithrombin group experienced thrombotic events postoperatively(p = 0.001).
Conclusions Patients receiving continued antithrombotic therapy had an increased risk of minor postoperative bleeding;however, they are a high-risk group for thrombotic events.
Keywords Open inguinal hernia repair · Antithrombotic therapy · Anticoagulation · Antiplatelets

Introduction
Advances in medical science have allowed people to live
longer. Thus, surgeons worldwide now frequently operate
on a population with increasingly advanced age. Elderly
patients are more likely to have cardiovascular comorbidities* K. Miyazaki
kyosukemiyazaki1@me.com
1

Department of Gastroenterological Surgery II, Hokkaido
University Graduate School of Medicine, Sapporo, Japan2

Department of Surgery, Steel Memorial Muroran Hospital,
Muroran, Japan

3

Miyazaki Surgery and Hernia Clinic, Kita 5 Nishi 2,
Chuo-ku, Sapporo, Japanand thus receive antiplatelet therapy and/or anticoagulation
therapy. Antithrombotic therapy involves both antiplatelet
and anticoagulation therapies. Although both antiplatelet
and anticoagulation therapies have diﬀerent mechanismsof action, they are vital to prevent further cardiovascularthrombotic events in high-risk patients; however, they alsopose the risk of hemorrhage [1]. In these patients, surgeons
should decide whether to continue these medications perioperatively, while considering the increased risk of bleeding
and thrombotic events.
Several guidelines have been published in the past decade to aid surgeons in the decision-making process on the
perioperative management of antithrombotic medication[2]. Most guidelines recommend assessing the risk of bleeding and thrombotic events associated with the procedure[2]. In most types of general surgery, whenever possible,

13

Vol.:(0123456789)

Author's personal copy
Herniaantithrombotic medications are typically discontinued for a
fixed period prior to undergoing elective surgery, with heparin bridging in high-risk patients [3]. These antithrombin
medications are restarted after hemostasis is achieved. While
heparin bridging is indicated in patients receiving anticoagulant therapy, it is also used in patients receiving anti-platelet
therapy, despite a lack of evidence for its eﬃcacy [4]. A
recent study of patients undergoing gastric endoscopic submucosal dissection showed an increased rate of thrombosis
in the group discontinuing antithrombotic therapy comparedto that in the group continuing the therapy or using bridging therapy [5]. In recent years, it has been recommended
that these therapies be continued in procedures with a low
risk of bleeding, such as dermatological procedures, cataract
surgery, and polypectomy, especially in patients with a highrisk of thrombotic events [6–8, 8].
A study from the Herniamed Registry, a real-world datarepository, showed that surgeons regularly perform hernia
surgery for patients receiving antithrombic therapy [9].
There is, however, a lack of evidence on the perioperative
management of antithrombotic therapy in inguinal hernia
surgery. Randomized controlled trials in this field are few
and those reported in the literature included a small sample
size. These studies have shown that continuation of antiplatelet therapy through common elective general surgicalprocedures, such as inguinal hernia repair does not lead toincreased bleeding [10, 11]. However, studies on anticoagulant therapy have shown conflicting results [12, 13].
The Miyazaki Surgery and Hernia Clinic is a specialized
center providing ambulatory surgery for inguinal hernia. We
have performed over 7000 inguinal hernia surgeries to date.
In our experience, open inguinal hernia repair has a low
risk of perioperative bleeding if the appropriate precautions
are taken. Since January 2008, our center began performing
open inguinal hernia repair for patients while continuing
antithrombotic medications. Thus, we aimed to analyze thesafety of open inguinal hernia repair in patients continuing
antithrombotic medication.

Patients

Methods

Surgical and anesthetic techniques

Ethical issues

All surgeries were performed by the same surgeon, who
has performed over 7000 open inguinal hernia repair surgeries. The anesthesia method was decided upon based oneach patient’s age and comorbidities. All patients underwent surgery using a local anesthesia solution composedof 20 mL 1% lidocaine with epinephrine, 20 mL 0.25%
bupivacaine, and 80–120 mL normal saline. Epidural
anesthesia was selectively added for surgeries on patients
under 60 years of age and those not taking antithrombotic

This retrospective study was approved by the institutional
review board of Hokkaido University (Med 18-037). The
notice for this retrospective study was published on the website of the institute and the patients were given the rightto opt out. The researcher analyzing the data did not haveaccess to the personal information of the patients. Prior
to surgery, the risk of both continuation or cessation of
antithrombotic medications was explained to all the patients.

13

All adult patients above the age of 20 years who underwent open inguinal hernia repair surgery in our clinic fromJanuary 2008 to March 2019 were included in the study.
Patients who stopped taking antithrombotic medications
before surgery for any reason were excluded from the analysis. Patients who underwent the surgery while continuing
the antithrombotic therapy were labeled the antithrombingroup, and patients who were not under any antithrombotic
medication were deemed the control group. The patientsin the antithrombin groups were further divided into fourgroups for subgroup analysis: patients receiving only asingle medication of low-dose aspirin (aspirin group);
patients receiving multiple antithrombotic medications(multiple medication group); patients receiving a single
medication of antiplatelet medications other than low-dose
aspirin (other antiplatelets group); and patients receiving asingle medication of anticoagulation therapy (anticoagulation group). Prothrombin time international normalized
ratio (PT-INR) was assessed in patients receiving warfarin therapy, and only patients with good warfarin control
with PT-INR below three underwent surgery. Postoperative data, including surgery time, anesthesia time, postoperative bleeding, reoperation, and thrombotic events,
were compared between groups. Postoperative bleeding
was defined as postoperative hematomas or postoperative
bleeding detected at follow-up visit or emergency visit.
Thrombotic events were defined as events of a thrombotic
nature such as myocardial infarction, cerebral infarction,transient ischemic attacks, and deep venous thrombosis
occurring within one week of the surgery. All patients
underwent surgery on an outpatient surgery basis and followed up on postoperative day 7, and again one monthafter surgery. All surgical and postoperative data wereentered by the surgeon in a database. The groin areas of all
the patients with suspected postoperative bleeding eventswere photographed with their consent during the postoperative visit and stored separately.

Author's personal copy
Herniamedication. General anesthesia was administered if the
epidural or local anesthesia was not adequate.
The surgical technique was also tailored according topatient characteristics. High ligation was used in young
patients with small indirect hernias (European Hernia Society classification L1). We selected tension-free mesh repair
for other types of hernia. Primary hernias (L2, L3, M1–3)
were repaired using mainly preperitoneal mesh repair orbilayer mesh repair. If diﬃculty in dissection was expected
due to possible adhesions in the preperitoneal space fromprior surgery, onlay mesh repair or plug repair were selected.
Femoral hernia (F1–3) was repaired using plug repair byfemoral approach. The appropriate mesh was selected inrecurrent hernias based on the extent of dissection of thepreperitoneal space in the primary hernia repair.
To minimize the risk of bleeding, care was taken to minimize blunt dissections in all surgeries. During dissection, a
local anesthesia solution was used to separate the plane ofdissection and cautery was used for dissection. Superficial
epigastric vessels were ligated in all cases.

Statistical analysis
Data are presented as mean (standard deviation). The Student’s t test was used to compare the data between the twogroups. Analysis of variance (ANOVA) test was used tocompare data between multiple groups. The χ2 test andFisher’s exact test were used to compare categorical data.
Propensity score-matching was used to match the background characteristics to reduce selection bias between two
groups. For this analysis, variables such as age, sex, bodymass index, hernia classification, surgical method used,anesthesia method used, primary or recurrent hernia, unilateral or bilateral, and complicated or simple case, werechosen. Complicated cases were defined as the presenceof either cord lipoma, Nuck canal cyst, scrotal hernia, or
strangulated hernia. The cases from the antithrombin groupwere matched with cases in the control group using theTable 1 Medications andmedical conditions of thepatients in antithrombin groupnearest-neighbor algorithm without replacement at the ratioof 1:1 with a matching tolerance of 0.05 to create a matched
control group.
A two-tailed p value of < 0.05 was considered statistically significant in all analyses. Propensity score-matching
was done using MatchIt package (Version: 2.4-21) for R (Rfor Windows version 3.1.0; The R Foundation for Statistical Computing, Vienna, Austria). The rest of the statisticalanalyses were performed using SPSS version 17 (IBM, New
York, USA).

Results
During the study period, inguinal hernia repair was performed in 4870 adult patients. Of these, 537 patients werereceiving some type of antithrombotic therapy. A total of
523 patients underwent open inguinal hernia repair while
continuing their antithrombotic medications. Most patients(83%) were using a single antithrombotic medication, and75.8% of the medications used were antiplatelet therapies
with aspirin being the most common medication, followed
by warfarin and clopidogrel (Table 1). Cerebral infraction,
atrial fibrillation, and coronary artery disease were the mostcommon medical conditions for which antithrombotic therapy was prescribed (Table 1).
Compared to patients in the control group, the patients inthe antithrombin group were older and had higher body massindex. The group also had a higher proportion of men, bilateral cases, and complicated cases, as well as more direct hernias repaired using the preperitoneal mesh repair technique.
No patients in the antithrombin group were given epidural
anesthesia (Table 2). For the patients in the antithrombingroup, except for age, no significant diﬀerence was foundin the background characteristics of the patients in the subgroups (Table 3).
Both surgery time and anesthesia time were comparable in the antithrombin group and control group (Table 4).

Medications(n= 612a)

Medical Conditions(n= 544 a)

Antiplatelet therapy
AspirinClopidogrel
Ticlopidine
Cilostazol
Other antiplatelets
Anticoagulation therapy
Warfarin
Direct oral anti coagulants

464 (75.8%)301 (49.2%)
86 (13.8%)
36 (5.9%)30 (4.9%)
11 (1.8%)
146 (24.2%)
92 (15.0%)
56 (9.2%)

Cerebral infraction
Atrial fibrillation
Coronary artery disease
Other heart condition
Arterial stenosis
OthersUnknown

169 (31.1%)
140 (25.7%)
135 (24.8%)
42 (7.7%)
12 (2.2%)
29 (5.3%)
17 (3.1%)

Data presented as number of patients (%)

aSome patients had multiple conditions and were under multiple medications

13

Author's personal copy
HerniaTable 2 Background of thepatients in both the groups
Age
Sex male
Height (cms)
Weight (kg)
Unilateral cases
Complicated cases
Nuck canal cyst
Cord lipoma
Scrotal hernia
Irreducible hernia
Other
Primary hernia
Hernia type
LateralMedialFemoralCombined
Surgery typeTissue repair
Onlay
Preperitoneal repair
Plug and patch
Bilayer
Anesthesia type
Local
Epidural
GeneralAll data

Matched data

CG (n= 4333) ATG (n= 523) p

mCG (n= 523) ATG (n= 523) p

57.4 (15.8)3553 (82.0%)
165.6 (7.9)
62.3 (10.4)
4281 (98.8%)1184 (27.3)
205 (4.7%)509 (11.7%)
395 (9.1%)
56 (1.6%)
19 (0.4%)
4307 (95.0%)

72.9 (9.8)
484 (92.5%)
163.9 (7.1)
62.0 (9.0)
522 (99.8%)102 (19.5%)
066 (12.6%)
29 (5.5%)
4 (0.8%)3 (0.6%)490 (93.7%)

3264 (75.3%)
851 (19.6%)
101 (2.3%)
117 (2.7%)356 (68.1%)
127 (24.3%)
13 (2.5%)
27 (5.2%)

76 (1.8%)
63 (1.5%)2375 (54.8%)935 (21.6%)
884 (20.4%)

1 (0.2%)25 (4.8%)296 (56.6%)
91 (17.4%)
110 (21.0%)3167 (73.1%)
1084 (25.0%)
82 (1.9%)521 (99.6%)
02 (0.4%)< 0.001* 72.5 (9.7)< 0.001* 488 (93.3%)< 0.001* 163.5 (7.4)
0.48
61.9 (9.0)
0.04* 523 (100%)< 0.001* 93 (17.8%)
051 (9.8%)
33 (6.3%)
7 (1.3%)2 (0.4%)0.2
493 (94.3%)< 0.001*353 (67.5%)
140 (26.8%)
11 (2.1%)
19 (3.6%)< 0.001*1 (0.2%)18 (3.4%)
305 (58.3%)
92 (17.6%)
107 (20.5%)< 0.001*521 (99.6%)
1 (0.2%)1 (0.2%)72.9 (9.8)
484 (92.5%)
163.9 (7.1)
62.0 (9.0)
522 (99.8%)102 (19.5%)
066 (12.6%)
29 (5.5%)
4 (0.8%)3 (0.6%)490 (93.7%)
356 (68.1%)
127 (24.3%)
13 (2.5%)
27 (5.2%)
1 (0.2%)25 (4.8%)296 (56.6%)
91 (17.4%)
110 (21.0%)521 (99.6%)
02 (0.4%)

0.54
0.63
0.35
0.98
1.00
0.53

0.80
0.60

0.86

0.51

Data of presented as mean (standard deviation). Categorical data presented as number of patients (%)
CG Control Group (Patients not under any antithrombotic therapy), ATG Antithrombin group (Patientundergoing surgery while continuing antithrombotic therapy), mCG matched Control Group (Patients fromcontrol group matched with the patients from Antithrombin group)*

Statistically significant diﬀerence with the p value of < 0.05

Additionally, no diﬀerence was seen in the surgery time oranesthesia time between the subgroups of the antithrombingroup (Table 5). Drains were placed due to intraoperative
bleeding in two patients in the antithrombin group and four
patients in the control group (Table 6). Of all patients undergoing surgery during the study period, there were 17 patients(0.35%) with postoperative bleeding. The rate of postoperative hemorrhage was statistically higher in the antithrombingroup compared to the control group (p < 0.001) (Table 6).
Among patients in the antithrombin group, postoperative
bleeding was highest in the multiple medication group(4.7%) followed by the anticoagulation group (3.6%); thisdiﬀerence was statistically significant (p = 0.04) (Table 7).
However, most of these patients presented with wound
hematoma, and only three patients presented with scrotal
hematomas (1 in the control group; 1 in other antiplatelets

13

group; and 1 in anticoagulant group). Most of the bleeding was managed conservatively. Two patients each in the
antithrombin group (1 in multiple medications and 1 inanticoagulation group) and control groups required surgicalintervention to drain hematomas. Three patients had cardiovascular thrombotic events within 1 week of surgery in
the antithrombin group (p = 0.001) (Table 6). These threepatients were receiving single medication of low-dose aspirin (Table 7). There was no diﬀerence between other postoperative events between groups (Table 6).
After propensity score-matching, there were 523 cases
each in the matched control group and antithrombin groups(Fig. 1). No significant diﬀerences were observed between
the backgrounds of both groups after propensity scorematching (Table 2). Both surgery time and anesthesia
time were similar in the groups (Table 4). The prevalenceAuthor's personal copy
HerniaTable 3 Background of thepatients under diﬀerent types ofantithrombotic therapy
Age
Sex male
Height (cms)
Weight (kg)
Unilateral cases
Complicated cases
Nuck canal cyst
Cord lipoma
Scrotal hernia
Irreducible hernia
Primary hernia
Hernia type
LateralMedialFemoralCombined
Surgery typeTissue repair
Onlay
Preperitoneal repair
Plug and patch
Bilayer
Anesthesia type
Local
Epidural
GeneralAsprin only (n= 230)

Multiple medications (n= 85)

Otherantiplatelets(n= 98)

Anticoagup
lants (n= 110)71.8 (10.1)
208 (90.4%)
163.8 (7.4)
61.6 (9.8)
229 (99.6%)
102 (19.5%)
033 (14.3%)
12 (5.2%)
2 (0.9%)215 (93.5%)

75.0 (9.2)
81 (95.3%)
164.5 (6.7)
62.7 (8.3)
85 (100%)
102 (19.5%)
0
11 (12.9%)9 (10.6%)
0 (0.0%)81 (95.3%)

72.0 (9.4)
95 (96.9%)
163.6 (6.3)
61.6 (6.9)
98 (100%)
102 (19.5%)
0
10 (10.2%)
6 (6.1%)1 (1.0%)92 (93.9%)

74.2 (9.8)
100 (90.9%)
164.3 (7.6)
62.4 (9.8)
110 (100%)
102 (19.5%)
0
12 (10.9%)
2 (1.8%)1 (0.9%)102 (92.7%)

159 (69.1%)
59 (25.7%)
4 (1.7%)8 (3.5%)56 (65.9%)
21 (24.7%)
1 (1.2%)7 (8.2%)69 (70.4%)
24 (24.5%)
1 (1.0%)4 (4.1%)72 (65.5%)
23 (20.9%)
7 (6.4%)8 (7.3%)0 (0%)
12 (5.2%)
129 (56.1%)
39 (17.0%)
50 (21.7%)

1 (1.2%)3 (3.5%)55 (64.7%)
10 (11.8%)
16 (18.8%)

0 (0.0%)4 (4.1%)48 (49.0%)
19 (19.4%)
27 (27.6%)

0 (0.0%)6 (5.5%)64 (58.2%)
23 (20.9%)
17 (15.5%)229 (99.6%)
01 (0.4%)84 (98.8%)
0
1 (1.2%)

98 (100%)00 (0.0%)110 (100%)00 (0.0%)

0.02*
0.13
0.78
0.74
0.74
0.17

0.90
0.14

0.29

0.53

Data of presented as mean (standard deviation). Categorical data presented as number of patients (%)*

Statistically significant diﬀerence with the p value of < 0.05

Table 4 Surgical data of thepatients in both the groups inunilateral cases

All data

Surgery time (mins)
Anesthesia time (mins)

Matched data

CG (n= 4281)

ATG (n= 522)PmCG (n= 523)

ATG (n= 522)p

53.7 (12.3)
69.6 (13.1)

54.7 (12.2)
68.5 (12.4)

0.10
0.07

54.4 (13.2)
68.3 (11.3)

54.7 (12.2)
68.5 (12.4)

0.74
0.79

Data presented as mean (standard deviation)
CG Control Group (Patients not under any antithrombotic therapy), ATG Antithrombin group (Patientundergoing surgery while continuing antithrombotic therapy), mCG matched Control Group (Patients from
CG matched with the patients from ATG)

Table 5 Surgical data of thepatients only under aspirin andother antithrombotic therapy in
Unilateral cases

Surgery time (mins)
Anesthesia time (mins)

Asprin only (n= 230)

Multiple medications (n= 85)

Otherantiplatelets(n= 98)

Anticoagulants(n= 110)p54.8 (11.4)
68.8 (11.3)

55.4 (14.6)
68.9 (14.2)

54.4 (12.2)
68.4 (12.7)

54.8 (12.5)
67.9 (13.1)

0.96
0.92

Data presented as mean (standard deviation)

13

Author's personal copy
HerniaTable 6 Postoperative data of the patients in both the groups. Data presented as number of cases (%)
All data

Intraoperative drain placement
Bleeding
Scrotal hematoma
Wound hematoma
Reoperations
Postoperative thrombosis events
Postoperative other events
Drainage of lymphatic fluids
Re-suturing
Admission due to pain
Colon cancer
Asthma attack
Syncope

Matched data

CG (n= 4333)

ATG (n= 523)

4 (0.09%)
7 (0.16%)1 (0.02%)
6 (0.12%)2 (0.05%)
0 (0%)
6 (0.12%)2 (0.02%)
1 (0.05%)
1 (0.02%)0 (0%)
1 (0.02%)
1 (0.02%)2 (0.38%)
10 (1.9%)
2 (0.38%)
8 (1.53%)
2 (0.38%)
3 (0.58%)
1 (0.19%)
0 (0%)
0 (0%)
0 (0%)
1 (0.19%)
0 (0%)
0 (0%)

p0.13< 0.001*

0.06
0.001*
0.55

mCG (n= 523)

ATG (n= 523)p

0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)

2 (0.38%)
10 (1. 9%)
2 (0.38%)
8 (1.53%)
2 (0.38%)
3 (0.58%)
1 (0.19%)
0 (0%)
0 (0%)
0 (0%)1
0 (0%)
0 (0%)

0.25
0.002*

0.25
0.25
1

CG Control Group (Patients not under any antithrombotic therapy), ATG Antithrombin group (Patient undergoing surgery while continuing
antithrombotic therapy), mCG matched Control Group (Patients from CG matched with the patients from ATG)*

Statistically significant diﬀerence with p value of < 0.05

Table 7 Postoperative data of
the patients only under aspirin
and other antithrombotic
therapy

Intraoperative drain placement
Postoperative bleeding
Scrotal hematoma
Wound hematoma
Reoperations
Postoperative thrombosis events
Postoperative other events
Colon cancer

Asprin only
(n= 230)

Multiple medications (n= 85)

Otherantiplatelets(n= 98)

Anticoagup
lants (n= 110)

0 (0%)
1 (0.4%)0 (0%)
1 (0.4%)0 (0%)
3 (1.3%)0 (0%)
0 (0%)

1 (1.2%)4 (4.7%)0 (0%)
4 (4.7%)
1 (1.2%)0 (0%)
0 (0%)
1 (0.34%)

1 (1.0%)1 (1.0%)1 (1.0%)0 (0%)
0 (0%)
0 (0%)
0 (0%)
0 (0%)

0 (0%)
4 (3.6%)
1 (0.9%)3 (2.7%)1 (0.9%)0 (0%)
1 (0.9%)1 (0.9%)

0.29
0.04*

0.36
0.28
0.29

Data presented as number of cases (%)*

Statistically significant diﬀerence with p value of < 0.05

of postoperative bleeding was statistically higher in the
antithrombin group (p = 0.002); however, other complications did not differ significantly in the matched data
(Table 6).

Discussion

Fig. 1 Study protocol

13

In this retrospective study, we demonstrated that while thecontinuation of antithrombotic therapy increased the rateof minor postoperative bleeding, it did not increase the reoperation rate or mortality. Patients taking antithrombotic
medications, especially aspirin, had a higher risk of cardiovascular thrombotic events than those who were not prescribed such medications. To further validate the results,

Author's personal copy
Herniawe performed propensity score-matching to match the background characteristics of patients receiving antithrombotic
medications and those not receiving these medications.
Our data shows that open inguinal hernia repair performed by an experienced surgeon has a low risk for bleeding with an overall hemorrhage rate of 0.35%. The rate of
postoperative hemorrhage was highest (4.7%) in patients taking multiple antithrombotic medications. The rate of hemorrhage was statistically higher in patients in the antithrombingroup compared to those in the control group. Among thepatients receiving antithrombotic therapy, patients in themultiple medication group and anticoagulation group hada higher rate of postoperative hemorrhage compared to thatin the aspirin group and that in the other antiplatelets group.
However, most of these hemorrhages were minor wound
hematomas and were managed conservatively. It should be
noted that only two patients in this series required surgical intervention to remove hematomas. Even in the groupwith the highest rate of reoperation (multiple medicationgroup), only 1.2% of the patient required reoperation. Thesefindings are similar to those of previously reported studies. However, most of these studies had a small sample size
[10, 11, 14, 15]. Few studies have shown increased risk of
postoperative bleeding and hematomas in patients receiving
antithrombotic medication [9, 12, 16]. Among these studies,
the study from the Herniamed Registry reported postoperative bleeding rate and reoperation rate of 3.91% and 2.26%,
respectively, in patients receiving antithrombotic therapy orwith coagulopathy, compared with 1.12% and 1.01% in controls [9]. A study from the Mayo Clinic with a large sample
size reported a hematoma rate of 1.4% and a reoperation
rate of 0.54% [12]. While these studies showed increased
bleeding with antithrombotic therapy, it should be noted thatno studies, including our study have shown life-threatening
complications due to postoperative hemorrhage.
Patients are prescribed antithrombotic medication primarily for prophylactic reasons to prevent thrombotic
events. In our study, despite patients continuing their medications through surgery, three patients (0.6%) developed
thromboembolic events. This number was significantly
higher than that in patients not on the medication, making them a high-risk group. However, studies on hernia
repair have rarely reported postoperative cardiovascular
events. In the report by Ong et al. [15], two patients (2.4%)
who discontinued aspirin perioperatively and one patient(1.7%) who continued aspirin developed cardiovascularthrombotic events. However, the study was not adequately
powered due to the small sample size and thus could not
determine a statistical significance between the occurrenceof thrombotic events in these patients. Data from otherprocedures have shown an increase in thrombotic eventsin patients discontinuing antithrombotic medications [5].
A recent national level population-based cohort study from

Sweden found that discontinuing aspirin, the most common drug in our study, increased the risk of cardiovascular
events by 37%, and most events occurred within 2 weeks
of ceasing the medication use [17]. Data from other studies show similar results with short-term discontinuation of
antiplatelet therapy and anticoagulant medications, including direct oral anticoagulants [18–20].
In summary, our data and evidence suggest that, while
continuing antithrombotic therapy, especially in thosereceiving multiple medications and anticoagulation therapy, there is an increased risk of bleeding or hematoma
after hernia surgery. However, the bleeding or hematoma
is usually minor and can be managed conservatively.
Conversely, the risk of thromboembolic events increased
with temporary cessation. Our data also indicated thatpatients receiving antithrombotic therapy had a higher
risk of thromboembolic events. We also need to consider
that while postoperative hematomas and bleeding in open
inguinal hernia repair is rarely life threatening, thromboembolic events can be fatal or result in severe disability[21]. Thus, despite the increased incidence of postoperative bleeding, we consider that it is justified to continue
antithrombotic medication perioperatively in open hernia
repair surgery as this decreases the risk of thromboembolic
events.
This study has several limitations. First, it is a singlecenter study, and all surgeries were performed by one highly
experienced surgeon. The results might not be applicable toall surgeons and centers. However, meticulous dissection
using local anesthesia solution, and electrocautery, which
are the basic principles of surgery, were used to achieve ourresults. With attention to dissection in the correct plane andby minimizing bleeding in all surgeries, we feel that similar results can be achieved in any setting. The study is also
limited by its retrospective nature; it remains possible that
unknown confounding factors exist. Although we tried tominimize this using propensity score-matching to match thebackground characteristics of the two groups, all the confounding factors may not have been addressed. To truly test
this hypothesis, a properly powered randomized controlled
trial between the group continuing antithrombotic medications and the group ceasing the medications prior to surgery
is needed. However, a randomized controlled trial may be
unethical if we consider our data. Even while continuing the
medications, the patients receiving antithrombotic medication had a higher risk of thromboembolic events, throughthere was no increase in the risk of severe complications.
Although a single center study, this study boasts of a large
sample size and included almost all cases of patients receiving antithrombotic medications over a period of 11 years.
We feel justified to continue oﬀering this therapy to ourpatients even without the evidence from a randomized controlled trial.

13

Author's personal copy
HerniaConclusion
Patients receiving antithrombotic therapy have a high risk ofthrombotic events. Our study showed that, while the risk of
postoperative bleeding increased with antithrombotic therapy except aspirin, all types of open inguinal hernia repair
surgeries can be safely performed continuing this therapy.
Acknowledgements Dr. Kyosuke Miyazaki is an advisor to BARD.
Funding None.

Compliance with ethical standards
Conflict of interest All authors declare that they have no conflict ofinterest.
Ethical approval This retrospective study was approved by the institutional review board of Hokkaido University (Med 18-037). The noticefor this retrospective study was published on the website of the instituteand the patients were given the right to opt out.
Human and animal rights Animals were not used in this study.
Informed consent Prior to surgery, the risk of both continuation or cessation of antithrombotic medications was explained to all the patients.

References
1. Yeung LYY, Sarani B, Weinberg JA, McBeth PB, May AK(2016) Surgeon’s guide to anticoagulant and antiplatelet medications part two: antiplatelet agents and perioperative management of long-term anticoagulation. Trauma Surg Acute Care
Open 1(1):e000022. https://doi.org/10.1136/tsaco-2016-000022
2. Douketis JD, Spyropoulos AC, Spencer FA, Mayr M, Jaﬀer AK,
Eckman MH, Dunn AS, Kunz R (2012) Perioperative management of antithrombotic therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 141(2Suppl):e326S–e350S. https://doi.org/10.1378/chest.11-2298
3. van Veen JJ, Makris M (2015) Management of peri-operative
anti-thrombotic therapy. Anaesthesia 70(Suppl 1):58–67. https://doi.org/10.1111/anae.12900e21-53
4. Capodanno D, Musumeci G, Lettieri C, Limbruno U, Senni
M, Guagliumi G, Valsecchi O, Angiolillo DJ, Rossini R(2015) Impact of bridging with perioperative low-molecularweight heparin on cardiac and bleeding outcomes of stented
patients undergoing non-cardiac surgery. Thromb Haemostasis
114(2):423–431. https://doi.org/10.1160/th14-12-1057
5. Igarashi K, Takizawa K, Kakushima N, Tanaka M, Kawata N,
Yoshida M, Ito S, Imai K, Hotta K, Ishiwatari H, Matsubayashi
H, Ono H (2017) Should antithrombotic therapy be stopped inpatients undergoing gastric endoscopic submucosal dissection?
Surg Endosc 31(4):1746–1753. https://doi.org/10.1007/s0046
4-016-5167-4
6. Palamaras I, Semkova K (2015) Perioperative management ofand recommendations for antithrombotic medications in dermatological surgery. Br J Dermatol 172(3):597–605. https ://doi.
org/10.1111/bjd.13362

13

7. Chen G, Barkmeier AJ (2014) Perioperative management ofantithrombotic medications in vitreoretinal surgery. Int Ophthalmol Clin 54(2):199–213. https://doi.org/10.1097/iio.00000
00000000024
8. Dezsi CA, Dezsi BB, Dezsi AD (2017) Management of dental patients receiving antiplatelet therapy or chronic oral anticoagulation: a review of the latest evidence. Eur J Gen Pract23(1):196–201. https://doi.org/10.1080/13814788.2017.13506
45
9. Kockerling F, Roessing C, Adolf D, Schug-Pass C, Jacob D(2016) Has endoscopic (TEP, TAPP) or open inguinal hernia
repair a higher risk of bleeding in patients with coagulopathy
or antithrombotic therapy? Data from the Herniamed Registry.
Surg Endosc 30(5):2073–2081. https://doi.org/10.1007/s0046
4-015-4456-7
10. Chu EW, Chernoguz A, Divino CM (2016) The evaluation ofclopidogrel use in perioperative general surgery patients: a prospective randomized controlled trial. Am J Surg 211(6):1019–
1025. https://doi.org/10.1016/j.amjsurg.2015.05.036
11. Antolovic D, Rakow A, Contin P, Ulrich A, Rahbari NN,
Buchler MW, Weitz J, Koch M (2012) A randomised controlled pilot trial to evaluate and optimize the use of antiplatelet agents in the perioperative management in patients
undergoing general and abdominal surgery—the APAP trial(ISRCTN45810007). Langenbeck’s Arch Surg 397(2):297–306.
https://doi.org/10.1007/s00423-011-0867-7
12. Zeb MH, Pandian TK, El Khatib MM, Naik ND, Chandra
A, Morris DS, Smoot RL, Farley DR (2016) Risk factors
for postoperative hematoma after inguinal hernia repair: an
update. J Surg Res 205(1):33–37. https ://doi.org/10.1016/j.
jss.2016.06.002
13. Sanders DL, Shahid MK, Ahlijah B, Raitt JE, Kingsnorth AN(2008) Inguinal hernia repair in the anticoagulated patient:a retrospective analysis. Hernia 12(6):589–592. https ://doi.
org/10.1007/s10029-008-0405-xdiscussion 667-588
14. Ho CH, Wu CC, Wu CC, Tsai YC (2018) Laparoscopic total
extraperitoneal inguinal hernia repair is safe and feasible inpatients with continuation of antithrombotics. J Minim Access
Surg. https://doi.org/10.4103/jmas.JMAS_128_18
15. Ong W, Shen T, Tan WB, Lomanto D (2016) Is preoperative
withdrawal of aspirin necessary in patients undergoing elective
inguinal hernia repair? Surg Endosc 30(12):5542–5549. https://doi.org/10.1007/s00464-016-4926-6
16. McLemore EC, Harold KL, Cha SS, Johnson DJ, Fowl RJ(2006) The safety of open inguinal herniorraphy in patients onchronic warfarin therapy. Am J Surg 192(6):860–864. https://doi.org/10.1016/j.amjsurg.2006.08.058
17. Sundstrom J, Hedberg J, Thuresson M, Aarskog P, Johannesen
KM, Oldgren J (2017) Low-dose aspirin discontinuation andrisk of cardiovascular events: a Swedish Nationwide, population-based cohort study. Circulation 136(13):1183–1192. https://doi.org/10.1161/circulationaha.117.028321
18. Vene N, Mavri A, Gubensek M, Tratar G, Vizintin Cuderman T,
Pohar Perme M, Blinc A (2016) Risk of thromboembolic eventsin patients with non-valvular atrial fibrillation after dabigatranor rivaroxaban discontinuation—data from the ljubljana registry. PLoS ONE 11(6):e0156943. https://doi.org/10.1371/journal.pone.0156943
19. Garcia DA, Regan S, Henault LE, Upadhyay A, Baker J, Othman
M, Hylek EM (2008) Risk of thromboembolism with short-term
interruption of warfarin therapy. Arch Intern Med 168(1):63–
69. https://doi.org/10.1001/archinternmed.2007.23
20. Eisenberg MJ, Richard PR, Libersan D, Filion KB (2009) Safetyof short-term discontinuation of antiplatelet therapy in patientswith drug-eluting stents. Circulation 119(12):1634–1642. https://doi.org/10.1161/circulationaha.108.813667

Author's personal copy
Hernia
21. Mashour GA, Shanks AM, Kheterpal S (2011) Perioperative
stroke and associated mortality after noncardiac, nonneurologic surgery. Anesthesiology 114(6):1289–1296. https ://doi.
org/10.1097/ALN.0b013e318216e7f4

Publisher’s Note Springer Nature remains neutral with regard tojurisdictional claims in published maps and institutional aﬃliations.

13